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_ PATHOLOGICAL
PLANT ANATOMY

‘DR. ERNST KUSTER

"Lecturer in Botany i in the University at Halle A. s.

RSTn:

Authorized Translation by Frances Dortance ~

WITH ‘121 ILLUSTRATIONS IN ‘THE TEXT

PATHOLOGICAL PLANT ANATOMY
By
Dr. Ernst Kuster
Lecturer in Botany in the University at Halle a, 5,

Authorized Translation by Frances Dorranoe

With 121 Illustrations in the Toxt

/ TRANSLATOR'S NOTE
It is with the deepest gratitude that the translator ack-
nowledges the inestimable assistance ef Professors Jones and
Humphrey of the University of Wisconsin and their students,
Messrs, Yampolsky and Drechsler, who have criticized the man-
uscript as to technical rendition and general form,

December 1913

Preface

A few years ago in my "Contributions on the Anatomy of
Galis", I pointed out the fact, that in judging abnormal plant
tissues, not only a compnrison of normal and abnormal forms is
of great importance but also a comparison of the abnormal with
one another, and I mentioned at the time a few abnormal phenbmena,
which seemed especially to demand a compar&tive consideration.

It is intended to give in the present book, a detailed com-
paretive treatment of abnormal plant tissues, I have regarded
it as my province to describe briefly their life-history and his-
tology, to study the causes of their production, and to compare
them one with another on a basis of ontogenetic, histoiogical
and etiological data. I take the liberty herewith of laying the
result of these considerations, before the botanical world as
the outline of a Pathological Plant Anatomy.

Immediately after my removal from Munich to Halle a, S., I
began the necessary experiments in the Botanical Institute here.
With great liberality its director, Professor Kiebs, placed the
abundant resources of the laboratory and the garden at my dis-
posal. For the many favors, by means of which Professor Klebs
was always ready to support me in my work, and for much vaiuable
stimulation, I am heartily grateful to my esteemed chief. I owe
also, sincere thanks to my publisher, Dr. Fischer in Jena, for
his courteous consideration of ail my wishes and for the excellent
manner in which he has gotten up the book,

Finajiy I wish to thank the many friends and fellow botan-
ists who have assisted me in my work by sending me experimental
matter and literature.

Halle a. S&S, Botanical Institute of the University
January 1903
E, Kust er

TABLE OF CONTENTS A

Su TROpUE TION bee tee tere Gi oat Gtareratae Sie paar eet eters meu
CHAPTER I

marerotrel Perera went eer Met tenecat ne Gana pA Adead sw seoas tahoe 6

1. Restitution of the cell eee See et ree rere a 8

Cedi ememprane.; 3.5 «sk os cies eae wee a RE eRe ee ee ere 8

POL. SOONCe ne yisraee sree tere ee eke ee seeaeee. eo

Be MOSCLTUTLON Of the tiSeuce ., ccas icc daweeedbeaeeaeen. 2

CHAPTER II

HIPOPLASIA cosas laws Goa teh eb aaa Ree Peete Awe eee. ee
A. Number of celis’ ee ee ee tr rere eee er ery 18
EPamie? C1SSU66 3 62nd ears bois TREES Ae
SOCCndary TASSNbS oo cee ecce sak noche seeseneeeeeean Ae

Be AAG OL Cle: COLTS uaa ds wy kewnae Krenn bau ee
C. Differentiation of the cells ant tissues ........... 26
i, Formation Of Ene COLL ,c:saccsccignesvstewsscun 26
FOrmM OF the C61] gcc eee wes se anak “a: orem Gpakaapeeene “Ou
Col = MeMDrRNG .4.c04 cae che PERE RR RSE SHES EOE eee Cel
Cell-contents ..... eRe Een Cod
2. Differentiation ef the CLeSte 4k Sicuweeeeeween COL
Epidermis, mesophyll ...... Lani aee sees 41
Conducting and mechanical tissues VEhenekeaueeen “Se

CHAPTER JZ
METAPLASIA Cr ees eoweaneore ent nee ee ena 54
alge Content. of the cell oordboeoseervreowmoevewnrsevereotstvneavee Bee Gov ee 55
B, CGlL membrane 54... sss eee tenes eaearnanssaeowertwe: OF

CHAPTER IV
— HYPERTROPHY oo pt eee meee ee eee eee Pe ee ee a ee ee ee en ee ee ee ee B3
Un lesn Cnses eacaty 1a len a gee ee ene n eae ee ee 67
2. Tissues of etiolated plants 46@se seein teeressees SCZ
Ss Byperhydric GisSves .ccs ks dae ecw ne Pe Oe ee ee ee;
&, Lenticels and bark excrescences ,........4-+-: eae lee
BD, Imtumescences 4.4 cuales dectedee see Gteeasnunsecax OO
6. Abnormal succulence ... cere ese cucve Ste aeepess OG
4, Callus-hypertrophy 1... - cee eec cence cn veer sscvces keae “BF
Axes Pe eee eee ae a eueonvnveve oe hoover e 88
: LEAVES . ice r eee ChENGK POR EEDE CRRA EM SR ES er re ae

ee DVIOSOS gaa ens wne oaces Waetatecled aiae abe eae acRae aware se
TVIONSS AN -GUGUS wicnivaenusetokanonee tees teeagewsee (Oe
Tyloses in secretion reservoirs and resin ducts .. 99
Tyloses in stomatal cavities ...cseesaceuee tiara ao
6; Call -hyportvophies 4 <.j.45 240+ seer sageer cece vavenaxe 20)
Bo MOMIORMLE 5 cucu nedee ona COs eeRee Ss eeeeE ase LOL
- Synshitriun galls ingle a [eps dadous ee teeeein- abe
Erineum structures co... cece cece ee teecerees LOS

B. Ground tissue ..cessceces ei s4 es ess sow e sees ee Os

Root- HEB ocak nae ea nee ea eer anew sent es 112
Fungus-hyphae eesevreneeraeee manera eeseneoonee see rae eee nro 113
SAGHONOSS. 4. ace sssaseds sane gene? ey ee er re ee
Delia PUDOS 4.004.054 uce ea eeeeoe setulae dawned eee te
invoiution forms of bacteria BCs sae eo ee eee CO
¥, Multinucloar giant cells ........05. ee Fowreue. de

CHAPTER V
a HYPERPLASIA eoeos-eowrvovraesanvnevveeesaeanvreteh ore eee e eer ee es eee Coe Se 122
A. Homoeoplastic tissue .......---04. ; ee er ee ee Lee
1. uocelized tissue excrescences of “homoeoplastic
: GCHBFACTEY c¢.6<4 s4a-0s Serre e eC r T Tee Re ee
II, Abnormal development ‘of individual tissue forms 126
1, Activity-homoeoplasia ......... eee rer er i:
2, Correlation-homoeoplasia .....,.ccee cree . 134
3, Callus~homoeoplasia ..,........ (oar ewes pe eo

. Page
By Heteroplastic t4 TISBUOS sede cas Mie ee eee ee Ser Ce er ee 136
~ Ly Cox coe on by ber opie one Soe dette tect tenmaihe cagaine 137
* ae Callus ee es aoe esos ereevene eunse L3S
External form of the callus Bilin ices te doen erga caeieg. Lae
Origin. OF Uke CaliMe 92 os wiwadaae ecm une aee 142
Life history ef the callus ..,.e scene pecacesees 143
Histology of the callus ,..........4. Spade paeaien Ge
Conditions of callus formation etree nem eeeunee 150
Formation of organs in callus bon ($48 so eeaedeene: Loe
3, Wound-wood ,,, ee roe ae ee eer ree an 156
Histological composition ‘and course of fibres.
dr MOUNAHWEOd. cs Nae vee becw oe pu ee T eT eee ere ee
Tissues furnishing wound-wood ,.,..,...... 162
Cuter form and period of development of wound—,
wood, Conditions of its formation .,,....,.-+. 163
Tissues resembling vound-woo0d ... cece cece eee .. 164
4, Wound-oork rea Pate trovanerenvereose neon se ee ne eee neee eos 167
5. Galls Pee veo artoaewe re eo ero dernerterer ee rev an een aeoeenee 170
* iy RERRDLOSIGS, bei cada de nneed way an ene ee eee eee s 176
dee Primary tissues Gob BRS ea Ww eae we ew eae oS 180
£5 Seoondary TASEUOS .. serene Te ere 182
Abnormal wood igeoate hierniana wou eres 183
HonOrmal Bore p00. esas seksi va waea was oes 8S ge 38S
Witehes-brooms and. staghend Grreoueeneueet oe
De PROSGDIOGMES ay caidee ewecueees s Sa bee eS 189
1. External forn and sourse of development
Qf, PrOSOPLASMAS ...... ees eee ev eeouse ee
:. Weal fold Galle ..ccvceas ere
2. BAG P0218 a c2andset wena es ferro 192
Be WALLER GALLS oc. .csaucne sr eweew ean 193
4. ‘Medullary A118 ....... eee reeeeene 195
iL. BA ptelenioay (vaven Chere ees apie rae nw age ee
« Protective tissues ......... ease 205
BPpidermal tissues ......,..00.-6-4 205
Mechanical tissues ....... cwame?s se 208
A. Nobritive issues 41.4. ccnse cases 218
- Nutritive epidermis ....,....... se BLE
Nutgitive parenchyma ..... ie eee eae SED
3, Assimilatory CIGSUGS .a.5c85 en gees O28
_, 4 Vasoylar tissues f....... eoees caacg SLO
5. Aerating tissues ,........-. 00. cy ee
6, Secretious and secretion reservoir 220
APPENDIX ...,..... eT Sate cen men . 223
Oytology ,.... cope eee sd OER eM ae aa ORES
Phenomens ef degeneration ee ee ee 225
Miero-chemical CONGICION ju vawedeaciu 226
CHAPTER VI
— GENERAL OBSERVATIONS ON THE ETIOLOGY AND DEVELOPMENT OF PATH+
OL@GICAL PLANT TISSUES, DISCUSSIONS OF GENERAL PATHOLOGY.
DEORE Oe MUTE fae ade ant oe ea ch eae cae Uenlecee a wren eee
A, Concerning the active factors..................-. sway 230
, anfluence of mechanical pressure and strain. 235
2; TOMPOTALUEC ccs cnc cccceccaccanscectecsersnccese e236
&,. Daght.... aes ae ae near eo 237
4. Chemical substances, jk Ree G icasare panmewee eee
Trophic effects, sig eee: i hale Rie Wl esessraanee iaeaea BOO
Toxic effects, eeotowoteeoee ee @apaeheeoe@ee eevee we Po BD 240
é, Turgor, osmotic pressure and diffusion-durrents. 241
B, On reaction to stimuli.......... eer ee rs rreces 243
1, Size of the cells ..........., nanos rei Rca Hi 247
&. Porm of the cells ....... ienigeivess naka Lee
3, Internal structure of the cells ......... ccgaere 2220
a. On, the sapacity for reaction....... neon se foe ceegae COs
» p or Sade % eee eee PSE E DSR RGronees “He T2
2, Ground tissue....... Rages ee Nie Cone oa wee Oe
3. Vasablnar, bundle tissue. A ph tba Bee Silanes jas < 257

6

Figure 1.
(5, 12)

Pigure 2,
(p. 14)

Figure 3 e
(p. 17)

Figure 4,
(p. 19)

Figure 5.
(p. 23)

Figure 6.
(p. 26)

Figure 7.
(p. 27)

Figure 8,
(pe 29)

Figure 9,
(pe 32).

Figure 10.
(De 42} *

4ygnema filament.

iY.
LIST OF ILLUSTRATIONS.

Urtica dicica.

Truncated hair with regen-
ated tip.

(Original).

aa Plasmolysed cells, In
both cells sptfrally twisted bodies,
(After Kkebs).

Marchantia rhizoids growing through other

truncated ones. One of the parenchyma
eelis lying ag the base of the trichome

is growing out into a compensatory hair.
(a). In b a second, outgrowth. (After Kny).

zea Mays. Half of a cross-section through

' @ root, which had regenerated after spiit-
ting. The cells of the epidermis and ©xo~
dermis are considerably smaller on the
Side regenerated (the lower side in the
figure) than on the original upper surface.
(After Lopriore), “

Fagus silvatica. Oross-sections through
leaves exposed to varying amounts of light.

A, leaf grown in medium intensity. B. typ-
ical sun~leaf, C, typical shade-leaf, p,
palisade pazenchyma, sch. spongy parenchyma.
1, intercellular spaces. (After Stahl, from
Hertwig., "Zelle und Gewebe").

Erigeron canadensis. A, cross-section through
a normal stem with richly developed second~
ary wood. B, sross-section through the
stem of a greatly dwarfed specimen; the
secondary tissues are lacking. p. primary
tissues (xylem and phloem), s. secondary
tissues { of the same), sk, Sclerenchyma.
(After Gauchery).

Euastrum verrucosum. Cells grown in sugar
solution; a, abnormally formed individual;
b, dwarf example, (After Klebs).

Ficus stipulata, A, part of a cross-section

through a sumleaf; b, through a shade-
Leaf, (After Stahl) ry

Pinus austriaca. Cross-section through a

Lunularia.

needle; a, grown in the usual exposure

to light (interbupted light); b, in con-
tinuous exposure to electric light. (After
Bonnier),

At the left, cross-section

rough a noymally developed thallus (After
Nestler, Naturl Pflanzenfam, Bd. I, 3, p 17)
at the right, cross-section through a spec-
imen grown with insufficient light. (After
Beauverie) .

Figure ll.
“(pe 47)

Figure 12.
(De 51)

Figure 13,
(pe 63)

Figure 14.
(ne 70)

Pigure 15.
(. 71).

Figure 16.
(De 73).

Figure 17.
(pe 75)

Figure 18,
(p. 80).

Pigure 19,
(De 80)

Figure 20.
(pe 84).

Figure 21.
(pe 85)

Ve

Cardamine pratensis. Crossesections of
Leaves, a, terrestial form; b, aquatic
form, (After Schenck).

Ranunculus fluitans, Cross-sectibns through
ge a, of the aquatic forn,
(magnif. 90); b, of the terrestrial
(magnif. 60). (After Schenck).

Lunvlaria, Irregular thickening of the walls
in the rootehairs, At the left, sphaefoe
crystalloid thickenings. AT the righ
conical and bearelike forms. (AftéT Lan-
mermayr) .

Spirogyra. Diagrams of multicellular cells.
Below, a cell containing 8 nuclei, but
with incomplete formation of cross walls.
(After vy. Wisselingh).

Bacterium Pasteurianum, Development; trans-
ormation of short Glubs to long threads

when grown on double=beer agar 40.5 de~
grees C, a, chain of 8 short clubs after
6, and after 20 hours (a' a" a"'); b,
chain of 5 short clubs after 5 and 9 hours
(b? and b"); 6 and d, after 10 and after
21 hours respectively. (After Hansen, from
Lafar "Techn, Mykologie").

Solanum tuberestm. Hypertrophied guard cells.
(After Stapf).

Prunus spinosa. Some celis from a lenticel
excrescence, (After Devaux).

Ribes aureum. Cutting. The upper part
Shows strong outgrowths and broad rifts
in the bark, (Original)

Ribes aureum. Oross=section thpough part
Of greatly hypertrophied bark. Above,
cork, (K), below, bark cells grown out
into long pouches (H); the immature
periderm elements have also been enlarged
greatly by stretching. (Original).

Cassia tomentosa. Cross-sections through
part of a leaf, The cells of the upper-
most mesophyll layer have swollen up to
an "intumescence” and have split the
epidermis. (After Sorauer).

Ficus elastica. Intumescence of the leaf.
The cells of the uppermost layer of
mesophyll have elongated and pressed the
epidermal cells together. Only the up=
per half of the leaf is dram. (Original)

Pigure 22.
(pe 86)

Figure 23,
(p. 88)

Pigure 24,
(p. 92)

Figure 25.
(De 94)

Figure 26.
(p. 95)

Figure 27.
(pe 96)

pi fane 28.

Pigure 29.
(p. 99)

Figure 30.
(p. 99)

Figure 31.
(De 100)

Figure 32.
(pe 100)

Figure 33.
(p. 106)

Figure 34.
(p. 106)

VI.

Hibiscus vitifolius. Intumescence of the
leat. The celis of the upper epidermis
heve been greatly enlarged, s. S. stomato.
(After Dale).

Conocéphalus ovatus,

(After
Haberlandt).

Intumescence.,

Padina Pavonia. Callus hynertrophies on

pieces of thallus, (Original)

Cattleya, Cross-section through the edge
of yound on leaf. The exposed, have
grovm out into large pouches. (Original)

Cattleya. Single cell of the wound shown in
the preceding figure, more highly magni-
fied. The cell-wall is thickened in meshes.
(Original).

fradescantia virginica. Callusehypertrophy
of the epidermal cells. (After Miehe),.

Cross=section through a stalk, which lateral
pressure has split longitudinally in four
places. (f f f' f') (Diagram, after Massart)

Canna indica. Annular duct in longitudinal
Section. The wood parenchyma cell at the
left is forming two tyloses. (After Molisch)

Musa Ensete. Spiral duct in longitudinal
section. The wood parenchyma cells at the
left have grown out to one or more tyloses
of unequal size. (After Molisch).

Robinia Pseuda-acacia. Pitted duct in cross=
section. Numerous parenchyma cells have
grown out to tyloses., In @ =a may be seen
the connection of the tyloses with their
mother cells. (after Strasburger ,"Lehrbuch")

Mesvilodaphne Sassafras. Cross-section
through old vood. The undermosnt duct con~
tains only one stone=tylosis, the upper
ones contain, besides stone-tyloses, also
relatively thin-walled ones, (After Molisch

Nradescantia varidis. Obstructed stomata of

@ foliage leat, The epidermal cells next
the guard cells have formed vesicular
outgrowths on the under side, (After Haber~
Landt).

Pilea elegans. Obstructed stomatum of the
upperside of the leaf. The mesophyll cells
have grown into the inner cavity, (After
Haberlandt.)

Pigure 35,
+(Bi 108]

Figure 36.
(p. 109)

Figure 37.
(p. 112)

Figure 38.
({p» 113)

Figure 39.
(p. 114)

Figure 40,
fp. 114)

Figure 41.
(p. 118)

Pigure 42,
(p. 118)

Figure 43.
(p. 119)

Figure 44.
(p. 121)

Figure 45,
(p. 121)

Figure 46.
(p. 122)

Figure 47,
(p. 124)

a hee tpn He Me Tages time Lowe tape nee now

Vil.

a Draba aizoides, cross=section of a leaf.

The epidermat celis are infected by Syn-
chtrium Drabae (After Lidi)+, b, Myosovis
epidermal cells grown out like hairs, in-
fected oy Synchtrium Myosotidis. (After

Schréter

a, Synchytrium Anemones, all epidermal cells,

Bear nex, the nitritive cell, have be=

come eniarged. b, Synchytrium Drabae,

By division, a wart has been produced,

on the apex of which lies the large nu-
, tritive cell, (After Ludi)

Stipa pennata. a, Piece of a blade infected
by Tarsonemus, b, some epidermal cells
more highly magnified. (After Massalongo).

Tillia., Cross-section through a leaf of the
inden, bearing Erineum. The epidermal
cells, on both sides, have grown out in-
to long cylindrical pouches. (Original)

Acer. Cross-section through a leaf with
rineum on the under side. (Original)

Alnus latifolia. Some hairs of its Hrineum.

(Origine),

Syceas. The zone of a cycas root inhabited
by algae. The intercellular spaces be-~
tween the hypertrophied cells ere inhab-
ited by Anabaena threads. (After Life,
"Tuberlike rootlets of Cycas reooenta).

Acer. Part of a cross-section through the
So-called window-gall of the maple,
(Original).

Viburnum Lantana. Part of-a cross-section
through the vesule-gall. (Original).

Acer campestris. a, Brineum hair. (Original)
b, deformed root hair. (After Schwarz).

Phyteuma. a, pathological hair~formations of
hairs on an inflorescence galt, (Or deena)
er

b and c. deformed root hairs.

Schwarz).

Sinapis. Root hairs of seedlings after treat-
ment with dilute sublimate solution.
(Original).

Rozites gonglyophora. "Kohl-rabi mound" from
the fungus gardens of the lower Brazilian

i

Atta-~species. (After Moller).

eh te em tar Na a SAI nl Cone ame nd Ae am eh mee Tageh Oe SOU Reh Tame ND GE Se mee ed neh AU co ce cee em Me eed Ge Te ee hie We ee ee On

1. Beitr. 2. Kenntn. d. Chytridiaceen. Hedwigia, 1901,

Ba. Aly Be l.

Figure 48,
(pe 126).

Pigure 50.
(pe 128)

Figure 61.

Figure 52.

(p e 130)

Figure 53.
(pe 130)

Figure 54,
(pe 134)

Figure 55.
(p. 136)

Figure 56.
(pe 137)

Figure 57.
(p. 159)

Figure 58,
(pe 144)

Figurel50.
(pe 148)

Figure 60.
(p. 158)

Figure 61.
(p. 156)

S eeeanatieanaienel

Vilds

Vavcheria Notommata gall on Vaucheria.
After Rothcrt).

Circaea lutetiana. a, Cross-section through
an eel root gall , later stage. Numer-
ous giant cells are visible, the nuclei
of which are beginning to degenerate
and break down. b, irregularly lobated
nuclei from a gient cell (Amitosis by
"hudding"). In these are numerous
nucleoli of different sizes. c, single

dant cell with numerous nuclei,
After Tischler).

Part of a cross-section through ©» root wen
“all with multinuclear giant cells.
After Toume;)}.

Basidiobolus ranarum. Multinuclear giant
cells. (After Raciborsii).

Dividing nucleus from a giant cell. (After
Prillieux) .

Ulnus campestris. The leaf at the left has
formed an extensive sac gall, after
infection with Schizoneura langginosa.

Quercus, Two cynipides galls. At the left,
“Cynips polycera; at the right Cynips
aries.

Hormidium nitens. Abnormal cell division
after treatment with congo red.
(After Klebs).

eta. Cross-section through a yellow sugar
beet, which bears severhl ridge-like
tissue excrescences, extending longi-
tudinally. (After de Vries).

Fagus. Beach leaf with two galls of

Hormonyia
fagi. At a, some anastomoses have been
ormed between pairs of lateral ribs.

Compare also the text. (Original)

Phaseolus multiflorus. Callus homooplasia
from stalk. Above the normal hard
bast bundles, may be séen the abnormal
phloem and mylem parts, produced
after injury. At the right, a medul-
lary ray. (After Schilberszky) .

Populus pyramidalis. a and b, greatly devel-

Oped callus tissue (2/1). the latter
with numerous sprouts. (Original).

Lanium orvala. Stalk with strong callus roll.
: (Original).

Figure 62.
3. 159)

Figure 63.
(p. 159)

Figure 64.
(pe 160)

Figure 65.
(p. 161)

Figure 66-6
(bd. 161)

Figure 67»
(pe 165)

Figure 68.
(p. 166)

Figure 69.
{pe 177)

Figure 70.
(pe 178)

Figure a4,
(p. 178)

Figure 72.
(p. 184)

IX.

Longitudinal section through the end of a
cutting bearing a callus, At c~c extensive
callus masses have developed from the
wambium. H, wood, R, bark. (Original)

Populus. Cross-section through the end of a
cutting, cut slanting, bearing callus,
Below, xylem with duct (G) and medulhary
vay (M), above, large celled callus. At
R the cut surfece, (Oviginal).

Ulmus., Longitudinal section through the
WLohde" wedge. H wood, R. bark, 0 "Lohde
wedge" produced from the vambium. Compare
also the text. (Xriginal)

Abies cephalonica. Sngential longitudinal
section of the upper edge of a’ girdling
wound. Above, normal trauhéids, below,
(near the edge of the wound) parenchyma,
in the middle, some cells which show above
a tracheid character, below, that of wood
parenchyma cells. (After Maule).

Populus pyramidalis. Cross-section through the
upper end of 2 cutting which had been cut
slanting. H, wood, M groups of bast
fibres, C, cahlus of the bark, below it,
callus of the cambium, The cells of the
callus in regularly radial rows, indicated
in the figure by curved lines. (original)

Populus pyramidalis. Part of the callus tis-
SUC. etween the thin-walled parenchyma
cells lies a tracheid. (Original).

Pyrus Malus. Thread-like cell excrescences
rom the core. On the outer side of the
membrane (left in the figure) drop-like
rotuberances are visible. (After Sorauer)

Abies cephalonica. Tangential longitudinal
section from wound wood. Above, transition
bo the normal course of the fibres; below
course of the fibres along the edge of the
wound; in the middle the knarl-gene.
(After Maule).

Cydonia japonica. Tracheids from wound wood,
eae eee Spiral band, partly without
t. {After Vochting).

Diagramiatic pepresentations of a wound wood
knat]. {After Maule).

Fagus. Cross-section of part of a branch of
beech bearing a sphaeroblast. In the bark
lies an isulated sphareoblast with wood,
bark and medullary rays. {After Krick).

4

Figure 73.
(pe. 187)

Figure 74.
(p. 199)

Figure 7B.
(De 200)

Figure .76.
(p. 202)

Figure 77.
{De 203)

Figure 78.
(p. 205)

Figure 79,
(pe 208)

Pigure 80.
(pe. 218)

Figure 61.
{. 214)

xX.

Catalpa. Tissue ressmbling wound cork from
‘branch. (Place of rupture of bud).
(Original)

Vaccinium Vitis Idaea. a, cross-section
through a leaf, the swelling of which
has »een induced by infection of its
central portion with Exobasidium Vac-
cinii. b, part of a leaf(highly magni-
fied) which illustrates the difference
between normal tissue (at the left) and
the diseased( at the right). The hyphae
of the fungus ere not shown in the
drawing. (After Woronin).

_Crataegus Oxyacantha. Cross=section through

a leat infected with Aphis Oxyecanthae.
(Original)

Pyrus Malus. A branch infected for several

‘years by the hlood louse, bearing
clustered "canker" structures. (After
Prillieux).

Gymnosporangium juniperinum. Tangential long~

{tudinal séction through the wood gall.
Only one abnormally broadened medullary
ray {above at the left) has been drawn,
the others are only indicated by white

fields. (After Wornle).

Longitudinal section through the gall of the
blood louse, (Schizoneura lanigera) . In
@, the cells are Still arranged in recog-
nizable longitudinal rews; their walls
‘are thickened. In b, thin-walled gall
parenchyma without recognizable, longi-
Sudinal rows; two parenchymatic tracheidse
(After Prillieux) .

Fagus. Longitudinel section through the gell

of the beech wood louse (Chermes Feet)
Above, cork cells (k), below normal bast
tissue (b). In the middle abundant gall
parenchyma (p) in which are enclosed two
zroups of stone celis (sk}. The prosen-
chymatic elements of the bast have been
pushed aside in curves and misplaced by
the increasing bark parenchyma. (After
R. Hartig).

Cross-section through the gall of Syachytr iv _
&bilificum, the nutritive cell in the
middle. (Original).

Production of sac gall, digrarmatically re-
produced. (Original).

Figure 82.
(p. 214)

Figure 83.

Pigure 84.
(pe. 216)

Figure 85.

Figure 86.
(p. 217)

Figure 87.
(p. 218)

Figure 88.
(p. 220)

Figure 89.
{p. 220)

pa ke

Fragaria vesca. Cross-section through a

Phytoptus (mite) gall. (Original).

Diagrammatic reproduction of a Cynipides wall-
ed-gall. (Taschenbergi-gall) a, early
stage, b-d various later stages of_the
circumvallation. (After Beyerinck)+

Quercus. Production of the many chambered

walled gall of Cynips terminalis. At

the left, vegetative cone of the Quercus;
the upper part (vp. ok) has been sawed
off by the mother insect, The eggs have
been deposited on the surface of the
stump (rt). At the right, circumvall-
ation of the eggs by the outgrowing tis-
sue (gp. "gall-plastem"). A to G dif-
ferent stages of circumvallation. Na
nutritive yolk, Lk larval chamber, Fl
egg~stalk. (After Beyerinck)

Prunus spinosae Sacegall with "orifirial wall"

A, crosS=section through a mite gall,
(Eriophyes similis). B, cross-section
through a mite gall of Salix Caprea.
(A, Original, B, after Frank).

Two developmental stages of the gall of
Hormonyia fagi. At the left, circumval-
lation; at the right, sac-formation, 2,
dividing layer; b, tissue folds. (After
Busgen) .

Young developmental stage of the gall of
Hormomyia piligera. The dotted lines at
the left indicate the regular arrange~
ment in rows of the parenchyma cells.
The thick-walled tissues are indicated
by shading. a~a ring roll, 1, larval
cavity, e, the upper epidermis of the
leaf. (Original)

Salix. One-chambered "enclosed" medullary

gall of Nematus Vallisnerii. L, larval
cavity. The inner tissue containing
chlorophyll is indicated by a darker
shade. (Original)

Quercus. Cross-section through the "free" med-

ullary gall of Biorrhiza aptera on an
oak branch. (After Beyerinck).

Figure 90. Parinarium obtusifolium. Cross-section through

(pe 221)

a leat gall. The epidermis is drawn as a
heavy line. The thick-walled tissues are
represented by shading, the direction in-
dicating the arrangement in rows of the
Sclerenchymatic elements.L,larval cavity.
(Priginal).

1. Beob. ub. d. ersten Entwickel. einiger Cynipiden~-
gallen. Akad. Wiss. Amsterdam, 1882.

Figure 91.

Pigure 92,
I) pe 225)

Figure 93,
(De 226)

Figure 94.
(p. 226)

Figure 95.
(p. 227)

Figure 96.
(p. 229)

Figure 97.
(pe 229)

Figure 98.
($. 230)

Figure 99.
(p. 231)

Pigure 100.

(p. 235)

Figure 101.

(p. 236)

Figure 102. Quercus conferta. Oak gall of Heurouys pun

(p. 237)

XII.

Fraxinus. Section through two “walled galls"
of Diplosis botulearia. In A the midrib
of a leaflet is infected; in B, the leaf
ppondle, at the right, and at the left,
are visible three vascular bundles.
(Original) °

Part of a cross-section through a gall of
Pemphigus marsupialis. (Original) .

Banisteria. Part of a cross-section of a
eal through the peripheral section of an

undetermined gall. P, the unchanged pal-
isade layer; m, in, mechanical mantle.
(Compare also figure 108 E). (Original).
4

Cross-section through lense-shaped leaf-gall.
The cell rows in the interior are indica-
ted by dotted lines. L, larval chamber;
diagrammatic. (Original)

Populus pyramidalis, A, longitudinal section
through the Ieaf stem which bears a gall
of Pemphigus bursarius. B, section through
the tissue roll, more highly magnified.
(Original).

Crass=section through the edge of the gall of
Cecidomyia tiliacea. (Original).

Part of a cross-section through the gall of
Tetraneura Ulmi. (Qriginal).

Cross-section through a young gall of Nematus
gallarum. Ep, epidermis; H, a hair; J,
larval chamber. (Original).

Ulmus, Part of a cross~section of a cecidonyia
gall, The epidermal cells have been re-
-peatedly divided by cross-walls. (E).

Original).

4, Epidermis of the gall of Nematus gallarun.

B, The game of Andricus quadrilineatus.

(driginal).

Part of a cross-section of the gall of Jace
quinia Schiedeana Mez, The upper spper-
ficial cells are torn. The walls of the
deeper cell lagers are thickened. In a,
is isklustrated the extension of this
thickening of the walls to deeper tissue
layers, (Original).

ismatis., a, cross-section through : all.
Tt, Larval chamber, b and c, some hairs,
at c, T-shaped forms. In b, irregular -

forms;~ from herbarium material. (Original)

Aaa: s

Figure 104. Part of crossesSection from the gall of Horn-

ome fagi. k, crystal reservoir, g. Vase
cular bundles, ii, mechanical mantel, N.
nutritive tissue. (Original).

Figure 104, Cross-section through the gall of Cecidomyia

(pe 240)

_Cerris (half). AA inner mechanical mantel;
B, outer mechanical mantel. (palisade~like
sclereids}. (Original).

Figure 105. Part of cross-section through the mechanical

(p. 241)

tissue of the gall of Diastrophus Poten~
tilleae. N, nutritive tissuc; R, gall-bark.
(Original).

Pigure 106. Cuercus. Part of cross-section through the

(242)

Figure 107. Quercus Wislizeni.

(pe 242)

Figure 108.
(p. 245)

Figure 109,
(pe 246)

Figure 110.
(p. 247)

Figure lil.
(De 248)

Figure Jie,
(p. 249)

Figure 113.
(p. 251)

Balls of Acraspis macropterae on the oak.
A, outer mantle; B, inner mechanical
mantel. In E, part of the epidermis more
highly magnified. (Original).

Irregularly thickened

scléerids from an undetermined Cynipes
gall. (Original).

Some diagrammatic formal types of the mech~
anical gall-tissue. A, ball-shaped gall;
B, “louse gall"; C, medullary gall of
Cecidomyia tiliecea; D, medulary gall of.
6. Cerris; £, medullary gall of Banisteria
F, Walled gall; G, curled leaf gall; H,
gall of Diplosis globuli; I, gall of D.

“_botularia. (Original).

Cross-section through the gall of_Cynips
Mayri. The mechanical tissue is in icated
by Shading. (Original).

Fraxinus. Tissue closing the Botularia gall.

- G, Larval chamber, (Original).

Cross-section through an undetermined
Afriean gall of an Anberstiee. The mech-
enical mantle. (shaded) sonsists of two
separated parts. (Original).

Gall of Cecidomyia tiliacea. The gall, grow~
ing internally frees itself and finally
opens with a lid. (After Kerner).

Some nutritive hairs from sac galls. a, Acer,
Erineumlike hairs from a Phytoptus mite
gall; b, Ulmus effusa, papillae-like
heirs from the sac gall of Tetraneura
compressa. (Original). |

*

‘ XIV.

Figure 114. Guercus Wislinzeni. Cross-section through
{pe 252) an undebérmined Cynips gall. Ep, epi-
dermis; M, outer mechanical mantle;
St, outer nutritive mantle filled with
starch. Mp inner mechanical mantle.

The inner nutritive mantle lies within
Mp and is not dravm.(Originel).

Figure 115. acer. Cross-Section through the maple gall
(p. 252) Of Pediaspis Aceris. The innermost cells
contain thick, cloudea cytoplasm and
numerous oil-drops. In some may be seen
clear vacuoles. (Orisinel)

Figure 116. Lignin bodies from various galls. a, early
(p. 253) developmental stages from the gall of
Cynips tinctoria. b, later stages
Cyaips strobilana. (a, after Hartwich,
, Original).

Figure 117. Acer Pseudo-ylantanus. Part of crossS~
(pe 255) section through @ Sac gall of Phytontus
macrorrhynchus. (Orisinal).

Pigure 118. Some cells from the "star-eparenchyma"
(p. 256) (aerating tissue) of the Kollari gall.
(Original).

Figure 119. Quercus Wislezeni. Longitudinal section
(p. 259) through a cynipos gall which encloses
three cavities. In E, a structure
resembling a secretory sac, beneath it
a layer of cells thickened on one side,
fr. thick-walled trichome. (Original).

Figure 120. Oxalis crasscaués. A, normal starch grains.
(pe 283) B, annormal sterch grains; from a
“leaf tuber" of the same plant.
"after Vochting.)

Figure 121. Quercus. A, Some libriform fibres and pieces
(p. 288) of ducts. B, cells from the gall of
Spathegzaster baccearum. (Original).

~-y<

1j1, Under Heteroplastic tissues, Read Correlation-

De
Pe

he teroplasmase

i, line 40 - Read in nature for as naturee
2) line 61 - Cormophytes for oormophytes.
7 note 4 ~ Read uncertain for unsafe.

11, line
13, line
15, line
19, note
19, note
21, note

‘21, Line

25, ine
S1, line
34, line
54, note

40, note
40, note
42, line
42, note
43, note

18 = Read restrained for sustained.

2- Insert semicolon after nucleuse
3,7Read 1877 for 1887.

1,~line 8, Read 1882 for 1892.

2,-line 6, Read XII for XIII.

4 ~line 3, Read T869 for 1889.

12, ~Read (a) for (a).

25,- Read composed “for exposed.

2 + Read Kinoplasmatic for kinspessmatonse
8 ~- Read by for bute

4 - Change second note 4 to Note 5 and omit

Note 5.

12 - Read medial for denail.

2,cline 5 = Read CXXXII for CXXII.

6, - Read Weak for Wak,

1, line 23 - Read we are for weres

3, line 15 ~ Read green and on for gree and one.

45, lines 19-20 - Read Arrested developm ments for ar-

47, line

restment formationse

“SB = Read an for ands

47, line 13 - Insert numeral 1 for foot-note after

48, note
49, line

53, line
57, note
68, line
58, line
59, line

59, line
59, line
65, line

greffaé,

1, line 7 - Read between them for between the.
6 = Read than shade for that shade, omitting
C Ome »
10 ~ Read pe 27 for pe 37
1 - Read dependence for independence.
30 ~ Read Parilla for Barilla.
37 = protein for aJtpumen.
1 - Read suiphate and phospate for sulphid
and phosphid.s —

43 - Read pores for sporese
45 - Read cells for wellss

52 - Read in for by.

66 « Insert foot notes - 1) Beneke, Re Bin Fall von

‘68, line

68, line
70, line
80, line
51, note
81, note
83, line
89, line
oo, ise
90, Line
90, Lane
91, Line
92, line

Osteoid. Chondrosarkom der Harblase, mit
Bemerkungen tib, Metaplasieé. Virchow's Arch.
f. pathol. Anats 1900 Bd. CLXI, p, 70,

100, 2) Ziele us. Wege ds. Entwickelungsmechanik,
1892. Gesamm. Abhandl., 1895, Bd. II, pe 80
Anme

27 - Read divided for divisede

28, Read Communicating for communicated.

19.- Read Through for Though.

23 - Read but that for but aht

1, line 11 - Read Ba. VIII for Bad. Cilts.

Ly line chy Read Bd. Le . fOr Bae 1.

7 Insert foot note numeral 2 after Copeland.
7 = Read growing for gowing.

20 - Read bark for barl.

20 - Read sacs for Case

36 - Read Lamium for Laminua.

30 ~- Read hairs for hard.

16 - Read CaSO, for CoS04.

oe

. 94, note 2, line 18 -- Read CXXXI for CXXI.

96, line 18 ~ Read Cassia for Ca Cassicas

96, note 1, line 1 - Read cited for city.

100, line 7 - Read factors for factorys.

101, line 42, Read provein for albumen.

103, liue 1 ~ Read Briosi for Briosei.

105, note 1, line 16, - Read Bd, IV for Bd. V.

» 106, line 30 - Reac on for in-.one another.

110, foot note 3 ~ Read Remke for Reinke; Pampalone, II.
for Pampalone i.e. ,
111, line 8, Read protein for albumen.
114, line i", Read are for all.
117, Poot note 1., Bad. X™ for yr Baw X XC.
129, line 27 - Read tracheal for or trachae.
130, line 14 - Véchting for Kécnting.
157, line 5 = Insert of after treatment.
158, line 33, - Read if for in.
140, line 10, Read 92 for 82.
142, line 30, Branched for branches.
149, note 2, line omitted after line 5, Landwirtsch.
Jahr. 1885, Bs XIV, p. 465. Pra#l Unterse.
W, Schutz - ue Kernholz d. Laubbdume.
155, line 35 in the dark for the barks
161, line 42,-Read mobility for nobility.
161, line 43,- Read tracheid gnarits or balls for
: tracheid guares on balls.
161, line 52 = axillary for acillary.
167, line 55 - Insert are after like.
171, line 5, # Read gall for fall.
L71, note 1 - Kekis for Knxls.
1735, line 44 - Read of for or contact.
174, line @1 - Read Beyerinck for Bacerinck.
175, line 25 - Read Hymenoptera for sumenep teres
i777, Line 35 = Add asitically after par =
179, line 29, Read- mosses for woods.
180, line 13 ~ protein for albumen.
Le, Line 9 = On 207 Os
189, line 39 = “formations for farmentations.
198, line 40 - Omit wound before normal tissue.
202, line 12 ~ Read contrast for contracte
2C4, line 50.- Read protein for aloumen.
204, line 39 ~ Read galls for falls.
205, line 12 = Read parenchymatos for parenchymatic.
205, line 14,- Read parenchymatos for parenchymatic.
206, line 4 - ceived for crived.
207, line 4 - Insert etc. after Lasiopteras
209, line 23 - Read leaf for lead.
2ll, line 36 - Read ash gall for ask gall.
212, line 44 = Omit period after politus.
212, line 47 - RL +4 is formed for if Formed.
216, line 21 - Read mantel for mental.
217, line 5 = Read lith=like forms for Ligh-like forms
219, note 1 - Read (p. 152) for (ps 252).
220, line 6 = Read when the for then the

“9

223, note 2,-line 10, Read p. 289 for ps 269.

226, line ri ~Read which owe for which oo

EOL, Lane ,~Insert. any between in and other.

pol, lane ie ~Read conditioned for conditions.

255, line 54 .- Read If we would for if we could

etl, line 46,- Read are set free even for ang
set. free even.

242, line 19, - Read cell-microcosmos for cell-
microosmos.

242, line 21, - - Read ef the for to thes

243, line O3.. ~ Read than than under for then under.

245, line 10, ~ Read can assert | for blurred word.

249, line 7, - Read trichome for trichon.

251, line 16, - Read owes its for blurred word.

254, line 13, - Read gall-piastem for gall-plastein

254, note 1, Line 11, Read plizstem for plastein.

255, line 22, - Read figure 27.

256, line 22, - Read grouzd tissue for blurred word,

257, line 49, - Read -icsen for ~toeen

258, line 24, - Read foises us for forces ag.

258, line 39, - Read ways in for ways ib»

(2)

(2)

Introduction Z

We “characterize as abnormal all those forms which deviate
from a norm, Since a comparative consideration of different
kinds of form-groups leads to the establishment of different
kinds of norms, the meaning of the word abnormal will have to vary
in accordance with the groups under immediate observation, When
studying organisms we have to establish a norm by comparing rep-
resentatives of a species, This norm will differ from that es-
tablished in the consideration of greater form-groups. Therefore
in speaking of abnormal forms, we will have to define the limita-
tion of the form-groups, to accord with the investigation with
which we are then occupied. Botanists commonly consider the
growth in thickness of the tree-like Liliaceae, many lianes and
so forth, 38 abnormal because it differs essentially from the
grosth in thickness in the other phanerogams, In this case the
norm has been deducéd from a consideration of all phanerogams. If
we find double buttercups. or fasciated dandelions in the meadow,
and plum pockets, cankers, etc, on fruit trees, we term them ab—
normal formations, because a comparative consideration of the in-
dividuals of similar species leads to the establishment of a norm,
characterized by single flowers, simple scapes, trees free from
canker and so forth. Abnormalities of this kind are also called
pathological phenomena or diseases. In this it is assumed, that
the functional efficiency of the "abnormal" organism or organs is,
in some way and in varying degrees, below that of "normal" ones.

Not all pathological forms found in the plant kingdom are
Suited for consideration in the manner proposed, only those cases
will be discussed in which cells and tissues of abnormal kinds are
formed. The comparative treatment of these cases leads to the
founding of a “Pathological Plant Anatomy", the characteristic
features of which the author has sought to outline in the present
work. ,

Before taking up a detailed consideration to the abundant
material furnished by the study of pathological plant tissues,
we must first decide whether it is possible to formulate an exact
definition for the toncept of the “pathological”, in contradis-
tinction to the normal, :

In my opinion, the efforts of earlier authors to define
“pathological”, when working with plant diseases, have only proved
the impossibility of any sharp. division into normal or healthy
and abnormal or pathological, #8 nature, This is as impossible
as an exact distinction between the plant and the animel kingdoms,
Forms -will always be found, of which the frue classification re-
mains uncertain. We will not undertake the hopeless task of find-
ing an entirely satisfactory definition; the same difficulties
exist also for the relatively limited sphere of our anatomical
considerations, that are found in the whole province of pathology.
We will only inquire which are the characteristics common at
least to the majority of the forms which we, in accordance with
general usage, are to designate as pathological,

4

No useful result whatever is obtained by taking into consid-
eration the histology of abnormal tissues, The anatomical struc-
ture of pathological tissues shows the greatest diversity conceiv-
able, This will be fully demonstrated later, No features are
found in common, Similar conditions exist in considering their
etiology, for the most varied of external conditions may cause
the formation of pathological tissue, We obtain useful results
only when we teke into consideration the physiological peculiar-
ities of the tissues. All the cases which we can deSignate as
pathological in the plant involve the omission or weakening of
some function. Either the tissues are retarded in their func-
tional efficiency; that is in their normal formation by some kind

(3)

r 2
of unfluences, or tissues functionally efficient undergo subse-
quent changes. In this latter case they lose whotly or in part
their ability to function, or new tissues are produced on the
plant body of such a nafure that the diseased and deformed or-
gans either do not serve the organism as a whole, or at least
less than those termed normal, Accordingly, the following tis-
sues among others may be considered as pathological;- the color-
less mesophyll of etiolated leaves which through leck of light
is kept from developing into functionally efficient tissues, and
the assimilatory tissue whose chloroplats degenerate under the
influence of external factors, thus rendering the celis incap-
able of assimilation. Further, new formations like galls, are
to be designated as pathological, Their tissues do not serve
the organism as a whole, and not infrequentiy considerable quan-
tities of nutritive material are lost to the organism through
their formation. To pathological tissues may be added also
wound cork, formed after injury, and "callus" tissue, although
the first, by closing the wound, protects the functional effi-
fiency of the organism as a whole, and the second, by a new for-
mation of roots and shoots, has the power of regenerating the
Original size and efficiency of the mutilated plant body. In
both cases tissues are concerned in whose formation not so much
1S accomplished for the organism as a whole, as under normal con-
ditions, that is, as would have been produced by the normal tis-
Sues of the organism of its integrity had not been destroyed.

Emphasis of the functional characters by which abnormal
cells and tissues are distinguished makes possible the rough
limitation of the field of our work. Any sharp distinction be-
tween the pathological and the normal cannot, however, be car-
ried through in this way. In many cases, the difficulty of *judg-
ing with certainty of the physiological values of the different
tissues would prevent this. A microscopical investigation of
their structure does not always enable one to decide as to their
physiological significance, and often for technical reasons, the
tissues in doubtful cases.are not accessible for experimental
investigation. In listing definite tissue forms under any one ,
of our chapters, we must be guided by histology and etiology as_
well as by analogous cases. However, I hope we will not need to
deviate from the path indicated by the physiological point of
view emphasized above,

The valuation of cells and tissues according to their physi-
Ological efficiency reveals the characteristics common to all
pathological tissues. When forming groups and sub-groups within
the field of our work, it will be advisable to consider ontogen-
etic and histological points of view as the most important.
Therefore, we will unite pathological tissues of similar life
history and similar histology ana discuss them in independent

groups.

Various principles of classification are open to us, we may
either describe successively, the individual tissue forms and
organs of the plants, and the many variations from the normal
structure found in them under certain conditions or we may anal-
yse processes of growth, maturation and differentiation through
which abnormal cells and tissues arise, and unite them into in-
dependent groups produced by similar processes, without consid-
ering which tissue appears changed pathologically, or what or-
gans are involved, In the first case a specialized pathological
anatomy would result, in the other case a general one. Since we
will have to take into consideration, plants of the most widely
different sorts, one-celled as well as mamy-celled, thallophytes
as well as oSormophytes, it seems advantageous to me to arrange
our material from the point ef view of general pathological
anatomy. In the concluding chapter there will be opportunity
far sketching in ourline, a special anatomy, at least for the

3

_ if normal individuals of a species are tested for the func-
as efficiency of all their eorts and then those Jee
Pe ae gr entirely of pathological tissue, it will be found
s individuals normally constructed attain a maximum of func-~
ag efficiency, while that of the others remains more or less

(4) ie ow this maximum, no matter what may be the nature of their
oe on the normal histology. Conditions are different,
wever, if we consider the life history and histology of the
cells and tissue instead of their functional efficiency. Cases
may be found where individuals constructed abnormally may’ surpass
ae te ae fall Short of the normally developed examples, so far
of the humber, size, and internal structure of their individual
ements aré concerned. The normal course of development takes,
SO to Speak, a poliden mean from which it can deviate moré or less
pone in either direction, Proportions of size, number, etc.
: aracteristic for normal tissue,furnish a standard for the fluc-
uating values to be measured in plants differently diseased,
_ It is thus evident that a division of the material into two
principal groups is advisable for the histological considerations
of the subsequent "general pathological plant anatomy”: :

1, The number, size or differentiation of the cells of path-
ological tissues remains more or less below the normal, There-
fore in one or more ways, the tissues remain in a Stage of incom-
plete development. We designate as Hypoplasie those abnormal
processes of formation which - compared with the corresponding
normal processes of development - appear retarded as it were and
end prematurely. :

2. The pathological cells and tissues exceed the conditions
of differentiation and growth characteristic of normal individ-
uais, The diversity of forms found to arise through such pro-
cesses of differentiation and growth necessitates a subdivision
into several independent groups,

a. In the simplest case, the abnormal cells differ from nor-
mal ones only in their internal structure in the nature of their
contents, the character of their membranes, etc. We use the
term Metaplasia for the processes of differentiation, by which
the cells of any tissue supplement their normal qualities or ex-
change them for new ones,

b. In other cases, the abnorml cells differ from normal
enes in size, Abnormal increase in cell size we term Hyper-
trophy. it is not fundamentally important whether the histology
of the cells concerned remains similar to that of normal one's
er is changed in some way, mt

c, If cell division follows cell growth we speak of Hyper-
plasia, The number of abnormal formations which comes into exis-
tence through hyperplasia is extraordinarily large, and the his-
tological composition of the newly produced tissue is exceeding-—
ly varied,’ Later we will have to undertake a further division
of this great group.

Finally there are still to be considered,

3. The Restitution Processes, After injury and mutilation
of the plant body, the injured living part often reacts in such
away, that the lost ‘part is formed anew, If the structures
arising after mutilation resemble those lost, we speak of
restitution. Although the tissues thus produced possess, there -

(5) fore, qualities of the normal ones, they may nevertheless be in-

cluded in pathological anatomy, since the formation of the regene

erated tissues, like that of many pathological tissues, requires

an outlay of energy and material which is saved to the plant de-

veloping jn gn undisturbed manner. On account of the correspon-

dence between normal and regenerated tissues, the latter must be
the first division of this work,

(6)

4

The processes of differentiation and growth thus briefly
characterized lead to the formation of the following five
chapters.

I, - Restitution,
II. - Hypoplasia,
III, ~ Metaplasia,
IV, Hypertrophy,

¥. - Hyperpjasia,

In all cases, with words like hyperplasia, ete, we are con-
cerned primarily with the naming of processes, Hyperplasia, for
example, is the process leading to the formation of eéli1 out-
growths, Howe¥er, we will, in the following chapters, take the
liberty of designating by the same terms, the actual product of
the process of growth or division, etc. The cell outgrowth it-
self is a hyperplasia,~ the abnormally enlarged ceil a hyper-
trophy and so forth, In this we will follow the example of the
physician who in the same way uses both abstractly and concrete-
iy the terms here named,

‘

Z
: The aifficulties encountered in defining the whole pro-
vince are met again when establishing single groups, In many
of these we must give up absolutely sharp boundaries, For in-
stance, "hypertrophy and hyperplasia” often merge into one an-
other since, under certain external conditions, in organisms of
certain constitution, and in a certain stage of disease, only
enlargement of the celis takes phace, while in others cell-di-
vision may also arise, The few debatable cases in which defin-

‘ite disease-phenomena seem to belogg to one chapter or to the
other, should not prevent us, however, from leaving both of the
groups naméd to stand independently side by side.

At this point, we must call attention to certain limita- |
tions which influence us in the definition of ovr subject. Ali
pathological structures of ceils and tissues should not come
under our consideration:- the finer nuclear and protoplasmic
structures are excluded first of all. The many results furnish-
ed in the past few years by cytological investigation also throw
light in part upon abnormal ¢ell and nuclear structures. How-
ever, the lack of unity, in judging of normal structural rela-
tions, which still prevails even among scientists, seems to
prove that the time for a comprehensive consideration of abnor-
mal conditions has not yet come. We will rest content by call-
ing attention in¢identally to changes in nuclear and ptoto-
plasmic structures, associated with hypertrophy of the cells or
hyperplasia, etc. and in conelusiom point out some problems and
give some bibliographical citations. The further phenomena of
degeneration and @issolution so often noticeable in cytoplasm,
nucleus, chromatophores and cell-membrane will be exeluded.
Some remarks en the phenomena of degeneration may be found in
Chapter V.. Finally micro-chemical conditions which vary from
the normal and are found in pathological cell and tissue forms
will be mentioned only incidentally. Irregular reactions of
the cell contents and membranes have more to do with abnormal
metabolism of diseased plants, than with their pathological .
tissue structures,the discussion of which is our sole task. For
the rest, compare the concluding remarks in Chapter V.

Since in forming groups and sub-groups, we will take pains
to place the most natural boundaries possible to the separate
divisions of our work, we. must consider practicably, besides

ontogenetic and histological features of pathological plant ;
‘tissues, still other distinctive ones, Among these, etiologi-

cal features are of first importance. In every form of patho-
Logical development we will inquire for the causes producing it.
The influence upon tissue formation. of abnormal supply of light,
abnormal nutritive conditions, abnormal water supply, and many
others, should be investigated. It will be found that abnormal

(7)

tissues, which may be traced. back etiologically to similar

causes often correspond with one another in their structural re-

lations, Therefore it is possible, without forcing matters, to
unite a,consideration of the etiology with that of the material
divided according to ontogenetic and histological characters.

Moreover, most forms of pathological plant tissues and very

diverse ones may be traced back to factors other than those a-
bovenamed. They are produced partly by injury, partly by infes-
tation with parasites, animal or plant. All abnormal tissues,
arising from “wound stimuli", will be designated as "callus for-
mations" in the widest sense of the word. We will have to speak
of callus-hypertrophy, callus-hyperplesia and so forth, accord-
ing to the way in which the tissues are affected. On the other
hand, gall-formation will be spoken of, when parasitic organisms
of any kind whatever cause the formation of abnormal cells and
tissues. We will report later in detail on gall-hypertrophy,
gall-hyperplasia and so forth.

Although a descriptive treatment of pathological plant tis-
sues and @ study of their development will especially deepen
and broaden our knowledge of the histologicel development of
the plants, vet we will be obliged in considering the etiologi-
cal side to place above all physiological questions. We will
have to test the ways in which various factors affect the plant,
and the capacity for reaction of various cells and tissues to
certain stimuli; we will be led from the study of forms to the
physiology of developmert especially of a pathological nature.
In this way also "pathological plant anatomy" will furnishccon-
tributions to the field, which we will follow Roux in designa-
ting as the developmental-mechanics of the organisms.

It will be found that almost all pertinent questions are
easily subjected to experimental treatment. The phytopatholo-
gist is in the favorable position of being able to produce ex-
perimentally the abnormal tissues in which he is interested. In
most cases, our knowledge of the factors at work does not ex--
tend beyond the very beginning; indeed there is such urgent need
of a thorough further analysis of these factors that the answer-
ing of most questions, and indeed the devisive ones, must be
held over for future researches,

In each division we will follow the discussion of develop-
mental and histological character by remarks upon etiology and
developmental-mechanies, In the concluding chapter, we will re-
capitulate briefly all that has been ascertained as yet concern-
ing the ways in which the different forces may act.

The subsequent treatment of different abnormal tissue forms
will include a series of examples to illustrate each of these
forms and attention will be called to the pertinent literature.
Of course, it is not in our province to mention all the plants
capable of producing abnormal tissues, nor describe all the ab-
normal structures made known by personal investigation or by
the statements of earlier authors. A multiplicity of examples
is to be avoided, such as could have been given easily for in-
stance in the. chapter on galls. Instead of describing exhaus-
tively all known cases which would be suitable in a manual, we
will sift the available material and limit ourselves to depict-
ing those cases important because of a wide-spread distribution,
or in any way interesting theoretically. Moreover we have not
striven for a complete survey of all the iiterature concerned
with abnormal celis or tissues. Articles-will not be named
which recapitulate only what is universally known, or which re-
port new facts insufficiently. If,in spite of my endeavors to
reproduce all that is essential, important contributions have
escaped me, I ask for the forbearance of my reader, in view of
the wide range of literature here used,

“

(8) CHAPTER I, 6
RESTITUTION

* :

Living plants or plant organs are often stimulated to pro-
cesses of growth and to the formation of certain kinds of new
structures by the violent removal of some already existing part,
If this leads to the rebuilding or transformation of organs,
different results are concejvable.

1, The newly formed portions arise on the place of amputa-
tion and resemble the lost portion in all essential points. If
for example, the tip of a root is removed a new root tip will be
formed at the pace of injury. Decapitated shoots often vevelop
callus on the surface of the cut and from this numerous adventi-
tious shoots; many marine algae proliferate abundantly on the
cut surface; other similar examples might be cited.

2. The newly formed portions resemble in all essential
points those lost; they are not produced, however, at the place
of injury, but at a greater or lesser distance from it. If,for
exampie, we remove from a root not only the tip but also older
portions further back, no regeneration takes place as inl. On
the contrary, the cut root is incited to the formation of lat-
eral roots which arise above the place of amputation.

35, The newly formed parts arise on the surface of the cut,
but do not resemble the lost parts (heteromorphosis). Cases of
this kind arise when, for example, root cuttings of Taraxacum
develop leafy shoots on the apical surface of the injury, i. e.
on the one toward the root apex, or when seedlings of Bryopsis
form rhizoids instead of lost “sprouting parts".

4. The newly formed portions neither resemble those lost
nor are they produced on the surface of amputation, Sachs found
in the case of Cucurbita that after the removal of all shoot buds,
the root buds, present in gach leaf axil, developed into knot-
like structures, Vochting* re¢ently described his observations
on certain species of Brassica, where, after the removal of the
vegetative points from all sprouts, he found leaf-cushions trans-—
(9) forming in the same way, It should be noticed that the newly
formed portions arise from organs already existing, at least in
their incipiency.

The processes of regeneration result in a reproduction of ‘
the original forms, or structures similar to them can be created,
only in the cases named under 1, in which the new parts are pro-
duced at the place of injury and resemble those lost in all es-
sential points. Various modifications are still conceivable,
however, either the surface of the injury in its entirety takes
part in the regeneration, or only portions of it; further, at
the place of injury, there arise either one nev form alone or
several of equal value, near one another, Adventitious shoots
of leafy plants, as well as the proliferation of the thallophy-
tes, capable of regeneration, in this process pass first through
a stage similar to the "juvenile-forms"; the former with simple
leaves, the latter with a cord-like thallus base,

A complete agreement of the lost with the newly formed or-
gan, a restitution ad integrum, will be attained only when the
following conditions are fulfilled:-

-_— Fr oe eo =
nr i

1 Yochting, Zur experimentellen Anatomie. Nachr. k, Ges.
Wiss, Gottingen, 1902, Heft 5,

(10)

’ (3

(a) When the entire injured organ takes part in the
. regeneration,
(b) When only one new organ arises at the plece of
injury.
(c) When the appearance of "juvenile-forms", or primi-
tive developmental stages, do not exclude agreement

Processes of restitution, by which an organ is produced en-
tirely similar to the one lost, are rare in the plant kingdom,
Roots from Which the extreme tips heave been removed regenerate
the lost part+, According to Peters, the tip of the sprovt of
smal}, Hefianthus plants 1s capable of regeneration”. Acoording
to Gobel? the prothallium of the Polypodiaceae, the pseudo-bulbs
of Drepanophyllum end Eriopus, if injyred by grazing animals,
oan likewise regenerate the lost part“, The question, whether
mutilated leaves are also able to regenerate parts that have been
lost, until most recently an open question, pas just been affirn-
atively answered by the experiments of Gobel” on Polypodium Her-
aoleum and by Pischinger's® on Streptocarpus and Monophyilaea. |
If finally, we include the new structures on wounded: unicellular
organisms (Siphoneae), to which we shall return later, then all
se aorue of true restitution in the plant world will have

een named,

Observations similar to these on the restoration of whole
organs and organisms may be made on the restitution of oells and
tissues, It will be necessary to make investigations in order to
see whether the cells, injured by the mutilation of any portion
of the plant, are healed by the regeneration of their membrane,
their protoplast and so forth, thus regaining their original form
or composition:- entirely independent of the question, whether
the organism as a whole resumes at the same time its former size
gnd normal form, In the second place, the question must be dis-
cussed, whether, after injury, a tissue can be produced from the
parts there exposed, which agrees in all particulars with the
normal superficial tissues;- in other words, whether, at the
place of injury, a normal epidermis or a normal membrane of any
kind whatever can be formed, no matter if the reproduction of
such tissue is connected with a complete compensation for organs
possibly lost.

Soa A ee ed _- _-_ —_ - - - - = = -_-_ =-

Wurzel., Cohn's Beitr. z. Biol. d. Pflanz., 1872, Bé. I, p. 21;
Prantl, Untersuch, ub, ad. Regeneration d. Vegetationspunktes an
Angiospermenwurzein. Arb. 4, Wurzburger Institutes, 1874, Bd.I,
p. 546, Roots cut in half longitudinally are also capable of re-
generation, Compare Lopriore, Ueb, ad. Regeneration gespaltener
Wurzeln. Nova Acta Ac, Leop, Carol., 1896, Bd. LXVI, p. 233.

Paters, Beitr. 2. Kenntnis d. Wundheilung bei Helianthus
annuus L, und Polygonum cuspidatum Sieb. u. Zuce. Diss. Gotting-—
en, 1897, p. 109.

. Organographis, Bd. I, pv. 37; further, Uber Regeneration
im Pflanzenreich, Biol, Centralbl,, 1902, Bd, XXII, p. 385, <=

; Uber Regeneration im Pflanzenreich, loc, cit. p. 508,
Therein references to unsafe statements on leaf regeneration.
5 ne a eae
Correns, Untersuch. ub, a. Vermehrung 44 fitibmoose, 1899,

p. 57, 58, 236, a sae eee 4

hs Age? : - ee P e 8 si as
6 Yeb, Bau u. Regeneration aap Assimilatdongapparates von
Streptocarpus und Ménophyllae4, Sifzungsber/ Akai/ Wiss, Wien,
Math, Naturw, Cl., 1902, Ba, ckt, Abts 1, pd 278i

I, RESTITUTION OF THE CELL 8

_ Plant cells are not capable of living for a long time in
an injured condition. After injury to the cell membrane, or
after the mutilation of the protoplast, either the cell is des-
troyed, or changes take place in it, which result in a repro-
duction of the status quo ante, or of a condition similar to it
and of equal value physiologically. These we can designate as
healing processes,

The question as to the restitution of the cell-membrane is
of the first importance, On the one hand, experimental inter-
ference with the integrity of the cell-wall and its connection
with the protoplast may be carried out most easily; on the other
hand, new cell-membrane formations may usually be proved without
difficulty in the object under experimentation, We are thus rela-
ple | well informed as to the processes of cell-membrane res-

ution.

Various kinds of injury must evidently be considered here,
We may remove some layers from the cell-membranes without com-
ing in contact with the protoplast itself; we may expose the
protoplast by breaking the continuity of its cellulose covering,
i. e, by pricking or cutting, or we may loosen the protoplast
from its membrane in places, or on all sides, by plasmolysis.

Because of technique, it will be possible to effect the
first kind of injury only in cases of unusually strong cell-
walls, That the layers whch have been torn off can be replaced,
has been proved by Tittman~ with Agave americana, Aloe ligulata
and A, sulcata, As is well known, the cuticle on the leaves of
these plants is very strongly developed, and may be removed
without noticeable damage to the protoplasts. In damp places
the newly formed cuticle is weaker than that formed under normal
conditions, Tittman observed regeneration of the wax coating on

' Ricinus communis, Rubus biflorus and Macleva cordata, Various
Sedum and Echeveria species lack this capacity for regenerating
wax,

(11) Very much greater significance is attached to those cases
cin which the protoplast in one way or another is exposed par-
tially or on all sides. fThe effect of injuries of this kind may
always be studied experimentally and easily in all cel] forms
and in all plants, The large celled Siphoneae are especially
suitable objects for these experiments, but it will be found
that in all the principal groups of the plant kingdom, plants
are known in whose cells healing processes may take place after
exposure of the protoplast and new membrane formation may be ob-
served, In any case, however, the capacity for regenerating the
cell-membrane is very much better developed among the lower
plants than among the higher ones,

The experiment, which should throw light upon the conditions
of the cell after exposure of the protoplast, is most successful
when it is possible to separate the protoplast partially or en-
tirely from its wall, leaving it at the same time unmutilated,
Plasmolysis is an excellent condition for obtaining this result.

Klebs* has proved that protoplasts can be incited to the
formation of new membranes by plasmolytic separation from the

1 Beobacht, liber Bildung und Regeneration d. Periderms,
ad. Epidermis, des Wachsuberzuges u, d. Cuticula einiger Gewachse,
Pringsheim's Jahrb. f, Wiss, Bot., 1897, Bd. XXX, p. 116.

@ Beitr. 2, Phys. der Pflanzenzelle. Untersuch, d. Bot.
Inst, Tubingen, 1888, Ba, II, p. 489.

(12)

cell wall. Representatives of the most varied plant groups,-
algae (Vaucheria, Zygnema, Mesocarpus, Spirogyre, Oedogoniun,
Conferva, Chartophora, Stigeoclonium, Cladophora), mosses
(Funari& leaves), ferns, (prothallia of gymnograms), and mon-
ocotyledonous growths (leaves from Elodea canadensis), fur-
nished results which agreed in all @SSential points, To be
sure, the formation of the new membrane required a verying
length of time in @ifferent representatives; Vauchcrie occasion-
ally formed the new well covering in 10 per cent gluoose within
the first hour, Conferva and cells of prothellia efter 1 to 2
days, Zygnema needed 3 to 4 days, cells from Funtrie and Dlodéa
8 to 10 days and more, On the other hand'it was not possibie,
by means of plasmoiysis in sugar solution, to inoite cells of
the Desmidiacesae (Desmidium, Euastrum, Gosmarium, Ponium, Pleu-
rotaenium, Closterium, Tetmemorus) nor of the Diatoms (Melosira)
to the formation of new membranes, Equally without resulis were
the experiments on many prothallia (Blechnum, Coratopteris), on
Lemna and Vallisneria, as well as on dicotyledons {Symphoricar-
pus). As fer as the latter are concerned, the negative result
of the experiments my be due to the manmr in which they vere
carried on, as chosen by Klebs, or to the nature of his exper-
imental objects, At ail events, his supposition that the capa-
city for forming new membranes does not extend to dicotyledons
generaily, is not pertinent in this géneral conception, The
rotopiast in root hairs of dicotyledons forms new membranes
after the action of plagmolysis . This is true aiso of the pro-
toplast of pollen tubes”, Still further, Townsend found the
formation of new membranes in plasmolysed sieve tubes in Bryonia
and Cucurbita*, Further similar examples will be noted later.

Piasmolysis is known to attain varying degrees, depending
upon the nature and concentration of the solution employed; i.e.,
the protoplasmic membrane may be loosened from the wall only in
places or it may be drawn together into a ball, which is separ-
ated from the cell-wall on all sides. in the first case only a
new cap-like layer is produced, at tached on all sides to the
old cell-wall which is still in contact with the protoplast; in
the second case, a complete sheath is produced around the proto-
plasmic mass,

_-_ _ - = ~— - Co -_- —

beraubten Protopl. Flora, 1890, Bd. LXXIII, p. 314. “Acqua, Con-
trib, alla conosc. d, cellula veget. Malpighia, 1891, Vol. V, p.
3, The same process takes place "normaily" in the cap-formation
of the root hairs of the Java-fern Drymogiossum nummularifolium
and D. piloselloides {Aecvurding to Haberiandt, Physiol, Pflanzen~
anatomie, 2 Aufl, 1896, p. 192): "By Longer continued drought,
the protoplasm; to wit, of the root hairs whith are drying up,
together with the cell-nucleus in the basal part of the hair, is
drawn back, above which becomes noticeable a more or less regu-
lar contraction of the body of the hair, At this point a mem-
brane cap is then formed, which bounds the capsulated protoplast
of the hair from the dried up part, The latter drops off and tle
resulting root-hair base waits only for the resuscitating drop of
water in ordér to grow out at once into a new hair," Reinhardt
(Plasmolytische Studien z. Kenntnis des Wachstums der Zellmembren,
Festschr. f, Schwendener, 1899, p. 425) has already raised the
question, whether the cap formations in the bast, (Krabbe, Beitr.
z. Kenntnis der Struktur u, 4d. Wachstums vegetab, Zellhaute.
Pringsheim's Jahrb. f. wiss. Bot,, 1887, Bd. XVIII, p. 346) may
not also be placed on an equal footing with the above mentioned
abnormal formations,

e Townsend, Einfl, des Zellkerns auf a, Bii¢.ung der Zell-
haut, Pringsheim's Jahrb, f. wiss, Bot., 1897, Ba. XXX, p. 484.

(13)

10
; More examples may be given for these cases than for those
in which, as after plasmolysis, a new formation of the cell-
wall takes place after injury to the cells and after violent

removal of pieces of cell-wall, with which is connected a sim-
ultaneous loss of living cell substance,

In the first place there should be mentioned here also,
the much investigated Siphoneae+, which in part, can heal their
wounds even in avery short time by a new formation of cell-
wall, All Siphoneae which have been tested, (Anadyonene, Bo-
trydium, Bryopsis, Caulerpa, Codium, Derbesia, Halimeda, Mdotea,
Valonia, Vaucheria) are capable, without exception, of reotoring
the cell-wall, The Phycomycetds, which resemble the Siphoneae
and which, in forming soar membranes are also protected by the
narrow lumen width of their mycelial tubes, act also like the
Syphoneae“,

So far as is known, in almost all cases, the injured cells
of higher plants lack the ability of restitution, It is imma-
terial whether the results of the protoplasmic loss play the
chief role, whether the contact of the exposed protoplasm with
the external environments acts as a distributing factor, or
whether other factors turn the scales:- in any case, the in-
jured cells almost always break down without having healed their
cell-walls, As yet only a few exceptions are known,

If the upper part of the nettle hair of Urttca dioioca is
broken off, it is immaterial whether only the tip or a larger
part be lost - the protoplast now and then forms a delicate
Scar membrane at a varying distance from the surface of the
break. In one case on a mutilated hair, I found a new, very
delicate walled tip, not absolutely regular. (Compare figure 1),

Perhaps even regeneration of the tip becomes possible un-
der suitable conditions, so that the same nettle hair may again
become effective as a weapon,, Moreover Kallen® has already an-
nounced, that the hairs of Urtica urens can close their wounds
with membranes. It is very possible that the nettle-hair cells
of Urtica can also be incited to the formation of membrane
caps by means of plasmolysis.

1 of the abundant ligerature, the following may be named:
Hanstein, Ueb. d, Lebensfahigkeit der Vaucheria-Belle. Sitz.
Ber. G@, Niederrhein. Ges, Bonn, 1872; Hanstein, Reproduktion
und Reduktion von Vaucheria-Zellen, Yanstein's Botan. Abhandl.,
1880, Ba. IV, p. 45; Schmitz, Beob, ub, d, vielkernigen Zellen
d, Siphonocladiaceen, ‘Festchr. ad, naturforsch, Ges, Halle 1879,
p. 275; Noll, Ueb, den Einfluss der Lage auf d., Morphol, Aus-
bildung einiger Siphoneen. Arb. d. Bot. Ingt. Wurzburg, 1888,
Bd, III, p. 466; Wakker, Die Neubildungen an abgeschnittenen
Blattern von Caulerpa prolifera, Kon, Akad. Wetensch, Amsterdam,
Bd, III, 2, p. 251; Kjemm, Ueber Caulerpa prolifera. Flora 1893,
Ba. LXXVII, p. 460; Kuster, Ueber Vernarbungs-und Proliferations—.
erschein, bei Meeresalgen, Flora, 1899. Bad. LXXXVI, p. 143;
Winkler, Ueber Polsritat, Regeneration und Heteromorphose bei
Bryopsis, Pringsheim's Jahrb. f. wissenschaftliche Bot. 1900
Ba, XXXV, p. 449; Prowazek, Beitr. 2, Protoplasmaphysiologie.
Biol. Cbl,, 1901, Bd. XXI, p. 87.

2 Compare especially Van Tieghem, Mouv. rech, s. 1, Mucor-
ineens, Ann. Sc, Nat. Bot., 4, ser., Tom, 1, 1875, p. 19.

5 pas Verhalten a@, Protopl. in d. Gew. v. Urtica urens
entwicklungsgeschichtlich dargestellt. “Flora, 1882, Ba. LXV,
—P. 65,

(14)

ll

The latex tubes may be mentioned as a second example which,
after injury, are healed in the.same way by the formation of
membrane caps. Tison observed the latter,in Morus alba and
others after the dropping of their leaves™, The latex tubes as
well as nettle hairs prove again that even the cells of dicoty-
ledons are capable of forming their membranes anew,

If, by injuring the cells, we succeed in exposing the proto-
plasts on all sides, as described above for plasmolytica procesees,
we then have @ special case, -which, however, does not disclose
anything essentially new, Through this injury protoplasmia
masses of various sizes are often extended from thg ‘large cells
of the Siphoneae, which given favorable conditions”, are capable
of enclosing themselves with new cell wails, :

In this connection it should be noted that many Siphoneae
may also heal their wounds in other ways than by reforming the
cell.walls. If a turgid cell of Valonia utricularis be pricked,
a fine stream jets forth. When, however, the jetting of tas -
liquid is sustained by a gentile finger pressure, it soon ceases
and @ gall-like protoplasmic plug free from chlorophyll, which
closes the wound, is formed at the prick point. Later the for-
mation of a new piece of membrane follows this provisional iig-
ature, In the case of strong secs of Bryopsis, after injury and
the resulting ejection of protoplasmic fragments, a plug of a
granulay substance is formed which I consider disorganized pro-
toplasm’, The formation of these peculiar stoppage masses in in-
jured cells may be followed under the microscope. The production
of the granular mass gives an appearance Similar to that formed
by the hardening of a drop of wax, Sometimes crystais of percep-
tible size are formed in this stoppage mass, the growth of which
may be followed satisfactorily under the microscope, although
all:the processes here described take place in the fraction of
a minute, The latex tubes are also closed after injury by coag-
ulation plugs.

Among the scar-membranes formed after plasmolysis or after
injury, we find some which entirely resemble normal ones in _
structure and capacity of growth, and still others, showing some
variations, as, for example, in the above memtioned scar-membrane
of Urtica, which remains very delicate and, more noticeably in
Algae, in whose cells Klebs found that soft, weakly refractive
membranes, ob¥iously very rich in water, were produced after
plasmolysis. (Spirogyra, Mesocarpus). Presumably, the action of
the foreign medium surrounding the cell (10 to 15 per cent sugar
solution) lies at the bottom of this.

It should be observed still further that all the newly formed
membranes are not capable of growth. While in many Siphoneae, it
may be demonstrated that scar-membranes often make a prolific sur-
face growth soon after their formation, still in the case of cell-
walls of other plants formed after plasmolysis, this growth is
regularly lacking, for example, in the cells of Elodea or Funaria
as cited by Klebs. In the plasmolysed and newly enclosed cells
of Oedogonium, no growth takes place, only division and the forma—
tion of Swarm spores, Where growth results, it leads in many

seis Rist em est tees tee ce da eR se ah see eee eS ea a a Fa eh ee ni ie ee ee a ee

Caen 1900, :

2 Compare Klebs and Schmitz in place mentioned. Further
Haberlandt, Ueb. die Lage des Kerns in sich entwickelnden Pflanz—
enzellen, Ber. d. D, Bot. Ges. 1887, BA. V, p. 211 and others.

3 Compare Kuster, Ueb, Derbesia and Bryopsis. Ber. d. D.
Bot. Ges. 1899, Bd. XVII, p. 77.

(15)

12

cases 6@ the development of abnormal types. In the case of
Zygnema,*as described by Klebs, irregular, spirally twisted
structures are produced.. (Compare figure 2). I found that
growth of the scar-membrane of Anadyomene in aquarium culture,
always leads to abnormal rhizoid-like forms, Undoubtedly in

both cases the abnormal activity of the growth may, under suit-
able culture-conditions, be replaced by normal formative processes

Finally those conditions are still to be discussed, the ful-
filiment of which must be considered as taken for granted in the
processes of restitution already deseribed,

Experiments with protozoa have proved that isolated cyto-
piasm oan form no new nucleus from its own substance and that is-
olated nuclei are just as little able to form cytoplasm, The rée-
generation of the cytoplasm presupposes a fragment of cytoplasn,
the regeneration of the nucleus, a fragment of the nucleus, Fur-
ther - regeneration of the cytoplasmic bodies from a remzxmt of
cytoplasm can take place only when a nucleus, or a fragment of a
nucleus, remains Connected with it and, conversely, a nuclear
fregment can be restored to c. normal nucleus, only when the cy-
toplasm, or 2 remnnnt of it, remains attached to this fragment.
Isolated nuclei without cytoplasm and cytoplesmic msses without
nuclei are incapable of living for eny length of time+, At least
parts of cytoplasm ond nuclei must remain united, if there is
to be any restitution of the cell.

These interrelationships were first observed in protozoa,
whose large, easily, dissectable nuclei make them favorable objects
for experimentation”, but for 2 long time they were misconstrued,
inesmuch as the activities of the nucleus, the "element of the
cell which bears the inheritcble characters ond qualities", weré
considered as the alpha and omega of 211 regeneration progesses,
and the importance of the cytoplasm completely overlooked”,

It is evident, #rom what has been said above, thet the well
so important for plent cells, can be regenerated also on cell
fregments which lack it entirely, and that further, its new fornm-
ation is produced from the cytoplasm, The fact that the cyto-
plasm can build a new wall only in the presence of and under the
influence of the nucleus is important here, Schmitz wes the first
to prove that isolated cytoplasmic fragments from cells of the
multi-nucleqgted Siphonocladiacene can remain capable of life end
of forming new independent cells, i. e. can provide themselves
with a new wall, only if the severed cytoplasmic mass has taken

” 1 Comp.re Verworn, Physiol, Bedeutung des Zellkerns.
Pfluger's Archiv, 1891, Bad. Li, p. l.

. The first experiments originated with Nussbaum (Ueb, spon-
tane und Kunstliche Teilung, Sitz,-Ber, d. Niederrh. Ges., Bonn
1884, Ueb. d. Teilbarkeit der lebendigen Materie. Arch, f.

mikr., Anat. 1886, Ba, XXVI, p, 485) and Gruber (Ueb. kunstl.
Teilung bei Infusorien I and II, Biol. Chl., 1884, Bd. IV, p.
717 and 1885, Bd. V, p. 137, Beitr, zur Kenntnis der Phys. wu.
Biol, der Protozoen, Ber. d, Naturforsch. Ges. Freiburg, 1886,

Ba, ty 2).

3 Compere especially Verworn, Allgem, Physiologie, 1895,
p. 486 ff. Theoretical discussions, on the significance ef the
nuclgus by Lgeb. Warum ist die Regeneration kernloser Protopjes-—
mastucke unmoglich oder erschwert? Arch. f, Entw.-Mech,, 1899,
Bd, VIII, p. 689.

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13

with it one or more nuclei from the mother cell, Klebs? has
treated in detail the significance of the nucleus enucleated
cytoplasmic pieces from the ceils of Zygaema, Spirogyra and
Oedogonium, or of Funeria, remained living a long time, to be
sure, in cane-sugar solution and, in the case of Spirogyra and
Zygnema, formed starch in their chromatophores, but never walls.
Haberlandt's experiments® continue those of Schmitz and Klebs,
and give the same results. According to Prowazek floc, cit} the
greater the number of nuclei contained by the cytoplasmic mass,
the more quickly these regenerate’. The theory brovght forward
by Palla {loc., cit.) that cytoplasmic pieces without nuclei are
also capable of forming cell-walls has been disproved by the
work of Acqua and Townsend (loc. cit.).

The last named author took an important step forward when he
discovered the distant effect of the nucleus. Even pieces of cy-
toplasm free from nuclei are capable of forming membranes if the
influence of the nucleus can be extended to them by means of con-
necting strands from distant portions containing nuclei or from
uninjured cells lying at a distance, In this, however, a "living
continuity” is necessary, contact alone being insufficient for
the transference of this influence, The best data on the influ-
ence carried from cell to cell is given by the experiments with
Sieve tubes of Cucurbita and Bryonia which lack nuclei, but which
may form new walls after piasmolysis. in no case could the for-
mation of membranes be observed in the completely isolated, cyto-
plasmic masses of the sieve tubes which had passed out of the
tubes, Townsend proved the transmission under the influence of
neighboring cells containing nuclei, of the wall-forming stimulus
to a distance of several millimeters under the influence of
neighboring cells containing nuclei-:.

Nothing is known as yet of any after effect of the nucleus

1 Compare Tagebl, der Berliner Naturf.-Vers,, 1886, p. 194;
Veb. d. Einfluss d, Kernes in der Zelie, Biol, Cbl, 1887, Bd.
VII, p. 161; Beitr. 2, Phys. d. Pflanzenzelle. Ber. d. D. Bot,
Ges,, 1887, Bd. V, p. 181; further the detailed publication
already quoted,

2 Besides the above quoted articles compare, Ueb, d.
Bezieh, zw. Funktion and Lage des Zellkernes b. D. Pfi. 1887;
Ueb, Einkapselung des Protoplasmas mit Rucksicht auf 4d. Funktion
des Zellkernes, Sitz,-Ber. Akad. Wiss. Wien, math.-naturw, Kl,,
1889, Bd. XCVIII, Abt. 1, p. 190.

3 ruber, (loc. cit,) states, that pieces of protozoa
reform complete bodies the more quickly, the larger the nuclear
fragment, which they have carried with them. :

4 By this distant yeaection of the nucleus the above quoted
observations of Pa2la {lec, cit.) may well be explained, as well
as those of A, Griittner, Ueb. die Erzeugung von kernlosen
Zellen etc,, (Diss, Erlangen, 1897). Strumpf tried in another
Way to harmonize the different results with one another; he ex-
presses the gonjecture that the cytopiasm of young cells, even
without nuclej{, may form membranes, but that the old cells need
the reaction ef the nucleus. (Zur Histologie der Kiefer, Anz.
Akad, Wiss, Krakau, 1898, p, 312).

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+ , 14
upon enucleated pieces of ce1lt,

«

Scar membranes occur in most plants of which the cytoplasm
is found capable of forming them’, so far as the above described
action of the nucleus is made possible. In some other plants it
appears that the conditions for wall-formation are not yet ex-
hausted with this; at least, according to Klebs, in plasmolyzed
cells of Zygnema the influence of light is a further condition
for wall-formation,

We have spoken as yet only of the restitution of the wall.
Unfortunately, we are imperfectly informed as to the regenera--
tion of the living cell elements. The fact that notiieted ecélls,
whose wounds have been heeled by a new formation of membrane,
can continue growth has been emphasized for different kinds of
plants, Since the cells during and after growth contain norma]
protoplasmic quantities,- so far as an estimate allows of any
decision, it may be accepted that the mutilated protoplasmic
body is capable of a restitutionary growth, Nothing has yet
been learned as to whether nuclear fragments, as in the case of
protozoa, can also grow into normal nuclei, whether mutilated
chromatophores, as those of the conjugates, can attain their
normal Size by growth, whether in mature assimilatory cells,
after the removal of some protoplasm and chlorophyll body, all
that remains in the cell can be excited to division;- and mich
more of the same kind.

2, RESTITUTION OF THE TISSUES

In the following, those processes of restitution will be
discussed, in which the injured cells themselves are not healed,
but in which intact cells near the injured ones make reparation
by growth, eventually also bh division. At least two cells will
therefore take part in the whole process, the one injured and
the one making restitution.

. This, the simplest case, is realized in the liverworts;
for example, in Marechantia, If the long, unicellular rhizoids
are out off from youthful parts of the thallus, compensatory
hairs are formed, even after a few days, one of the neighboring
cells of the trichome base (compare figure 3a) developes into
an unicellular hair. The compensatory hair grows out through
the oavity of the mutilated one, and from the end of the stump,
into the substratum. The lumen of this substitute hair is often
noticeably narrower than that of the normal hair.

1 Gruber, (Beitr. z. Kenntnis d. Phyz. u. Biol, ad. Proto-
zoen in place mentioned p, 13) states that in fragments of pro-
tozoa, lacking nucleus, incomplete peristomic regions may still
develop as a result of an after effect of the nucleus, Accord-
ing to Balbiana (Nouv. rech, exper. sur la merdtomie des infus.
ciliees Arch.de Microgr, 1891/1892, T. IV, p. 369) an after ef-
fect can be demonstrated only in so far, that a constriction is
found in those nucleus-free pieces of individuals, which were
taken directly before their cell-division, Never, however, does
complete cell-division take place; on the contrary, the two
halves fuse again.

. To be sure, there are exceptional cases, in which even
in the dgrk (Klebs loc. cit., p. 541} “a formation of cell walls
takes place about the # herical protoplests. In pure sugar sol-
utions I have observed this very rarely, while, on the contrary,
in sugar congo ref, & number of protoplasts in each larger cul-
ture of Zygnpma C. werg surrounded with a red cell-wall".

: 15
Diaphyses of this kind were thoroughly described for Mar-
chantia and Lunularia by Kny*. Since my experiments have proved
that any desired number of compensatory structures may be called
forth by cutting back the rhizoids, this development of the par-
enchyma cells on the trichome base may be brought into undoubted
connection with the wound stimulus or its results, To conclude
from Kny's data, other factors also seem able to excite a stimu-
lus, Similar to the one usually associated with the nutilation
of the rhizoid, At least Kny states that diaphyses oceur also in
rhizoids in which the membrane is intact. Then the secondary
hairs find at the tip of the primary ones an energetic opposition
to further elongation, which may lead to a bending and curling.
(18) Kny observed further that even a tertiary hair may develop in a
Secondary (Fig, 3b) and that, occasionally, two cells at the
base of the primary rhizoid, instead of one, may develop into
compensatory hairs,

_ _In the case of many multicellular algae, the thallus of
which is made up of filaments consisting of rows of simple cells,
(for example, Trentepohlia) similar regeneration phenomena take
place after the removal of the growing tip, The uppermost cell,
left intact, continues the growth of the mutilated filament.
Therefore, thg regenerating phenomena of growth proceeds here also
from one cell*,

In the case of the higher plants, restitution processes of
this, the simplest kind, are rare, The p ocesses of healing and
regeneration observed by Miehe on Tradescantia virginica are some -

‘ what comparable to the diaphyses of Marchantia rhizoids. After
the dying off of single epidermal cells, or small cell groups,
the wound is closed over by the growth of the intact neighboring
cells. In this way, one may occasionally find single cells com-
pletely filling out the gap of the dead neighboring elements. I
will return later to these phenomena. (Chapter IV, 4).

Regeneration of tissues, brought about by unlimited division
of the exposed cells, often takes place in thallephytes in so far
as a differentiation of pith and bark tissue may be recognized
in them,

In the sclerotia of Coprinus stercorarius, investigated by
Brefeld, the outer coat consists of Six to eight layers, with
black guticularized walls, If these are removed, the inner cells
regenerate anew outer coat, “Some division in the inner cells,
as well as the very close association of the cells which have di-
vided to produce the thinner tissue -of the outer coat together
with a stretching of the eutermost cell-layers to form the great
cells of this coat are the processes, which must necessarily
take plgee, in order to develop the outer coat from the inner
cells”, This experiment may be repeated with sclerotia, as long
as the inner substance lasts, ’

Algae, especially the Florideae, behave similarly in the ex-
tent to which they exhibit tissue with disginguishable pith and
bark, By truncations and tears, or after removal of the bark, a

1 Eigentuml, Durchwachsungen an den Wurzelhaaren zweier
Marchantiaceen, Verh. Bot. Ver, Prov, Brandenburg, 1880, Bd.

XBI, p. 2.

; 2 Illustrations in de Wildeman: Sur la reparation chez
quelques algues, Mem, cour, et autres mem. acad, Belgique,
1609, 2, IVIIIs

x

3 Brefeld, Botanische Untersuch, uber Schimmelpilze, 18937,
Ba, III, p. 25.

(19)

(20)

. 16

small-celled bark, rich in chromatophores, is regenerated from
the large, colorless, or Slightly colored cells of the pith.
According to Massart~ some brown algae (Laminaria, Pelvetia) also
behave in this way; in them e small celled soar-tissue is also
produced from the exposed inner layers, which resembles the hormal
bark tissue,

Only a few cases of tissue restitution are knowm in the high-
er plants, The periderm is on the whole easily regenerated, “the
epidermis, however, not always, Although in "physiological" in-
juries, by means of which perforated or secreted leaves of d.ffer-
ent plants obtain their characteristic form, a tissue is forme,’
at the edge of the wound, which corresponds with the epidermis”,
yet when the integrity of the stems end the leaves is violently
distrubed generally no new formation of the epidermis takes place.
Tittmen has proved this definitely by countless experiments, Ac-
cording to Messart (loc, cit. p. 55) the leaves of Lysimachia
vulgaria seemingly form an exception to the rule; they regenerate
normal hair-bearing epidermis, when injured in a very young stage.
In roots, the cbjlity to form new epidermis after injury is wide-
spread; Lopriore* observed on split roots the formation of norml
epidermis provided with root heirs. (Compare fig. 4). In the for-
mation of leteral roots also & typical epidermis arises from the
derivatives of the more deeply lying leyers of tissue.

Finally the regeneration of the vascular bundles is to be
mentioned, Roots and shoots which have been Split lengthwise will
complete each helf of the fibro-vascular system to a complete cen-
tral cylinéer}. In monocotyledons, regeneration of roots takes
place by the simultaneous restoration of epidermis, phloem end
xylem. In dicotyledons, however, the endodermis is regenerated
first, later the xylem and phloem (Compare again fig. 4). In the
same way, after splitting shoots of Salix, Aristolochia, Lonicerg,
Sambucus and many others, Kny observed the production of wound
tissue from pith, cambium and bark, in which @ new cambium was
formed. This was connected'on both sides with the cambium of the
normal vascular-bundle, ond, like this, produced xylem elements
towards the inner phloem elements towards the outer side, The
investigations of Kny and Lopriore make it probable that very
many, if not all, vhanerogams possess the ability to restore des-
troyed central cylinders.

— ee eee -—-— = —-— — — — -— == = — — -— — — — — Fe Fe Zr ll - - = —_ =

autres,mem. Acad. So. Belgique, 1898, T, LVII.
Tittmann, loc, cit. p. 117.

2 Schwarz, Fr., tiber die Entstehung der Lochér and Fin-
buechtungen an dem Blett von Philodendron pertusum, Sitzungsber,
Akad. Wissensch. Wien, 1878, Bd. LXXVII, Apt. 1, p. 367;
Lippitsch, Ueber das Finreissen der Laubblatter der Musaceen
and einiger verwendter Pflanzen, Oest. Bot. Zédtschr., 1889,
Bad. XXXIX, p. 206.

4 Uber Regeneration gespaltener Wurzeln, loc. cit. Comnare
also Ber. D. Deutsch. Bot. Ges., 1892, Bd. X, p. 76. .

5 Compare especially Kny, Ueber xunstliche Verdoppelung
des Leitbindelkreises im Stamme der Dikotyl. Sitzungsher. Naturf.
Fr, Berlin, 1877, p. 189. Lopriore, loc.cit. end Vorlaufige
Mitteilung uber die Regeneration gespaltener Stammspitzen. Ber.
der Deutsch, bot. Ges,, 1895, Bd, XIII, p. 410.

CHAPTER II

HYPOPLASIA

al

We speak of Hypoplasia if an organism or one of its
parts does not attain a normal development but ends its de-
velopment prematurely, so that forms or characteristics ap-
pear fixed as final, which, under normal conditions, belong
only transitorily to the organisms or organs concerned. To
put it briefly, Hypoplasia is defective development, and its
products remain in one or in several respects below the re-~
sults of normal development. The development of the organ-
isms or organs appears as though "arrested", on which account
we can term the products of 2 hypoplastic process arrested
developments.’ From the aforesaid it follows that in
treating of arrested developments, we will be concerned only
with forms and pecularities of the organisms and thier parts,
already known from the ontogeny pf normal individuals.

The discussion of arrested=development devolves upon
either morphologists or anatomists, according to whether the
argestment may be recognized in the maturing of whole organs,
or in the development of the cells and tissues. On the morph-
ological side a large number of obsgrvations have been col-
lected and utilized scientifically. They prove that the
arrested development of similar organs can result very dif-
ferently, since very different stages of the normal progress
of development appear to be "fixed". In addition to this,
it is proved that those processes of growth and differenti-
ation are not always equally arrested, which in a normal
course of development, are associated in time and place.
Thus, for example, very different kinds of arrested-devel-
opments may be pointed out in leaves. In many such cases,
the leaves vary from those normally developed in the small-
ness of their size. The etiolated sprouts of many plants
furnish examples of this. In other cases the leaves are
less retarded in size than in form; for example, in the case
of specimens of Sagittaria grown under water, of the Ret-
inospora form of many conifers, different galls on the tips
of the shoots, etc. Thirdly, the form of the leaf may re-
main undeveloped. Either the initial folding and curling
of the leaf blade is retained, as in the artificially forced
branches of Aesculus, Gingko, etc.; in the etiolated speci-
mens of Viola; in many leaf galls (Phytoptus mites on Rosa,
Fagus, ete.); or the inclination of the leaf to the axis re-
mains as it was at first,- for instance, in Willow leaves
unfolded under water, in the galls on the tips of Glechom
shoots (Cecidomyia), etc. Of course the leaves may also
"remain below the normal" in more than one respect. The
examples here chosen should demonstrate at the same time that
arrested developments of the same character can be produced
by the most varied influences.

L. The word Hypolasia is derived from the terminology of
the medical science; the term arrested development has long
been familiar to botanists.

2. Compare especially Gobel, Organographie, 1898, p. 121,
and the literature quoted therein.

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18

The diversity manifested in the arrestment of cell and
of tisgue development is very Similar. Either the number
of the cells composing a certain organ or forming a certain
definite tissue, remain below the normal, or the size of the
individual cells is smaller than under normal conditions,or
finally, the internal structure of the cells and the differ-
entiation of tne tissues stops at # primitive stage, Hence

the succeeding elaborations follow without further discussion.

Arrested developments of the most varied kinds are to be
observed abundantly, on the one hand, in many plants in navc~
ure, or on the other hand, may be readily called forth by ©
experimental interference at any time. Since, furthermore,
arrested development of cells and tissues is often combined
with some obvious external characteristics, the attention of
the botanist has been repeatedly directed to then. Corres-
pondingly, a surprisingly large number of reports may be
found in the literature bearing upon the same abnormal con-
ditions. On account of the often very inadequate content
of the works, it will be sufficient to mention only selected
ones in the discussion which follows,

A. NUMBER OF CELLS.

We have spoken already of arrested developments, in
which the bulk of whole organisms or single orrans remained
begow the normal ~roportions. In so-called Nenism, that is,
when the plants attain only a fifth or a tenth of their normal
size as a result of continued drought or unfavorable nutri-
tion, a corresponding reduction of the size of the cells
to a fifth or a tenth of their normal proportions does not
take place parallel to the reduction of the. plant volume;
on the contrary, the cells of the dwarf specimens consist
essentially of cells approximately as large as those of
normal individuals; the small size of the starved indivi-
duals being hiefly brought about by a reduction in the
mumber of cells.

Similar conditions exist if only single organs, leaves,
blossoms, fruits, and not entire plants are dwarfed. For our
histological consideration, however, in both cases, only those
come into question in which decfease in the number of eelis in
connection with a shortening of the internodes, a reduction
of the leaf-blade, etc. brings about a variation in the his-
tology of the organs concerned. Such cases exist, for ex-
ample, if the number of the cell layers in the mesophyll de~
creases, if, by the disappearance of one or more palisade lay-
ers, the proportion between palisade and spongy parenchyna

i

1, Compare for instance, Mdller, H., Beitr. zur Kenntnis
der Verzgwergung (Nanismus). Landwirtschaftl. Jahrb., 1884,
Bd. XIII, pe 167 and especially Gauchery, Rec, sur le nanisme
vegetel, Ann. Soc. Nat. Bot., VIII, serie, T. IX, 1899,
p. 61. (Further literature is quoted therein.}

19

is changed, and so forth. Some histological varictions of this
kind are to be discussed in the following.

1. The structure of the leaf tissue is dependent, to a
high degree, on the action of external factors, the number of
cell-layers which form the mesophyll and epidermal tissues varies
with the life conditions of the plant. The difference between

(24) the leaves of many plants exposed to the rays of light and those
grown, in Shade, verified by Stahl and other authors, is well-
known", In the mesophyll of the sun leaves of Fagus silvatica
(compare fig. 5 b.) Six to eignt or even more coll iayers Lie
one above the other,- in the shade leaves only three (fig. 5c).
With the medium supply of light, the development of the meso-
phyll keeps the mean, (fig. 5a). This arrestment, due to in-
sufficient exposure to light, is undergone also by the mesophyll
of other plants, further by the epidermis of those piants, which
normally develop a many-layered upper covering. Figure 8 demon-
strates the difference between the epidermis of a sun leaf, and
@ Shade leaf of Ficus stipulata; the cross divisions are iack-
ing in the leaf kept in shade. We will return later to other
differences between shade and sun leaves,

The characteristic development of shade and sun leaves is
determined less by light itself than by transpiration, which
proceeds in the latter much more actively than in the former.
On this account, leaves with the scantily developed mesophyll
of shade leaves,may be produced in damp air with an abundant
supply of light’. .

Griffon® verified the reduction of the number of layers
in Canna, Chrysanthemum and others, in his comparison of the
pale green vgrieties with those normally green.

1 Compare especially Stahl, Ueber den Einfluss der Lich-
tintensitat auf Struktur und Anordnung des Assimilationspar-
enchyms,. Bot, Zeitung, 1880, Bd, XXXVIII, p. 868. Ueber den
Einfluss des sonnigen und schattigen Standortes auf die Aus-
bildung der Laubblatter. Jenaische Zeitschr. f. Naturwissen-
schaften, 1883, Bd. XVI. Further, Pick, Ueber den Einfluss
des Lichtes auf die Gestalt und Orientierung der Zellen des
Assimilationsgewebes, Botan, Centrabl, 1892, Bd, XI, p. 400;
Haberlandt, Physiol. Pflanzenanatomie, 2. Aufl. 1896, p. 252.
(More literature references therein), Compare also the lit-
erature quoted on the following pages.

= Compare the experiments of Lothelier, Rech. sur les pl.
a piquants. Rev. gen, de Bot,, 1893, T. V. p. 480; further
Vesque, Sur les causes et sur les limites des variations de
structure des vegetaux, Ann, Agron,, 1884, T, IX and X.
Vesque et Viet. De l'infl. due millev sur la struct. anat,
des. vegetaux. Ann, Sc, Nat. Bot., VI. serie, T. XIII, 1881,
p. 167.

3 ttassimilation chlorophyllienne et la coloration, Ann,
Sc, Nat. Bot., VIII, serie, ¥. X. 1889, p. l.

4

: 20

This dependence on external factors, as shown in meso-
phyll and epidermis, in reference to the number of cells
and layers, is proved also in the multicellular hairs of v
many plants, the tissues of the bark, and still others, and
always in the sense that with decreased transpiration few-
er €ells and cell Layers are formed than under normal con-
ditions;-1

& The reduction of the cell number in the products of
the cambium is very striking. The varying amount of the an-
nual increase of our trees is well known, its dependence up-
on external factors having been proved by research. Factors
acting locally re involved if the growth activity of the
cambium is retarded by strong pressure,”%, or if the increase
in growth continuous y remains less on the windy side than
on the opposite one. tne effect of disturbances in nutri#
tion or that of unfavorable cyimatic life conditions, iS ex-
pressed equally in all parts. In the far north or in an
Alpine climate the activity of growth of the cambial ring
4s Blyays' FeSS than in lower altitudes or temperate

at? ug 5 Oger observed this arrestement in plants kept

eee andi ed eek
wo ee ee ee ee me ee eae

1. Mitteilungen Uber das Blattegewebe einiger Moose
(Reduktion der Laméllen bei FPeuchtkultur) in Gobal, Organ-
Ographie, p. 364.

2. Kuster, Ueber Stammverwachsungen. Pringsheim's
Jahrb, f. Wiss. Bot., 1899, Bd. XXXIII, p. 487.

3. Hartig, R. Wachstumsuntersuchungen an Fichten.
Forstl.- Naturwissensch. Zeitschr., 1896, Bd. V, ps l.
Compare also Busgan Bau und Leben unserer Waldbaume, Jena
1897, pe 98, 99, and the literature quoted therein. (Schwein-
furth and others.)

4, Hartig, loc. cit. also Zeitschr. f. Forstl- und.
Jagdwesen, 1871, Bd. III, p. 340 (Holzuntersuch., 1901,
p- 5) and other places,

5. Lazniewski, Beitr. z. Biol. der Alpenflanzep.
Flora, 1896, Bd. LXXXII, p. 224. Kraus, Bemerkungen ub.
Alter~ u. Wachstumsverh. ostgrénlandischer Holzgewachse. II.
Deutsche Nordpolfahrt, 1874. Kihlman, Pflanzenbiol. Studien
aus Russisch-Lappland. Acta Soc. F. et Fl. Fennica, fT. VI,
Nr. 3. Helsingfors 1890. In Pinus silvestris, H. Hoffman
observed an abnormal lobated wood-body which was produced
by local arrestment of the formation of xylem. (Ueber ab-
normale Holzbildung. Centrabl. f. ges. Fortwesen, 1878,
p. 612; Compare Just, Jahresber., 1878, Bd. VI, 2, P- LIST}.

21
ver dry ,t etc. The cork meristem also acts like the
Cc ium. According to Douliot it is less active on the 2
Shaded side of the branch than on that exposed to light.

It is not surprising that the growth activity of the
cambial ring not only loses its normal intensity by con-
tinued and sufficiently intensive action of the disturbing
factors, but also in places comes temporarily to a complete
standstill. As a matter of course we do not need to re=
peat the fact that each’ process of growth presupposes a
minimum of heat supply , nutrition, etc. We will call ate
tention only to a few cases in which the interruption of
the normal processes of growth brings about variations in
the histology of the plants or of parts of them. Unfavor-=
able conditions of light and nutritign retard in places
the setting of the cambial activity.° or can bring it to
a Standstill for a number of years, or even permanently.
Weak Spruces distontinue their srowth in thickness in the
lower parts of the trunk; the brambles behave similarly.
Mer floc. cit.) observed on hyponastic conifer branches
that the normal growth in thickness progressed only in a
longitudinal half, and thus led to the formation of half
of an annual ring. How far “normal” life conditions and
*normal" phenomona of growth are involved in the produc=
tion of semi-annual rings is an open question.

Finally, even factors with a narrowly

(26)

1. Oger, Etude, exper. de l'action de l'humid, du
sol sur la struct. de la tige et d. feuilles. C. R. Acad.
Sce Paris, 1892, T. CXV, p- 525. Further references on
reduced cambium activity are to be found in the treatises
quoted on page 26, ff.

2. Douliot, Rech. sur la periderme. Ann. Sc. Nat.
BO. Serie Vil, Ts KZ, 1G89, Be Sed? Intl. dé ta tum, Sur
le devels du leipe, Journs de Bote 19890. Til pe 222.

3. Hartig. Untersuchungen ub. die Entstehung u.d.
Eigenschaft des Eichenholzes. Forstl.-Naturw. Zeitschr.
1884,-Bd. III, pe. 1, Mer, sur les causes de variation de
la densite des bois. Bull.soc. Bot. France,1892, Tom.XXXIX
ps 95, Ste.

4. Hartig, Das Aussetzen der Jahresringe bei unter-~
druckten Stammen. Zeitschrift f. Forst ~ und Jagdwesen,
1889, Bd. I, p. 471. Ueber den Entwickeiungsgang der Fichte
im geschlossenen Bestande nach Hohe, Form und Inhalt. Forstl
Hturw. Zeitschr. 1892, Bd., I, pe 169, ete.

5. Compare also Lammermayr, Beitrage z. Kenntniss
der Heterotrophie v. Holz. u. Rinde. Sitzungsber, Akad.
Wiss, Wein, math=<naturw. Klasse, 1901, Bd. CX.

27

22

limited field of action may in places arrest growth in thick-
ness, such as strong pressure (Kuster, loc. cit.) disturban-
ces in nutrition due to parasites, etc.t

In conclusion, still a reference to dwarf forms, the
anatomy of which Gaucher (loc. cit.) has described in detail.
According to his observations, the scanty development of the
secondary tissues or their complete absence may be added to
the constant histological characteristics of dwarf forms.

In many cases no meristematic zone whatever is demonstrable
between xylem and phloem, in others a cambium appears, which
develops, however, only @ moderate activity. Figure 6 makes
very clear the difference between a normal sten (a) and 2
awarfed one {B) of Erigeron canadensis. Between the two ex-
tremes here shown, all transitomal forms with more or less
well developed secondary tissues are possible.

as a matter of course, in the present discussion, only
a limited number of examples is given, which might easily have
been increased. A continuation of their enumeration would
give, however, no new points of view, and may well be aban-
doned. For the rest, the literature quoted in the succeed-
ing divisions cites numerous other examples of hypoplastic
decrease of the cell number.

B. SIZE QO. THE CHLLS

AS may be supposed from the very beginning, abnormally
small cells,- when considered ontogenetically may be produced

in different ways:

They may divide anew, before they have reached the

Size which the cells under normal conditions usually have
when ready to divide. No law exists which would bring cell
division into compulsory dependence upon a definite cell-
Size. This method of production plays an especial part in
the case of lower organisms which increase by division. Or
the growth in length following the last cell division, is
either omitted or ends prematurely; or the cells end the

" course of their development prematurely, so that all the

processes of grovth and division are lacking, which uncer
normal development would still have taken place in them.

In the following description it will prove advisable
not to take as a basis developmental differences in the dis-
tribution of materials, but to describe in order the phen-
omena of arrestment in different organisms and kinds of tis-
sue. We will begin therefore, with an example of the first-
named mode of development. i

spesie =

1. Brunchorst, Nogle norske shovsygdomme. Bergens
Mus. Aarbog. 1892.- Just. Jahresbericht, Bd. Aula, pe. 438,
(einseitige nach Infektion met Peridermium Pini). Mer, Le
chaudron du sapin. Rev. gens. de Bote, 1894, T. VI, ps 153.

23

In his_,"Contributions to the Biology of the Plant
Celt Klebst describes a singular observation on Eust-
rum _verrucosum. These Algae were cultivated in a 10 per
cent cane sugar solution. No Plasmolysis took place: on
the contrary, the cells began to divide, whereby active
growth was so hindered that the daughter cells divided
anew before they had attained their normal form; the nex
generation did the same. Thus, not only abnormally formed
cells were produced which varied greatly from the type of
the species (compare fig. 7a), but dwarf Specimens also,
appreciably smaller than their normal progénitors and
living only a short time (compare fig. 7b). The theory
that some form of arrestment exists here is justifiable,
Since the growth activity of the single cell ends_premat-
urely, resulting in abnormally small individuals.

In higher plants, when hypoplasia is shown by the pro-
duction of abnormally small cells, the conditions are gen-
(28) erally such that the period of elongation, which under
normal conditions, would follow the last cell-division
either does not take place or ends prematurely.

Of course it is gmpossible to differentiate sharply
between arrested developments of this kind and "normally"
developed tissues. Some tissues, as for example, the pal-
isade parenchyma of many leaves and the cork and the 7
primary bark of some woody plants are exposed of cells of
nearly equal size. In other tissues, such as the endodermis
of Fiscus elastica and the xylem of many woody plants, the
volume of elements of equal value physiologically and _
histologicglly, fluctuates within wide boundaries, Hartig
and Sanio “ have proved for tracheal tubes, tracheids, and
wood fibres of various trees, that their size is not only
dependednt upon the season in which they are produced as
shown by a study of the annual rings, but that in various
annual growths, et varying heights in trees, etc. elements
of regularly varying size may be met with.Since, in spite.of
all differences in normal individuals a constant average

—e ee
A me et ee cme tees eae Ht eee pe NE oe eee Ree ee Ges Sm te Wales ee me RN Nom tae i fy Me et wanes ee Ae fim wee Gem Mee fee em wom Meet Me Pee es ee ge ee ee

1. Tubinger Untersuchungen, 1888, Bd.11,3,p. 547.

2, It is to similar factors that also the "bastard
form" belonging to the genus Zuastrum and described by
Bennet, may well owe its production. Ann. sf Bot. 1889,
Vols IVe U7.

3. Hartig, Th. Vollstandige Naturgeschichte d. forstl,
Kulturpflanzen Deutschlands, 1851, p. 207. Sanio, Ver-
gleich. Untersuchungen uber die Elementarogane des Holz-
korpers. Bot. Zeit. 1863, Bd. XXI, p. 128; Vergleich,
Untersuchungen uber die Elementarogane des HolzkorperSe
Bot. Zeit. 1863, Bd. XXI, p.,128; Vergleich, Untersuchun=
gen uber Zusammensetzung des Holzkorpers, ibid., De 596.
Ueber die Grosse der Holzzellen in d. gemeinen Kiefer,
PringBheim's Jahrb. f. wissensch. Bot. 1872, Bd. VIII,p.
401, Anat. ad. Bei. Keizer, ibid. 1873, Bd. IX, p. 50% Com
pare further Hammerle, Zur. Organisation von Acer Pseudo~
platenus. Bibl. Bot. Nr, 80, 1900, and the literature
quote. therein.

29

24

Size of the cell is demémstrable, an examination into the

size development of cells for phenomona of arrestment will
not be, purposeless,

Amelung ascertained that "in the case of parts of
plants morphologically equal, the medium cell-sizes re-
main the same in spite of extraordinary differences in
size. The question must still be discussed whether
plant organs, dwarfed by the force of abnormal life con-
ditions, lack of water, insufficient nutrition, etc. are
composed of elements of equal size with normal organs. If
it was necessary above to emphasize the fact that abnormal-
ly small organisms or organs are produced exclusively or
predominantly by reduction of the cell number, it should
now be added, that reduction of the cell size in all cases
which are to be designated as arrested developments, in
which, therefore no compensation takes place through in-
crease of the cell-number, must lead necessarily to the
formation of abnormally small, slender organs. In many
eases, moreover, reduction of the cell number is combined
with a decrease in cell-volumne. We will therefore have
to return repeatedly to the examples given above.

To be sure, dwarf~forms, at&éining only a fifth or a
tenth of the normal size, as stated above, do not consist
of cells proportionately decreased in size; yet an evident
reduction of the volumne may be verified, at least in cer-
tain kinds of cells. It is interesting that many kinds are
somewhat more susceptible than others and many easily re-
main below the normal size development, while others, even
in highly dwarfed specimens, retain their normal size. Those
tmacheal tubes, in which a reduction in diameter may be
constantly recognized, belong to the first class. (Compare
fig. 6). The epidermal cells of leaf blades generally
retain their normal volumng , while the cells of the meso-
phyll are greatly reduced.

Influences, other than those which call forth the
"dwarfing" of whole plants, also arrest very appreciably
the growth of the mesophyll cells. First of all, a com-
parison of sun and shade leaves proves this: in the latter
not only the mesophyll cells are often greatly shortened,

,but even the epidermal cells may be very small, for in-

stance, in\Ricus stipulata, (compare fig. 8a and b.) The
same reduction in cell size may be verified in those var-
ieties with pale green leaves, which Griffon (loc. cit.)

1. Ueber mittlere Zellengrossen. Flora, 1893, Bd. LXXVII,
pe 176. Compare also Schnegg, Beitr. zur Kenntnis der Gat-
tung Gunnera, Ibid., 1902, Ba. XC, p. 161

2 Compare especially Gauchery, loc. cit. As exceptions
are mentioned the dwarf leaves of Polygonum Fagopyrum the
epidermal cells of which are perceptibly smaller than thosee
of normally grown specimens. Compare further H. Moller,
loc. cit. Sorauer, Einfluss 4. Luftfeuchtigkeit. Bot,
Zeitge, 1878, Ba. XXXVI, De le

30

25

ihvestigated in variegated plants, in specimens in-
jured by parasites, etc. FPinally,cells which are consid-
erably smaller than normal ones may be grown in such a
Way experimentally that an increase in cell volume is
mechanically prevented by putting the young parts of the
plant in plaster casts. If the nor4amal process of cell
Givision takes place at the same time, abnormally small
cells are produced,

Abnormally narrow tracheal tubes are found not only in
the fibroevascular bundles of dwarf specimens, but also
in poorly nourished individuals, in etiolated plants, and
in individuals infected by fungi or arrested in their de~
velopment by gall—producing animals.

The products of the cambium also are variously ar
rested in size, develop ; by diverse factors. Very
strong pressure may arrest the normal development of wood
cells.# In the same wey small~celled wood results
from disturbances in nutrition. Hartig has proved repeat-
edly in pines, that the tracheids are smaller in weakly
grown specimens than in those normally developed. The
lumen width of traeheal tubes in secondary xylem, especial-
ly is asp easily changed by all possible injurious in-
fluences. Among others, Wiedersheim's interesting ex-
periments give much information as to the effect on growth
4n- length of xylem elemenits.®.

; 1. Timpe, Beitrag zur Kenntnis der Panachierung. Dis
sertation Gottingen,1900; Leist, Ueber den Einfluss des al-
pinen Standorts auf die Ausbildung 4. Laubbl. Mitteil.
Vaturf. Ges. Bern, 1889. Klebahn, Ueber eine Krankh. Ver-
anderung d, Anemone nemorosa etc. Ber. d. D. bot. Gesselsch.
1897, Bd. XV, pe 257.

2. Compare the experiments of Hottes, Ueber den Einfl.
yon Druckwirkungen auf die Wurzel von Vicia Faba. Disserta-
tion Bonn, 1901. ;

3. Compare for example, Pethrbridge, Beitr. 2. Kenntn.
d. Einwirkung der anorganischen Salze auf die Entwickelung
und den Bau d. Pfl. Dissertation Gottingen 1899; further
bibliographical references therein.

4, Krabbe, Ueber ad. Wachstum d. Verdickungsringes u.d.
jungen Holazzellen. Abhandl. Akad. Wiss., Berlin 1884,

o ole
. 5. Die Verschiedenheiten in der Qualitat und un anat.
Bau des FPichtenholzes. Forstl.~ Naturwiss. Zeitschr., 1892,
Ba. 1, pe 209. Wachstumsunters. an Fichten, ibid. 1896, Bd.
V, pe l. Further examples are described by H. Vv. Mohl
{Einige anat. wu. piysiol. Bemerk. uber d. Holz der Baum-
wurzeln, Bot. Zeifg., 1862, Bd. XX, pe 269; Wiejer, Ueber,
Bezieh. zw. d. sekund. Dickenwachstum vu. d. Ernahrungs-
verhaltnissen der Baume. Tharander fosstl. Jahrb. 1892,

Bd. XLII, p. 72; Holzbildung auf Kosten 4. Reserve-materials
der Pflanzen, ibid. Bd. XLVII, p. 172.

6. Ueber d, Einfl. d. Belastung auf die Ausbildung von
Holz. und Bastkoper bei Traurbaumen.Pringsheim's Jahrb.f.wiss
Bot. ,1902,Bd. XXXVII,p 41. Compare also what is Stated later
for "Rotholz" (Chapter V. A.)

; ‘ 26

This author gscertained in different woody plants that
wood cells couhd not attain their normal length under the
influence of artificial mechanical strain. To be sure,
the differences are not very great, in Fagus silvatica
var. pendula, the wood cells of normal branches, for ex=

ample, bear to weighted ones :
29.525, etc. 6 nes, a proportion of 33.224 to

: To return finally to the statements made at the be~
ginning of this section,~ it can be proved forthwith that
most of the examples of reduction in cell-size given here
also. furnish examples of the second of the two modes of
growth described above. AS examples of the first named mode
of those given here only the phenomena observed by Klebs
in Euastrum come under our consideration,~ as well as the
case of the plant which had been put into a plaster cast,
and which was studied by Hottes.

C. DIFFERENTIATION OF THE CELLS AND TISSUES

_ An organ attains its specific character through dis-
tinct processes of differentiation enacted in its cells
Yather than by the number and volume of the cells composing
it. The cells attain a characteristic form by definitely
regulated or localized growth. Further, the histology and
physiology of the cell is determined by the formation of
Living or lifeless cell contents, by thickening of the cell
walls, and by modification of its chemical composition. In
most cases, the formation of the cells of an organ differs
according to their position in it, so that finally the
area organ is composed of elements of very different

inds.

In the study of arrested developments, those cases come
first under consideration in which the formative procéss
of individual celis stops prematurely, so far as form,
wall, or contents are concerned; secondly those in which
the cells of a tissue or an organ, varying in the same sense
from the normal procedure, are developed and produce a ho-
mogenous tissue instead of well differentiated layers.

hy FORMATION OF THE CELL

Both of the essential elements of the cell,- cytoplasm

31 and nucleus,» are excluded here from our discussion. As yet,
only very little has been definitely ascertained concern-
ing the structural peculiarities of cytoplasm and only in
isolated cases have we been half way instructed ontogen-
etically about the production of definite structural dif-
ferences. Conditions, so far as the nucleus is concerned,
are more favorable. In some ciliates (Oxytrichides), in
the formation of nuclei, with two or more parts, or even
rosette-like, and in the distinctive formation of macro-
and micro-nuclei, we may See complicated processes just as
in the phenomena visible in karyokinesis, the production
of which may doubtless be arrested or completely suppressed
by more or’ less violent experimental interference. AS is
well-known, it has been possible repeatedly to cause the
production of the more simple amitotic stages of cell-
division.

32

id 27

instead of complicated karyokinetic ones.! Since eytolo~
gical.problems lie outside our subject, we return, with
this one reference, to the treatment of the grosser an
atomical structures.

FORM OF THE CELL

The more highly organized a cell form mey be under
normal conditions, the more susceptible it is to the action
of factors vhich arrest development.

In higher plants, we usually find only very simple cell
forms in individuals normally matured, However, “protec=
tive palisade cells" may be cited as examples of the oppo-
site. In fact in gymosperms as in angiosperms it may be
proved, that under abnormal life-conditions, the "protective
palisade" cells may be replaced by Simple cell forms. The
needles in Pinus austriaca, developed in Bonnier's © ex»
periments under consant illumination,- we will return later
to this series of experiments,- contained Simple polyhedric
parenchyma elements as shown in figure 9, instead of the
normal protective palisade cells. Klebahn (loc. cit.) ob-
Served the same replacement by simpler forms in leaves of
the anemone, after fungus infection,

The arresting action of unfavorable life conditions upon
the development of the cell form may’ be pointed out much
more emphatically in the unicellular, highly organized
Siphoneze. The Codiacese are easy to investigate and are
especially instructive. In normal specimens of Udotea
Desfontainii the leaf-like part of the thallus is composed
of elongated sacs, arranged parallel and extending length-
wise, from which spring numerous, diversely ramified side-
branches with a limited period of growth. The later in turnn
are also extensively branched and repeatedly lobated and
dove-tail themselves together by means of their short ram
ifications,° thereby giving the thallus the necessary firm
consistency. Under artificial cultivation, extending over
Several months, the appearance is completely changed. ‘The
above mentioned papallel sacs show an abundant and undimin-
ished growth activity which is often indeed increased, branch~
ing abundantly but not forming any more "stunted shoots",
The firm connection between the single sacs is thus lacking;
the thallus totally loses its characteristic form, the iso-
lated sacs form a loose green reticulum over the neighboring
ones;~ the formal and functional difference between the
Single parts of the cell is lost entirely. Codium tomentosum

1. Compare Gerassimow, Die kernlosen Zellen d. Conjugaten
Bull. Soc. Imp. Natur. Moscou 1892; Nathansohn,Physiol. Unter-

_ Such. ub. amitotische Kernteilung. Pringsheim's Jahrb.1909,

Bd, RXXV,p. 48;Hacker,Mitosen im Gefolge amitosenahnlicher
Kernteilungen. Anat. Anz., 1900, Bd. XVII, pe 9.
2. Bonnier. Infl. de la lumiere electr. continue s. la-
forme et la struct. d. pl. Rev. gen. de Bot.,1895, T.VII,p.241
3. Illustration in Kister Anat. und Biol. d. adriat.
Codiaceen. Flora, 1898, Bd, LXXXV, p. 181.

33

7 a8

behaves in the same way. The outer layer of its normal
thallus is composed of "palisade tubes", swollen to a club
Shape, and arranged perpendicular to the surface. On their
tips arise the slender unbranchec "trichome tubes" which
are Sharply cut off from them. All these differences are
lost during longer cultivation. The trichome tubes be~
come similar to the others, if still at all recognizable,
as such, they branch extensively, etc. It is not known

as yet whether in these and similar cases the arrested de~
velopments may be traced back to scarcity of light, insuf-
ficient oxygen supply, or to other factors, Finally the
phenomena of arrestment exhibited by Struvea should be con~
Sidered. They furnish indeed nothing essentially new, but
may find mention here because_of their biological interest.
According to Weber van Bosse 1 » Struvea delicatula lives
at times in symbiosis with a fungus (Halichondria) ‘but

then oniy develops filaments, resembling Vaucheria, instead
of the characteristic extensively branched shoots, just

as do the Udotea and Codium specimens in our cultures. The
author compares the form of the alga, simplified by sym-
biosis, to Spongocladie vaucheriaeformis. Undoubtedly,
aoe ovservations may be placed in iline with those quoted
anoves

Also in the case of the more simply formed Siphon-
aceae, the distinct formation of different cell parts is
omitted under certain.conditions, for example in Bryopsis.
In Vaucheria the vegetative parte of the filaments are
known to be all alike. Only those parts of the cell serv-
ing for propagation are differently constructed. That even
this difference in form may be igst, is proved by the oog-
onia which develop vegetatively.

In the case of the Diatomeae and Peridineae also, in
which highly organized cell-forms are abundant, analogous
"simplifications" must be found if one looks for them.
Rattray described abnormal forms for Aulacodiscuc, in which
the characteristic protuberances were lacking.Y Cf the un-
icellular Chlorophyceae, Scendesmus acutus, for example,
comes under our consideration, which with an excess o2
organic food, may lose its tips,* etce

CELL MEMBRANE

Arrested development of the cell membrane is expressed
for the most part by the partial or entire cessation of its
secondary growth in thickness. The cells of the epidermis,
the ducts, the sclerenchyma and collenchyma cells then
show only moderately thickened walls, or the formation of

1. Etudes s. des. algues de l'archipel malaisien I. Ann
Jard. Bot. Buitenzorg, 1890, Vol. VIII, p. 79.

2. Klebs, Beding. d. Fortpfl. bei einigen Algen und
Pilzen. Jena k896, p. 102.

3, Notes on some abnormal forms of Aulacodiscus Ehrbe
J. of Bot., 1888, Vol. XXVI, pe 97.

4, Beijerinck, Kulturversuche mit Zoochlorelien,
Lichenengonidien u. Se Ww. Botan. Zeits., 1890, Ba. XLVIII,
pe 724.

34

‘ 29

the sclerenchyma and collenchyma may even be entirely sup~
pressed. f

In most cases, hypoplasia is caused by disturbances in
nutrition,—~ it boing immaterial whether shade plants and
shade leaves are concerned, plants cultivated under watex
or in places saturated vith vapor, whose transpiration
current is thus insufficient for providing them with the
necessary food stuffs, also etiolated specimens, or even
when the disturbance is caased by infection with parasitic
fungi.t In all cases, as far as the membrance is concerned
the same symptoms are involved. At the same time, in all
plants having insufficient transpiration currents, we may
prove that there is only a weak development of the cuticle
of the epidermal cells. Weakly developed cell-membranes
are frequently found in dwarfed specimens, in which the for
mation of the mechanically effective tissue is often en-
tirely suppressed.” When diatoms under unfavorable life
conditions show a more weakly developed shell structure
than under normal conditions, it may be traced back to sim
ilar arrestment of the growth in thickness. According to
Heribaud 5, the striation of the shells of Gomphoema, Nav-
icula, Stauroneis, and Synedra, is only slightly pronounced
when the cultures are kept in weak light. According to
Karsten 4, the formation of the little silicious rods in
Sceletonema costatum is suppressed when the organisms are
left absolutely undisturbed on the bottom of the culture
dish. In the first case, the arrestment of the cell~mem
brane development may be traced back to the decreased as
Similatory activity of the cells; in Karsten's experiment
the dormant celis will also have been placed under more un~
favorable nutritive and respiratory conditions than those
cells which, in uninterrupted passive motion, are carried
continuously to layers of water containing food-stuffs,
and rich in oxygen.
fe aa Se a Say ais i ha a a a ces eee ta ie ees a ees fee ve eee

1. Compare the above mentioned literature on shade
leaves, aS well as the articles quoted in Chapter IV, 2.
Further, Wakker, Untersuchungen Bier den Etnfluss parasit-
ischer Pilze auf ihre Nahrpfl., Pringsheim's Jahrb. f. wiss
Bot., 1892, Bd. XXIV, p. 499. Tubeuf, Pflanzenkrankh.
durch kryptogame Parasiten verursacht. Berlin 1895, p. 53,
ff. Kny, Hine Abnormitat in der Abgrenzung der Jahresringe.
Sitze-Ber, Naturg.— Fr. Berlin, 1890, p. 138 (Thin walled
autumn wood). It is very remarkable that in badly nour- -
ished specimens the cells in the central cylinder of the
roots have abnormally thick walls. (Observations on water
cultures by Pethybridge loc. cit.). (Compare Chapter III).

2. Compare especially Gauchery, loc. cit.

3e De l'infl. de la lumiere et de l'altitude sur la
striation des valves des Diatomees. C. R. Acad. Sc. Paris,
1894, T. CXVIII, p. 82.

4, Die Formverdnderung v. Sceletonema costatum (Grev)
Grun und ihre Abhangigkeit von d4usseren Faktoren. Wissensch.
Meeresuntersuch., 1898, Bd. III, p. 13.

30

Secondiy, chemical changes, which the cell wall in
many éases, undergoes in the course of its development,
especially in a process of lignifiecation, must be consid-
ered, While the growth in thickness of the cell wall may
be arrested in different plants, and by very different kinds
of disturbing influences, the cases are rare in which thick-
mned cell walls, like those of the selerenchyma, the ducts,
etc, are excluded from lignification, Examples are fur-
nished by the Crataegus branches infected with Roestelia, of
which the medullery parenchym. remains unlignified (Wakker
loc, cit.), the Raphanus shoots attacked by Cystopus, whose
ducts remain unlignified, etc, It is remarkeble that even
under the life conditions, which are furnished our fruit
trees under cultivation, the lignifying process may be omit-
ted. Perhaps abundant water supply and excessive nutrition
are the decisive factors, Sorauer© found partially unligni-
fied pith in the fruit spurs.

‘Finally, the phenomena of reabsorption must be consid-
ered, which under normal conditions, occur in the membranes
of many cells and lead to the building of the so-called
cell fusions, for instance: in the sieve tubes. Inder non-
mal conditions this reabsorption can be omitted, for exam-
ple, only tracheids may be developed instead of ducts.
Since, under the action of unfavorable life conditions,
the width of the lumen of the ducts decreases greatly, it
is not always easy to give information concerning the occur-
rence or the omission of this fusion, Wakker found that
reabsorption was omitted in different plants which were
infected with fungi (Vaccinium with Exobasidium, Crataegus
with Roestelia, Rhamnus with Aecidium). Doubtless, in
etiolated leaves and stems and in individuals which have
matured with arrested transpiration, the same arrestment
may be demonstrated in the formation of the elements which
convey water,

Finally under the influence of arresting factors, the
formation of cross walls may remain so incomplete, that
instead of separate spaces, chambers may arise communicat-
ing with one another, or in the end, the formation of the
cross walls is entirely omitted, If the cells continue their
growth simultaneously, abnormally large cells are produced,
and if their nuclei also divide at the same time they result

(35) in multinucleated cells of abnormal capacity, For the
present, we will be content with a brief reference to arrest-
ed developments of this kind. On account of the external
conformity existing between cells of abnormal size produced
by arrestment of the membrane formation, and those of abnof-
mal size developed by abnormal growth (hypertrophy) we will
postpone their closer discussion to the fourth chapter,

In what way arresting factors influence the de-
velopment of cross walls has been ascertained as yet only
1 Peglion, Studio anat, di als. impertrofie indotte dal
Cystopus candiéus in als. org. di Raphanus Raphanistrum.
Riv, pat. veg. 1892, Vol. I, p. 265.

e Nachweis der Verweichlichung der Zweige unserer Obst-
baume durch die Kultur, Zeitschr. f. Pflanzenkrankh., 1892,
Ba. II, p. 66, 143-

36

ol

for a few cases. It is known that newely produced cross
walls are formed from the system of kinopessmatons. "spindle
fibres", which become visible during karyokinesis, or re-
main independent of the nuclear division figure. After it
has been proved that karyokinesis may be replaced by simpler
amitotic stages of cell division, by means of various kinds
of experimental interference, we will have to investigate
more closely in what way normal anitotic division of the
body influences the mode of formation of cross walls.

In Oedogonium, whose cross wall formation is known
to be initiated by the deposition of a cellulose ring, a
Simplified mode of wall formation without the celluose ring
may be observed as the result of abundant sugar nutrition.~

CELL CONTENTS

Of the special contents of the plant cells which come
under our consideration, the chromatophores and especially
the chloroplasts afe the most important, not only on account
of their wide distribution in the plant kingdom and their
important physiological significance, but also on account
of their sensitiveness to various external factors, by
which their development is easily and often arrestede _

The development of the chloroplasts can be arrested in
many wayS,~ the number of chlorophyll grains waich are un-
ited in one cell remains below the normal, or the individual
chlorophyll grains do not attain their normal character, |
remaining small, or free from chlorophyll, or they end their
existence as chlorophyll grains, instead of developing into
yellow or red chromatophores,

The number of chlorophyll grains remains below normal
in the cells of many vapiegeted leaves, in many varieties
with pale green leaves,* and in plants cultivated in places
with atmosphere saturated with vapor. Under the same con-
ditions, the size of the individual grains also is often
abnormally small. I do not doubt that under the influence
of certain "arresting" factors, even the form of those’ in-
dividual chromatophores can undergo a "Simplification",
which, aS is well known in the gase of many green algae,
diatoms and brown and red algae, are remarkable for their
complex characteristic organization.

Those cases demand especial attention in which the
formation of the characteristic green coloring matter, the
chlorophyll, in the chromatophores, is abnormally omitted.
As is well known, the formation of ‘the chlorophyll takes
place only within certain temperature Limits. It aes
poses, further, with some exceptions, the action of light,

eee ewe eee ee eee ee ee tee ee ee ee :
Nee re ms cae ee pee te te ee ee ne ee ee ee tee ee me ee es ee -

1. Klebs, Bedingungen der Fortpfl. Bei Algen und
Pilzen Jena, 1896, p. 288.
2. Compare Griffin loc. cit.

* 32

the presence of iron anid of certain organic food materials.
Hence if follows that under differently combined, abnormal
life conditions, the formation of the green coloring matter
may be Suppressed. It is known that, in the spring, without
experimental interference, temperature can influence bulbous
growths, grain seedlings, etc., and that these at a low
temperature develop yellowish leaves, The minimum temper=
ature for chlorophyll formation in the "variegated" cabbage
variety, Brassica oleracea acephala, studied by Molisch® is
much higher than in the above case, In cold frames, at a
temperature of 4 to 7 degrees C. in winter, the plants de-
veloped green and white dappled leaves, or leaves completely
free from chlorophyll, which, however, became green later

if the plants were brought into a temperature of from 12 to
15 degrees C. The leaves newky formed in the warm chamber
were always perfectly green. The fact that, under the cul-
ture in the cold frame, the leaf tissue negr the veins re~-
mained predominantly free from chlorophyll, while the other
perts of the lamina developed the coloring matter in a norml
manner, is worth consideration.

The influence of nutrition may not be ascertained so
easily by experiment, since the chemical compounds import-
ant for the formation of chlorophyll are produced by the
activity of the cells themselves. But the observations
should indeed be considered nere, regarding the close con-
nection which appears .to exist between the leaf variegation
of "variegated" plants, and the place in which they grow.
According to Ernst? , a variegated specimen of Solanum ali-
gerum, transplanted into garden soil, became monochromatic.

1, On the necessity of the latter, compare Palladin.
Ergrinen and Wachstum der etiolerten Blatter. Ber, der
Deutsch, bot. Gees, 1891, Bd. IX, pe 429.

2. Compare Sachs, Ueber den Einfluss der femperatur aug
das Ergriinen der Blatter. Flora, 1864, Bd. XLVII, p. 497,
Wiesner, Entstehung des Chlorophylls, 1877, p- 95. Ritzame
Bos, Ergrunungsmangel infolge zu niederer Fruhlingstemper-
atur. KXeitschr. f. Pflanzenkrankh., 1892, Bd. IT, p. 156.

‘3, Ueb, die Panachure des Kohles. Ber d. D. bot. Bes.
L9OL, Bd. XIX, po Se. ;

4, Timpe (loc. cit. p. 7) reports on a specimen of,,
Ulmus scabra var. viminelis in the Botanical Garden in Got-
¢ingen, whose spring shoots bore leaves speckled with yel-
low, which retained their variation until autumn, While the
mid~summer shoots developed pure green leaves. It may be
possible that here also an effect of the lower Spring tem
veraturé is present. Also, as is well known, in bulbous
growths, forced in spring, the pale color remains constant
in spite of a subsequent increase of temperature.

5. Botan. Miscellaneen. Bot. Zeite., 1876, Bd.
XXXIV, Pe S0«:

33

Boucha! made similar statements. concerning Plectogyne, Phal~
aris, Zea, Kerria, etc. Fortunately, we have had no thoro

, and reliable test of the question as to the influence ex»

» ercised by the quality of the soil, the supply of water,
and of light on plants tending toward variegation. The ques-
tion also, whether the pecularity of the white leaved con»
dition may be carried over to normally colored specimens by

*,scions or by inoculation with sap, has not yet been suffi-

(38}ciently explained. the. sypposition of a “contagium vivium

fluidum" which Beijerinck had suggested, appears but little
Suited for solving the problem. That unimown individual
pecularities play a part in the appearance of white leaved
plants, is made probable by the often observed seedlings free .
from chlorophyll which appear here and there among those which
have become green normally.

The effect of deficiency of light and iron is sufficient-
ly well known. In the dark, or without iron, pale plants ave
produced which are capable of developing only a yellowish
colloring matter, instead of the norpal green pigment. Accord-
ing to Kohifs recent investigations,° the yellow pigment is
to be designated carotin. The deficiency of normal pigment
in Specimens cultivated in the absence of iron, is termed
chlorosis or icturus, with plants grow in darkness, it is
mown as etiolation. In plants which grow in a substratum
containing iron, the symptoms of chlorosis may also become
apparent if the cells of the plant or definite parts of them
are incapable of taking up sufficient amounts of iron. The
chlorosis found in vines appears to be of this kind. ips

te Sitgungsber. Ges. Naturf, Freunde Berlin, 1870, ...
pe 40 and 1871, pe 19, 66. Compare here also Lindemuth.
Vegetative Bastarderzeugung durch Impfung. lLandwirtsch.
Jahrb., 1878, Bd. VII, p. 887. ;
... Be Veber ein contagium vivum fluidum als Ursache der
Fleckenkrankh. der Tabaksblatter. Centrabl, f. Bakteriol
‘3 @te., 1899, 2. Abth. Ba. V,.p. 27. Further, the attempt at.
“explantation made by Woods should be mentioned, (The des-.
truction of chlorophyll by oxydizing enzymes. Ibid., p. 745),
which calls attention to the richness of variegated leaves
in ozydizing enzymes and to the action of these in destroy-
ing chlorophyll. The same author. publiished.")bservations on.
the Mosaid disease of tobacco” (United States Department of
Agriculture, B. P. 0, Bull, No., 18,.1902). ,The oxydizing
enzymes produced after injury, as well.as under the influence -.
of poisons after parasitic infection will. have great signi-
ficance undoubtedly for the pathology of plant cells. and tis-
sues. . (Compare besides Janowski in Ztschr. f. Pfle~ Krankh.
'.« 8. Untersuchungen Uber das Carotin und seine phys.
Bedeutung in der Pfl. Leipzig. 1902. :

38

, 34

Above all others, the seedlings of many gymnosperms
and also various algae are to be counted as exceptions to
the rule, so far as the need of light is concerned. They
become green even in the dark, if the food materials of the
endosperm are at their disposal , i¢. if organic food is
furnished them from without. Well worth noticing is the
fact, that the formation of chlorophyll can be suppressed,
at least for lower organisms, buy an over-abundant supply
of orgenic food. Zumstein 2 obtained in this way colorless
Euglena (E. gracilis) in which the green cglor was restored
by the use of organic substances, Kersten found analogies
in diatoms,

All organs, not turning gfeen normally, but for some
reaSon, remaining colorless or yellow, contain chromato-
phores which are yellowish pigmented or conpletely color-
less. Their number per cell often remains below the normel,
their Size usually is sub=normal elso; often chromatophores
being demonstrable only in the form of tiny grains, In many
kings of variegated leaves, they appear to be entirely lack-
ing in the white parts, as, for instance, according to Wink
ler+ in Pandamus Veitchi,

Finally those arrested developments should be consid-
ered, in which normal chlorophyll grains are indeed, devel~
oped but are "hindered" from transforming into yellow or red
chromatophores, A good example of this is given by the

ee wee SY SS
RO em ne ne tae ea nae ee ae ce et ee Oe ee ee nee es —_

1. Literature citations Artari, Zur Brnahrungsphys. de
grunen Algen, Bericht d. D. Bot. Ges., 1901, Bd. AIX, Dele
Compare also Matruchot and Molliard. Variations de siructure
sous l'infl, du milieu nutritif. Rev. Gen. Bot. 1902 ,T.XI1V,118.

2. Z. Morph. use Phys. der Evglena Gracilis. Pringsheim's

Jahrb. f, wiss. Bot., 1900, Bd. XXXIV, p. 149. Compare Bei~
jerinck, Kulturversuche mit Zoochlorellen etc. Bot. Ztg.1890,
Bd, XLVIIL, p. 724 (Beobacht. an Scendesmus); Kruger, Uebs
einige aus Saftflussen reingezuchete Algene Zopfs Beitre,
1894, Bd. IV, Kurze Charakteristik einiger neid. Organismen
im Saftflusse d. Laubbaume. Hedwigia, 1894, Bd. XXXIII,p.241.
Matruchot and Molliard, Variations de struct. d'une Algue
Verbe 6tc., Loe, cit,

3. Ueb. farblose Diatomeen. Flora, 1901 (Erganzungsband)

de xX » pe 404 : ;
‘ gra foer de Starkebildung aM a. verschiedenar-
tigen Chromatophoren. Pringsheim's Jahrb. f. wiss. oe
Bd. XXXII, p. 525. Compare also Frank, Krankh. d. Pfl., 4,
Aufl. Bd. I, p. 225, and other places, Zimmermann, Morph. u.
Phys. d. Pflanzenzelle, 1893, p. 31, 53; Timpe, loc. cit.,
Pantenelli, Studi sull' albinismo vek regno vegetale. Mal-

ighi 902, Vol. XV, pe 3635. '
oe hae ee K. HeIERS o: Binwirkung 4d. SchildlBuse aut das
Pflanzengewebe. Jahrb. Hamburg.wiss.Anat.1900?Bd.XVII ,5.Beiheft

5. Einfl, d. Lichtes auf d. herbstl. Verfarbung ad. Laubes
Sitzungsber. Niederrhein. Ges. Natur - u. Heilkunde-Bonn,
1B91, pe 80.

39

; 35

Noll observed in Ampelopsis, etc,,that leavcs vartly covered
by other leaves did not turn rea. At times one can also
perceive in leaves infected by fungi, that certein parts
remain green for a noticeablty long time.

In connection with chromatophores, a few other brief
remarks on the red pigment of plants (anthocyanin) are
appropos. Its formation also is connected with definite con-
ditions. In the study of these we meet again with the face
tors which are concerned in the formation of chlorophyll;
first of sll, light. The dependence of the anthocyanin for =
mation upon the action of light difiers from that of the
chlorophyll formation in that only in the case of certain
plants and organs is light indespensible for the development
of the red coloring matter. Many rhizomss, roots, bulbs,
and tubers which, under normal conditions, remain continu-~
ously without light, are richly provided with anthocyanin.

On the otherhand, there are organs which develop the red

‘coloring matter only upon exposure to light; for instance,

seedlings of Polygonum fagopyrum, which Batalin® investi-
gated carefully. The fact has long been known to breeders
and to those interested in plants, that the formation of
pigment is suppressed in red leaved ornamental plants culti-
vated in the shade. According to Pynaert, the dependence uf-
on light is especially noticeable in Alternanthera atropur=
purpa and Coleus. The blossoms of many plants also need
the action of light for the development of their red and
blue pigments; other plants, however, open normally-colored
blossoms in the dark, or blossoms that remain only a little
below the normal in the intensity of their colorjng. uke}
Orchis ustulata , only the hood loses its color. Fruits,
aS well aS blossoms, behave dissimalarly in the formation
of pigment under abnormal conditions of life. The fact that
apricots, apples, pears, etc. only redden on the side ex-
posed to the sun, has been cited often since Senebier. On
the other hand, Laurent? has proved that vines with blue

1. Binfl. d. Lichtes auf. d. herbstl. Verfarbund 4d.
Iuabes. Sitzungsber. Niederrhein. Ges. Natur = u. Heilkunde
Bonn, 1891, pa 80%

2.Die Einwirkung des Iichtes auf die Bildung d. roten
Pigm. Acta Horti Petrop., 1879, T. VI.

3. De l'infl. de la lumiere sur la veget. de pl. culti-
vees en serre. Bull. Congr. Intern. de Bot. &t dfHortic.186¢,
p. 229. Therein also further examples (Dracaena, Pandanus
Veitchi, Saxifraga and others.) The leaves of the red beet de-
velop red coloring matter even in the dark(predominantly on
the veining.

4, Compare the notes by Askenasy, Ueber den Einfluss
des Lichtes auf die Farbe der Blute. Bot. Zeitung, 1876,Bd.
XXXIV, p. 1. also Benlaygue, Infl. de l'obseurite s. 1. devel.
d. fleurs. C. R. Acad. Sc. Paris 1901,1.CKXZZII, p. 720.

5. Infl, de la radiation Ss, la, caloration des raisins.
C. R. Soc. Roy, Bot. Belgique, 1890, T.-XXIX, 2. p. 71.

(40)

#6

fruits are not dependent on the action of a direct sup«
ply of light for the formation of their pigment, In all
cases in which an interdependence between exposure to
light and formation of pigment may be recognized, we may
venture to assume that a specific action of light does not
jie at the root of the matter, but that nutritive con
ditions, altered by the influence of the light represent
the decisive factors, Askenay (loc. cit.) observed that
shoots of Antirrhinum majus and Digitalis purpurpa, from
Which the leaves had been removed, developed white blos-
soms, clearly the result of a disturbance in nutrition

due to the loss of the leaves, Laurent (loc cit.) ob»
tained the same results by shading the leaves, while let-
ting the blossoms develop in the light. Unfortunately,

he did not name the plants with which he experimenved. In
the case of Syringa the inflorescences, below which Laurent
had girdled the branches, developed only pale blossoms, the
grapes from blue stock were incompletely colored if the
food supply was cut off by girdling. Coloration was en-
tirely absent if the grapes of girdled shoots were elso
kept at the same time in the dark. Accordingly, it is
very probable that blossoms which, under normal nutritive
conditions, can develop their pigment only by exposure to
light, can become red or blue even in the dark, if in some
artificial way the necessary food stuff can be supplied
them in sufficient quantities. Doubtless, it will also be
possible to suppress the formation of red pigment in blos=
soms by unfavorable conditions of transpiration.

Finally the influence of climatic pecularities on
the formation of pigment may also be explained by distur-
bances in nourishment. The reports that Petunia and Brach-
ycome in Indial as well as Carduus nutans in the neighbor~
hood of the sulphur baths of Pjatigorek (Russia)® deserve
consideration and indeed, confirmation. For the present,
the factors are still unknown which cause the appearance
of So-called albinos in different plants,~ individuals with
white bloosoms or fruits, instead cf those normally colored
red. The fact that many homogenous bacteria, under certain
cultural conditions, temporarily lose the ability of pro-
@ueing coloring matter, for instance, Micrococous prodig-
iosus at a high temperature (40 Degrees C.) may be men-
tioned in passing. With the bacteria whose formation of
pigment may be suppressed, the coloring matter is not ~
found in the cells themselves, but is excreted by them into
the surrounding medium.

ee ee ee mee ee ee ce ee ee em ee ee eee

1. Gard. Chron., 1881, 1, p. 627.

2. Riesenkampf, Bemerkungen Uber einige in verschied-
enen Gegenden des russSischen Reiches vorkommende Anomalien
in der Form and Barbe der Gewachse, Bull. Soc. Imp. Natur.
Moscou, 1882, p. 85.

%

37

We can dispose briefly of the cell inclusions which, ix
additions to the chromatophores, come under our consideration.
Particularly important are the crystals of calcium oxalate,
the formation and distribution of which is, to a high de
gree, dependent on external factors. <A. F. W. Schimper,
Kohl, Wehner, and others* have already furnished contri-
butions to the knowledge of the conditions under which
the normal formation of the erystals takes place, Their
results, however, are not without contradictions end a thor-
ough comprehensible treatment of the question is still want-
ing. It may only be said with certainty that lowered trans~
piration decreases the number of crystals; shade leaves con-
tain fewer crystals than do sun leaves and specimens culti-
vated in moist air, or without light, are also poor in
erystals, as likewise are parts of variegated leaves free
from chtorophyll. According to Rauwenhoff*, etiolated spec-
imens of Polygonum cuspidatum entirely lack crystalls. More
investigations of this would be desirable. Vandevelde®? proved
further , that leaves bearing galls are especially poor
in crystals. Future investigators will have to notice
whether abnormal life conditions can also influence the form
of the individual crystals and possibly prevent the develop-

Wee ee ge ie ney et A ee me eta ee ee te err dome ce nae ee ems tee es ce ee ee ee me ee i ee ee te es eee ee ee oe

we Schimper, A. F. W. Ueber Kalkoxalatbildung in den
Blattern, Bot. Zeitg., 1888, Bd. XLVI, p. 65. Kohl, Anat,-phys.
Untersuchungen der Xalksalze und Riesselsalze in der Pfl.,
Marburg, £889, p. 50, and elsewhere. Wehmer, Die Oxalatab-
scheidung im Verlauf der Sprossentwicklung u. s. Ww. Bot. Zeiftg.
1891, Bd. XLIX, pe 149. Zur Frage nach dem Fehlem oxals,.
Salze. Landwirtsch. Versuchsstat., 1892, Bd. XL, pe. 109.
Among other literature may be mentioned, Monteverde, Uber den
EHinfluss des Lichtes auf die Bildung des oxals. Kalkes in der
Pfl. (Russiah). Arb. Petersb. Naturf. Ges. Bd. XVIII, p. 46.
Cuboni, App s. anat. e fisiol. d. foglie d. vite. Riv. Enol.
e Viticolt., Serie II, Vol. II (compare Bot. Cbl., 1884,
Ba. XVII, p. 332). Dufour, Infl. de la lumiere s. la forme et
la struct. d. fevilles. Am. Sc. Nat. Bot. VII, serie, T. V.
1889, p. 311. Buscalouni. Studii sui cristalli di ossalato
di calcio. Malpighia, 1896, Vol. IX, p. 469.

2. S. 1. causes et 1. formes anormales d. pl. qui. crois=
sent d. l'obscurite. Ann. Se. Nat. Bot., VI. Serie, T. V-
1877, p. 267.

3. Bijdr. tot de phys. d. gallen; het aschgehalte d. an~
getocte bladern, Bot. Jaarb. Dodonea, 1896, Bd. VIII,p. 102.

(41)

. 38

ment of regular individual forms. It is but natural that
the formation of the calcium-oxalate crystals is greatly
retarded or entirely absent in the culture of seedlings in
media free from calcium. Cysoliths behave like crystals,
their normal development being conditioned by the_calciun
supply. If this is lacking, according to Charyret only the
stem of the cystolith will be deposited, the formation of the
cellulose head being omitted. Cystoliths are scantily
formed in leaves sufficiently exposed to the light.” Hence,
as in the cases reported above, a lowering of the transpir~
ation seems to be determinative; at least I have obtaine2
rudimentary cystoliths in leaves of Ficus elastica, if trans-~
piration was arrested, even with a continuous exposure to
light. Etiolated leaves of Acanthaceae form normal cysto-
liths, while, under the same conditions, in Moraceae and
Urticaceae these remain rudimentary. The calcium incrusta-
tions are arrested by lack of light. The hairs of the Bor-
ragineae also remgin poor in calcium in etiolated speci-
mens, (according to Chareyre.) Melnikoff reported eystoliths
free from calcium.?

2.DIFFERENTIATION OF THE TISSUE

An arrestment of tissue differentiation occuws in ail
those cases in which the elements of certain cell complexes
develop in the same way as contrasted with the fact that
under normal conditions, certain individual cells or cell
groups would be formed differently from adjacent ones. Hy
poplasia is thus shown, in that a homogenous tissue is pro»
duced, where under normal conditions we find one composed of
well-differentiated layers and groups. It is evident that
this kind of hypoplasia cannot find expression in all organ-
isms. We must at once exclude the unicellular organisms,
which do not live in colonies, and the multicellular ones
composed only of similar cells. As is well known, however,
in most multicellular plants,- even in the algae and fungi,
an evident tissue differentiation is recognizable.

Before we pass to these, a few words are necessary con-
cerning unicellular organisms. Only those come under our con-
sideration which are united into colonies with easily dis-
tinguishable components, as, for instance, many of the plank
ton diatoms which form chains, the end member of each chain
often being differentiated from the others. Colonies of
gcendesms caudatus behave similarly; their end cells are

ee ere ee ee ee ee ee ee ee mee cae ee ee ee ee ee ee ee te ee

1. S. L'origine et la formation trichomatique de quelques
eystoliths. C. R. Acad. Sc. Paris, 1883, T. XCIII, p. 1073.
Sur la form. d. cystol. et leur resorption. Ibid., p. 1594.
Nouv. Rech. s. 1. cysStol. Rev. de Sc. Nat., Montpellier,III,
eerzte, T. Tit, Pe Seo%

2. Ficus elastica according to Kohl, loe. cit. p. 39

3. Untersuch. Ub. d. Borkommen d. CaCOz in Pfl. Disserta-
tion Bonn, 1877, p. 35. Compare with this also Kohl, loc. cit.
p. 141, and the observations of Mollisch on Cystoliths nor-
mally free from calcium (Qest. Bot. Zeitschr., 1892, Bd.
XXXII, pa 345.)

39
furnighed with long delicate gelatinous horns. As Sennt

has shown, the formation of the horns is lacking under ab-
normal life conditions, nutrient solutions, in the usual
concentration and rich in oxygen or highly concentrated
nutrient solutions without the addition of oxygen, while
the gelatine is formed as a uniform coating on all parts of
the colony. A Similar arrestment in the differentiation of
the colonies might also be obtained, under certain conditions
in the diatoms just mentioned, or in Pediastrum eranulatum,
whose lamelliform colony is composed of polygonal cells
two-armed at the edge, etc. The same arrestment may be
Studied further in the colonies of individuals lacking
membrane such as those known as plasmodia in the Myxomycetes.
When the fruit bodies of Dictyostelium mucoroides are being
formed under normal life conditions, a division of labor
appears among those individuals which have united themselves
into a plasmodium (rather, a pseudoplasmodium) of such a
kind, that a part of the Amoeba mass is used for the forpa~

{42)tion of a stem, and the rest is transformed into spores.
Recently the interesting evidence has been produced by Potts
thet 5 under certain abnormal conditions this differentia-
tion is omitted, that under water, as well as on concentra-
ted nutritive agar ( 5.5. per cent. KNOz ) the whole amoeba
mass is transformed into spores and that, couversely, in
development under a layer of oil, sterile stem cells are
formed without exception. Consequently, first one and then
the other process of differentiation is eliminated from the
course of development of the cell aggregate.

As far as the differentiation of the tissues of the
multicellular growths is concerned, it may be said, regard-
less of their diversity, that there is, in general, no argan
whose tissues could not be arrested in their differentiation
by factors acting more or less energetically. Thas, as
before, we will limite outselves to the treatment here of
a few tissue forms.

Observations on the arrestment of tissue differentia-
tion may be made so easily, without troublesome experiments
that there exists a real superfluity of reports on this sub-
ject. In listing the authors, a choice will therefore suf-
fice, especially as many of these reports give inadequate
datae

From the list of thallophytes and cellular cryptogams
the Narchantiaceae furnish an instructive example. The
structure of the normally developed thallus is well known.

(43)Its elements are at the left in figure 10; an epidermis

1. Ueber einige koloniesbild. einzellige Algen.
Bot. Zeitung, 1999, Bd. LVII, p. 39.

2. Brefeld, Untersuch. aus. d. Gesamtgebiet de
Mykologie, Heft VI, Gdbel, Organographie. 1898, p. @l.

B, Zur. Physjologie des Dictyostelium mucoroides.
: @ 1 !
Flora, 1902, Ba. XCI (Ergénsungsbd.) p. 261.

(43)

40

whigh bears rhizoids; a colorless parenchyma free from in~
terstices, the cells of which have in part slightly re-
riculated and thickened walls; an assimilatory parenchyma
and an upper epidermis, broken through by breathing pores.
This complicated structure is almost entirely lost in speci~
mens cultivated in weak light or in rooms saturated with
vapor. The assimilatory threads, lying under the epidermis
of the upper side, and the thick-walled parenchyma cells
disappear entirely; the thallus is composed in all its parts
of similarly formed cells; small amounts of chlorophyll may
be found in all the layers, in a superficial position some-
what more abundnatly than in a more demial one. ‘Compare
Tags 10, right.)

Various other interesting examples might still be
chosea@ from the list of Bryophytes, of which Ikwill here
name only two. In Bryum argenteum the cells in the UE
PEE PABD OF THE LBAves dies and fill with air, thereby
giving a charactezistic silvér sheen to the shoots, AS
Gobel has proved,” this differentiation of the leaf is
lacking when the moss is cultivated in a damp place j_
the cells of the leaf apex remain alive and green. This
differentiation, originating through the dying off of
certain cell groups, is found also in other moss varic~
ties and may be suppressed in them (Compare Gobel) _
Leucobryum glaucum retains its structure, even when it
is cultivated under water. Oehlmann® observed, further
a lack of differentiation in the “rudimentary leaves |
of Sphagnum which he obtained by cultivating the moss in
poor nutritive media and with weak exposure to light.
While normal leaves are composed of small green and large
colorless cells, both kinds of cells are about equally
large in the rudimentary leaves and also arranged es
sentially different from those in the normal leaf. AS :
a matter of course, entirely similar phenomena of arrest~
ment may appear also in the richly differentiated Gia
of many Euthallgphyte groups; marine algae furnish ave
orable material*,especially those specimens which are

-_

oo oe ae ee ae or ee rer i

1. Stahl, loc. cit. Ruge, Beitr. z. Kenntn. d. veg. Ore.

d. Lebermoose, Flora, 1693, Bd. LXXVII, p. 294, Beauverie, ig
d. modific. morph. et. anat. de thalles de Marchantia ae XZ Vv
nularia obtenues experimentatement. Soc. Linn. Lyon 1898, T. X&l

pe 57, Gobel. Organographie, 1901, p. 301, etc.

2. Ueb. d, Einfl. dl. Lichtes auf. d. Gestaltung der Kak-

teen u. and Pfl. Flora, 1896, Bd. LXXXII, p- 1. Further Organ~

ographie, pe 368. Compare also Geneau De Lamarliere

and Maheu, Jd.

Sur le flore des mousses des cavernes. C. R- Acad. Sc. Paris,
L901, .. CXXII, pe 921.

3. Veget. Fortpfl. d. Sphagnaceen etc. Dissertation Frei-

burg i. Schw. 1898.

4. Compare for example, Peterson. Note s. 1. crampons chez

le laminaria saccharina,. Bot. Not., Bd. XXI, pe 319.

Al

grown,in artificial cultures,~ also Hymenomycetes. In mine:
and other moist localities without light, deformed mushroom

have repeatedly been collected, whose tissue differentia-
tion remains sub-normal.

(44)In the vascular plants, we will briefly discuss in order the
formation of the epidermis, the mesophyll and the conducting
and mechanical tissues.

Epidermis, mesophyll. In cross sections through leaves
and stems, one usually finds the epidermis, in so far as the
primary dermatogen is still retained, Sharply separated from
the tissue lying beneath it. Taking no account of differen-
ces in size existing, on the one hand, in cells of the epi-
dermis, and the other hand, in those of the mesophyll and
the primary bark, the distinguishable content of chlorophyll,
the characteristic form of the mesophyll cells, the thick-
ening of the walls of the bark cells, and many others, may
Still become important, according to the plant species con-
cerned. The difference between the epidermis and the tissue
layers hying beneath it, can be eliminated or at least de-
creased Since the inner tissues lose their capacity for char=
acteristic formation, as in the needles of Pinus austriaca,
illustriated in figure 9, in which the cells of the hypoderm
aS well aS those of the epidermis have remained thin-walled,
or aS in many dwarf specimens in which there is lacking a
formation of mechanical tissue in the bark.© This can also
take place if the cells of the epidermis follow the course
of development that under normal life conditions falls only
to the lot of the more deeply lying layers. Abundant chloro-
phyll is developed in submerged epidermal cells, for instance,
in the leaves of Sagittaria, which are forced to develop |
below the surface of the water. .

t
If the cells of the epidermis are compared with one
another a Yery different degree of "division of labor" may
be recognized in their formative and functional characters;
not infrequently, such a division is lost altogether. In
many leaves the epidermis of the upper side shows a complete-
ly homogeneous tissue-plate composed throughout of the same
kinds of cells. In the majority of cases elements of dif-
ferent kinds take part in the composition. If we take no
account of those plants in which certain epidermal cells un-
dergo especial development as crystal reservoirs, secreting
glands or idioplasto-containing cystoliths, three especially
1. Compare for example, v. Bambeka, S. un exemplaire
monstrueux de Polyporus sulfureus. Bull. Soc. Mycol. France,
1906, Ts AVILL, ‘ps Sas

2. Concerning leaves of the witches brooms on Abies,
and the like, compare, |:elow, Chapter V, B, 5.

3. Compare Costantin, Rech. s. 1. Sagitatfre. Bull. Soc.
Bote Nrance, 1685, 2. XXXIT, pe 216.

r 42
important forms of upper-dermatogen celis, or rather of
their’ derivatives come into question,- guard cells, hairs,
and slimy epidermal cells.

An arrestment of the development of the guard cells
may be brought about in various plants by wéll known means.
Lowered transpiration and wek illumination cause a de-
crease of Stomata. According to Stapf's count, in Solanwa
tuberosum , there is, under normal conditions, one Stoma
for every 46 epidermal cells. In the specimens which he
let mature in gaslight, a pair of guard cells occurred
for every £04 epidermal cells. The same reduction may
be proved for shade leaves.

(45) Contact with running water acts just as does retention
in damp air, but often more energetically. According to
Mer, leaves floating below the surfact of the water do not
dévelop so many stomata es those which reach the surface.
In some plants, finally, the formation of stomata is omit-
ted entirely under the action of moisture. In many plants
which "normally" develop air and water leaves, stomata are
found only on the former; in Stratiotes the submerged part
of the leaf is free from stomata, while that above the
water possesses some. Stomata are entirely or almost en-
tirely lacking in leaves of Marsilia which develop under

Ll. Stapf, Beitr. zur Kenntnis d. Einfl. geanderter
Vegetationsbeding. auf die Formbildung der Pflanzenorg.
etc. Verh. Zool. Bot. Ges., 1879, Bd. XXVIII, p. 238. From
the further statements of Stapf, we gather that in the
“vapor~form" a stoma, occurred for every 50 epidermal cells,
in that cultivatéd in a room, only one for every 113. Re-
gular relations between the differentiation of the epider~
mis and the external factors may not be understood from
this; only so much is clear, that the number of the stomata
often decreases under abnormal cultural conditions. Dufour
made observations on shade leaves (Infl. de la lumiere s.
1, structure d. feuilles. Bull. Soc. Bot. France, 1886,

t. XXXIII, p. 92.) and Mar (Observe s. la repartition d.
stomates etc. Ibid. pe 121.) They proved that shade leaves
possess fewer stomata than sun leaves. Brenner (Unters an
eigenen Fettpfl. Flora, 1900, Bd. LXXXVII, p. 387) arrived
at the same results in the case of Mesembryanthemum, in that,
when cultivated in a damp place, 19 to 23 stomata were
found, instead of 50 to 52, as in a normal leaf. It is

very remarkable that in the caSe of other succulents under
Similar cultural conditions, the number of the stomata in-
ereases, (in Crassula 110 to 160 or 100 to 110, instead

of 90 or 70, as in the normal leaf.) Here also wére not

in a position to set up any rule. Compare alSo the results
of W. Wollny, Unters. ub. d. Hinfl. d. Luftfeuchtigkeit

auf das Wachstum der Pfl. (Diss.). Forsch. Gebiet Agrikul-
tur-Physik, 1898, Bd. XX. Further literature is cited in

the following references.

43
water .+ _To this type belongs -also, I suspect, the As-

plenium obtusifoluim var. aquatica, in which Biesenhagen®
described the tissue differcntiation as strongly yoaced

and the stomata lecking; still others might be mentioned.®2

Conditions for the formation of hairs sre sittilar to
those for the formation of stomata. Because of the ease
of macroscopie control the dependence of pubesence on
Glimate and culture conditions found early consideration.*
The trichomes are also arrested in Aevelopment by the fac-
tors referred tog Etiolated plants, plants transpiring
poorly, or those vegetating under water, develop only scanty
hair ‘coveringwe

1. Costantin, Etude, s, 1, feuilles s. pl. aquatiques,Ann.
Sce Mat. Bot. 1886, 7% ser.,T, III, ps 94, also Infl. du mil-
dieu aquatique s. 1.stomates, Bull. Soc. Bot, France,1885,

Te. XXXII, p.» 259. Schmidt E,, Hinige Beob. 3 Anat. d. Veg-
etationsorg. ve Polygonum. Diss. ,Bonn 1879. Massart, L'’ac~
commodation individualle chez Polygonum amphebium. Bull. Jard.
Bot. Bruxelles, 1902, Vol. I, fase. 2.

2, Ueber hygrophile Farne. Flora 1892, (Erganzungsband)
Bad. LXXVI, pe 157. Concerning leaves of the witches brooms
of ferns, compare below, Chapter V, B. 5.

3. The question, whether the formation of the stomata may
be suppressed by unfavorable life conditions may have been
one of the first in the province of pathological plant ana~
tomy Which were taken up experimentally. In his “Anatome
der Pflanzen" (Berlin 1807) Rudolph refuted the statement
of De Candolle (1801) according to whose explanation, “la
lumiere e$t encore necessaire au development des pores, Les
plants etiolees n'en ont aucun." Rudolph found in etiolated
Leaves of Ipomoea carnea and I. violacea stomata in normal
numbers, just as in the young leaves of the bamboo, of calla
etc., Which he had not exposed to light. In the case of the
variegated leaves of Arundo Donax, A. colorata, Agave amer-
icana, etc. (which Rudolph wlso reckoned among etiolated
ones), equal numbers of pores were found, according to him,
on the gree, and one the etiolated parts of the leaves.
Aga:n Rudolph refuted the further statement of De Candolle
(iod. cit) that land plants, grown under water, can no long-
er form stomata. Experiments with Mentha prove the opposite.
“Any one who grows under water one of the plants designed to
grown on dry land, will not thereby take away its pores".
(Rudolph, loc. cit.)

4. Compare thése textbooks from the beginning of the
last century. One may here also be referred back to Goethe.

5. Some citations of literature: Kraus, C., Beob. Ub.
Haarbildung, sunachst an Kartoffeltrieben. Flora, 1876, Bd.
LIX, pe 153; Kerner, Pflanzenleben, 1898, Bd. II,p. 449:
Costantin, loc. cit. Schober, Ueb. d. Wachst. d. Pflanzen-
haare an etiolierten Blatt-u.Achsenorganen.dZetschr. f. ges.
Naturwiss., 1886,Bd. LUIII,p. 586; Kraus, Aug. Beitr.z.Kenn-
a. Keimung. W. S. W. unter Wasser. Diss. Kiel. 1901; W. Wol-
Iney, loc. cit.

: 44.
(46) With suitable objects, complete absence of pubescence may
even be obtained; for instance, in potato-rsprouts, in
Polygonum amphibium, (according to Kerner) and others.

The formation of reoté hairs, known to be especially
Sensitive objects, can also be easily arrested, or’ entire
ly suppressed. In many plants grown in water eultures,
the formation of root~hairs may be omitted. In other cases
we find it disappearing only in nutrient solutions of un-
Suitable composition. Thus Schwarz found root hairs pro-
ducei in weak solutions 0.2 per cent of KNOsz, but not in
strong ones, 1,5 per cent. The qualitative composition of
the nutrient solution is also of great significence, Trad-
escantia roots remain incompletely pubescent in nutrient
media free from calcium, while, in solutions containing
calciun, the hairs are numbrous and well formeda.t

The investigetions of slimy epidermal cells does not
furnish anything essentially new. ‘They are lacking in the
aquatic form of Polygonum amphibium,“, in specimens of _Salix
retusa and Daphne striata, when cultivated in the moist
air.8 Their development may be argested also by fungus in-
fection, + as well as by the unknown factors causing the
variegation of leaves,

‘1. Schwarz, Die Wurzelh. d. Pfl. Tdbinger Untersuch, Ba.
I, pe 135. Loew, Ueb. de phusiol. Funktionen der Calciunm-
und Magnesiumsalze im Pflanzenorganismus., Flora, 1892, Bd.
LXXV, pe 368. According to Dassonville (Infl. des sels min-
eraux Ss. la forme et la structure des vegetaux. Rev. gene de
Bot., 1896, T. VIII, pe 284.) the formation of hairs is
omitted in distilled water. Compare with this also the state-
ments of Pathybridge, (loc. cit.). If, according to these ;
statements, the formation of the root hairs can be suppresse
by exposure to light, we may see in this only an pee ‘
action of the light, which is made effective by fluctua ie
in transpiration and turgor. Compare here, also Reinhardt,
Plasmolytische Studien z. Kenntnis 4. Wachstums d, Zellmem-
bran. Festchr. fe Schwendener, 1898, p. 425.

2, Volkens, Standort und anat. Bau. Jahrb. Berl. Garten,
1885, Bd. i De Le

3, Lazniewski, Beitr. Ze Biol. d. Alpenpfl. Blora, 1896,
Bd. LXXXII, p. 224.

4, Negar, Beitr. 2. Biol. d. Evysipheen. Flora, 1902, Bd.
XC. Pe 221,

5. Timpe, loc. cit. Beobachtungen an Crataegus monogyna
and Ulmus campestris.

(47)

ap

ted leaves, which below the epidermis of the upper side’
dewlop one or more rows of palisede cells, end below these,
several layers of spongy parenchyma. If the differentia-
tion of the mesophyll is arrested, a homogenous led&f tissue
is produced, composed throughout of more or less round
elements resembling those of the typical spongy parenchyma,
or in which the cells have developed into palisade cells,
but in a lesserv number of layers than under normal condi-
tions. This arrestement of differentiation is recognizable
in land plants cultivated under water, in etiolated leaves,
in shede leaves, under cultivation, in too great drought or
in places saturated with vapor, with the exclusion of car-
bon dioxide, after infection with animal or vegetable par-
asites, under the influence of Alpine and northerly cli-
mates and, as it seems, also under the action of other
factors. In all these cases, the palisade tissue disap-
pears partially, usually, however, entirely, (compare figs.
5 and 11), end a homogenous mesophyll is produced, By the
abnormal life conéitions named here, the same arrestment
formations, so far aS leaf structure is concerned, may be
obtained in very many different plants and plants of a var-
ied nature, Still it is certain, that in plants of char-
acteristic life habits, the normal development of many tis-
sues presupposes also the fulfillment of special conditions.
Thus, for instance, according to J. Schmidt, loc. cit.,

the normal leaf structure is attained only by providing the

ees = we ee ee
ee ee eee ne ne ee ee ne ee ee ee 7

1. The abundant literature on this question makes more ©
necessary than ever, a limitation to a few examples. Dufour,
Infl. de la lumiere s. 1. feuilles. Amn. So. Wat. Bot. Vil,
series, 1887, T. V. pe 311. Stahl, loc. cit. Vesque and
Viet, Infl. du milieu s. 1. vegetaux. Amn. Se. Nat. Bot.

VI, Serie 1881, T. XII, p. 179. Lotheliar, Infl. d. L'etat
hygrometrique et ade l'eclairement s. 1. tiges et 1. feuilles
d. ple a piquants. These Lille, 1893; Rech. Ss. l. pls 2
piquants. Rev. gen. Bot., 1895, T. Vs pe 480. Mer, Reche

Se le causes de la struct. d. feuilles. Bull. 50Ce Bote
France, 1883, T. XXX. De 110. Schmidt, J. Om ydre faktorers
inflydelse pea Levbladets anat. bygning hos en af vore as
strandpl. Boot. Bidske., 1899, Bd. XXIi, Pp. 145. a ca
Etudes, S, 1. feuilles d. pl. aquatiques. Ann. Sc. Nate ave
VIL, servic, 1866, 7. TIT, ps 24. Schenck, Ueb. Strukturan
erung submers veget. Landpflanzen. Bere de D. Bot. Ges.,
1884, Bd. II, p. 481. Keller Biol. Studien I; os seamless
fahigkeit phanerog. Landpfl. an. d. leben im Wasser. ee :
Centrabl., 1897, Bd. XVII, pe 99. Duchartre, Infl. de rea
secheresse S. 1. vegetation et la struct. de 1'Igname =
Chine (Dioscorea Batatas). Bull. Séc. Bot. France, 1885,
™, XXXII, pe 156. Theodorasco, Infi. de 1facide eevee te
Se la forme et la struct. d. pl. Rev. gen. de Bote, - ,

T, XI, pe 445. Moliiard , Rech. S. Le Gee1gies ee ai
Ann, Sc. Nate Bot. 8 me serie, 1895, T. I, De 67. Har est
Anat. Vergleichung 4. Hexenbesen d. Weisstanne Me pre .
Sprossen ders. Dissertation Freiburg 1. Bra, ae ns ae
Einfl, ad. alp. Standortes auf d. Ausbildung ad. Leb 2 : ale
Naturf. Ges. Bern. 1889, Borgesen, Bidrag til Kundska ee
arkiske Pl. Bladbygning. Bot. Tidskr. 1899, Bd. xix, Be °
Bonnier, Infl. de la lum, elect. continue 5S. la forme e

la struct. d. pl. Rev. gen. Bot., 1895, Tf. VII, p. 241.

(48)

46
plants with sodium chloria.+

Conducting and Mechanical Tissues. Even in the dis-
cussion of the axis much may be Said concerning the differ-
entiation of the epidermis, of the assimilatory tissue in
the bark, etc. In general, all that was said in the dis~
cussion of leaves also holds good here. In the same way

a consideration of the conducting and mechanical tissues,
which in general determine the histology of the axis, fur-
nishes nothing essentially nev. In arrested development

of the axes, the vascular bundles decrease in number, the
individual bundics are impoverished, the equipment with
mechanical protecting sheaths degenerates or disappears
entircly; instead of connected "mechanical rings", isolated
groups of thick-walled elements are produced, and the col-
lenchyma cords in the bark occur sparingly or not formed at
all, The same reduction of tissue-differentiation may be
obtained in roots, as in axes. In these the same factors
are everywhere decisiye as in the reduction of mesophyll
differentiation, etc.“ The investigations of Thouvenin
deserve’ especial mention; he retarded the development

of the tissues by the action of mechanical pressure, The
mechanical tissues in the stem of the Zinnia remained be-
low; the standard.

Zalenski* showed, further, that the length of the
vascular bundles, calculated by the surface of the leaf~
blade, is dependent upon external factors in such a way,

ca eaae me ey se et me Senn ta ean ci, a Ns tae aja em a eee meee nea eet
tere ee re a ee et ee ee ee _ ee -_— ee -

1. Compare also the cultural experiments of Brick,
Beitr. 2. Biol. u, vergleich. Anat. 4. baltischen Strandpfl.
Schr, Naturforsch. Ges. Danzig,1888,N.?.Ba.VII,1,Heft Glam.

2. The above quoted authors, Bonnier, Borgesen, Costan-
tin, Dufour, Gauchery, Hartmann, Kelier, Kohl, lothelier,
Rauwenhofi, Schenck, Stapf, Teodoresco, Vesque and Viet
should be compared, Compare further Perseke, Uber die Form
veranderung d. Wurzel in Erde u. Wasser, Dissertation, Lei-
pzig, 1877. Costantin. Infl. du sejour sous le sol sil. ay
struct. anat. a. tiges. Bull. Soc. Bot., France 1883, 1. '
p. 230. Et. comp. a. tiges. aeriennes et sout, d. Dicotyl. A
Ann. SCa Nat. Bove, 1883, VL, serie, 7, XVI, Pe 4. Rech. meg
struct, de la tige a. pl. aquatiques. Ibid., 1884, Vi. serie,
T, XIX, p. 287. Dassonville, Action des sels. Se la ee
et la structure d. veget. Rev. gen. de Bot., 1896, 7. ‘
pe 284, and 1898, T. X., pe 15. Farmer and Chandler ee
ially (on the iniluence of carbon dioxide etc, Proc. a se
1902, Vol. LXX, ps 413) made investigations on the influen
exerted by a superabundance of carbonic acid.

os , 5 longe-
3. Des modifications apportees par une traction
itudinale de la tige, C.R. Acad. Sc. Paris ,1900,T.CXXX,p-663.

j j id. Pflan-
4. Ueb. de Ausbildung d. Nervation b. verscheid.
gen. Ber. d, Ds Bot. Ges. 1902, Bd. XX, pe 433.

(49)

a”
that-in plants grown in moist places, therefore in weakly
transpiring individuals, the whole length of the vascular
bundles is less than in those transpiring strongly. It
will doubtless be possible to demonstrate the same hypopi-

asia also in a comparison of the sun and shade leaves of
our deciduous trees , ete.

In the weakiy grown specimens, which Daniel
grew from the seeds of and Alliaria, grafted on
a furnip-rooted cabbage, (Brassica Napobrassica)
nothing but arrested development occurs, One will
not dare, from the appearance of scanty tissue dif-
ferentiation, to conclude upon a "creation des var=
ieties nouvelles au moyen de la greffe,”, as
Daniel attempts to do. ,

The study of the anatomy of blossoms and fruit and con-
sideration of the Secondary tissues can furnish further
material for our consideration. Also the differentiation
of anthers and anther partitions, as well as ovale and the
differentiation of the fruit and-seed recoptacles is sub-
ject to the action of the same arresting factors, of which
mention has so often been made,” In cambial products, ar-
restment in tissue-differentiation is shown by the fact that
the difference in xylem in autumn and spring wood disappears,
or, at least, degenerates strongly.

~_ oe ee re ee
Se ee ee em mee es ene em tame ee tae ee tae me ee ee ee ee ee

1. C, R. Acad. Sc. Paris, 1694, T, CXVIII, py 992.

yee Wieler, (Ueb. Bezieh, zw. d. sek, Dickenwachst. ude
Ernahrungsverhaltn. ad. Baume. Thar. Forstl. Jahrb,, 1892,Bd,
XLII, p. 72) saw that the formation of the annual rings could
be lacking. Kny (Eine Abnormitat in d. Abgrenzung d. Jahres-
ringe. Sitzungsber. Naturf. Fr. Berlin, 1890, pe» 138) ob-
served thin walled autumn wood; further statements also in
Verh. Bot. Ver. Prov. Brandenourg, 1879 (Ueb. d. Verdoppel-
ung ad. Jahresringe). On the anatomy of the stamens and ovules
one Should compare, for example, Guignard, S. 1. organes—
reproducteurs des hybrides vegetaux. C. R. Acad. Sc. Paris,
1886, T. CIII, p. 769. Amelung, Ueb. Etiolement. Flora,
1894, Bd. LXXVIII p. 204, on the normal arrested, develop-
ments. Compare also Familler, Biogenet, Unters, ub. Verkum-
merte od. umgebildete Sexualorgane, Flora, 1896, Bd. LXXXII,
p. 153. The stamens of the_cleistogamic blossoms in places
do not develop any fibro-cellis(Lecler Du Sablon, Rech. s. 1.
fleurs cleistogames. Rev. gen. de Bot., 1900 7. XII, p, 305.
RosSler, Beitr. 2. Kleistogamie, Flora, 1900, Bd. LXXXVII,

e 479). :

: The same arrestment in differentiation might be
brought about also by exposure to weak light or the action
of damp air, On arrested developments of Ovula compare also
Muller-Thurgau, 2. Jahresber. Versuchsstat. Wadensweil, and
Still others, on arrested developments of the fruit and
seed pods, compare for example, Amelung, (loc. cit.) who
harvested deformed Cucurbita seed on cultures in the dark.
It is well known that fruits attacked by Exoascus Pruni
form no hard pit.

us

(50)

48

* The question still remains to be setlled whether there
is foundation and cause for giving a biological signifi-
cance to the above described hypoplastic tissue formations,
especially to those manifested by incomplete tissue dit-
ferentiation, and to claim them as purposeful reastions
of the organism to definite external agents.

In my opinion, there is no reason whatever for this.
If we, first of all, confine ourselves to the "shade leaves"
it is evident that their mesophyll retains, in more than
one respect, the tharacter of young, undeveloped leaves,
While in the sun leaves, even these evidences are sooner
or later lost by characteristic processes of growth and
differentiation. According to Stahl, the mesophyll of the
sun leaves of Lactuca Scariola which are oriented vertical-
ly, consists throughout of palisade cells; horizontal __
leaves which get the light only on the side, develop palis-
ade t¢elis only on the side exposed to the light, while
they are entirely absent in leaves grown in Shady places.
Also Some species of Iris do not develop palisade cells
when growing in the shade. In other cases, even in shadey
places, palisade cells are produced, but in a lesser devel-
opment than in leaves exposed to the light. Because the
characteristic palisade cells, oriented with their long |
axis perpendicular to the surface of the organ, are not pro=
duced, leaves grown in the shade remain similar to young,
uniifferentiated ones, so far as the form of their cells
is concerned, and besides the cells of leaves grown in the
Shade remind one also, in number and size, of the conditions
found in undeveloped leaves, i think that the appearance
of such arrested developments in no way proves the ability —
of the plants and leaves, "to adjust the formation of bored
assimilatory parenchyma, in a self-regulating manner, to e
given intensity of light".“ For this is needed primarily
the experimental proof that a leaf-blade, with mesophyll
free from palisade cells, is capable of a more ea ae 4
assimilatory activity in the shade, than is a leaf provide

_ ee
——— ee ee ee ee
a ye ee ee ee eee oe ee te Oe fo ne te em ee te te

le In many cases the spongy parenchyma cells of shade
leaves show strong growth parallel to the surface of aa
leaf. AS Stahl also has already indicated (loc. cit. p- :
this stretching is to be traced back to the action of se -
anical factors, and explained oy the energetic ee >
the leaf ribs, which stretch a little the tissue fiel : =
lying between the,. The same factors will help to explai
also the porosity of the tissue in shade leaves.

2. Haberlandt. Physiol. Pflanzenanat., 2. Aufl.,
Leipzig, 1896, pe 253.

49

with palisade cells. In any case, it has not yet been show
that shade’ leaves with their porous mesophyll structure supply
the lgaves with a strong transpiratory current. Geneau de Lamar-
liere* found, on the contrary, that sum-leaves transpire more
Strongly than shade leaves under similar external conditions.
That sun leaves transpire more strongly in sunshine, that shade
leaves in the shade seems & matter of course and even the scanty
supplying of food substances to those leaves grown in shade ex
plains the fact that their tissues do not develop so luxuriantly,
nor are they so completely differentiated as the mesophyll of the
strongly transpiring and thereby well-nourised leaves, untfold—
ing in sunshine, :

; If we recognize in the formation of shade leaves, not an
adjustment to definite light conditions, but only the unavoid-
able product of some arresting factors, the correspondence of
Shade leaves with leaves of plants from Alpine habitats, as
b¥ought forward by Leist, loses its remarkableness and we need
no complicated explantation for the fact that land plants,
placed under water, develop leaf-blades with the homogeneous
Structure of "shade~leaves". Schenck (loc. cit. p. 464) seems
indeed to find in phenomena of the lest kind also a purposeful
structure adjusted to the abnormal conditions:~ "the submerged
plants live in a medium, which absorbs the rays of light more
Strongly than does the air; in a medium which places only dif-
fuse light at the disposal of plants living in it. Water plants
aS well as shade plants must consequently be retarded so far as
the development of the assimilatory tissue is concerned.' acy
however, the action of moist air is enough to produce the same
homogeneous tissue structure, if the factors effective in ae
regions S i iciently i case nov con-
recto mane Vet, amoutticd engly anaLVEPap Whe Bake’ tizaue form
in certain plants, we will be able to attach very little value
to explanatory experiments of this kind. In my opinion,up to
the present, no reason exists for recognizing the mesophyll struc~
ture of shade leaves, and the parts of plants grown under water
aS anything other than arrested, (continued on page 50)

SS ae — home ik ea Sie SS ee. —
sd ~~

1. Stahl characterized it as "right well conceivable" (loc.
cit. p. 37) that with very weak light, preference will be shown
for shade leaves, since the ability to bring the chlorophyll
grains into the favorable position,- the horizontal position~ A
makes possible a more productive utilization of the seanty Ligh
than can be the case in the tough sun-leaves, whose chlorophyll
grains take up a position less favorable for weak Light.

2, Rech. physiol. s. 1. feuilles devel. a l'ombre et au
soleil. Rev. gen, de Bot., 1896, Y. VIII, p, 481

3, The investigations as to the influence of Alpine life
conditions on the tissue formation of plants have led to very
dissimilar results in different places and in the testing of
different plants, Compare especially Wagner, Aw, Bue Kenntn.
des Blattbaues der Alpenfl. u. desen. biolog. Bedeutung. Sitz-
ungsber, Akad. Wiss. Wien, 1892, Ba. Cl.

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50

developments, i. e. tissues scentily de¥eloped as compared
with the "normal " ones. ,

Fig. 12, Showing a cross-section through the leaf tip
of the land form of Ranunculus fluitans side by side with
that through: the leaf of the water form, should make pos~
Sible a comparison between the leaf structure of plants
known aS typical water dwellers, and such as become "water
plants" only thruough the compulsion of the experiment, or
of unfavorable external conditions. In both cases mesophyll
cells of very simple round form are produced. This correse
pondence however, makes so much the lesss superfluous the
experimental proof that the round cell functions better under
such air conditions as are offered to submerged parts of
plants, than do the paliseade cells, since the appearance of
that simple cell form shows, as we have seen, no specific

‘effect of the diffuse light and the life under water. What

complicated accessory Suppositions would become necessary

for the preparation of teleogical explanations, if those
mesophyhl structures resembling shade leaves should now be
considered also in the light of appropriate reactions, pro~-
duced under the influence of the too great drought, under that
of a lack of carbon dioxide, upon the action of animal para~
sites or upon other disturbances in their nutrition?

In my opinion similar sonsiderations stand in the way
also of the biological explanation of other arrested devel-
opments. .

The stems of Cardamine growing under water develop,
according to Schenck, no mechanical tissues; the "formation
of these is unnecessary under water, for the water itself by
means of its greater density keeps the plant in position
favorable for light."1 How is it, however, with those
plants which mature in moist air and do not develop mechan-
ical tissue, or indeed, with those experimental plants of
Thouvenin's, although for them it would have been just as
"necessary " or indeed, more than necessary than for the
specimens living under normal conditions? Further $ through
a scanty development of the medullary ray, the vascular
bundles in the water form of Cardamine move somewhat toward
the center, “a tendency which in typical water plants has —
led to the formation of axillary vascular fibres." According
to Schenck guch an arrangement is “purposeful" for water
plants, since by this means the tensile strength of the ax-
illary parts developing under water is increased. It may
seem here as if the variation of the water form from the
normal should be explained as a purposeful transformation.
Prom my point of view, however, this cannot enter into the ais
cussion, because keeping the plants in standing water cannot
be of equal significance with keeping it in running water for
only in the latter is the tension produced. Besides, the
reduction of the pith, by which the vascular bundles seem
shoved out of place towards the center, takes place also under
other cultural conditions; for example, in strongly etiolated

we ee
ee al
ee ng en tee tee ee Re ee me ee es Ore ree oe me on

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51

Pimally it is equally unjustifiable to dcduce from con~
ditions under which certain tissue formations cannot devel—
op conculsions as to the functions which they would have .
performed under normal conditions. Tissues not developed
in cultures in moist air are not thereby justified as ar-
rangements to provide against too high transpiration. We
come nearer the truth indeed through the assumption that
plants in moist cultures, etc. "cannot" develop definite
tissue forms, than by the supposition that the plant no
longer develops these forms, because ther are "no longer
necessary" to it.

Taken all in all, the tissue hypoplasias as yet known,
do not seem to me suitable to prove the capacity of the
plant for a self-regulating adjustment to unfavorable ex
ternal conditions.

eee Ore te we ee ee

We have already spoken repeatedly of the factors by
which hypoplasias are produced. If we glance once more over
the facts at hand, we can verify the statement that almost
all of the described hypoplasias may be traced back to
scanty nourishment. It is hence evident that the plants
vegetating in distilled water and those cultivated in the
dark or without carbon dioxid, in which we have ascertained
hypoplasias, are more poorly nourished than normal ones.
However, the same holds good also for the individuals which
have been grown in moist places or under water, which at
once, with a normal degree of transpiration, lose the supply
of food. substance which is necessary for normal tissue
formations.

It becomes evident, especially in the higher plants,
that, with insufficient nourishment, not only certain pro-
cesses of growth, formation, and differentiation become im-
possible, but that usually a large number of varied pro-
cesses also are lacking. Arrestment in the differentiation
of the tissues makes itself evident not only in one tissue
form of an organ, but usually in several, often in all. Only
when the injurious influencés are moderately effective do
we occasionally find that the development of the "more sus-
ceptible” tissue forms, such as, for example, the ducts, is
influenced, and that the development of those more resistant,
for example, the epidermis, comes to maturity unchanged.
According to our present knowledge, there are no factors
Which even when acting energetically, influence only one
tissue form, and thus prevent normal development.

The discussion of this point seemed necessary
in view of the contents of a later chapter. We will
see later thah, by increased utilization, the forma-
tion of individual tissues of the plant can be en
couraged, while the development of others, on which
no increased demands are made, does not exceed the
normal amount. It would be conceivable that, as
a result of abnormally weak demand upon them, those
tissues forms, of which less is required, would re-
main below the normal in their development while the

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52

otners, would develop normally. It isa question whether the
activity~hypoplasia, of which we will speak later in detail,

lets an inactivity hypoplasia be set up in opposition wu it.
I have already indicated that cases of this kind are not yet
known. The comparison of plants matured under water, which
are supported by the surrounding medium, on which account
but little is required of them mechanically, with individuals
from moist cultures on which mechanical demands are made,
makes it perhaps impossible { see above) to explain the omis-
Sion of the mechanical tissues in the former as “inactivity
hypoplasia". Besides this, all tissue forms in plants matured
under water are weakly developed, just as in Specimens grown
in moisture or in the dark. ‘There is no foundation for the
Supposition that a reduction of the mechanical tissues would
result from none-utilization. For the same reasons we may
not speak of “inactivity-hypoplasis" when no normal assimil-
atory tissue is developed in plants grown in cultures in
the dark, or in places free from carbon dioxide, from which

‘the opportunity of assimilation was taken away, etc.

Tschirch= explains the weak development of the mech-
anical ring in weeping varieties of different trees by the
fact that less rigidity is required of their branches than
of those of upright forms, Experimental proofs supporting
Tschirch's supposition do not exist, rather, Wiedersheim! s*
new investigations make it seem impossible that the slight
surplus of mechanical requisition to which the branches of
upright forms occasionally the young branching ones, are
subjected, :could incite the branches of the weeping forms
to a stronger formation of their mechanical ring. Therefore,
we are not justified in terming this “inactivity-—hypoplasia.”

et ae eee ee eee ap many ee es ee

Tissue hypoplasias similar to those expressed in plants
by a reduction of the cell size, decrease of the cell number
and simplification of the cell and tissue differentiation,
may doubtless be pointed out in the same diversity in_animal

organisms.

eee raw, a ee ee ee ee ee ne me me me ee eee ee ee ee

1. Beitr. z. Kenntn. d. mechan. Gewebesystems. Prings-
heim's Jahrb. f.< wiss, Bots, 1685, Ba. AVL, De S29.

5. Uebe d. Binfl. d. Belastung auf d. Ausbildung v.
Holz- and Bastkorper bei Trauerbaumen , Ibid., 1902,
Bd. XXXVIII, p. 41.

53

* Protozoa seem to offer an especially favorable mater-
ial for investigation. Among others, the investigations
enil Maupast throw light on many points of the question
interesting us. In starvation cultures very numerous
dwarf specimens arise, since the organisms always divide
before they are "fully grown". At the same time, the
processes of diitrerentiation taking place in normal cells,
are partially "arrested"; the cilia, the undulating mem-
branes, indeed the mouth parts, are either not developed
at all, or only to a reduced size. (Compare above p. 37).

In higher animais, and especially in man, éncomplete
tissue differentiations, corresponding to the hypoplasias
above described, appear only rarely, at least, the patho-
logical literature which I know throws only scanty light
on this. As a well-known example, I will name the bones
in rhactitis, in which the histological characters of the
cattilage are retained longer than in normal bones.
Further, tissue hypoplasia is present if succulent epithe-—
lial layers do not horniffy,- and the like.

Pe eg ee ee ee ee ee ee eee ee ee ee ee ee a ee ee

1. Compare for example, Sur la multiplication ad.
infusoires cilies. Arch. zool. exp. et gen. 1888, eme.
Sere q Le VL.

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CHAPTER III 5A
METAPLASIA

4
After disposing in the preceding chapter of these cells or

tissues which remain in some way below the normal in development
we will discuss in the following Sections, those which in some ”
way exceed the normal, In the simplest case, an abnormal ad-
vance in development may result from changes in the cell-char-
acter, without involving any increase in volume or any process

of division,

The changes in cell character, exclusive of the last named
processes may differ very widely among themselves, Either a
breaking down of the cell content, or of a definite pert of it,
is involved; the organs of the cell, partially or as a whole, be-
come incapable of functioning and die, or disappear completely.
Changes of this kind are callea regressive, or the transforma-
tions show that the cells perform new functions, or the cytoplasm
has been increased in them, or new organs are formed, and the
like. Changes of this kind are called progressive, Since inre-
gressive changes, the symptoms of degeneration and necrosis are
involved which should be Kept out of our consideration, only pro-
gressive changes are to be treated of in the present chapter, We
will define Metaplasia as every progressive change of any, cell
which is not connected with cell-growth and cell-division’.

Since our distinction between regressive and progressive
changes is based upon physiological peculiarities of the cells
concerned and since, further, in judging of the latter we are of-
ten led to conclusions, the drawing of which is made possible by
the anatomical character of the cells and tissues, it is evident
that we will not always be able to decide with certainty whether
& change in the cell body is to be termed progressive or regres-
sive. Besides the undoubtedly progressive changes, our discussion
should also take into consideration those others for which our
present slight knowledge of their cell-lif¥e makes no final de-
cision possible.

Metaplasia plays a much more modest role in the abnormal
histology of plants than in the animal or human body. In the
latter metapl:sia from varying causes becomes the foundation of
many important, pathological processes, in as much as definite
tissues change their character and are transformed into other
kinds, To be sure such @ transition is possible only between
nearly related forms, especially among the different connective
tissues. Nevertheless, in metaplasia the original character of
the transformed cells can become entirely unrecognizable, for ex-
ample, if reticulated connective tissue be chanfed into fatty
tissue, In plants, the number of observed transformations is very
much less than in animal tissue and, moreover, in all cases the
original character of the plant cells changed metaplastically
remains readily recognizable, The reasons for this are not hard
to find, While in the metaplasia of animal tissues the form of
the cells is capable of very extensive changes, in plant cells
the ferm remains constantly fixed by the firm cellulose ceverihg
ef the individual elements. Change in form is made possible only

‘by growth, and therefore is not involved in changes of a purely

metaplastis character,

Metaplastic changes are produced in the cells of plants es-.
pecially by the formation of new cell contents, or by changes
the membrane,- through growth in thickness.

-_- - _ a
-_-_ = =- _-_ = _— _— -~— =

d SQ far as I know, Virchow introduced the term metaplasia..
He states that "persistency of the cells in the changing of the
tissue~character, is characteristic of this process", Virchow's
Lecture "Ueber Metaplasie” (in s. Arch. f. path, Anat. 1884, Bd,
XQVII. v. 410) is also of great interest fer non-medical men.

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I, CONTENT OF THE CELL BS

The formation of chlorophyll in cells, which normally remaiz:
free frome chlorophyll, is one of the most frequent and anet strik-.
ing metaplastic changes, The action of light, which, as is weji-
known, is indispensible for most phants in the formation of ch .sr-
ophyll, often calls forth a metaplastic greening in organs which
under normal eonditions would have been kept from the light;
tubers, buibs, rhizomes and roots of teny plants, as elso the cot-
yledons of many seedlings, commonly germinating in the soil, be-
come green in light, According to the prevailing theory of the
production of chloroplasts we must assume that the colorless ¢hro-
matophores (leucoplasts) present in the cells of underground or-
gens are transformed under the influence of light into cerriexs

of green coloring metter, In this connection it is worthy c? uote
that in all underground organs only a moderate degrée of green-
coloration is obtainable when they become green metaplasticaly.
Their shade differs widely from the color of typical assimijatery
organs, and resembles rather the pale green of many lower or side
leaves or the coieoptila of some grasses, Cotyledons cf Vicia

and others, removed from the stem of the seedling, become greén-
relatively strongly when left in the light. It must be observed
further that not all colorless cells and organs become green
through the action of light; while the roots of Cucurbita, Menyan-
thes, Zea and many others may then become a paie green; the roots
of other piants remain permenently colorless, pellen tubes are or-
gans on chlorophyll-bearing plants which have never been changed.
to green, ond they remain colorless even under the prolonged in-
fluence of light and cultivation under the most varied conditions
In these and similar cases, we must for the present leave unset-
tled the question, whether this occurs only because the “right”
combination of conditions has not yet been found which would meke
possible the turning green of these organs, or whether they have
lost the ability to form chlorephyll, i. e., the possession of
leucoplasts capable of deveicpment,. .

Bonnier@ found that the tissue of his experimental plants,
which were uninterruptedly exposed to the light of arc-lamps,
turned green even to the pith,- the cells of the medullary rays
and of the medulla, normaliy colorless, contained chiorophyll.
But whether the appearance of the chloropiasts may be considered
as an effect of the continuous exposure to light is not demon-
strated with certainty by Bonnier's investigations.

Without doubt other action than thut of light can induce also
a metaplastic greening, The formation of chlorophyll in hy per -
trophied epidermal cells, which will be considered later, favors
this as well as the "turning green" of corollas, anthers and ovules
from the action of parasites, the treatment of which belongs to
the province of pathological mor phology”,

More exact proof is still needed as to how far an increase
of chlorophy}1 grains can be incited py the action of chemicals,

ee od shay es Seem ees a ee ee I i ee eh ee

2 tnfl, de la lumiere electrique continue s. la forme et la
forme af pl. Rev, gen, Bot., 1895, T, VII, p. 241.

W
e The statements of C. Kraus, (Ueb. kunstl. Chlorophyller- .
zeugung in leb. Pfl, bei Lichtausschluss, Landwirtsch. Versuchsstat
1877, Ba, XX, p. 415), according to which etiolated plants can bs
incited to the formation of chlorophyll by methyl alcohol or by
mechanical arrestment of their growth in length, need testing.

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56
especially poisonous ones, According to the investigations of
Rumm and others, treatment with Bordeaux mixture causes a deep
green coloration of the plants under experiment. Pethybridge
makes the same statement for his wheat plants. which were ecuiti-
vated in a solution containing sodium chioridt,

Just as in the formation of chlorophyll, a metaplastic
change of the cell character can also be produced in tissues nor-
mally colorless, by the deveicpment of red pigmemt dissolved in
the celi sap, As mentioned above (p, 38), the formtion of this
red pigment 1s dependent in many plants on the action of light
and of good nutrition, and may therefore be suppressed by the re--
moval of Aight and of nutritive materials, Conversely, the ques-
tion must now be asked, whether the production of red coloring
matter can be induced in cells, normaiiy colorless, by the effect
of light on organs which, under normai cond*tions, are deveicped
in the dark, or Likewise by a surplus of light, or, further, by
an increased suppiy of nutritive material, In fact the observa-
tions on Calluna vulgaris, Azolla and many others show that es-
pecially Intense lighting causes'‘a red coloration, ,The same is
true of many succulents (Opuntia, Sedum and others)”, It has
been proved further that plants transferred from the plains to
high mountains, often develop red coloring matter in the new hab-
itat, ,supposedly under the influence of the Alpine abundance of
light’. The same red coloration as an effect of intense lighting
is conspicuous in the vegetation of the far North*, Finally cr-
gans which under normal conditions are kept from the action of
the light, such as roots and others, are often colored red, if
they are forced to live in the light (roots of Salix®, Zea,
Begonia and others),

Further the question must still be asked as to the influ-
ence of the food supply on metaplastic pigment-formation, Overton®
has show that in plants of the most varied kinds, the formation
of red coloring matter - often indeed extraordinarily proiific -
takes place if opportunity is given the plants to take up an
abundance of sugar (grape, invert- or cane-). TLeaves of Taraxaxun,

i Compare ,,for example Rumm: Ueb. d, Wirkung der Kupfer pra-
parate bei Bekampfung der sog. Blattfallkrankheit der Weinrebe.
Ber, d, D. Bot. Ges. 1893, Bd. XI, p. 79. Pethybridge, Beitr, 2.
Kenntn, d, Einwirkung d. anorg, Salze auf die Entwickelung and
ad. Bau, d. Pfl. Dissertation Gottigen 1899.- Some observations
on the influence of the nucleus on the growth and fgrmation of the
chjorophyll bands in Spirogyra by Gerassimoff, Abhangigkeit d.
Grosse d, Zelle v. ad. Menge ihrer Kernmasse, Zeitschr, allg.
Physiol, 1902, Bad. 1, p. #220,

= Compare Mchl, Vermischte,Schriften, 1645, p. 386, 390;
further Askenasy, Ueb. a. Zerstoruag d, Chlorophylis lebender Pri.
durch d, Licht, Bot, Zeitg., 1875, Bd. XXXIII, p. 497, Pick, Ueb.
d. Bedeutung ad. roten Farbstoffes bei d. Phanerogamen u, die Be-
zieh. ders, z, Starkewanderung, Bot, Cbi., 1863, Bd. XVI, p. 315.
DeVries, Ueb. @. Aggregation im Protoplasma v, Drosera rotundi-
folia, Bot, Zeitg,, 1886, Bd. XLIV, p. 1 and many others.

5 Compare Kerner, Pflanzenleben, 1898, Bd. IT.

+ Wulff, Th, Bot, Beobacht. aus Spitzbdergen. Lund 1902.

5 Compare also Schell, Ueb, Pigmentbila@ung in d. wurzeln |
einiger Salix-arten 95, Naturf.-Vers, Kasan. Russisch. (Just's
Jahresber., Bd. V, p. 562).

6 Beob, u. Versuche ub. ad, Auftreten v. rotem Zellsaft
wet net Deinoshoim's Jahrb. ff, wiss, Bot., 1899, Bd. XXXIII,

f

89)

ous

of many Saxifrages and Crassulaceae etc,, if placed in a sugar
solution, color an intense red after a few days,

The red coloration appears very abundantly after injury.
The edges of wounds on mutilated stems and injured leaves are
often colored very intensely, First of all it remains uncertain,
whether contact with the air, disturbance in the conducting paths
and the consequonces of these or some other factor brings about
the reddening, The experiments which I made on leaves of Saxi-
frage ligulate are interesting, The fully grown leaves of this
plent, under such life conditions as cre offered in conservator-
ies, are @ succulent. green, but free from red pigment, Only the
younger leaves of the experimental plants were slightly reddened
on the edge, as also on the underside of the larger veins. -If a
fully grown leaf was out through the mid rib, a red coloration of
the wound took place after a few days,- at times only after one
or two weeks; but only the side of the wound tovard the tip of the
leaf beoame colored, while the opposite side remained unpigmented.
It ig evident that the same conditions, as regards the changes of
oxygen supply eto., exist on both edges of the wound, In order
to explain the one-sided formtion of pigment, I would Jike to re-
turn to the old assumption of the decreased sap flow which causes
an accumulation of the food stuffs above the place of injury.
The formation of red coloring matter may perhaps be explained as
the result of superabundant nutrition of certain cells, just as
in Overton's experiments. I would also like to propose the same
explanation for the red coloration of wounds in other plants. As
in Saxifraga ligulata, the accumulation of food stuffs is pro-
ducéd by destruction of the conducting paths and the accugulation
of the contents, or, in its turn, represents the result of es-
pecial stimuli, produced after the injury. In Saxifraga ligulate,
moreover, only the tissue on the veins themselves becomes red,
most intensely so, immediately at the place of injury, but clearly
recognizable even at a distance of 1 to 1-1/2 cm. from the wound”,

The formation of pigment which takes place through the ac-
tion of many parasitic organisms:- mostly to be sure in connec-
tion with cell growth and division, may possibly have a similar
explanation, Since it is now known that even in those places a
Strong assimilation of proteids and starch often takes place, the
possibility may be considered that here also the formation of pig-
ment is caused by the supplying of food substances, Local redden-
ing and early ripening upgder the influence of parasites was des-
cribed recently by Kochs®”, In the latter instance, the formation
of pigment under the influence of light may also be traceable to
nutritive factors,

Overton goes still further in his attempt to explain uni-
formly the phenomenon of pigment-formation. As is well known,
a lowering of the temperature accelerates the reddening ef many

bln =— = Oem ee

of foodstuffs, necessarily produced by destruction of the conduct-
ing paths, may be recognized in wounded or notched branches, whose
leayes, according to Linsbauer (Finige Bemerk, uber Anthokyanbil-
dung, Oest. botan, Zeitschr., 1901, Bd. LI, p. 1, therein also ref-
erences to the oldér literature), turn red above the place of in-
jury, below it, however, remaining normally green. This distinc-
tion may be explained just as the one observed on Saxifrage leaves,
Linsbauer explains the reddening very generally by the distrubances
in the transference of material and explains in this way also
Uverton's results, "Production and transference of material stand
in an entirely unusual misproportion to one another (Linsbauer)".
The dissimilarity in the proportion of neighboring parts of branch-
es and pieces of leaves above and below the normal spot is natur-
ally not explained by this.

°
VW
ee . . we | QCAhstIAQanan ant A Dfinnnoncov

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58

plants, Overton calls attention to the fact that low tempera-
tures may possibly effect an increased concentration of the sugar
contained in the cell.

In conclusion, the metaplastic formations of coloring mat-
ter jn the so-called graft-hybrids must be considered, Linde-'
muth”, in his grafting experiments with various potato species,
grafted above ground the pale green shoot of the "calico" variety
with the violet shoot of the "Zebra", After 14 days the grafted
axiliary pant below the place of coalescence had reddened active-
ly. It is wholly improbable that the reddening of the under part
was produced by the downward conduction of the pigment; it has
not yet been observed, that red pigment can wander from cell to
cell. Also nothing "dg known of the esistence of eny chromogenic
or leuco-connection, to which this ability to wander could be due.
We would dare speak of a graft-hybrid, only if it had been made
probable that the cells of the stock had been incited, by the
cells of the engrafted scion, to the formation of materiel other-
wise foréign to them, In my opinion it is, however, very much
more probable that the injury, perhaps in connection with some
factors effective at the time of coalescence, led to the forma-
tion of the red pigment*, In the described phenomena on red
coloration I can discover no proof of any graft-hybrid nature of
the potato plants described,

Further study of the conditions under which the development
of the red pigment ef the cell sap occurs is greatly desired and
promises most interesting disclosures. It is still undecided
whether a11 the phenomena of abnormel red coloration may be fully
explained by the relation to gutrition discovered by Overton.

I call attention to Molisch's®’ observations, according to which
young plants of Barilla nankinensis and Iresine Lindeni were
colored more strongly in a nutrient solution free from nitrogen,
than in cultures in spring water, Overton also made similar ob-
servations,

We may conclude briefly our views in regard to the cell con-
tents, which besides the chloroplasts, takes part in metaplastic
changes, We have spoken already of the enrichmart of many cells
with albumen and starch under the influence of parasitic fungi
or animals, Most remarkable are the accumulations of starch
whies Nobha observed repeatedly in his experimenta} plants (Poly-
gonum fagopyrum) when unsuitably nourished, Nobbe* saw"a sutfo-
cating Surplus of starch grains" accumulating in the parenchyma
cells of leaves of plants which were insufficiently provided with
echlorin, Nutrition with unfavorable potassium salts (saltpeter,

i Vegetative Bastarderzeugung durch Impfung. Landwirtsch.
Jahrb., 1678, Bd. VII, p. 887.

é Compare also the negative results of Laurent, Nouv. rech,
s. la greffe de la pomme de terre, C. R. Soc, Roy. Bot. Belgique,
1900,T, XXXIX, p. 85.

3 Blattgrun u, Blumenblau. Schr. Ver. 2. Verbreitung natur-
wiss, Kenntn,, Wien, 1889-90, Bd. XXX. Further it should be test -
ed whether energetic ventilation of a tissue is also influential
in the formation of red coloring matter, Nienhaus (Zur Bildung
plauer u. violetter Farbstoffe in Pflanzenteilen, Schweiz, Wochen-
schr, f, Chemie u. Pharm,, 1895, Nr. 1) states that in the unripe
fruit of Solanum nigrum the pigment formation developed first in
the places of injury Gnd near the stomata.

4 Ueber ad. physiol, Funktion des Chlors in d. Pfl. Land-
wirtsch. Versuchsstat,, Bd, VII, 1865, p. 371.

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59

potassium sulphid, potassium phosphid) carried with it the same
phenomena, of disease, in leaves and internodes an abnormal in-
crease of the starch content made itself feit, at least tempor-
arily!, Nobba observed Similar phenomeya in buckwhgat plants,
which had been robbed ef their blossoms*, Schimper” obtained ;
the same accumulntion of starch in leaves of Tradescantia Selloi,
oultivated in nutrient solutions free from calcium, in ail
these and similar cases the cells @re clearly unable even to
develop the diastatic ferments necessary for the solution of
starch,

Similer changes in the cell charcoter will possibly be
produced @lso by abnormal deposits of crystals} however, cases
of this kind are as yet unknown to us,

2, CELL MEMBRANE

Metaplasia of the cells can be produced by changes in the
cell wall, only in so far as the membrane influences the quali-
ties of the cell by abnormal growth in thickness or by changes
of its chemical character,

In the case of growth in thickness of the membrane, two kinds
of thickenings should be distinguished: either the protoplasmic
membrane forms characteristic thickenings of the wall by the reg-
ular formation and distribution of bordered pits, or an irregular
deposit of cellulose is laid down here and there on the normal
cell membrane, sometimes abundantly, sometimes sparsely, causing
the production of massive lumps, or of delicate protuberances,
or the like, In metaplastic changes of cell character, wall
thickenings of the first kind are very rare; as yet, I know of
them only in one single plant family. The second kind of cellu-
lose deposit, which never makes any regular recognizable distri-
bution of the newly produced material and is distinguished by an
absence of bordered pits, ocours more abundantly. To be sure
there exists one case in which it cannot be decided definitely
whether a degenerative process is present or note.

Regular wall-thickenings and also the formation off bordered
pits were observed by v. Bretfeld in different orchids”, whose
leaves were scarred, after injury, by the formation of "netted
duct” cells. In leaves of Cymbidium alcifolium, C. ensifolium,
Laelia anceps, Epidendron ciliare, C. vite#iinum, Ocvomeria

raminifolia, Maxillaria pallidiflora and M, crassifolia, &

layer consisting of One or more cell-layers" is conspicuous be-
low the destroyed celis and is distinguished from common mesophyll
by a massive thickening of the cell walls. These are not thicken-
ed uniformly, but contain spores of different sizes, delicately
circumscribed, which taken together give the appearance of retic-
ulafed walls, The same wells occur in the orchid leaf near the
vascular bundle. During the thickening of the cell walls, the
cytoplasmic contents of the cell, - the chlorophyll and starch

_-_ = =o

-— = OO a Sm
mmm meme

1 Nobbe. Schroder and Erdmann. Ueb. a, organische Leistung
des K, in a. 'Pfl, Landw. Versuchsstat,, Bd. XIII, p. 321, 386 ff.
Compare besides Frank and Sorauer (quoted p. 91, Note 5).

e Nobbe; Landwirtsch, Versuchsstat,, 1865, Ba. VII, p. 385
and Bd. XIII, p. 390.

Ww
3 gur Frage a. Assimilation 4. Mineralsalze durch d, grune
Pfl. Flere, 1889, Bd, LXXIII, p. 20%,

4 veb, Vernarbung und Blattfall, Pringsheim's Jahrb, f.
wiss, Bot., 1879, Ba, XII, p, 133.

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60

grains,- disappear and the nucleus breaks dowm, Later we will
again refer to the "tendency" of orchids toward the formation
of netted duct cells, (Chap. IV. 4),

Cellulose deposits without any regular arrangement and
without bordered pits occur in very different plants end after
very different kinds of disturbances,

These oellulose deposits form an especial group, end are
produced by the penetration of foreign bodies into the living
cell. The form of the newly-produced cellulose masses is then
determined not by the quality of the cells forming the cellu-
lose, but by the form of the foreign body, As is well knom,
the crystals of calcium oxalete within the cells are often sur-
rounded by a cellulose mantle, which coalesces in one or more
places with the wall of the cell containing it. (Rosanoff's
crystals). Other paraplasmatic cell enclosures are also sur-
rounded at times with a cellulose covering, such as the oil
drops in the cells of the Piperaceae, Aristolochiaceae, Laura-
ceae, Similar cellulose formation is incited in abnormal cases
when fungus hyphae penetraté into the protoplast. First of all
a ecesllulose button forms at the place of infection. Later a
Sheath is produced around the penetrating hypha, and passes
through the whole cell as a tube, when the hypha has traversed
the cell“. W. Magnus saw inside the cells of Neottia Nidus
avis, attacked by the fungus, clumps composgd of fungus and cy-
toplasmic fragments changing into cellulose”.

The cellulose sheaths of cells infected by fungi here des-
cribed should not be confused with the coverings which clothe
the sting canal of various plant lice throughout the lumina of
the cells and the intercellular spaces. Their mention my be
& propos here, since they were considered earlier to be path-
ological cellulose structures, Millardeg designated them as
"bourrelets de cellulose", and Prillieux’ made the same mistake.
According to Busgen's thorough investigations, no product of
plant cells is involved in the sheath-like structures, but an
exoretion of the parasite, which hardens after the withdrawal
of the sting from the bundle of brjstles, surrounds it as a
firm tube and acts as @ protection~. The sheath substances
gives distinct protein reactions.

emma Pe elem

compare also Weber, Ueb. a, Pilz der Wurzelanschwellungen von
Junous bufonius. Bot. Zeitg., 1884, Bd. XLII, p. 369; Smith,
The Haustoria of the Erysipheae, Bot. Gaz. ,1900, Vol. XXIX,
p. 153; Jeffrey, The gametophyte of Borychium virginianum.
Univ. of Toronto Studies, Nr. 1, 1898, and many others.
(Jeffrey states that a sheath of cellulose is formed on]y in
case of the permeation of the cutinized walls in the interior
of the cell). Compare also the statements in W. Magnus.
(Next note).

2 Studien an d. Mycorrhiza y, Neottia Nidus avis. Prings-
heim's Jahrb, f, wiss. Bot., 1900, Bd. XXXV, p. 205,

3 Millardet, Hist. ad. princip. var, et especes de vignes
d'origine americ, qui résistent au Phylloxera, Paris, Bordeaux,
Milan, 1885, p. VIII (quoted from Busgen, see next note).
Prillieux, Etudes d. alterations prod. d, le bojs du pommier
etc, Ann, Inst. nat. agrog., 1877-1878, T. II, p. 39.

4 Buggen, Der Honigtau, biol. Unters. ub. Pfl. und
Pflanzenlause. Jena 1890,

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61

_ In other cases growth-arresting factors ore involved, es-
pecially any kind of disturbances ih nutrition by which a local
growth in thickness of the cell membrane is caused.

Klebs! observed in various algae very active thickening in
the restitution membrane of plasmolysed cells {Sompare above
p. 14). Either a uniformly thickened and distinctly striated
membrane is formed all around the contracting protoplasts, or
the cellulose is deposited tn excess at certain places, Here
end there knobbed and cone-like protuberanses are formed, which
project into the lumen. But it is impossible to observe that
the specific differentiation of the plant celis here influenced
the shape of the nev cellulose formtions, There often appear
in cells of the same kind, elliptical or conisa%. masses of cel-
lulosg, or masses deposited regulariy on ali sides of the
cells”, We observed the same thing in distivxbances of nutri-

- tion, or under the influence of factors arresting growth in the

roothairs, rhizoids (compare fig, 18), polien tubes, Siphoneae,
and other algee, Large cellulose misses are produced sometimes
Sphero-crystalloid in form, sometimes delicately "coralloid"
cones, or small branched beams, which traverse the lumen of the
cell diagonally (Noll), but lavers thickened with bordered

pits are never found among them,

Heavy wall thickenings resembling collenchyma occur, ac-
cording to Wortmann®?, in the epicotyl, epidermis and bark of
Phaseolus and other plants, if they are forcibly hindered in
carrying out their reaction curvatures. The thickenings occur
on that side of the axis in which the cells have prepared for
a reaction curvatures by an abundant accumulation of proto-
plasm.

_ According to the statements of several authors, heavy
wall thickenings appear in the fundamental tissue, as in the
vascular bundles of plants cultivated in nutrient solutions of

1 Beitr. z. Phys: d. Pflanzenzelle, Tubinger Unters.,
Bd, II, Heft 3 (1888), p. 489.

‘ z Compare Schaarschmidt, Zellhautverdickungen u. Cellulin-
korner bei Vaucherien and Charen. Bot. Cbi., 1885, Bd. XXII,
p. l. Further statements are to be found, for instance in
Stahl, Ueb. den Ruhezustand der Vaucheria geminata, Botan. Zeitg.,
1879, Ba, XXXVII, p. 129; Heinricher, 2. Kenntn. d. Algengattung
Sphaeroplea, Ber. d. D. Bot, Ges., 1883, Bd. I, p. 433; Noll,
Experim. Unters. lb, a. Wachstum d. Zellmembran, Abhandl. Senck-
enberg. Naturf, Ges., 1883, Ba. XV, p. 101, Zacharias, Ueb, Ent-
sheh. u. Wachstum @, Zellhaut. Ber. D. D. Bot. Ges., 1886, Bd.
Vi, p. LXIII. Haberlandt, Heb, Einkapselung d. Protopl. m.-
Rucksicht auf d. Funkt. d. Zellkerns. Sitzungsber. Akad. Wiss,
Wien, 1889, Ba. XCVJII, Abt. 1, p. 190. Tomaschek, Yeb, d. Ver-
dickungsschichten an kunstl. herborgeruf, Pollenschlauchen v. _
Colchicum autumn. Botan. Cbl., 1889, Bd. XXXIX, p. 1. Raciborski,
Ueb. d. Finfl. fuss, Bedingungen auf die Wachstumsweise des Bas-
idiobolus ranarum, Flora, 1896, Bad. LXXXII, p. 113. Sokolowa,
Ueb, d. Wachstum d. Wurzelh. u. Rhizoiden, Bvli, Soc. Imp. Nat.
Moscou, 1897, p. 167. La&mmermavr, Ueb, eigentumlich ausgebil-
dete innere Vorsprungsbildungen in 4. Rhizoiden v. Marchantieen.

Oesterr. Bot. Ztschr., 1898, Bad. L, p. 321 and many others.

3 gur Kenntnis der Reizbewegungen., Botan. Ztg. 1887, Bd,
XXXXV, p. 785, Elving; Zur Kenntn, ¢, Krummungsercheinungen 4.
Pfl. Ofversight Finska Vet. Soc, Forh., 1888, Bd. XXX.

62
two weak “concentration or of unsuitable composition’.

The above mentioned process of growth in thickness can be
combined also with changes in growth of the whole cell, That
is true of the netted-duct thickenings first named, as well as
of the irregular cellulose accumulations free from bordered
pits, We will have to return therefore in the next chapter to
Similar structures.

Changes in the ehemical composition of the membrane as
well as pathological changes of the cells, micro-chemically
dembnstrable, do not belong to our subject. Besides it is not
iuprobable, that, just as in the formation of abnormal cellu-
lose deposits, processes of a degenerative nature ere involved
in the production of foreign matters, which impregnate the cell -
wlose covering and change thereby the chemicel character of the
cell wall. In any case the death of the cell often follows..
Some few notes on suberization and lignification suffice here ..

In the case of rhizomes and petiole of some ferns, @.
browning of the cell-wall follows an injury, which makes itself
evident first in the middle cells, then also in the other lay-
ers of the cell’ wall. Rehention in water appears, in higher
plants, to cause the, suberization of the superficial tissucs’..
According to Tittman® the exposed cross walls of the cut hyphae
of Cladophora glomerata, develop a cuticle.

I. observed lignification of the cell walls without notice-
able growth in thickness in the leaves of Juglans under the in-
fluence of colonies of Lachnus Juglandis. ‘The leaf lice stayed
on the upper side of the leaves, in fact on the mid rib, and
brought the tissue lying over the rib to lignification. Simi-
ler effects might also be caused by other parasites which do
nat. form galls,

meme SS SS

—_— =—=— -— = ee

ts :

2 According to Costantin, Etude comp. da, tiges aeriennes et
souterraines des Dicot. Ann. So, Nat, Bot., 1883, 67° ser., T.
XVI, p. 4; also Rech. s. la struct, de la tige d, pl. aquatiques.
Ibid, 1884, 6M° ser,, T, XIX, p. 287. Sagvageau observed that
in aquatic plants Potamogeton and others, the cells lining the
air passage turned to cork after the intercellular spaces had
been filled with water./(Sur les feuilles de quelqu. monocotyléd.
aquatiques. Thése, Paris 1891, p. 181). According to Thoms.J.
(Anat. comp. et expér. ad. feuilles souterraines. Rev. Gen. de
Bot., 1900, 7. XII, p. 394) the cuticle of the under side of the
leaf is more conspicuous in the cultivation of shoots bearing
leaves under the surface of the ground than under normal condi-

tions,

OL.

5 Beob, uber Bildung u. Regeneration d, Periderms, d, _
Epidermis, ad. Wa@hsuberzuges, etc. Pringsheim's Jahrb. f. wiss.
Bot., 1897, Bd. XXX, p. 116.

4 xochs (loc. eid.) observed lignification (metaplasia) in’
twigs infected by Asterodiaspis quercicoie (Coccus Quercus).
Part of the t@ark cells grow greatly in & radial direction and
lignify later - others turn to wood, without any previous elon-
gation.

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CHAPTER IV.

ys!

—

HYPERTROPHY.

We understand by the term Hypertrophy, an abnormal pro-
cess of growth, which, with an ex@&usion of cell-division,
leads to the formation of abnormaily large cells. “Hyper-
trophy" to my mind", says Birchow-, "would be the case where
Single elements take up'a considerable amount of material.
thereby becoming larger, and also where, by the simultan-
eous enlargement of many elements, a whole organ finally
becomes distended." In the following description cases will
also come under discussion, on the one hand, where only
Single cells hypertrophy, on the other hand, those in which
all the elements of extensive cell groups enlarge and there-
by bring about an hypertrophy of the tissue. ‘The absorption
of material mentioned by Virchow, has been left out of the
question purposely in our definition. While in animal cells
in an overwhelming majority of cases, cell growth is assoc-
ieted with an increase of the living cytoplasmic contents,
and usually is identical with it, in plant cells, the ab-
sorption of water,- united with surface grovth of the cellu-
lose wall plays a prominent role as 2 phenomenon of growth.
Since it is difficult to decide in many cases, whether the
growth of the cells is associated with an abnormal ab-
Sorption of material or not, we will designate as hyper-
trophy only the abnormal increase in volume of the cells,~-
no matter if “over-novrishment’ of the cells concerned pre=
cedes the abnormal growth, or only an abundant absorption
of water,

It is evident that, by the word "hypertrophy", a process
is to be designated. Nevertheless, we will take the liberty
following the usuage of pathologists of: calling hypertro-
phies, the abnormally enlarged cells themselves and the
tissues altered by the cell growth. The same word may serve
to denote the process of growth and its tangible products.

As “hypertrophy in a wider sense of the word," many
pathologists designate also the growth ig amount due to an
increased number of the single elements.© I prefer to di-
vide them more strictly and to designate ail changes as _
hyperplasia. (Compare Chapter V) which are allied ‘rith pro-
cesses of division.

In the anatomical investigation of h pertrophies Beat
the plant world, different ontogenstic and histological

—-———_ ee re ee ee ee ee ee ee _ a een
eee cee fee ee ne ee es tee te ee ee ee
oh a ee ee ——

1. Cellularpathologie, 1858, p. 58.

2. Compare for instance, Ziegler, Allgem. Pathologie,
10, Aufl., 1901, p. 274.

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64
points of view will have to be taken into account.

In*regara to the cell-material from vhich the hyper-

‘trophied elements are derived various cases are conceivable:

cells of the most varied kinds, belonging to the most var-
ied tissue forms, epidermis, bark, mesophyll, vascular
bundle cells, etc., furnish hypertrophies, in short, all
cells which are still alive and whose membrances are still
capable of growth, can hypertrophy: as is well-known, lig-
nigied membranes achieve no further surface growth.

Various possibilities are conceivable also in the pro-
duction of abnormally large elements, just as before in the
discussion of abnormally small cells;-

ae Hither the hypertrophied cells are derived
from meristematic elements which, under normal con-
ditions, wouid have divided further, in which case
hypertrophies are indeed producéd by a continued
growth of the cells, but with no further division,
or only a tardy division takes place of such kind
that larger daughter cells arise than under normal
conditions:

b. Or cells are involved which continue longer
or more intensively than under normal conditions the
growth in length which follows the last division.

c. Or cells of a permanent tissue are concerned,
Which have previously ended their normal growths and
are excited to a subsequent increase by certain
external factors. :

It is not always easy to decide in detail to which of |
the growups here named the different kinds of hypertrophies
belong. The qualities of the abnormally large cells them
selves never throw light upon the kind of tissue-elements,
to which they may be %raced back ontegenetically. In the
over-whelming majority of cases, those mentioned second are
involved. Obviously, the most important difference between
the two modes is that the participating growth is abnormal
only in the second case: in cases of the first kind, the
abnormality lies alone in the omission of cell-division.
Since we have already characterized hypertrophy as an ab=
normal process of growth", it follows that strictly aan
ing we are not concerned in these with hypertrophies,- tha
therefore abnormally large cells can also be produced other=
Wise than by hypertrophy. Nevertheless, on account of the
external, correspondence with products of hypertrophical :
growth, examples of the first named mode of development mus
be discussed in the present chapter.

We will now fix our attention upon the process of growthe
The coefficient of increase is either equally large in all.
directions, or some special direction of growth may be re-

cognized. In the first case, the old proportions of the

cell changed hypertrophically will remain; the hypertrophied
cell will show an enlarged picture of the normal so far as

its form is regarded. In the second case, the proportions

Will be changed in some way, and a formal change in value
must appear; for instance, a Ssac-like cell will come from a

*

65

round one and the iike. The cases in which the cells make
abnonmal growth only in one direction are extraordinarily
frequent. In this connection it should be noted further

that, in many cases of hypertrophy, the cell membrane will
not be capable of abnormal growth in all its parts, but
only on certain sides and in limited regions. In the epi-
dermal cells; for example, in many cases only the outer
Wall makes any perceptible surface growth:- the form and
Size of the original epidérmal cell remaining permanently
recognizable. The added growth as well as the hypertrophied
cells, aS a whole, are independent, in their Shape of the
normal form of the original cell, and entirely different
from it. (Compare fig. 45). Further:- cells which are
enclosed on all sides by tissue, and indeed by tissue in-
Capable of growth, havé at their disposal only a limited
Space for their hypertrophic increase in volume, and only

a narrowly limited region of their membrane ean participate
in the surface growth. Thus this added growth appears often
as an independent appendage of the mother body of the cell,
whereby there results, as a matter of course, a complete
Change in the form of the hypertrovhied cell.

During, or after the increase in volume, the contents
of the cells and the structure of their walls usually under-
go Other and various changes. ‘The cases are relatively
rare in which such changes are entirely omitted and the an-
atomical character of the cell renains the same. There is
usually @ revaluation of the cell character: either regres»
Sive changes result, the cytoplasm is used up, the ceil
contents degenerate or are dissolved,- or progressive chang-
es take place, which give the cells new anatomical char-
acteristics and functions; the cells store up proteins,
Starches and fats, or they develop chlorophyll and red col-
Oring matter in the vacuoles, or their walls are thickened
characteristically. In hypertrophies of the first kind,
Which we will designate as kataplastic hypertrophies, the
anatomical state does not lead us to believe that the ab-
normal growth is produced by an increased supply bf food
stuffs, i.e., by "over-nutrition". On the contrary, the
processes deseribed make it often probable, that the cells
are dependent on their own contents for nutritive material
for the hypertrophic growth, thus exhausting it and there -
by preparing their own destruction. In cases of the second
kind, a combination, so to speak, of hypertrophy and meta«
plasia exists, we will speak of prosoplastic hypertrophy.
In these cases, the abnormal growth often is apparently
accompanied by an abundant supply of nutritive material,
if not caused by "over-nutrition". Indeed in them an in-
crease of the most important cell-organs is possible; be-
Sides the enrichment in cytoplasm there may be proved at
times, an increase of the nuclei. Such multi-nucleated
cells serve as transition-forms between hypertrophies and
those abnormal structures, by which division d# the cells
usually follows upon cell growth, that is hyperplasies.

I choose the designation "kataplastio hypertro-
phy" for abnormal increase in volume of the cells
connected with degenerative atrophy of their living
contents with reference to the temminology pro-

66

posed by Beheke ao Beneke designated the functional "de-
cline of the cell" ~ in my opinion very fittingly = as
“kataplasia". Since, in out case, the unmistakable decline
is associatiahed with increase in cell volume, it is very
natural to speak of kataplastic hypertrophy.

Evidently the abnormal processes of growth
here, in question are not unlike those which
Boux” has designated as processes of"purely
dimensional growth"... This is not dependent on
asSimilation, but predominantly on the deposition
of the original substance already on hand, while
“growth in amount" is produced by increase of
the specifically composed organic substance.

In plant cells, in the last phase of their nor-
mal development, the "dimensional growth" plays
evidently (compare Roux) a prominent part. The
increase in amount of the cells is not caused
by increase of their organic substance, but by
the enlargement of their vasuoles. Also, in the
cases of abnormal increase in size, designated
by us as Kataplastic, a "dimensional growth" is
involved, of which the products, however, are
here eSpecially characterized by the atrophy
and destruction of the cell-contents,

To be sure the etiology of hypertrophies has not been
eleared up for all cases. But rte the majerd ty the active
external factors have already been ascertained. Hyper-
trophies arise in gall-formations as reactions to chemical
Stimuli, further as a resubt of excess of water, after in-
jury and so forth. More details will be added in the dis-
cussion of the individual cases.

In a uniform consideration of life history, histology
and etiology, the following division of material is advis-
able.

1. Most simple cases; ie., those cases in which mer-
istematic cells (capable of division) grow
out to an unusual size, after the omission of
normal cell divisions.

2. Tissues of etiolated plants which, as a result
of lack of light, in moist air, etc., have
developed abnormally long internodes, leaf
stems, etc.

3. Hyperhydric cells and tissues, i.e., those pro-
ducgd by an excess of water.

4. Calluhypertrophies, i.e., those arising from in-
_ juries.

5. Tyloses, ie., hypertrophies by which only a nar-
rowly limited part of the cell wall is incited
to growth, filling out hollow places already
formed in the plant body.

6. Gall-hypertrophies, i.e., those produced by the
poison of the vegetable or animal parasites.

69)

67

aS appendix, we will udd to these the discussion
of hypertrophied fungus-hyphae, root-hairs,
and other cells with apical-srowth.

7. Multinuclear giant cells, which furnish the
transition to hyperplasias. In the detailed
discussion, it will be shown, that those groups
also are histologically well characterized for
which, in the present survey, only etiological
and ontogenetic characteristics have been cited.

Ll. SIMPLEST CASES

eet on Se ta me came oe Rae geen We ee

We will summarize as the “simplest cases" those in which
abnormally large cells are derived from elements of the nor=
mal plant body which are capable of growth and division.

; If, for example, the apical cell of an alga continues
its growth, but all division is omitted, under the influence
of abnormal life conditions, then abnormally large cells
arise, We have already answereé the obvious question, wheth-
er these are to be addded to the hypertrophies, or, perhaps
better, are to be designated as arrested developments, since
the growth which led to their formation is throoughly "nor-
mal" as such and the product is essentially characterized as
abnormal only by the omission of the process of division.

The external factors, whose actions bring about the,
production of abnormally large apicel cells, may vary. Kny
observed. that under the influence of parasites (Chytridium
apngcet Laram) the apical cells of the side branches of

ladostephys spongiosus discontinue their division, but con-
tinue their growth and thus swell out slub-shaped at the up-
per end. No changes whatever aire recognizable in the cell
contents. Similar phenomena of growth occur in Sphacelaria
tribuloides.

Padina Pavonia furnishes a further example. Specimens
of the dorso-ventrel algae, inverted so that they are ex~
posed to the light on their morphological under-side, uncoil
their spiral eage ani the cepls of the apical region swell
out into bladder-like forms.

The same changes observed on apical cells and in the
célls of the apical region can occur also in other cells_
Capable of growth and division. Our thi-d example should
also illustrate at the same time the case in which, under
abnormal life-conditions, only the division of the protopkast
and the formation of the crows—wall is omitted, while the

1. Entwickelung einer Chytridiee aus der Untergattung
Olpidium Sitzungsber. Naturf. Fr. Berlin, 1871,p. 93.

2. The vesicular cells of Antithamnion are not of paia-
Sitic origin but are normal forms.Compare Nestler Die Blesen-
zellen v. Antithamnion plumula u.s.f. Wiss. Meeresunters.,
Ne Be, 1898, Bas Lily

3. Bitter, Anat.u. Phys. vs Padina Pavonia.Ber.d.D.Bot.
Ges., 1899, Bd. XVII,p. 255,

68

= a i. : .
division of the nuclei takes its normel course, so that it

leades to the formation of multinuclear , abnormally
large cells. :

(70) WAgelil found a cell with two nuclei in a filament
of Spirogyra orthospira var Spivealis; it was twice as long
as the normal cell, Recently v. Wissenlingh®, who brought
half spoiled cultures of Spiroryra triformis to renewed
luxuriant development, obServed rultinuclcar cells in all
the filaments of the new cultures. (Compare vig. 14.)

The formation of cross-walls was éither suppressed entire-
ly, or only incomplete, ring-like wells, or wolls formed
only on one Side were produced. (Pig. 14, below.) The
cells contained 2, 3, 4, and 8 nuclei. In the multinuclear
cells v. Wisselingh measured an everage length of 397.5 wu.
in the largest among them 450 and 455 u. “Yet this length
is comparatively small. It is less than three times the
medium Length of the uninuclear cells". It is not pos»
Sible fo state in detail what conditions were decisive
for the production of the abnormally large cells in v. Wis-
Selingh's experiments.

. Gerassimoff obtained results similar to those of vV.
Wisselingh in the use of lower temperatures and by. treat-
ment with poisons (Chloral hydrate, ether, chloroform) «
The variation from the normal consisted in the fact that
a cell with no nucleus and one with two nuclei were pro-

-duced from an uni-nuclear cell by-division, or the new
cross=wall remained incomplete and divised the cell into
the two communicated? chambers.

The production of the multinuclear spirogyra cells
corresponds in all essential points with the formation of
the "long rods", which Hansen has described for Bacterium
Pesteurianum*, On double beer in a temperature of five de-
grees to perhaps 34 degrees C., the bacterium appears in
its "normal"form : there develop short rods, 2 us long,
lu. wide, united in chains. If the culture of the short

as pe cee ee te ee
— me ee ee ee ee ee ee
a (Rae te ete ee ate re pe ent ms cee: fare ce me ee ne Sie Oe es tm Bey ee ee ate Oe Oe oe ee

1. Pflanzenphys. Unters., 1885, Heft. I, pe 45.

2. Ueber mehrkernige Spirogyrazellen. Flora, 1900,
Ba., LXXXVII, p. 378.

3. Gerassimoff. Ueber adié kernlosen Zellen bei einigen
Konjugaten.full.Soc.Imp. Natur. Moscou,1892,p.140,Ueb. on
Verfahren,kernlose Zellen au erhalten(4ur Phys.d.Zelle) . ie 2
1896,.Further statements also concerning multinuclear cells
and cells without nuclei in de Bary (Konjugaten 1698 ee) ey
Strasburger (Zellbiddimg und Zellteilung,3 ,Aufl.1880,p.185.

4, Rech.S.l.bacteries acetifantes.Travaux du labor.dc
Carlsberg,1894, Vol. Iil.

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(72)

. 69

rods is continued on a fresh nutritive subs¢retum at 40 de-
grees C., the single cells grow out into long rods. In
other Words, the growth is continued, but the divisions taking
place under normal conditions are Suppressed and "long rods*
are produced which can become as long as 40 u. (Compare fic.
15). Qf the culture of long rods is again subjected toa
temperature of 54 degrees C. the previously "arrested" seg-
mentation is retrieved, the long cells divide into a large
number of short rods:= the "normal" cell-form from which we
Started is aSain formed. It would be of great interest to
learn more of the fate of probable cell-nuclei in the de-
Scribed processes of growth and division. We will speak
later of different changes of the same pacterium under sim-
ilar cultural conditions.

; Future experiments will have to determine whether pos=
sibly the cells of the primary meristem also may be able to
grow out of similar abnormally large elements. AS yet not
a case of the kind is known to me. |

Blazek, who studied the"influence of Benzol fumes on
cell-division" in the root tips of Pisum vativun,
proved~ that, under abnormal conditions, the nuclei
divide repeatedly while the division walls often are
not formed, so that multi-nuclear cells are produced.
If the roots are kept in a normal atmosphere, a re-
duction of the multinuclear cells becomes noticeable,
even after only two and one-half hours. According to
Blazek the nuclei of the cells unite with one another
and the cells return to the uni-nuclear normal con-
dition by "karyogamy". Conftrmation of this seems to
me most desirable.

To a certain extent, those multinuclear blastomeres,
the production of which in the eggs of echinoderms has
been studied by several exnerimenters, resemble the
multi-~nuclear plant cells here described. I refer
especially to the contributions of J. Loeb.& By the
action of mechanical pressure, under the influence
of osmotic disturbances (treatment with sea-water of
abnormally high or low salt content) or by artificial
warming of the eggs, segmentation is omitted while
the nuclear division takes mts normal course. Under
special circumstances, segmentation can take place
later.

2. TUSSUES OF ETIOLATED PLANTS.

Plants which are cultivated in the absence of light are
known to make a "false growth". Falsely grown or etiolated
plants are usually characterized by the slight development of
their leaf-blades, and by the excessive Lengthening of their
internodes and petioles.

lL. Abhandl. bohn. Akad., 1902, Bd. Xi, Nr. 17, Review by
Nemec in the Bot. Cbl., 1902, Bd. XC, p. 548.

2. Ueber Kernteilung ohne dgeliteilung. Arch. f. Entwickel-
ungsmechanik, 1896, Bd. II.

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70

The slight differentiation of tissues of etiolated plants
has been discussed above; their abnormally elongated organs
Sive rise to new questions.

We have spoken already of Amelung's statements concern
ing "medium cell sizes", Since it was determined that orgens
abnormally undeveloped in size are composed, in part at
least, of abnormally small cells, the supposition is obvious
that abnormally large organs are composed of especially large
cells, We will test this question on the elongated internodes
of etiolated plants,

Highly elongated internodes, petioles, etc., consist
~often if not always = of a greater number of cells than
corresponding normal organs. This kind of increase of the
cell-number is, however, in itself of no consequence for our
consideration, Since cell increase elone does not necessitate
any change in structural form. (Compa re Chapter V.) Of more
importance to us is the fact, that the abnormally elongated
internodes are composed of larger, longer cells, than the in-
ternodes of specimens of a normal growth. ‘Though the abnor-
mal size of the cells, the structural form shown in longitud-
inal sections, becomes essentially different from the normal.
In measurements of etiolated peduncles of Tulipa Gesneriana,
I found the cells of the ground tissue from a third to indeed
a half longer than in the normal ones; in especially highly
elongated peduncles tha cells actually became on the average
almost twice as long as under normal conditions. I found the
same proportions in the elongated organs of other etiolated
plants .-

‘

Of course the same is true also of plants which make an
abnormal growth in moist places. According to measurements
by Stapf, who cultivated potato plants under different con-
ditions, the length of the pedunclaxs epidermal cells in the
forms making an abnormal growth (cellar forms) and in normal
examples bore a proportion of 217 : 117, the diameter had in-
créased only a little. The guard cells too became larger,
they twist more and more strongly and at times continue their
growth so far that their ends touch (compare fig. 16), and_the
Stoma now has two separate openings. according to Brenner”,
in normal examples of Sedum dandroideum, in cross+sections of
the leaf , the dimensions of the epidermial cells bear the
proportion of 18 : 8, in specimens making an abnormal growth,
of 27 : 12: on the surface section of 11 :4.5 and 13 :7.5 re~
Spectively, etc. In Crassule pertulacea, Mesenbryanthemum

1. Compare also Koch, Abnorme Abanderungen wachsender Pflan-
zenorgane durch Beschattung. Berlin 1873 (Bot. Jahresber.,
1875, Bd. I, p. 283) and others.

2. Beitr. 2. Kenmntn. 4. EHinfl. geanderter Vegetationsbeding-
ungen auf die Formbildung a. Pflanzenorgane u. S. w. Verh.
Z0ol.= Bot. Ges. Wien, 1878, Bd. XXVIII, p. 231.

5. Unters. an einigen Pettpfl. Flora, 1900, Bd. LXXXVII,
p. 387, Compare also Kohl, Transpiration d. Pfl. u. ihre
Einwirkung auf ad. Ausbildung Pflanzl. Gew. Braunschweig, 1886.

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; ick
and others, Brenner proved "that the proportion between the
length and diameter of the cells was changed more in favor of
of the tangential diameter, the more moist the surrounding
ear, Often still other changes in the tissue structure
of specimens cultivated in moisture are combined with
these described, often papillae-like protuberances arise
in the upper epidermal celis, p brag hy forms ere replaced
by Such as have undulating outlines*, and so forth.

No119 recently called attention to the fact that
even under other conditions than those effective in
the dark and in moist cultures the same phenomena of
growth occur as in plants cultivated without light.
Thus, with Noll, we can speak of "starvation etiola-
tion", if the roots of Triticum, aS a result of un-
favorable nutriment which lacks nitrogen, are length-
ened excessively. The organs of some plants exper-
ience Similar abnormal effects upon infection by
parasites ~ to name a few instances, I will mention
the Euphorbiane, deformed by Uromyces, and the Anemoneae
infected by Pucciniase. Probaodly these abnormally
large organs are alSo0 composed of cells of abnormal
length. Very conspicuous for instance is the en-
largement of the cells (epitiermai} of the leaves of
Sempervivum infected by Endophyllum Sempervivi, which
grow out to an abnormal Length.

It is common to all the pathological phenomena here
cited , that in tl.em whole organs, internodes, leaves, -
whole shoots, etc., everywhere undergo the sane change in
anatomical structure; in those now to be discussed local-
ized excresences of single tissue layers and closely limit-
ed pathological areas will be recognizable in the hypere
trophy. While in the tissues of stiolatea plants, cells
are involved, which, from the “irst stages of their devcl-
opment, come under the influence of abnormal conditions,
and continue their growth beyond the normal boundaries,

1. Under the same conditions which led to the enlarge-
ment of the epidermal cells in Sedur dendroideum, Brenner
found that their volume decreased in 5. altissimum. In
general, according to his experiments, ju moist air, the
diameter of the cells of the leef, i.e. of the assimila-
ting and most stron:ly transpiring organs, was so length-
ened, that the surface communicating directly with the air
was enlarged. In the. cells of the petiole, tnis lengthening
takes place principally in the direction of the axiS.

(loc. cit. p. 464.)

2. Compare Brenner, loc. cit. The same undulated forms
occur in the "Sshade-leaves" (Mer. Rech. Ss. les. causes de
la structure des fenilles. Rev. Gen. de Bot. T. IV,1892,
p. 481); Vesque made explanatory experiments (see especial-
ly S. les. causes ét sur les limites des variations de
structure des vegetauz, Ann. agon. T. IX, 1884,p.481, mw. T.X
p. 14).FPurther literature citations in Brenner.

3. Ueb. d. Btiolement d. Pfl.Sitzungsber. Niederrhein.
Ges. Natur~ wnd Heilkunde, Bonn, 1901.

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72
we will be concerned in the following predominately with

hypertrophies produced under the action of external factors
in cells of the wrmanent tissue. (Divisions 3,4, 5.)

SeHYPHRHYDRIC TISSUES.

We will term hyperhydtric all those abnormal tissues
whose formation is to be traced back obviously to an excess
of water within the plant. This excess can be produced
on the cne hand by super~adundant absorption, on the other
hand by its reduced transpiration. The decrease of this
transpiration may be necessitated by the increasded humi~
dity of the surrounding atmospherg,by which the transpira-
tion of the plant is arrested, or by a weakening of the
transpiration ability of the plant, or finally may arise
after the destruction of the transpiratory organs.

It will be seén that the hyperhydric tissues form
an homogeneous group not only from an etiological point of
view, but also histologically:= they all arise from abnor-
mal enlargement of the cells, for which reason they are to
be included among hypertrophies. Further, among these, are
entirely lacking cases in which a prosoplastic fyvansforma-
tion of the cells (characteristic formation of the membrane)
the cell-contents, etc.) is associated with the abnormal
increase in volume. We see rather in the majority of cases
that, in the production of abnormally large cells, their
cytoplasmic content decreases and its elements already
formed, such ae the chlorophyll grains, gradually degenerate.
Further characteristics of hyperhydric cells and tissues
will be reported later.

In cases strongly affected, a division of the single
elements in some plants and in certain tissues at times,
follows the cell~enlargement. As all the groups and sub-
groups, which we have set up, may not be separated from
one another by completely sharp boundaries, an inclination
towards hyperplastic tissue changes manifests itself at
times even in the hyperhydric tissues. Nevertheless, all
hyperhydric tissues may readily be united for a common dis-
cussion in the present chapter.

ae Lenticels and bark excresences.

As is well-known, if the cuttings of willow, poplar,
alder, etc. are placed in water or in moist air, more or
less extensive masses of white tissue, usually very porous,
are formed on the lenticels of the cuttings. Schenck’ in-
veStigated more closeZy these well-known outgrowths® first

2. De Candolle Men s. 1. lenticelles des arbres et le
devel. d. racines qui en sortent. Ann. Sc. Nat. 1826, DeVLis
Mohl, Sind die Lenticellen als Wurzelknospen zu betrachten?
Hlora, 1632, Bd. 2V;. ps 68.

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While‘the air lenticels were covered by a cap of dead,
brown padding cells, Schenck found. "that from the submerged
lenticels a white spongy tissue develops in the form of a
thin plate, which might be as thick as 2mm". Schenck col~
lected Similar observations on Kupatorium cannabinum, Bidens
tripartitus and various other plants.

The anatomic investigation of the masses of white tis-
sue presents the same appearance in all cases. The out~
growths consist always of homogeneous elements, of round,
or elongated, thinewalled, colorless cells, with large in~
tercellular spaces, and often, like a kind of ster~parenchy-
ma cells, are connected with one another by the tips of
short projections (compare fig. 17); ~ in sone places they
lose all firm connection with each other, ani are deposited
aS isolated elements in porous layers on groups of cells
Still connected. The individuel cells are always free from
chlorophyll, have a thin layer of cytoplasm and a clear,
abundant cell-sap, - Schenck knew the anatomical character-
istics here listed; they caused him to compare lenticel
outgrowths with the "Aérenchyma" found on numerous water-=
plants, the water lenticels, according to him "represent
%o a certain extent, an aerenchymatic formation in isolated
places." Gobell, and v. Tubeuf’ consider the outgrowing
lenticel tissue as aerenchyma.

Now since this, according to Schenck, "represents a
tissue, which suffices for the respiratory requirements of
parts of plants remaining under water or in slime, i.e &.,
in media in which the supplying of oxygen must be substan=
tially difficult in comparison with that for organs found
in the air™,— since further the observations described lat-
ter make it little probable that the lenticels which Schenck
ascribed to the aerenchymatic formations of Jussiaea, Nep-
tunia, and others, possess this function, we will rather
avoid in the following their equalization with the aerenchy-
ma and will speak only of tissues resemblyng aerenchyma.

Ontogenttic investigations show that lenticel-excres-—
censes arise from normal lenticels by enlargement of the
phelloderm cells, therefore, in their formation, we have
to deal with hypertrophy. Devaux’ has proven in a few
instances that hypertrophy begins in the outer layers of
the phelloderm and extends to both of the innermost cell
layers. A new meristem is then produced from them. In
other cases the cells of all the phelloderm layers, to-
gether with the bark cells lying under the lenticel, hy-
pertrophy; the new lenticel-meristem arises then from the
more deeply lying layers of the bark tissue. According to

me ee
‘mem fee ee tren rm me ee ee ae ce ee ee ee re ee ee ee re ee ee ee ee tt fe et tes

lie Gober. Pflanzenbiol. Schilderungen, 1893, p. 261.

2. v. Tubeuf. Uev, Lenticellenwucherungen (Aerenchyma)
an Holzgewachsen. Forstl.-Naturw. Ztschr., 1896,p. 405.

3. Rech. Ss. 1. lenticelles. Ann Sc. Nat. Bot. 8me ser.
Pe ZL» L900, De 139s

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74
Devaux in exceptional cases, cell-division followed the
abnormal growth.

The growth of the pehlloderm celis takes place most
vigorously in a radial direction,-— elongated cells, similar
to Sausages in form, are produced, which often lose all firm
connection with one another in their longitudinal walls and
remain connected only by their tangential walls. They form’
lose cell rows, paralell to one another and arranged radial-
ly, which curve out on the surface of the lenticel~outgrowth
in flat undulations, and often separate into their individual
elements. In other cases the elongation in a radial direc-
tion is omitted and the cells remain spherical.

The degree of hypertrophic enlargement varies not only
in different species but also in lenticels of the same
Species. At times the growth of the individual cells is very
Slight, in which case the changes of the lenticel tissue
consists principally of a breaking up, or a complete macer-
ation of certain layers. It was not investigated more close~
ly to see how far external factors influence the mass of
hypertrophic growth.

Lenticel outgrowths of the kind described may be ob-
tained in the most varied specimens: roots and shoots bear-
ing lenticels form in an equal degree excresences resembling
aerenchyma. The lenticels of the potato tubers, the lenti-
cels of the leaf galls of Nematus gallarum , which lives on
the willow, etc., may easily be brought to the formation of
excresences, The age of the lenticell-bearing organ con-
cerned is of no importance; I found young shoots of Popu-
lus, Catalpa, Solanum tuberosum and others, cultivated in
a moist place which developed lenticels and lénttécel excres-
cences in the immediate vicinity of the growing tips of the
sprouts.

The works of v. Turbeuf and Devaux throw light on the
plants, on which lenticel-excresences have already been

observed,
‘Devaux observed hypertrophied tenticels on the shoots
of the following plants:

Ampelopsis quinguefolia, Marsdenia erecta,
Acer Negundo, Malus communis,
Alnus glutinosa, Morus alba,
Broussonetia papyrifera, Pelargonium zonale,
Coriaria myrtifolia, Platanus vulgaris,
Cydonia vulgaris, Pirus communis,
Diervilla grandiflora, Prunus div. Sp.
Daphne Gnidium Quercus pedunculata,
D. Laureola, Ribes rubrum,
Fraxinus excelsior, Robinia pSeud-acacia,
Ficus Carica, Salix dive Sp.

F. elastica, Sambucus nigra,
Gleditschia triacanthos, Spiraea Lanceolata,
Hedere helix, Syringa vulgaris,
Juglans regia, Filia Sitvestris,
Jasminum officinale, Ulmus campestris,

Ligustrum vulgare, Weigelia rosea,

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75
also on roots of the following:

Aralia Sieboldii, Prunus spinosa,
Cerasus aviun, guercus pedunculata,
Cydonia vulgaris, Qu. Suber.

Crataegus oxyacantha, Robinia pseud-acacia,
Fraxinus excelsior, Salix Caprea,

Ficus Carica, Solanum Dulcamara,
Ligustrum vulgare, S. Tuberosum L
Monstera deliciosa, Bambucus nigra,
Pandanus utilis, Ulmus campestris.

Ponulus alba.

According to Devaux hypertrophies were absent, however,
in shoots of,

Araucarie Cunninghami , Cupressus fastigiata,
Abies balsamea, Larix euronaea,

A. Cephsalonica,. Myrica Gale, 2

A. excclsa, ° Pinus Sylvestris
Buxus Sempervirens, P. maritima,

Cecrus Libani, P. Pinea,

Crataegus ‘oxvacantha, Rhus Cotinus

Corylus Aveéllana, Rh. Glabra.

and on the roots of,

Aesculus Hippocastanum Juglans regia,
Castanea vulgaris, Sarothamnus Scoparius,
Cunressus fastigiata, Tilia Silvestris,

EVvonymus europaeus |.

As Devaux himself has indicated, his reports on negative
results will possibly need correetion in a few points. It
still remains worth noticing, that lenticels have not as yet
been caused to hypertrophy in the conifers, not even the
large lenticels of Gingko, which v. Tubeuf and I have also
investigated.

The question of the conditions, under which the lenticel~
excrescences are developed deserves special consideration.

It was evident even to the earliest observers of these
structures that the production of the hypertrophies here
concerned is connected with the action of water. Thorough
experimental proof was undertaken first by V. Tubeuf and
later by Devaux. I can substantiate their results and
Supplement them by some new observations.

Cuttings of poplar and others, when placed in vater, pe-
come covered with lenticel-excrescences, not only on the
parts moistened, but also above the surface of the water, V.
Tubeuf has already brought up the question whether a stim -
ulus coming from the water is conducted upwards, or whether

the action of the moist air causes the production of the

ee -_——_——

oe ~~
ee na ey tee ee Ne me ne em me ate eee ee ee ees Cee Dee eo et th em .

1. Devaux means the tubers.

2, Compare Devaux, loc. cit. p. 10.

76

Same ex¥crescences, aS are found in the parts in con&et with
the water. V. Tubeuf and Devaux have agreed that it is the
vapor from the water, playing about the lenticels, which in-

cites the cells to hypertrophy. Contact with water, ina
liquid state is therefore not necessary, it is even suffi-
cient to bring pieces of twigs into an atmosphere, saturated
with wapor, in order to produce lenticel-excrescences,.

Although in willow cuttings and in other Species the
lenticels grow out more luxuriantly under water than in moist
air, there arise above and under the water excrescences almost
equally pronounced. here are, however, a number of plants
on whose cuttings the fommation of the excrescences takes
place more quickly and abundantly in moist air than under
water. Indeed cases are not mare, in which the excrescences
under water are entirely or almost entirely absent, but are
formed abundantly by the action of water vapor. Contact with
water in a liquid state arrests here the development of the
eerenchyma~like tissue. The difference between the moistened
and unmoistened parts of cuttings of Catalpa syringsefolia is
very evident. These cuttings form white masses only in moist
air. Cuttings of syringa and others act similarly. Excres-
-ecences is omitted further under water in the root»lenticels
of different varieties of Acer, while their tissue hyper-
trophies unusually actively in moist air. Those lenticels
of the potato tubers are still bo be mentioned, which form
lenticel-excrescences after having been kept several weeks in
moist air, but never under water,~ and many others.

I think the supposition is correct, that in the cases
mentioned, the exerescence of the lenticel tissue cannot
occur under the surface of the water on account of completely
Suspended transpiration and deficient supply of oxygen. I
am Supported in this assumption by observations on cuttings
of Syringa, Evonymus and others, in which the lenticels often

( grow out especially abundantly near the wound-surfaces,— sup-
79) posedly because the supply of air creates the most favorable
conditions.

It is of no consquence what external factors are decis-
ive in the omission of the lenticelyexcrescences under water.
In any case, the instances described make it scarcely prob-
able that the aerenchyma-like lenticel tissues are of signi-
ficance for the plant, in that their cell connection, with
its abundant interstices, makes the breathing of the plants
easier even with a more difficult supplying of oxygen, as
Schenck assumes with Jussiaea etc. In many cases, the afore-
Said excrescences are produced where there is no lack of air;
indeed in the case of many plants, their production seems to '
presuppose an abundant supply of air. The regection of
Schenck's explanation will be forced upon us also by a con-
Sideration of the bark excrescences described bélow,wihich
correspond in more than one way with the lenticel-excrescen-
ces already described.

— -— ee ee ee ee ee
Aaa EO gay A me Ta OH Eee HH Mme oft ee ted peer Se ete ee epee Ue eee tee Giey wete Mote ee St ee ee oe eo —— ——

1. Apparently different varieties of potatos act different-
ly; at least, I have often vaihly endeavored to obtain lenti-
cel excrescences in moist cultures of tubers, although in
other cases, under apparently similar external conditions,
their formation took place very abundantly.

77

_ If we observe for some time the development of different
kinds of cuttings in a saturated atmosphere, it will be seen
that the formation of the lenticel--excrescences here described
illustrates the first of those formations which their tissues’
experience under the influence of moist air. In some species,
the lenticels widen into rifts running lengthwise, which ex
pose in places the bark tissue of the cuttings and which can
enlarge to several centimetres long and up to one centimetre
wide, At the same time the bark swells up greatly. (Uompare
fig. 18.) All these changes arise from the hypertrophic
growth of the bark cells. We will later speak briefly of
bark-excrescences in the description of these processes of
growth.

The plant, in which I could obtain experimentally the
most extensive bark-excrescences is Ribes aureum. Since
this species is used as stock for standard gooseberry and
currant bushes and since, further, in this species the de-
scribed excrescences may be observed in nature without
forced experimental interference, practicat workers have given
repeated attention to this bark disease wick Sx«euuer~ desige
nates as “dropsy” jor oedema). As figure iS sicvs, boss-
Shaped swellings are formed on the diseased twig: which at
first are still surrounded by the cork-coverins but later ex-
pose their inner tissues in gaping rifts. Wounds of increas-
ing length and breadth are produced, until at last the swollen
bark tissue dies and collapses. Figure 19 gives a cross-sec-
tion through part of a boss-like bark excrescence still cov-
ered by cork. The parenchymatic cells of the bark have grown
out into long, sac-like cells of different form and size by
a perceptible growth in a radial direction, their length here
(80) and there réaches ten or twelve times their width. At times,
Scattered between the sacs radially arranged, may be found
elements which have been: stretched tangentially. The cells
of the bark meduhary rays also take part in the hypertrophic
growth. It should therefore be observed that, not only the
cells of the outermost bark layers, but all the zones even
up to the wood itself, can participate in the abnormal growth.

All hypertrophied elements have become completely or
nearly colorless, the chloropnyll has disappeared, the firm
comnection between the bark cells is lost, they are separated
everywhere from one another by large intercellular spaces,
the air-content of which gives the exposed bark tissue its
snowy lustre; in places the tissue disintegrates completely
into its individual elements. The cell walls are most deli-
cate, the contents consist of a thin layer of cytoplasm, and
a large, clear vacuole. The bark excrescences consist there-
fore of a tissue which corresponds in all essential points
with the aerenchyma-like products of the lenticsis:- a pro-

(81) nounced kataplastic hypertrophy is involved in tneir production.
There lie here and there between the greatly enlarged paren-
chyma cells gropps of prosenchymatic elements wnich do not take

, part in the enlargement.

Oem ee es cates mee eee ee ee ce ee toe ee et ee eee em re eae nae eine cae me a ee ene tee a ce ae em Manes Re we toy meme ay oe Bm me nm om

‘1. Compare especially Handb. d. Pflanzenkrankh., 2 Aufl.,
1886, Bd. I, pe 233.

78

fhe macroscopie symptoms, like the histological cone
ditions vary with the degree of the disease. In the case of
barks very strongly distended, I found that the young peri-
derm cells were being stretched in the same way as those of
the bark parenchymay and were groving out into sacs, oriented
radially. (Compare fig. 19). The cells of the corkemeristen
seem to remain unchanged. Here too, after the growth of the
cells, there follows the disintegration of the tissue into
its single elements.

_ Qutgrowths similar to those on cuttings of Ribes aureum
arise further, for example, on potato tuvers. At First,
when kept in a moist atmosphere, the above mentioned lenticel
excrescences are formed but then the cells in the neighbor»
ho@d.of the lenticels also hypertrophy. The cork covering
cracks up in radial rifts end im places is raised slightly
and falls off, producing round wounds up to + em. in diameter.
in which large~celled, crystalline, glistening bark tissue
is visible. Finally, these areas of excrescence, proceeding
from neighboring lenticels, fuse so that in the end little
scales are sloughed off here and there from the potato tuber.
The hypertrophied cells resemble essentially those of the Ribes
cuttings already described. The normal starch content of the
cells of the potato tuber has evkdently been used up in the
vigorous growth, and in any case the hypertrophied cells
no longer contain any starch or only scanty remains of it.

In Sambucus nhere, the rupture of the bark proceeds from
the fenticels; here also the young cork cells participate in
the hypertrophic growth. Yet I have not seen that such long
Sacs come from them as in the case of Ribes. Cuttings of
Gingko biloba also the lenticels of which seem incapable of

orming excrescences (see above), develop bark exerescences,.
The hypertrophied cells, which IT found in the bark of Gingko,
were however, not so reguiarly arranged radially as in Ribes
and others, but were oriented irregularly in different di-
rections. Bark excrescences appear further in the rose and
on the hypocotyl of Phaseolus yulgaris.+ 2 Still further they
appear on Pirus malus and Pirus communis,” and undoubtedly

1. Unfortunately Sorauer makes no detailed anatomical state~
ments. Perhaps the changes which he observed are identical
with those described by Perseka (Formverand. d. Wurzel. in
Wasser us Erde. Dissertaion Beipsig, 1877).

2» Compare d. Jahrsber d. Schles Centravalverins f, Gartner
ue Gartenfreunde, Breslau 1881; further Atkinson, Oedema on
apple trees. Rep. Agr. Exp. Sta. Ithaca, N. Y. 1893, p. 305;
also Sorauer's Angaben uber Streckung der Rindenzellen (Ueb.
Frostschorf an Aepfel» und Birnenstammen. Zeitschr, f. Pfl.
Krankh. 1691, Bde I, pe 137). A further statement of Sorauer's
(Nachweis der Verweichlichung der Zweige uns. Obsthaume durch
de Kultur. Ibid. 1892, Bd. II, pe 142). makes it supposable,
that the bark cells on the sowcalled fruit-wood of the pear
tree are more delicate and may be brought more easily to the
formation of hyperhydric excrescences experimentally than the
bark of other branches of the same species.

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79

on verymamy other plants, presupposing that their bark is
exposed to the action of sufficiently moist air. At times,
in the case of the Ribes, the hypertrophied swelling of the
bark combines with abnormally increased growth of wood, the
cells of which in any case seem to be elongated radially.

A closer investigation of the different bark excrescences
might well imake known many histological details, worth con
Sidering, although essentially the same symptoms are repeat
ed;- elongation of the parenchymatic elements of the bark,
chiefly in the direction of the radius, disappearance of
the cell-contents (starch, chlorophy11) and the omission

of every prosopkastic cell-change.

Sorauer has already treated the question as to the
external factors under whose action bark excrescences arise,
and has answered it experimentally“, According to him, the
causa morbi is excess of water,

In my experimentation with Ribes aureum, I proceeded
as follows:~ cuttings of shoots, several years old, were
put in a glass of water and also were brought into moist air.
Even before the end of two weeks, the swellings described
and the first rifts are produced on the parts above the
water; after possibly four weeks, extensive excrescences
and gaping wounds are visible;~ under water, on the contrary,
the bark tissue remains normal. Potato tubers acted simil-
arly to the Ribes cuttings; on them too, the bark excres-
cenees were produced only in moist air, not under water.

In the case of Sambucus and Gingko, I frequently observed
vigorous swellings on the moistened part. Observations on
potato tubers proved at, the same time that even uninjured
organs can form bark excrescences. Since nothing is known
as to whether potato tubers form bark excrescences in moist
soil, since further the excrescences are absent in tubers
lying in water, and since the immersed parts of Ribes cut=
tings retain their normal bark structure, it may be accepted
at least for these objects, that abundant supply of air is
one of the conditions causing bark hypertrophy. For its
production, as far the formation of the lenticel excres-
cences, the age of the tissue is apparently of no conse-
quence; at least, twigs of Ribes several years old as well
aS young shoots (according to Sorauer) form fhe same bark
excrescences,

The processes in Sambucus shoots and Ribes
cuttings described above in which even the young
periderm cells share in the hypertrophic change,

ae —— ee oe ae
pes we tne irs ey tn ess i eee en meee Ce ee ee cee ee tee tae few wae tem came ee ee hi cn et ey we me ramen en ees me em fey ym SR SO

1. Perhaps plants may still be found in Which the cells
of the bark parenchyma are incited, under the influence of
water or moist air, not only to growth but also to division,
as (according to Devaux) the cells of many lenticels,- def-
inite nutritive conditions being taken for granted in the
plant under experiment. Schenck (loc. cit.), De 568) ob-—
Served abundant division of the bark-parenchyma and the col-
lenchyma cells on the immersed parts of the stem of Artem~
isia vulgaris. It will be emphasized in the following sec~

fion also that division aften follows abnozihal cell-growth

in other forms of hyperhydric tissues.
2. Sorauer, Hand. & Pflanzenkrankh, p. 255, 20%

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80

reming one of the aerenchyma formations described by
Lewakoffskil and Schenck (ioc. cit.) in Lythrum salicaria,
Episobsne hirsutum, Lycopus europaeus, and many others.

oth authors’ found produced on the immersed part of the
Shoots a soft, spongy tissue the development of which Schenck
followed more closely. The bark cells on the swollen pieces
of the shoots are enlarge abnormally and the vroducts of the
cork meristem also havé grown out into long sacs, distended
radially, which leave large intercellular spaces open be~
tween them, just as in the bark cells;- essentially therefore
in the plants named, a similar tissue formation is caused by
contact with water as in our Ribes cuttings in moist air.
Schenck named the porous tissue, furnished by the cork mer-
istem, aerenchyma:-—"the phellogen of the above swamp plants
can have two positions structurally, and the one or the other
Will be developed according to the consistency of the medium.
What acts here as cause of the stimulation? It is not very
probable that the mere contact of the epidermis with water
may be considered as such; it should rather be supposed, that
the lack of oxygen of the inner tissues requirea& the develop-
ment of aerenchyma by the cytoplasm of the phellogen cells."
There can be no doubt in the case of the Ribes cuttings which
we studied, but'aht hack of air dogs not give rise to the
change of bark. and cork tissues; indeed the amount of air
furnished to the parts of shoots furrowed by the rifts is
evidently especially abundant and the formation of the ab-
normally large distended cells is lacking in the immersed
pieces of twigs which are kept from a supply of air. fhe
Similarity between our bark exerescences and the aerenchyma
tissues described by Schenck would therefore, be a purely
formal one. In the great similarity between lenticels and
bark excrescences, it would be advisable to keep’ them sep-

. arate from the typical Aerenchyma tissues formed, according
to Schenck's conception, by respiratory necessity. A supple~
mentary testing of the conditions under which the cork mer-
istem of Lythrum, etc., develops aerenchyma might not be
superfluous.

be. Intumescences.

When the cell-outgrowths, which in the case of Ribes and
others led to a total change of the surrounding tissue masses,
occur only in very limited areas, small pustules are produced,
which we, with Soraver, will designate as Intumescences. The
processes of growth by which they are produced are essentially
the same as in the case of the bark excrescences discussed
above, their production also presupposes the action of the same
external factors, only the size proportions and the habit of
growth of the excrescences differentiates it from them. Further,
excrescences which we term intumescences prefer the primary

—— a — ee ee ee
ee-eparet tend Wes meme aay ve One cue true mere ome ae ft Ge ahd Se fe ee Nt ee ON Hoe ee LY Oe EY eo Ee em ne cam me Se the Game fy Com Dene eame om ae ABS ns RY mary em none aoa em SED, ES

1. Ueb. de Einfl. d. Mediums auf die Form d. Pfl. Vergl-
Bot. Jahresber, 1873, pe 594.

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81

tissues, the bark of young shoots, the tissues of the leaves,
and blossoms. Sorauer~ has treated intumescences especially
thoroughly in numerous works, in the last few years other
authors have also turned their attention to them.

Intumescences are known on the branches of Eucalyptus rost-
rata, Acacia pendula, Lavatera, trimestris, Malope grandiflora

and others, Here and there, eSpecially on the side exposed to
the sun, the bark cells are elongated decidedly in a radial
direction, finally breeking through the epidermis and swelling
out as Spongy mounds of tissue masses. The cells of the prim
ary bark participate in the excrescence, the cells of the med-
ulary rays in the secondary phloem are also swollen, but only
in cases especially severely diseased, so that the formation
of intumescences is thus combined with processes of the kind
described above. These pustules on young branches do not fur-
nish further anything new for our anatomical consideration.

The intumescences produced on leaves deserve more attention.
Here and there on the upper or lower surfaces of the blades
arise small protuberances, greenish or whitish pustules of vary-
ing height and-extent. ‘The cells, by the growth of which these
forms are produced, originate usually in the mesophyll layers,
which are elongated perpendicularly to the surface of the leaf
(compare. fig. 20) and at times attain a length amounting to
two or three times the normal one. At the same time the strong~
er their growth, the more complete is the destruction of the
chlorophyll content, the walls of |’ “".:'~ hypertrophied celis
are usually delicate, the layer of cytoplasm thin, the central
vacuole large. Intumescences are produced also by distinct
kataplastic hypertrophy. The epidermis lying over the out-
growing mesophyll is then only raised and slightly distended,
as I found in the intumescences of Epilobium hirsutum, or it
is ruptured, as, for example, in the case of Cassia tomentosa
(compare fig. 20). In Ficus elastica (compare fig. 21) the
lower cells of the many layered épidérmis are pressed together
by the growing mesophyll cells and the space originally oc-
cupied by the former is finally filled entirely with mesophyll
cells. The mesophyll no longer adjoins the epidermis in ap-
proximately straight lines, but in éecidedly curved ones.

eee tee ee ae ee ee ee ce ree cae eee a fs ee ee ee ee ee ve ere ob te ee Ome Se mS Oe ta Od Oe Ge Oe oe a

1. Compare especially Sorauer, I. Handb. d. Pflanzen~
krankh, 1886, 2. Aufl., Bd. I, p. 222. Il. Ueber Gelbfleckig-
kett. Forsch. Geb. Agrikulturphysik, 1886, Bd. IX, pe 387.

III. Weitere Beobacht. uber Gelbfleckigkeit. Ibid., 1890, Bd.
XIII, pe 90. IV. Uebd. 4. Knotensucht des Gummibaumes. Prackt.
Ratg. f. Obst-u. Gartenbau, 1890, Nr. 4. V- Mitteil. aus de
Gebiet d. Phytopathologie II: Da6, symptomatische Bedeutung d.
Intumescenzen. Bot. Zeitg., 1890, Bd. XLVIII, p. 241. VI. In-
tumescenz bei Solanum floribundum. Zeitschr. f. Pflanzenkrankh.,
1897, Bd. VII, pe 122. VII. Intumescenz on Blattern (der Nelken) .
Ibid., 1898, Bd. CIII, p. 291, 294. VIII. Uber Intumescenzen
Ber, d. D. Bot. Ges., 1899, Bd. XVII, p. 456. Ix. Intumescenzen
an Bluten. Ibid., 1900, Bd. XIX, p- 115. Nypels described in-
tumescences on Antabotrys (Notes de pathologie veget. . R.

Soc. Bot. Belgique 1897, T. XXXVI, 2. Dp. 256), Noack on grape
berries (Treibhauskrankheit 4d. Weinrebe, Gartenflora 1901,

Ba. I, 619), etc.

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*

82
A comparison of various leaves bearing intumescences
Showed that, in different species, hypertrophy is connected
with certain cell-layers of the mesophyll. The uppermost
layer of the mesophyll in Eucalyptus globulus, e. rostrata,
Ficus elastica, Cassia tomentosa (compare figs. 20 and 21),etc.
participate chiefly. I found that the cells of the undermost
layer hypertrophy exclusively in Epilobium hirsutum, Accord~
ing to Sorauer, these take part predominantly in the formation
of the intumescence in Vitis, as well as in Solanum Lycoper~
Sicum Sorauer found distended cells above and below in
leaves of Solanum floribundium, a participation of the whole
mesophyll in carnations®*©, and in extreme cases, in Vitis. In
many plants; (for example, Pandamus javanicus, Cattleya, Cypri-
edium jaevigatun, Arelia paimata, Panax arborescens, Hedera,
felix. Canetiia japonica) , the elongation of the cells i8
only very Slight, So that no protuberances or only very flat
ones ate produced. The diseased leaf then shows yellow, trans-—
parent, usually circular spots = a symptom which Sorauer has
differentiated from other cases of yellow spotting as “"Aurigo"
(for literature, see above).

We have’ spoken only of the mesophyll. In fact, in most
intumescencés, this is the only participating tissue. In some
other cases, however, the epidermal cells also are changed.
Dale ° obserted Swellings of the epidermis on the upper as
well as on the underside in Hibiscus vitifolius, and on the
under epidermis in Ipomoea (Fig. 22), In the Sntumescence of
the tomato, mespphyll and epidermis hypertrophy.

There remains to be mentioned finally the fact, that in
Some intumescences not only an elongation of certain cells ele-
ments occurs, but also a division of the cells. A case de-
stribed by Sorauer is especially interesting. In carnation
leaves not only the mesophyll cells are stimulated to cross and
Longitudinal division, but at times the epidermal cells also
So that a cell body is formed from them. Even in intumescences
of other kinds, cell division may sometimes take place. These
exceptions te the rule should not prevent our treating the in-
tumescences as a unified group nor the finishing of this dis-
cussion in the present chapter.

Intumescences on the blossoms are known as yet only for
Cymbidium Lowi (according to Sorauer, loc. cit.)

a tenes a ee Geet a Sem tem ne Pe ee ey ea een ce Somes tee cee SS ee mms ee cre ee rae Re ah i me sy a ee ee ee ee Oe ae te ee ee ee

1. Atkinson: Oedema of the tomato. Rep. Agr. Exp. Sta.,
ithaca, Ns Ya,» L895, p. EOL.

2 Compare besides Sorauer, Prillieux, Intumescences s. 1.
feuilles des oillets malades. Bull. Sco. Bot. France, 1892, T.
XXXIX, pe 370

3. Investigations on the abnormal outgrowths or intum-
escences on Hibiscus vitifolius Linn. Phil. Trans. B., 1901,
Vol. CXCIV, p. 163. Compare further by the same author, In~-
tumescences of Hibiscus vitifolius. Ann. of Bot., 1899, Vol.
XIII, p. 622 and on certain outgrowths (intumescences) on the
green parts of Hibiscus vitifolius, Proc. Camb. Phil. Soc.,
1900, Vols X, part IV, ps 192.

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*

83

The question as to the external conditions by the action
of whieh intumescences are produced, has been repeatedly treat-
ed experimentally (Sorauer, Dale.) ‘They arise as a result of
"excess of water", if the plants under experiment develop an a
Saturated atmosphere. According to Dale, simultaneous action
of light is necessary in the gage of Hibiscus; no intumescences
have been formed under water. According to Copeland, they may
be developed on tomato-leaves by forcing water into the branches.

It is more difficult to answer the question as to what
factors determine whether mesophyll or epidermis, whether the
lower or upper cell layers of the leaf furnish the intumescence,.
From the constancy with which the undermost mesophyll ceils,
in Epjlobium hirsutum, for instance, are enlarged, or the cells
of the under epidermis in Ipomea, the possibility may be con~ .
sidered that some constant structural peculairities of the leaf
release the stimulus only in certain oell-layers, or make pos-
Sible a growth-reaction only for certain ones. Dale calls at-
tention to the fact that intumescences occur on both sides of
the leaves of Hibiscus vitifolius, which bear stomata on both
Sides, while Ipomea, with stomata occurring only on the under-
Side of the leaf develops intumescences only on this side. It
is indeed not improbable, that the formation of intumescences
is connected with the distribution of the stomata. This is
proved also by the structures of the Vitaceae, to be further
treated later (p. 90). But in no case has an explanation been
obtained by the discovery of these relationships which would
hold true for all cases, The examples cited above have already

shown this. I cajl attention once more to the intumescences on

the leaves of Picus elastica illustrated in fig. 21, which are
produced by growth of the uppermost palisade cells, aithough,

aS is well known, the leaves possess stomata only on the under
side. In the majority of cases differences in the position |
of the different cell-~layers will presumably determine partici-
pation or non-participation in the intumescence, Later we will
refer repeatedly to the fact that not all layers of the leaf~-
tissue are capable of reacting to the same stimulus in the same
Waye

Closer investigation is needed to prove how far the pro-
duction of intumescences is caused and favored by the treatment
of plants.with p oisons, especially with copper salts (compare
Sorauer) .*

In connection with the intumescences, which may be pro-
duced by the arrestment of transpiration or (according to Cope-
land) developed by the forcing in of water, a list of similar
formations may be mentioned in the following, corresponding to
developmentally and histologically. Haberlandt 3 developed in-

1. That does not exclude the fact that occasionally the form
mation of intumescences is incited by temporary moistening.

2, Binige Beobacht. bei. d. Anwendung v. Kupfermitteln ge- ~
gen ai Kartoffelkrankh . zeitschr. f. Pflanzenkrankh.1893,Bd. III,
De 366

3, Ueb. experimentelle Hervorrufung eines neuen Organs bei
Conocephalus ovatus Trec. Festchr. £. Schwendener, 1899,p. 104.

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84
tumescences by destroying the organs on the leaves of Conoce»
phalussovalus and C. suaveolens which eleminate water. The re-

sulting surplus of water caused the. formation of i

His, method consisted of painting the leaves of eee
experiment With a one per cent alchhdhic sublimate solution.

A few days after the potsoning of the hydrated, thick bunches
of colorless hairs (compare fis. 23) were found where groups of
transient glandular hairs had stood on the young, immature lean
In their production those parenchyma cells especially partici-
pated which enclose the vascular bundles,

_ . “@n a circular spot these cel’s are drawn out in anti-
clinic curves and grow into longs sacs, which remain unbrokenly
connected with one another at the base showing rather numerous
periclinic and, in part, anticlinic divisions, First a flat
conical or disc=shaped tissue body is produced, which breaks
thru the overlying leaf tissue (pelisade and water-tissues,
epidermis). Then the upper parts of the sacs grow out into long,
colorless haixvs, resembling root=hairs which stand out from one
another like bristles of a brush. Wot-infrequently distended
like clubs at the free end, they possess a living cytoplasmic
wall~covering with a roundish nucleus, On the edge of the disc-
like tissue body several rows of palisade cells are abundantly
elongated. Their chromataphores usually degenerate before this,
or at most remain in the lower part of the sacs, (loc. cit.
ps 109, 110)". Besides the palisade cells, those of the xylem
and of the wood-parenchyma in the vascular bundles can partici-
pate in this growth. After about a week, the delicate new form
ations disintegrate and are replaced by excrescences on the
underside of the leaf, from the epidermis and watér-tissue layer
of which unicellular or multicellulay water blisters are pro-
duced. Haberlandt compares these with the homologous organs of
Mesembrianthemum crystallinum. In my opinion, intumescences are
concerned here aS well as in the buaches of hairs differently
developed.

These are differentiated from those earlier described
by their ability to give off water. Haberlandt tries to
give them an especial significance, since he- considers
their formation an expedient reaction of the plant, which
after a Toss of the normal hydathodes, "can develop entire
ly new organs for eliminating water, essentially differ-
ent histologically, and of other developmental origin,
than any occuring in the normal developmen tal process of
the plant." I have already stated my view that there is no
necessity for speaking of these described excrescences as
the "new organs", and I have compared the compensatory
hydathodes described by Haberlandt with callus formations
since the latter at times have a similar structure and can
also accasionaly eliminate wotere® More apropos is a com-
parison with the above described intumescences with which
they also correspond etiologically. Haberlandt himself
has already called attention to the similarity betwsen the
structures which he developed artificially, and the hyper-
trophies observed by Sorauer and others. The question as
to whether the latter,like the compensatory organs of COno

Le Beitr. z. Anate d. Gallen, Flora, 1900, Bd. LXXXVII,p. 11”.

2. Compare here also Mollisch, Ueber lokalen Blutungsdruck
UW. Se Uraschen. Bot. Zeitg., 1902, Bde IX, pe 45.

85

cephalus » might be considered as expedient new structures
of the injured organisms has been answered by Haberlandt. He
declares that their significance as “incomplete appendages
for self-regulation" may possibly be admissable. Our present
knowledge of intumescences makes it seem more advisable to
me to class these with "bark-excrescences" as is done in the
present presentation, since they correspond with these etiol-
ogically and histologically . In my Opinion, neither the
intumescences nor the bark excrescences show recognizable
pecularities, on the ground of which we might describe them
as “expedient” functioning formations or as asdesposition
toward such formations.

Prillieux" cebservea conspicuous variations from the
normal in seedlings of different phatts, which we will discuss
jJater, He germinated seeds of Phaseolus, Cucurbita, etc. in
hot soil, the young plants grew but little in length, becoming,
however, very thick and finally deep, gaping cross-rifts appeared
on them. By anatomical investigations it was found that in all
tissues the cells of the hypocotyl had been greatly inlargeda,
that, for example, the cortical~sells measured redially four
times the normal . OccaSionally besides cell growth, cell di-~
viSion also occurred here,

I found difficulty in confirming the statements of Pril-
lieux, since he makes only meagre statements concerning his
methods, In my own experiments, pots with different kinds of
germiniating seedlings were so heated in a sandbath, that the
temperature of the soil was held continuously between 40 to 42
degrees Centigrade. A bell-Blass protected the cultures from
drying. The seedlings of Vicia stood the treatment best. Whit~

(90) ish pustules occurred finally in their epicotyl, which were
produced by growth of the epidermal and bark cells, and 1éd to
a rupturing of the epidermal tissue. Presumably, however, the
formation of these “intumescences" may be explained by the very
abundant amount of moisture in the air (resulting from the high
temperature), not by the action of the warmth itself. i outs
like to assume the same for Prillieux's results. Vesque* a].so

“Made experiments with heated soil in which “carrnosites" became
noticeable in the plants under experiment. Finally the "bead
glands" of the Ampelidaceae should be mentioned, which occur in
young branches, on petioles, leaf blades, and side-~Leaves of
many Vitis, Ampelopsis and Cissus species. Their connection
with the stomata is easily recognizable. The cells below the
Stomata grow into the air chamber and, by continued growth, push
1. Alterations prod. d. 1. pl. par la culture dans un sol
sur-chauffe,. Ann. SCe Nat. Bot., 1880, B serme, . 7. X., Pe 347.

2. Compare the remarks at the end of the chapter.

3. Compare especially Hofmeister Allg. Morph. d. Gew., 1868,
De 545; De Bary, Vergi.. Anat. d. Vegetationsozg., 1877, pe 68;
D'Arbaumont, Observations s. 1. stomates et les lenticel-les du
Cissus quinquifolia. Bull. Soc. Bot. France, 1877, T. XXIV,
Pe 18, 48; Solereder, System. Anat. d. Dikot, 1899, p. 253.

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86

up the epidermis thus forming little balls, elear as glass,
on the apex of which are to be found widely opened guard
cells. In their formation, cell division is not of rare 0c
currence. It must remain doubtful, whether the "bead glands"
of the Ampelidaceae may be considered as "normal" formations
or whether they are to be recktoned among the abnormal. ones.
It is certain that lack of light and noist+ air favor their
production. The bjological explanations proposed by Miller-
Thurgau end Penzig” do not seem to ne exactly satisfying.

ce Abnormal Succulence

We may speak of "abnormal succulence” when, for example,
it is possible to make those plants form "fleshy" leaves
Which under normal conditions, such as are characteristic of
leaf succulents, would develop delicate leaf blades,

Some experiments have already proved, that it is pos-
Sible to force wpon certain plants some pecularities of suc-
culents by’ means of treatment with salt solutions. As is
well known, the transpiratory power of plants decreases con-
Siderably under the influence of concentrated salt solutions,
Perhaps it is the decreased elimination of water vapor which
causes hypertrophic phenomena of growth in the experimental
plants nourished with strong salt solutions, causing a sim
ilarity in some respects to real holophytes.

We know but little concerning this last form of hyper~
trophic tissue. LeSage 3 developed artificial succulence of
the leaves by abundant doses of sodium chloride, especially
in Lepidium sativum. The cells of the mesophyll were elong-
ated greatly, Showing thereby the same disintegration of
their chlorophyll contents, as has been repeatedly described
for the hypertrophies of bark and mesophyll. The statements
of authors, however, do not always agree, in Pethybridge's
cultures the tissues of plants treated with NgCL remained

ee me nm cme A me Nar SS am i es me Gee ces te eet tee cee eS Neneh Se fu Afar Re A me Ne Sa pnt SS ee we tm So tes ee Nee ee ae me ew ee

1. Compare especially Hofmeister in loc. cit. Further .
Tomaschek, Ueber pathogene Emergenzen auf Ampelopsis heder-
acea. Oest. Bot. Zeigg. 1879, Bd. XXIX, _p. 87. Kreuz, En-
twickl. d. Lenticellen an beschatteten Zweigen von Ampelopsis
hederacea. Sitzungsb. Akad. Wiss. Wien. 1881, Bd. LXX<II,”
Abte I, pe 228 (here also Tomaschek, Oest. Bot. Zeitschr.,
1661, Bad. XEXI, pe 252).

Be Muller-Thurgau (Perldrusen d. WWWeinstocks. Weinbau u.
Weinhanéd, 1890, Bd. VIII, p. 178} sees in them organg pro-
tective against small animals. Penzig, fUeb. d. Peldruseén 4d.
Weinstocks ue. a. Prl. Atti Congr. Bot. Internaz. Genova,
1892, pe 257) considers them food-bodies, which are devoured
by mites or the like.

3. Rech. exper. S. 1. modifications d. feuilles chez
1. pl. maritimes. Rev. gen. de Bot., r900, T. IIT, p. 54.

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87
beloqw the normal in their development.+

In cultivation under water, Aug. Xraus® obtained
germinating seedlings with "fleshy" leaves (Helianthus,
_Lepidium sativem) which were composed of abnormally
Large cells, VesqueY obteined further "carnositas"
not only through cultivation in abnormally high temper-
atures {see above) but also by alternate watering of
the plants under exneriment with 5 (or 2.5) per cent.
mutrient solution and distilled water, The question
still remains unanswered to whet extent the "“fleshiness
of leaves in cultures in disadvantageous nutrient so~
lutions* may be considered in this connection.

In phenomena of abhormal succulence, as in ths-
sues of etiolated plants, tissue, formations are in-
volved by which whole organs undergo the same change
in all their parts.

4. CALLUS HYPERTROPHY

When, after injury, the living cells of an organ en-
Large without division, we speak of callus hypertrophy .«
The cells lying near the edge of the wound enlarge at times
to meny times their normal volume.

Just as'in the abnormal structures discussed in the
Last division, cell-division often follows the growth of
the cells after injury. Thus it is impossible to draw a
sharp line between the cases which belong here and those of
callus hyperplasias. We find in the same organs of the
same plant species that sometimes hypertrophic growth of
the exposed cells follows’injury, sometimes the formation
of extensive hyperplasias,- depending upon the conditions
of the organs involved’ and the external Llife-conditions.
In the present section, we will have to discuss those plants
and plant organs which are able to develop hypertrophies
after injury. We will have to consider also the conditions
under which after wound stimulation those organs and tissues
react with only cell»growth, which, in general, would be

1, Compare Pethybridge and Stange (cited above p. 57) arid

the literature cited by Stange.

2. Beitr. z. Kenntn,. d. Keisiung u. ersten Entwickle Ve
Landpfl. unter Wasser, Dissertation Keil, 1901.

3. Sur l. causes et s, 1. limites des variations de struc-
ture des veg. Ann. agron., T. IX, pe 481 and T. X., p. 14.
(Compare Bot. Chl. Bd. XVIII, p.259).

4. Nobbe, Ueb. d. physiol. Funktion des Chlors in d. Pils
Landwirtschéftl. Versuchsstate, 1865, Bd. VII, pe. 371. Nobbe
Schroder and Erdman; Ueb. d. organ. Leistung des Kaliums in
ds Pf1. Ibids, 1871, Bd, XIII, pe 321. “Compare for this
also Sorauer, Handb. ad. Pflanzenkrankh., 2, Aufl., 1886, Bd.

I, De 187 and Frank's Urteil (Krankh. d. Pfl., 2, Aufl.,

Bde I, pe 288).

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88
able &@ter injury to develop wound-wissue by cell“division.

We find callus-hypertrophies among thallophytes as well
as among higher plants. Only rerely does the histology of
the cells in this abnormal growth remain similar to the orig«
inal mormal one. Usually a retrogressive formation of the
contents takes’place. Here; as in the cells of the hyper~
hydric tissues, thé degeneration of the chlorophyll apparatus
plays a large part, the cytoplasm too may often decrease
noticeably. If progressive changes of the histological cell-
character appear during the hypertrophy, they involve only
the development of the membrane. Thus among the cases be~
longing here, we meet prosopkastie hypertrophies alongside
of those which bear more or less distinctly the character-
istics of _kataplastic hypertrophy.

_ . I obtained the most extensive callus~hypertrophies on
thallophytes in the case of Padina Pavonia. Little piecés of
the broad thallus were cultivated for weeks in’sea~water con=
teining sugar; the cells, laid bare by cutting, then grew out
into large; nearly colorless bladders, {compare fig. 24) which
always remained undivided. The walls of the hypertrophied.
cells were very delicase. I observed further extensive callus-
hypeftrophies on raggedly torn specimens of Nitophyllum wmcin-
atum, the outer walls of the hypertrophied cells were greatly
thickened, Bitter observed cone-like thickenings of the walls
in callus=hypertrophies of Padinea Pavonia.

In higher plants, at times in the tissues of the axes
and leaves, it is easy to obtain callus—hypertrophies, and
they have often been observed. Although in the algae above
named and in some'others cellsgrowth alone is brought about
by wound=stimulus, yet in my experience, in the case of high-
er plants, the cells of those tissues which can furnish callus<
hypertrophies are usually capable also of producing callus~
hyperplasias, External and internal factors ddetermine whether
only undivided abnormally large cells are produced, or wound=
tissue with more or less abundant cells.

Axes

Of the axillary tissues the bark and the wood»parenchyma
show a special "tendency" to the formation of callus-hyper-
trophies,

' My observations were made mostly'on cuttings of woody
plants, one end of which was under water, the other extending
into moist air. The bark cells of many plants are often stim
ulated under these conditions to hypertrophied growth. A few
examples should make clear the different kinds of changes ob-
served here.

~~ at ee wee Wee wey Mw yest pees SO Hee me op meee mm mm eee tp MRL Pe eh ene Une ce naam > ate eRe ent ape te Mw oe ee
bo i aad z

1. Zur Anat. us Phys. V. Padina Pavonia. Ber d. D.
Bot. Ges., 1899, Bd. XVII, pe 255.

a

89

produced which resembled the cells of normel bark tissue.
Large, well-preserved chlorophyll grains, lying in the hyper~
trophied cells, were conspicuous,~ I could not observe celle
division. In all others which I investigated, the chlorophyl
content went to pieces, just as in the cells of the hyper-
hydric tissues. Always in Fagus only single cells hypertro=
phied, gowing out into large, colorless, ball-like vesicles
always poor in cytoplasm. In cuttings of Sambucus I found
that the thick-walled cells of the collenchyma strands also
participated in the hypertrophy. In the cases I have studied
the surface gtowth of the membrane was restricted to the thin-
walled parts. This seems to hold good also for the collenchyma
cells of the Ricinus stalk which Massart+ saw hypertrophy
strongly after injury. I have never been able to observe in
cuttings of this kind that collenchyma cells can be stimulated
to cell-division after injury. In other plants the bark cells
are chiefly elongated, furnishing colorless sacs radially ar-
tanged. A very luxuriant growth fakes place, for instance,

on the cut surfaces of Syringa cuttings, the hypertrophied
barl cells of which are often from two to ten times aS long

as they are wide. _

As yet’ I have never observed that the bark cells of
woody plants, hypertrophied after injury, had undergone me~
taplastic. changes. In future investigations exceptions to
this rule may possibly be found. Combinations of abnormal
gvowth with metaplastic changes of the cell-character are
already Known in callus hypertrophies of leaves and in those
mentioned in the following lines.

{94) | Callus hypertrophies of an unusual kind are
illustrated by the tyloses which, as is well knovm,
are produced by the outgrowth of wood-parenchyma cells
after injury, thus filling the limina of the ducts.
Since only a small section of the parenchyma cell wall

takes part in the surface growth during the production
of tyloses, it is allowable to compare these with the
hypertrophied products of the cohlenchyma cells men-
tioned above. However, the tyloses differ'so essen-
tially from all other callus-hypertrophies, histoio-
gically and etiologically, that they may be reserved
for special consideration in the next section.

Leaves

Leaves of the monocotyledons and dicotyledons,— espec-
dally of the former,- often form after injury very volumin-
ous hypertrophies, from the exposed layers of their mesophyll.

Fig. 25 shows how far the growing cells may bn this way ex-
ceed their original volume. Thus the character of the cells
is changed generally, in the usual way, by the disappearance
of its cytoplasmic content and the disintegration of the chlo-
rophyll, without the development of new anatomical characters.
An exception worth noticing is made by Cattleya, doubtless
also by still other orchids. The cells on the edge of the
wound, illustrated in figure 25, form reticulated thickenings

_ ee ee te oe ee

SO Ra Re cae i ey pee an tee ME SO vans ONY FED Dene Saye Ae SO Lp Deel tn en Se comm Tina Sah meme Ome ee bee nies ara

1. La citatrisation chez 1. vegetaux. Mem. cour, etce
Acad. Belgique, 1898, 7. LVII, pe 44.

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(96)

90

of the membrane,.as is shown more highly magnified in fig.
26. in the lower part of the ceil, these are only narrow
meshes between the single thickened bands, which also are
strongly developed. in the upper part the bands are usually
flatter and sometimes partly interrupted. This case is of
Special interest since, aside from the tyloses, it is the
only one known to me in which hypertrophic growth, incited
by wouhd stimulus, is combined with the formation of a
Special kind of wall-thickening. Unfortunately I lacked
opportunity for investigating a larger number of other or
chids as to their callus-hypertrophies.

Miehe* has found in Tradescantia virginica an object
of which the epidermal cells may eaSily be caused to form
callus~hypertrophy. If, by any kind of interference, cells
or cell groups of the epidermis are killed or destroyed,
the empty places thus produced are filled out by the living
neighboring cells. By growth, flat swellings are produced
on them, which’ grow into the dead cells. The cavity is
finally closed, since all the neighboring cells hypertrophy
in the same way, and the cas formed from them lie close up-
on one another. (Compare fig. 27). If a single cell closes
the wound, this hypertrophying cell can reproduce the nor=
mal appearance almost completely. Its growth reminds one
of the processes which were described above in the “resti-
tution of the tissue". Even the guard cells can share by
growth in the closing of the vwonnd. While normal cells are
perhaps 0.18 mm. long and 0.03 mm. broad, Miehe found hy-
pertrophying ones become from 0.38 to 0.43 mm. long and 0.08
mne broad. Cell~division was not observed anywhere but it
May occur occasionally in Allium nutans, in which Miehe ob-
Served Similar regeneration processeSe

Among callus-hypertrophies I include also the
abnormally large cells which Haberlandt? recently
obtained in a culture of isolated tissue elements.
Isolated mesophyll cells from the upper leaves of
Laminum purpureum kept alive for weeks in Knop's
nutrient solution or in nutrient fluids containing
sugar and grew perceptibly at the same time thick-
ening their membranes either on 211 sides or only
in places. Haberlandt's statements concerning the

1. The tendency of many orchids to the formation of reti-
culated membrane thicking, as proved by v. Bretfeld (see
above pe 61), makes probable a positive issue for further
testing. It seems to have escaped v. Bretfield's attention
that the formation of the described thickenings of the wall
can be combined with luxuriant hypertrophic growth. I sur-
mise that the occurrence of metaplasy or prosoplastic aL ala
trophy depends on external conditions. Cultivation in @ nois
atmosphere might here, as so often, cayse or favor the pro-
duction of abnormally large cells. Through lack of material,
I could not test this question further.

2. Ueb. Wanderungen 4. pfl, Zellkernes.Flora,1901,Bde
LAXXVIII, pe 105.

3, Kulturversuche mkt isoliertin Pflanzenzellen Sitzungs--
per. Akad. Wiss. Wien, 1902, Bd. CXI, Abt. I, pe 69-

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OL

? become gradually smaller, assumed 2 yellowish tinge
and were transformed finally into very delicately
contoured, small leucoplasts. When kept in a one
per cent. Sugar solution, they decrease a little
in size, but keep their color; in stronger concen-
tration (3 to 5 per cent.) they remain as large and
as richly pigmented as before and often become more
intensely green than they were originally. Therefore
those same changes may appear in the culture of cells
in inorganic solutions, which we have found to so
often occur in hypertrophied cells within normal
tissues. Future investigations will determine,
whether it is possi ble to bring to hypertrophy cells
left in the tissue and then, by a simultaneous sup-
plying of carbohydrates or other nutritive substan-
ces, to prevent the retorgression of their chloro=-
phyll contents. Haberlandt assumes that, in isola
ted cells, the chlorophyll grains thrown upon their
own aSSimilation activity cannot be kept intact,
since they give up their assimilatory products to
the other cell-organs. Isolated assimilatroy cells
of Bichornia crassipes soon lost their chlorophyll
contents in the dark, if at the beginning of the
experiment. they contained no starch, “while they
remain intact if, in case of scanty or insignifi-
cant growth of the cells, they can make use at least
partially for themselves of the starch stored up in
them". Haberlandt obtained also giant cells with
thickened vralls in the culture of fragments of stam-
inal hards of Tradescantia.

Winkler (Bot. Zeitg., 1902, Bd. LX, Abt. 2, pe 264)
promised further communications concerning the fate of
isolated cells.

The conditions, under which the abnormally large cells,
termed cellus-hypertrophies, are produced, are still unknowm
to use Of the diverse new conditions which an injury creates
for the exposed cell, it has not yet been possible to Separ-
ate the stimulating ones from the ineffective, nor to recog~
nize the significance of the single factors by comparative
experimental studies of their specific effects. More acces-
Sible for experimental research is the problem, under what
conditions tissues of the same kind may be stimulated by in-
jury to hypertrophic or to hyperplestic changes. Doubtless
humidity plays a large part here; air containing much water
vapor promotes éxtenSive undivided growth, after injury to
living tissues, just as in the case of hyperhydric ones.

One of Massart's experiments (loc. cit. ) supports this. He

So split a stem of Ricinus by lateral pressure that two slits
were opened towards the pith-cavity, two others toward the
outside. (Compare fig. 28). In the slits f. f. opening to-
wards the outside, the exposed tissues reacted with abundant
cell-division; in f' f', on the contrary, only callus hyper
trophies appeared. Massart assumes that contact with the
open air makes possi ble the extensive reaction in the first
named slits, A comparison with different researches makes 1%
seem certain to me that the effect of moist air, which we may
presuppose to be present in the pith-cavity of the stem, vas_
the essential condition of Massart&s experiment. The signifi-
cance of transpiration lies supposedly in the fact that a more

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%

92

abundant current of nutritive substances flow to the cells in
which a-moderately vigorous elimination of water vapor is
possible. The differences, often shown by the comparison of
aqifferent examples of the same species under similar external
conditions, might be based upon dissimilar conditions of mu
trition of the objects under investigation.

Experimental investigations into the influence of abund-
ant nutrition on growth and cell-~division have lead as yet to
no positive result. At least, Haberlandt was not able to
bring isolated cells to celldivision by supplying abundant

nutritive substances (cane-sugar).

Recently Winkler reported in a preliminary statement
(loc. cit.) that isolated cells could be stimulated to divi-
sion by means of poisonous substances} isolated root-parenchy-
ma cells of Vicia Faba grew out to two or three celled threads,
if 0.002 per cent. CoS04 was added to the nutrient solution
(Knop $lus 1 per cent. cane-sugar). ;

5. TYLOSES

As tyloses are usually designated all those spherical
pouches found in the lumina of the ducts. and tracheids of
various vascular plants. They are known to be produced by
the growth into the lumen of the ducts of the adjacent par-
enchyma cells through the thin-walled parts upon which they
touch. The parenchyma cells do not divide = with very rare
exceptions — So that we can consider tyloses %o be hyper-
trophies. :

Tyloses are distinguished from other hypertrophies,
first of @11, by the fact that in their production only a
limited part of the membrane of the participating cells is
enlarged by surface growth. The position of these narrowly
bounded, growing membrane areas is determined by the releif
outline of the adjacent wall of the duct. In this way only
those parts of the parenchyma cell wall distend, which do
not lie under resistant, thickened membranous parts of the
ducts, Therefore, this explains forthwith the fact that the
formproportions of the cells producing tyloses are percep-
tibly changed during the growth, so that the hypertrophied
cell is not an enlarged reproduction of the normal one. The
cylindrical or spherical parenchyma cells acquire one or
more spherical or sac~-like elongated outgrowths, often of |
considerable size. Not infrequently the volume of the orig-
inal cells remains far below that of this newly produced
appendage. (Compare fig. 31). The tyloses are further charac-
terized by the fact that they fill out hollow places already
existing in the plant body. Thus, by the hypertrophy of cer-
tain cells, in the case of tyloses formation, there is brought
about neither increase in volume, nor change in the form of
the organs concerned, nor does it cause the formation of pus-
tules or swellings.

All larger cavities found in the plant body,- the
lumina of the ducts, the air chambers of the stomata and the
secretion cavities, may indeed be filled up by hypertrophic
growth of the living, adjacent cells. We will summarize as
tylose-formation all hypertrophies characterized by localized
surface growth of the membranes filling out any cavities in

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93
the plant body and will describe them briefly in the following.

1. The duct tyloses are best known:- They are the ones
which fill the lumina of the ducts and tracheids and are pro~
‘dapagls by hypertrophy. of the living parenchyma cells lying in

@ wood.

The knowledge of duct tyloses dates back to
Malpighi, who fovnd “oval and translucent little
sacs" enclosed in the ducts of Quercus,l The unm
named author in the Botanische Zeitung® investi-
gated their anatomy carefully. In his statements
the development of tyloses tyom parenchyma cells is
excellently described. Bohm? sought to explain the
production of the tyloses, first of all, by an ac-
sumulation of cytoplasm between the lamellae of the
duct walls, whose innermost layer grows out to form
the membrane of the tylose cell. He traced it back
later to an excretion of protoplasmic drops and their
Subsequent hardening.

The form of the tyloses is determined in the first place
by the nature of the thickening of the duct wall. If ring-
like thickenings are present the adjacent parenchyma cells

may produce a broadly~based outgrowth into the lumen of the
duct. (Compare fig. 29). The conditions in the spiral dusts
are similar, if the single spirals are not too flat, and the
thin membrane places are not too narrow. (Compare fig. 30).
If the ducts have bordered pits, only very narrow entrances
into the lumina of the ducts lie at the disposal of the grow
ing parenchyma cells. The body of the original cell and the
newly produced appendage are then united only by a narrow
isthmus. (Compare fig. 31). The form of the tyloses depends
still further upon whether the parenchyma cells grow out

“into the lumen of the duct, forming only one tylose for each

cell (fig. 31) or several at the same time (figs. 29 and 30)
whether therefore one or more appendages are produced on one

_ and the same parenchyma cell. Further, the space available

in the interior of the duct is of importance. Usually many
tyloses push against one another in the same duct and fill
the lumen with a pseudo-parenchymatic tissue, while they are
flattened against one another making necessary a polyhedric
form, (figs SL}. If the number of tyloses is small, they fill
the lumen of the duct, as round bladders or cylindrical sacs.
Complicated forms arise, if the tyloses grow out from one

1. Anatome Plantarum, 1675-1679, Tab. VI, Fig. 21.
Compare the translation by Mobius, Khassiker d. exakten Wiss-
ensch. Herausgeg. ve. Ostwald, 1901, Bd. CXX, pe 7, 32.

2. Unters tb. d. zellenartigen Ausflllungen der Gefasse,
in place mentioned, 1845, Bd. III, p. 225.

3. Ueb. Funktion und Genesis d. Zellen in da. Gefassen
des Holzes. Sitzungsber. Akad. Wiss. Wien, 1867, Bd. LV, Abt.
II, pe 851. Ueb. d. Funktion d. vegetabil. Gefasse. Bot. Zeitg.
1879, Bde XXXUII, pe 229.

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: 94
duct into another one, as Tison? snows in Hamamelis virginiana.
*
The size of the tyloses is greatly dependent upéan the
Space at their disposal. They sometimes grow out into cut
sducts, and then attain a considerable size. I have seen them

grow to gigantic sacs on the cut surfaces of Platanus cuttings
and incompletely cover the exposed surface of the wood.

Content and wall of the parenchyma cells, developing
tyloses, remain essentially unchanged in the case of tylose
formation. The nucleus of the parenchyma cell does not divide
(compare the footnote). Often it wanders over’ into the tylose
Usually the young tyloses seem to lack nuclei, since the
nucleus heave the mother cell only in late stages of tylose
development. The membranes of tyloses, as is true in many
other hypertrophies, are often very thinl In other cases,
massive thickenings of the walls may be observed and even cor~
responding bordered BAtS op the contact surfaces of adjacent
pyaoees (fig. 31). Moller? found very thick wall tyloses with
the habit of growth of stone wells (stone tyloses) in the
wood of Piratinera puianensis, Molisch (loc. cit.p. 273), in
Mespilodaphne Sassafras (compare Tig. 2s) In the case of

iratinera all the tyloses have become stone-cells, the ducts
being completely stopped up with them. By this means "the
homogeneity of the wood is significantly increased" (Molisch).
In Mespilodaphne the stone-tyloses alternate with relatively
thin-walled ones.(COmpare the figure). Thé wood-parenchyma
cells of Mespilodaphne, developing tyloses, are otherwise
rather thin-walled.

1. Rech. s. la chute dG. feuilles chez 1. Dicotyl. These

Caen, 1900. i

2. Molisch has shown already (Zur Kenntnis d. Thyllen, nebst
Beob. u. Wundheilung in d. Pfl. Sitzungsber. Akad. Wiss. Wien,
1888, Bd. XCVII, Abt. I, pe. 264), that the relations between
the growth of the cell wall and the position of the nucleus
in the ce{E, which Haberlandt proved for many cases (Ueb. die
Beziehungen zw. Funktion und Lage des Zellkerns, Jena, 1887)
are not always recognizable in the formation of tyloses, Sim
ilar cages, however, are not lacking in which the nucleus at
first remains at a distance from the distensions of the cell,
produced by superficial growth of the walls and wanders over’
into the appendage only when it is’finished, as, for example,
in the haustoria of the Erysipheae, which obtain their nuclei
only after concluding growth. The neucleus foress itself in
to the lumen of the haustorium through the thin neck of the
latter. (compare Smith, The Haustoria of the Erysipheae. Bot.
Gaze 1900, Vol. XXIX, p. 153, 167); further in the young
baSidia of the Basidiomycetes according to Maire (S. 1. cyto-
logie des Gastermmycetes. C. R. Acad. Sc. Pairs, 1900, T. EXXI,
Pp. 1246). According to K. Tamba (Die Herkunft der Zellkerne in
den Gefassthyllen von Cucurbita Sitzungsber. Phys. Mediz. Soc.
Erlangen, 1887, Bd. XIX, p. 4) the nucleus divides at times in
the’ parenchyma cells of Cucurbita producing tyloses, ane of the
daughter nuclei goes over tothe tylose, the other remains in

the mother cell. Closer testing would be much desired.

4. Rohstoffe des Tischler~ und Drechslergewerbes, 1883,
Bde Les De 143.

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95

As regards their contents, many tyloses correspond
to w6od=parenchyma cells, in vithai they store up adundant
starch. ‘Molisech found tyloses containing starch in Aris=
tolochia, Asarum, Robina, Maclura, Vitis, Ampelopsis, Morus,
Cuspidaria, Laurus, Ochroma, Sparmannia, Ficus and Ulmus,
so abundantly in the rhizomes of the Aristolochiaceae, that
the ducts seemed in places to be’ plugged up with starch.
Orystals, as contents of tyloses, are of little importance,
The tyloses of Sideroxylon cinereum often contein one crystal,
more rarely those of Maciura tincgoria, Piratinera guianemsis
Loxoptergiun Lorentzii, and Vitis Molisch found tylosas
of Oimis fTiTed With calcium carbonate. In regard to wound
hes gonteined in the tyloses, refer to the statements of

p at Bi

Anong the most important characteristics of tyloses
is the fsct that they are univellular, Despite the extent
which they often attain, cejli-division is omitted in almost 4
all cases, Molisch hes disproved the statements of de Bary.
(loc. cit.) Mrecul., Gris®, and others, who thought they had
observed a separation of the tyloses from the mother celle
MoLisch could prove multicellular tyloses only in the ex-
ceptional cases of Cuspidaria pterocarpa and Robina. Thor
ough proff is needed of the statements of Stoll® that the
wood in Passiflora quadrangularis takes part in callus form
ation by’means of tyloses, He says that these after repeated
division, fill out the lumen of the duct near a wounded sur
face with a tissue that finally presses out over the cut sur
faces

The distribution of tyloses in ducts is almost uni-
versal in vascular plants. They are found in the parts of
1. Compare here also Reess Fur Kritik de Bohm * schen
Ansicht ub. ds Entwickelungsgesch, und Funktion der Thyllen

Bots. Ztge 1868, Bde XX¥I, pe 1.

3. Molisch, loc. cit. pe 275 and Vergl. Anat. d. Holzes
der Ebenacéen u,. ihrer Verwandten, Sitzungsber. Akad. Wiss.
Wien, 1879, Bd. LXXX, Abt. I, De 65.

3e Uebs a. SekretibtLdung im \lund- u. Kernholz, Arch. f.
Pharmacie, 1899, Bde CCXXXVII, pe 369.

4. Vergle Anat, di Vegetationsorg, Pp. 178.
Be Trecul,, Rech, Se l'origine d. bourgeons adventifs. Ann.

Sc. Nate Bot. 1847,-3"° ser., T, VIII; ps. 273. Gris, Sur la
moelle des pl. ligneuses. Ibid., 1872, 57° ser. T. XIV, pe, 34.

6.'Ueb. de Bildung des Callus. Botan. Zeitg., 1874, Bdy
XXXII, pe 737.

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ee ee ee a ee tae

" 96

various plants above ground a8 well as in those under
ground, (rhizome, roots;, but, to be sure, not in the same
abundance in all families. fhe representatives of many a
group of the plant kingdom are directly characterized by
their "tendénecy" to abundant tylose formation such as the
Scitamineae, Laurineae, Juglandaceae, Salic’neae, Uréicaeeae,
Moraceae, Artcocarpaceae, Ulmaceae, Anacardiaceae, Vitaceae,
Cucurbitaceae, and Aristojochiaceae. In other families,
only single genera have the capacity for forming tyloses
(for example, Robina among the Papilionaceae}, gn still
others tylose formation is very’rare or is entirely lacking.
(Ebenaceae, Acerineae, Mimoseae, Rosaceae.

I repeat here the list of plants bearing tyloses as ;
given by Molish in a somewhat more extended forma and, }imit

myself therein to the statement of the generic names.

Abies (Raatz) ' Carica
Achyranthes | Carya
esculus, (Maule, Tison) Cassica
Alnus (Tison) Castanea
Ampélopsis Catal.pa
Arahia Celtis
Aristolochia(cf. also Tison) Chil.antus
Artocarpus Ciadrastis (Tison)
Arundo Coccoloba
Asarum Coleus
Banisteria Convolvulus (Dutailly)
Begonia Cornus (Maule)
Betula Corybya Corypha
Bignonia Cucumis
Boehmeria | : Cucurbita

, Broussonetia Cuspidaria
Bryonia Dahlia
Canna Diospyros

ee te ee ee ee ee
Sr ne eee ee cee Met sa Sa pe em mee SS a tae Gem te Gey Heme me MY Ss tg a pe nee ee ee ee ye ee te mee ee ee Ne ee es

1. Besides the literature already,city, compare also the
following works;~ Unger, Ueb. Ausfullung alternder u. ver-
letzter Spiralgefasse durch Zellgew, Sitzungsb. Akad. Wiss.
Wien, 1867, Bd. LVI, Abt. I, p. 751. Dutailly, Sur quelqu.
phenom. determ. par l'appraition tardive d'elem. nouv. d,s
tiges et 1. racines d. Dicot. These (Bordeaux(, Paris 187%.
Russow, Z. Kenntn. d. Holzes. imsonderheit d.,,Koniteren~
holzes, Bot. Cbl. 1883, Ba. XIII, p. 134. Prael. Vergl- :
Untersuch. ub. Schutz~ u. Kerhnholz ad. Laubb. Pringsheim's
Jahrb. f. Wiss, bot. 1888, Bd. XIX, p. 1. (compare Ber, d.
D. Bot. Ges., 1887, Bd. V, po 417). Williamson, On some
anemalous cells developed within the interior of the vascu-

lar and cellular tissues. etc. Amn. of Bot. 1888, Bd-I,p.
315. Conwentz, Ueber Th. u. thyllenahnl. Bildungen, vornehm-
lich im Holz a4. Bern-Stbénfaume. Ber. d. D. Bot. Gese 1889,
Bad. VII, p. 39). Tubeuf, Ueb. normale u. pathogene oe ee
ung ad. Holzpfl. u. s. w. Zeitschr. ges. Forst. u. Jagdw. 189
Bd. XXL, pl 385, Raatz. Uber Phyljenbild. in d. Tracheiden
der Koniferenholger, Berjghte d. D. Bot. Ges. 1892, Bd. X,
ps 183 (compare Gonwentz, ibidy,py, 218). Maule Der eee
lauf im Wundholz. Bibl. Bot. 1995, Bd. XXXIII, pe 5,6.Antei
d. sekund Holzes d. dikotyl Géwachse an d. Saftleitang u.s.w.
Wielér, Ueber ds Anteil ad. Pringsheim's Jahrb.f.wiss.Bot.
1888, Ba, XIX ,p382.Ueb,d. Vorkommen v.Verstopfungen in d Ge-

fassen’ monokot.‘u. dikot. Pfl.Meded.Proefsta. Mid-Java,1892.

“97

Blaegnus Philodendron
Euphorbia Fhyllanthsu
Fagus Picea (Raatz)
Ficus Pinus (Raats)
Fraxinus Piratinera
Gleditschia (Tison) Pistacia
Hamamelis (Tison) Plantageo
Hedera. Platanus
Hedychium Populus
Heliconia Portulaca
Humulus (Tubeuf) _ Prunus (Wieler)
Inula Pterocarya
Jatropha Quercus

Juglana Rhus
Koelreuteria Ricinus
Latania: Robina

Laurus Rosa (Maule)

~ Bigustrum Rubia
Loranthus Runiex (Dutailly)
Loxopteryzium Salix

Maclura Sambucus
Mansoa Santalun
Maranta Schinus
Micania Sideroxylum
Morus. Solanum

Musa Sparmannia
Ochroma Stigmatophylium
Olea Strelitzia .
Ostrya Taraxacum
Passiflora Thunbergia
Paulownia Ulnus

Perilla Urtica
Pharbitis Xanthoxylon (Tison)
: Vitis.

(104) So far as I known only ~oyathea insignis may be consid

ered aS a representative ot vascular cryptogams, in which
according to Conwentz (loc. cit. p. 36), tyloses appear
ain the old petioles.

_ wo moré important points are to be settled - the ques
tion as to the etiology of tyboses in the ducts and the
question as to their physiological significance.

It has not yet been made sufficiently clear, under
What conditions tyloses are produced. Beyond doubt, the
parenchyma cells are stimulated to tylose formation through
injury to the branches, roots, etc. Tylose formation ap-
pears as well in artifical pruning et¢., as in the "physio-
logical " injury, which defoliation brings with it; in Ro-
binda only a few hours suffice to bring about the formation

98

of tyloses after injury (according to Wieker) .- We may
therefore consider tyloses as callus-hypertrophies of the
bark and other tissues. Like these and other hypertrophies
tyloses also, as I have convinced myself by experiments
With Platanus cuttings,are furthered in their developement
by the action of air rich in moisture.

On the other hand, it tts well known that the formation
of tyLoses may occur in very. many plants, even without
previous injury. In the heartwood and in ageing sap-weod
the ducts are filled with them, The’question must remain
undecided whether *“*+. in heatt-wood, etc., Similar factors
act upon the parenchyma cells, as' =~ when branches are
cut off, or in any kind of injury, or whether other condi-.
wions than these, effective after injury, can cause the
formation of tyloses. The tyloses, independent of the
wouhd stimulus, appear, however, not only in ageing parts
of the trunk, but also in organs still very young; for
example, in the Cucurbitaceae. The conditions which cause
tylose formation in ageing organs seem therefore to be ful-
filled occasionally in young ones also.

There are still other statements, according to which
attacks by parasites exert an influence on the tylose for-
mation. gyiose formation is said to appear after infection
by fungi.

In order to be able to explain uniformly, the
production of tyloses in wound-wood and in heart-
wood, Bohm assumed that the filling of the ducts
with air, under the usual pressure, is the cause
of tylose formation. Molisch (loc. cit. pe 295)
has criticised this assumption; "In an injured
branch, tyloses are formed bery abundantly perhaps
1/4 to 1 cm. below the wound, somewhat farther
down markedly less frequently, until finally 2 to
3 cm. deeper they do not appear at all. If the sus-

1. Wiler, Ueb. d. Anhteil ad. sekund. Holzes der dikotyl.
Gew. an d. Saftleitung, etc. loc. cit. Fort the formation
of tyloses after the falling of the leaves, see Staby Uch.
d. Verschl. d. Blattnarben nach Abfall d. Bl. Flora,1883,
Bd. LXIX, p. 113. von Tieghem and Guignard, Observat. s. 1.
mecanisme de la chute d. feuilles. Bull. Soc. Bot. Brance
1662, T. 2RIX, pe Siz. Tison, loc. cits Therein also fur
ther bibl. Weber (Ueb. 4d. Binfl. hoh. Temperat. auf d. Fah~
igkeit ad. Holzes, den transpirationsstrom zu leiten. Ber.

é D. Bot. Ges. 1885, Bd. IIT, p. 345) obtained tyloses in
the vicinity of pieces of branches which had been killed by
heat.

2. Compare for instance, Mangin, Sur la maladié du Rouge
i. 1. pepinieres etc. C. R. Acad. Sc. Paris, 1894, T. CXIX
p.- 753 (Beob. an Ulnus and Ailanthus nach Infection durch
Nectria cirmmabarina). Prillieux and Delacroix. La gomose
bacillaire, maladie des Vignes. ANN. Inst. Nat. Agron.
1895, T. XIV.

99
pension of the negative air pressure in the ducts
were the only cause of tyvlose Sormation, then, cone
Sidering the well-known fact that the ducts usually
Stand in open continuity for far longer stretches ,~
often several meters long,- this would have to hold
good for much deeper distances."

The question as to the function of the tyloses in the
ducts causes great difficulty. The nature of the tyloses
described above male it certain that they influence the fune+
ctioning capacity of the duets of which they have possession.
Tyloses will stop up the water conduits by the close filling
which they produce in the ducts‘ end meke them incepable of
functioning. It seems doubtful, however, whether in this
effect of tyloses, we may look for their Significance from.
the view of physiological anatomy: for some eases indeed it
seems jimprobable. That tyloses are beneficicl on the surface
of sounds as obstructive precautions, may inceed be obvious,
bus it is inconcievable Why an obstruction of the conduits
Should also be adventageous: at times in uninjured parts;-
even in very young sections of shoots. Besides this, cases
are not lacking in which tyloses renain much too small fo
make a perfect stoppage. For these reasons, Haberlandt™ ase
Sunes that "the tyloses in somé way interfere with the pro»
cess of transporting materials, since they onlarge the contact
Surface of the parenchyme eells and ducts. ‘Thus, for example,
they could accelerate the compression o? hemorrhage in the
ducts, could force sugar into these ducts, or conversely like
haustoria, which they resemble, could draw out from the trans=
piratory current certain substances dissolved in it. The cire
cumstances that, according to Reess, the formation of tyloses
often continues a long time in ducts several years old, seems
to favot a function of this kind, it appears aS if the old
tyloses., having grown incapable of functioning, are replaced
by new ones.” Of course, for the present, this is all sup
position.

Thus, the search for a physiological significance of
the tyloses has not yet led to any satisfactory results. Per=
haps the assumption brings us nearest to the truth, which
suggests that many of these, like the hypertrophies already
described, do nothing for the well-being of the whole organism
but are to be considered as pathological formations in the
Sense discussed at the beginning of this book.

2. The secretion glands and the rosin ganals, like the lu-
mina of the ducts and tracheids may be filled up by tyloses
through the outgrorth of adjacent living parenchyma cells.
Among the cryptogams (Lycopodiun) , gynnospeims (Zamia, Pinus,
Larix, ete.), and various kinds of angiosperms (Rhus, Hyper-

= s
ee ee ee we ee ee ey ee ee
ee me es ta nae ye ee ale tee tee te ld ee i ee ee Oe pet ty le

1. Physiol. Pflanzenatomie, 2. Aufl., 1896, p. 283.

(106)

(107)

100

icum, the mucus tubes of Anthurium, etc.), large numbers of
cases of this sort are well knowl. ‘Tyloses of the secre~
tory+glands, like those of the ducts, arise on the one hand
after injury (as, for example, according to Tison, in aut
umnal defoliation), on the other hand as "phenomena of sen-
ility" without previous injury. But it would be impossible
to say what factorys incite their formation, and whether
they have any significance whatever for the life-activity of
the organism as a whole.

3, Finally, those tyloses remain still to be consider-
ed, which grow into the air chambers of the stomata and fill
them partially or entirely. Hypertrophies of this kind have
long been known in many plants; either the epidermal cells
lying adjacent to the guard cejls, grow out on the inside
into large bags, as Haberlandt* affirms for Tradescantia
viridis, (compare fig. 33) or the neighboring mesophyll
cells are distended and fill out the empty space. (fig. 34)
The second type is more frequent. Schwendener observed the
Same in Prunus Laurocerasus and Camellia japonica, Molisch,
in Tradescantia guianensis, T. zebrina Stl ir pilosa, and
in Begonia gunnérifolia, Haberlandt in Pitea elegans (fig. 34)
Mobius, in Ficus nerifolia, etc.” the intercéliular spaces
lying below the water clefts show at times a very similar
filling out. (Tropaeolum Lobbianum, Cephalotus follicularis.)
Occasionally the walls of the tyloses are greatly thickened
sp ra turned toward the guard cells. (Ficus, Pilea,

ge “e

It has not yet been observed whether tyloses aré
produced in the inner cavities of stomata after injury, but
it may be possible to prove this by future investigations.
They are produced chiefly on ageing organs, further, accord
ing to Haberlandt, on such as suffer from lack of water. A

l. Unger Anat. u. Phys. d. Pfl., Pest 1855, pe 213. Heg-
elmaier and Pfeffer im Tagebl. ad. Naturf.-Bers. Leipsig, 1872
pe 144, 145. Mavr, Ueb. d. Verteil. d. Harzes in uns. wich»
tigsten Nadelholzbaumen. Flora, 1883, Bd. LXVI, py 221, Ent-
teh. u. Verteil. d. Sekretionsorg. d. Fichte u.e Larche. Bot.
Chl», 1884, Bd. XX, p. 278. Trecul, s» 1. cellules qui ex-
istent a l'inter. d. canaux du suc propre du Brucea ferrug-
inea. C, R. Acad. Sc. Paris, 1887, T. CIV, p.12e23. Tschirch,
Angew, ‘Pfl.Anat., 1889, Bd. I, fig. 565. Conwentz, loc. cit.
Mobius, Japanische Lackhum, Rhus vernicifera. Abh. Senckenb.
Naturf. Ges, 1899, Bd. XX, p. 201. Costerus, Les petits point
fonces d. feuilles des Connarus. Amn. J. Bot. Buitenzorg.
1899, Suppl. If, p- 109.

2. Ueb. d. Bezieh. awe Funktion u. Lage des Zellkerns
bei ade PF 1. Jena 1887.

3. Schwendener, Bau und Meckanik ad. Spattoffn. 1881.Ges.
Abh. 1898, Bd.I,p. 62. Haberlandt, Physio], Pflanzenahatiomie
pe 400. Molisch loc. cit. Mobius, Beitr. a, Anat. d. FPicus-
Blatter. Ber, Senckonberg. Naturt. Ges. 1887, p. 117.

" 4e De Bary, Vergl. Anat. de Veget.-Org, LEB77 , Pe Bas
GSbel , Pflanzenbiol. Schild., 1891, 6a, II, p. 114.

(108)

| 103

thorough. experimental investigation of the question, whether
in such cases too great loss of water by transpiration ac-
tually ineites hypertrophic growth, would be eSpecially in-~
teresting since the only cases yet known are those in which
abnormally large cells are formed as a result of too slight
transpiration. The question whether tyloses of the air
Chambers are abba to decrease the water transpiration of

the leaves etc., in a way "expetient" for the organism,
needs further investigation. In many cases the surface
transpiring moisture might rather be increased by the abnorma
mal growth of the mesophyll cells.

Ge GALL HYPERTROPHIES

Those hypertrophies, which we will term gall~hyper-
trophies, have primarily a common etiological characteristic-
gall~hypertrophies are those which are produced by the ef-
fect of a poison given out by a foreign animal or vegetable
organism.

Yhe abnormal tissue products, histologically most
diverse, produced by the influence of foreign organisms, are
differentiated from the corresponding normal tissues less by
the size of their cells than by their number and their pe~
culiar tissue differentiation. We will have to consider
these supplementarily when discussing hyperplastic tissue
structures , (Chap. V). I will defer until then a few
general notes concerning galls, which are true also for the
forms produced only by a cell growth. A complete, sharp
line cannot be drawn in detail between hypertrophie and hy~
perplastic abnormal tissues even in those produced under the
influence of parasitic organisms. Netherless I consider
that the difference emphasized here is a suitable foundation
for the division and that it makes possible the drawing up
of groups and sub-groups, which may be termed "natural" ones
on account of their correspondence etiologically and histo-
logically. ;

In deciding the individual cases, the same questions
are to be discussed as in the earlier groups;- questions as
to the form of the hypertrophied cells and their internal
Structure. It must be shown that, in contrast to many other
hypertrophies, the formation of those induced by foreign
organisms is connected with an abundant supply of nutritive
materials, with an “over~nutrition" which finds its obvious
expression in an enormous accummlation of albumen, starch
of the like.

Gall~hypertrophies occur extraordinarily often in the
epidermal and fundamental tissues, in various plants and
under the influence of the various animal and vegetable par-
asites.

ae Epidermis.

In the next chapter it will be shown repeatedly that
the epidermal cells in general participate only moderately
in hyperplastic tissue formations; their "tendency" to cell
division is slight. In hypertrophies, however, the epidermal
cells play an important part, They are stimulated to growth
by different kinds of parasites and furnish products of oftcu
astounding size and surprising diversity.

108
SYNCHYTRIUM GALLS

The galls of the Synchytria (Chytridiaceae) furnish
iustructive examples which may be cited first of all because
of their simplicity. The course of development of these
Tungi; parasitic on different phanerogams, and their rela-

' visas to the host plant are extraordinarily Simple in as

much aS the whole life of one generation is enacted in one
cell of tie host plant. The swarm spores of the Synchytria
penetrate into the epidermal cells of the parts of the plants
above ground and incite the infected cells to active growth.
Figure 35a shows the simplest cage: the cells attacked by

the fungus (Synchytrium Drabae Ludi) have been enlarged, the
form of the hypertrophied cells, however, not varying es~
sentially from the normal . If the growth of the infected

epidermal cells becomes greater, they push the mesophyll

(109)

te ee

aside and grow into it as spherical or egg-shaped pouches,~-
often extending as far as the opposite epidermis,~ or they
Swell out towards the outside and produce small hairs, as in .
the gall-product of Syachy’z ium osotidis shown in fig. 35b.-
In the case of other Synchytria the nutritive cells assume
Still more complicated forms.

Besides the nutritive cell, in which the parasite re+
mains the neighboring cells of the epidermis can be incited
to abnormal growth, in which they do not change their form
essentially. (Compare fig. 36a.) Finally, if cell division
takes place near the nutritive cell, more or less extensive,
often round warts, or warts with stalks, are produced, in
whose centre, or at whose apex the nutritive cell may be
found. (Fig. 36b). In the production of such multicellular
cere therefore, hyperplastic tissue-changes are also in-~
volved.

It is not yet sufficiently clear, what
factors determine whether only the nutritive
cell of the parasite hypertrophies, or other
cells undergo an abnormal growth and division.
This much is certain, that the nature of the
parasites and the specific character of the host
Plants alone do not determine it, that there-
fore, the form of the galls cannot be ascribed
throughout and unreservedly to the systematic
characterisjics of the different Synchytrium
Species. Iudi especially has referred to the
change of the gall-form in the species naméd:-
“Usually when the warts are close together, Syn-
chytrium Drabae showed only those whose resting
Spores lie in.more or less distended epidermal
cells, and which have no further influence on
the neighboring cells,~ therefore, simple warts.
Not infrequently and usually where there is more
space at the disposal of the nutritive cell in its
development, where therefore the warts are not so
close together, the nutritive cell is distended

y
ee ee ee eee ay ae te ee dam me eee IS Me see ne itt Go lig Ott ee oer ee (00 et age Ome om eee ae me ee oom he he ees ee ee Oe eee ee

1. Schroter, Die Pflanzenparasiten aus ad. Gattung Synchy~
trium. Cohn's Beitr. 2. Biol. d. Pil. 1875, Bd. I, 1, pe 1.

(110)

103

towards the inside and displaces its neigh-
bors. The wart can then be termed "half-
composite". Finally, however, it may happen-
and this is found to take place in all pe~
duncles,~ that a one or more layered, cup-
like covering grows about the nutritive cell,
as in the case of Synchytrium Mercuriales.

It is there designated as a composite wart.—
In Ludi*s contributions are found also refer~
ences to those of earlier authors upon this
qquestion,

The fact that after infection with Synchtria and dur-
ing the abnormal growth of the "nutritive cells", appreci-
able amounts of nutritive stuffs may indeed be brought to
them, aS Stated above under gall hypertrophies in general,
is proved first and foremost by the growth and increase of
the parasite. No other means of nutrition are at its dis-
posal than these contained in its nutritive cells In vig-
orous consumption, however, there does not occur any strike
ing accumulation of proteins, which is characteristic of
many other hypertrophies. The formation of red coloring
matter has been observed repeatedly in infected cells.

ERINEUM- STRUCTURES

As the second group of the gall~hypertrophies of the
epidermis, there follows that of Erineum-structures, which
surpass in diversity of form all other hypertrophies known
in the plant kingdom.

In the accepted text books of plant pathology all
those mite-galls are summarized as felt«galls or Erineum
structures, which appear to the naked eye as “felt-like
coatings" of the infected plant organ. This limitation may
suffice for the needs of the practical worker, but for our
purpose a sharper formulation might be advisable. In cross-
secfions of the diseased leaf, etc. it is shown, that the
felt-like covering has been produced only by the outgrowth
(hypertrophy) of epidermal cells (compare fig.38), or that
besides the hairs, multicellular cones and ridges have been
produced by the excrescence of the fundamental tissue. Felt-
galls of the second kind will be mentioned in the chapter
on hyperplasia. In the present chapter, we are concerned
only with the first named case. As Evineum-structures we
will consider in the following only those variations from
the normal which are caused by mites, and which like many
Synchytrium galls, are characterized by hair-like hyper-
trophy of the epidermal cells.© The knowledge of the Erinea

Peed ney tah es fp Men om ps Wem bane pue fate toy ey wens ft ment Stes A guy fd wh ger ND Se fat ep rt Se Hate ty WP ime ah mee Ss tm Sanh hm Sem tae nh Se em ce sy mm em ng may

2. I consider it expedient to retain the old designation
"Erineum", in spite of the change in meaning of the word
Since Persoon. Tass below). On the other hand, it appears
to me inexpedient, at the least very unnecessary, to pro-
vide the newly found Erineum structures {from the standpoint)
of the binominal method of nomenclature) with a particular
“species” name.

(133)

104

dates back to Malpighi* who observed,on grape leaves the
white coat of hairs caused by mites. This formation was
not investigated more closely until the end of the 18th
century, Persoon (1798) considered the abnormal hairg to
be fungi, which he united into a new gents "Erineum".” Link
and Fries4 differentiated _several genera, according to the
Worm of the hairs. Unger® , corrected their error and
ascertained that the threads described by the authors named
were not fungi, but hypertrophied epidermal cells. The next
step forward was brought about by the knowledge that the
described hypertrophies were caused by mites. Eve was the
first to discover them among the Erineum hairs®, and to
recognize them correstly as the cause of mal-formation. The
development and life~history of tthe mites have been deter-
mined since then by the numerous investigations of Siebold,

.
‘es Were Sm Some pated test ey ay we ey: ne Pa mee Nr ee tent me eee ee nee tee Me Mt toe mt Ye ee te en me oe ewer ete ee sane gee tees Pe san et wee me fray aw we teed Does me coe ee em oD ta See

1. Anatome Plantarum, London, 16751679.

2. The "Erineum populinum", which Malpighi at any rate
knew, is produced by tissue outgrowth, not by hypertrophy
of the epidermal cells. Concerning the galls described by
Malpighi, compare Massalongo, Le galle nell, Anatome Pl.
di» M, Malpighi Melpighia, 18698, Vol. XII, p. 10, and v.
Schlechtendal, Melpighi's Abhandl. de variis plantarum tu-
moribus et excrescencbiis, Bot. Zeitg.e, 1866, Bd. XXIV,
De 217,

3. Persoon, Tentamen dispos. method. fungorum, 1798,p.45.

4, Link (Berl. Mag. Naturf, Fr., 1809, p. 21) distin-

ished between Erineum Pers. and Rubigo n. sp.-Fries,
Observ. mycol, 1815, 7. I, P. 217, Syst. mycol. 1829, T. —
III, pe 520) distinguished three general, Taphrta, Erineum,
and Phyllerium, which he united into Phylleriaceae. Per-
soon himself later (Mycol. europ., T, II, p. 2) named |
Phyllerium, Grumaria {Rubigo Lk.) and Taphria as subdivi—
sions of his genus Erineum. Schlechtendal (Denkschr. Bot.
Ges, Regensburg, 1822, p. 73) and Kunze, (Mycol. Hefte Il,
Leipzig, 1823, p. 133} furnished further aves tLsattOne
from the same standpoint as that of the above named authors.

5, Die Exantheme der Pfl. und einige mit diesen ver~
wandte Krankheiten der GewashBe pathogenetisch und noso-
graphisch dargestellt. Wien 1833, p. 376. Meyen ee
pathologie, 1841, p. 242.) later expressed himself as
Unger, concerning the nature of Erineum.

6. Fee, Men. Ss. 1, groupe des Phylleriacees. Paris et
Strasbourg, 1834,

(112)

P 105

Landois, Thomas, Brioski, Frank, Appel and others.+ ‘the
studies of Nalepa, threw light primarily on the diverse forms
of the parasites.

Erineum hatis always form more or less thick turf-
like groups for which there is no definite external form
or definite size-proportions,.

It. is common for all Erineum structures that the
outer walls of the epidermal cells either take part en~
tirely in the growth of these calls or predominantly. Thus
it is evident that the hypertrophied cell oannot display
an enlarged reproduction of the normal epidermal cell, but
a change of its cell proportions must be associateé with the
increase in its volumme.

In the simplest case, short papillae are produced
by the “out-pushing" of the epidermal cells. If the growth
of these cells continues, sac»like hairs are produced, slend~
er, cylindrical forms with rounded tips, or. club-like, dis-
tended ones with slender bosses and spherical or mushroom
like heads, .

Erineum galls with papillae-like elements are rare.
Of ceurse the sacelike hypertrophied cells undergo a pap
illae~like first atage,. Qne may even see at times on the
edge of the Erineum turf that the growth of the individual
Clements stops permanently in the papillae-stage. Only rare~
ly is the matured turf composed throughout of papillae-like
elements, An example is pictured in fig. 37. A piece of

1. Siébold, Ber, Schles, Ges. Vaterland. Kulture, Entomolog,

“Sektion, 1850, p. 88. Landois, Eine Milbe (Phytoptus Vitis,

Land.} als Ursache des Traubenmisswachses. Ztsch. f£. wiss.
Zool, 1864, Bd. XIV, p. 363. Thomas, Fr. as the most impor~
tant of his works should be mentioned-Ueber Phytoptus Duj. u
eine grossere Anzahl never od. wenig gekannter Missbildungen
ue S. f. Ztsch. f, d. ges. Naturwiss., 1869, Bd. XXXIII,

p. 314. Zur Entstehung 4. Milbengallen u. verwandter Pflan-
zenauswuchse, Bot. Zeitg., 1872, Bd. XXX, pe 281. Entwickel-
ungsgeschichte ee ee eee an Prunus. Ztsch, f.
d. ges . Naturwiss., 1872, Bad. XXXIX, p. 193, Beitre. 2.
Kenntn, der Milbengallen u. Gallenmilben. Ibid. 1875, Bd.
XLII, p. 513. Aeltere’u. neve Beob. ub. Phytoptocedidien.
Ibid., 169%, Bd. KLIX, p. 329. Briosi, Sulia Phytoptosi della
vite, N. Giorn., Bot. Ital. 1877, Vol. IX, p. 23. Compare
Just's Jahresber., 1876, Bd. V, pe 1234. Frank krankh. 4d.
Pfl,, 1, Aufl. 1880, p. 671, 2. Aufl., 1896, Bd. III, p.
40ff. Appel, Ueber Phyto- und Zoomorphosen, Konigsberg,
1899, p. 41.

et Ge ty th wn

Phytoptus. Verh. naturhist-mediz.Ver. Heidelberg,Bd. I,p. 46,
Veb. Phyt. Tiliarum, Ibid. Bd. III, p. 163).

(113)

(114)

: 106

(Tarsonemus) and have grown out to short, broad papillae with
& granular outer surface”. Tarsonemus induces similar papil-
‘Lae on other Gramineae also (Stipa capillate, Triticum repens).

In the majority of cases, the Brineum turf consists of
slender, cylindrica] hairs of equal thickness and with rounded
tips. In the leaves of Alnus, Tilia, Fagus, and other trees,
the turfs occur on the upper or under side of the leaves, more
rarely on corresponding areas of both leaf~surfaoces (Compare
fig. 38). They form extroordinerily thickfelts, since cll or
nearly all the epidermal cells on the infected place in the
leaf hypertrophy es is shown in the illustration,

The non-cylindrical hairs, occurring on the leaves of
Prunus Padus, Betuln, Acer apd others, have different forms in
the different Erineun-galls, Either heirs with slender bases
are found, which grow bronder toward the tip and end with a
round tip, or those with a sharply set-off, ball-like or roller-
like hend, or with a flet ond mushroom-like one (Compare fig.
39), or they are depressed on the top, thereby becoming ofp-
like, Ifa tendency towards branching shows itself, lobated
forms are produced (Pig, 44a), I observed unusual hair forms
in the case of on Erineum of Alnus latifolie, which produced 4
powdery ooating en the underside of the lear, The hoirs, by
their ramifiontion, hed assumed a racemose form and the great -
est variety was visible among them. A few hairs of this Erin-
sum are shown in Fig. 40. In contract to the Erineum gells
with slender, cylindrical hairs, bnly isolated epidermal cells
have been transformed hypertrophically in those forms which
have sphericel or mushroom-like elements, os showm by Frénk,
loc. cit, (fig. 39). When the hairs are close together, their
heads may often touch one enother, be flattened out in one an-
other, or even dovetail together vith their short processes

For the histology of the single Erineum cells,- as in
the case of other gall-hypertrophies,- the cbundant supply of
nutritive substances is important, which is connected with the
growth of the infected cells, The abundance of nutrition 1s
demonstrated by the growth in thickness of the walls and es—
pecially by the storing up of proteins, starch and fatty oil
in the interior of the hair cells.

The thickening of the well is less conspicuous in the
simple cylindrical forms than in those distended like clubs,
Especially the parts of the vall toward the outer side are
often very thick, Thickened and pitted also are the side and
inner walls of the epidermal cells which have grown out to
Erineum sacs, but are still united with the tissue of the epi-
dermis. Similer changes occur at times in places where the
Rrineum hairs touch one another. According to Prank the
Slender hairs of the linden Erineum ("Erineum tiliae") can Co~
alesce at the pleces of contact and form corresponding pits,
just as do the tyloses which touch each other inside of the
lumen of 2 duct (p. 100). In the case of club-like hairs, the
heads, provided with short outgrovths, sometimes coalesce and
furnish a kind of pseudo-parenchymatic tissue; Frank observed
pit-like thin places in the membranee of the contact-surfaces.

-_ = =~

_-_ =
eee elma

| > Massalongo, Intorno all’ acarocecidio della Stipa pen-
nata L., caugato dal Tarsonemus Canestrinii, N. Giorn, Bot.

- gtal., 169%, 3.8, Vol. IV, p. 103.
ha aie

(115)

107

The content of the Erineum hairs is extraordinarily rich
in proteins, the vacuoles often contain red coloring matter
(Tilia, Almus, etc.). In Acer, Vitis and others only scanty
amounts of chlorophyll are developed. The club-like hairs

of a maple Erineum are very striking; in these an immense quan-
tity of small starch grains are deposited, or smal&zer numbers
of often very composite starch grains lie next one another

like mosaic stones, filling the lumen of the cell. In other
hairs of the same Erineum form, fatty oil is found instead of
Starch, which takes up part of the lumen of the. bark in Splei
did menisci or makes of thé whole cell a filled oil-sac. Smal
atarch grains and isolated oil drops occur frequently in the
case of other Erineum forms. In those forms which I have in~
vestigated, a cell nucleus may be found in each hair, whose
position, at least on the matured hairs, was not constant. I
discovered the nuclei in club-like hairs sometimes in the stalk
and sometimes in the head part.

Simultaneously with the change of the epidermal celis in

the Erineum formation, the cell of the mesophyll also may some-
times be altered. They. too gain at times in volume and not in-
frequently store up abundant starch. Generally their chloro-
phyll fades then. This co-operation of the mesophyll may be
recognized macroseopically by the fact that the leaf occasion-
ally appears to have been pushed out into cuculli on the places
infected by the felt-gall. This warping always takes place in
such a way that the Erineum turf lies on the concave side.
The tissue structure of the mesophyll on the infected places
either remains normal (fig. 39) or arrested development, be~
comes evident tn the processes of differentiation, the meso-
phyll then remaining homegenous. (Compare fig, 38).

Finally those gall forms should be mentioned briefly,
whose abnormal hairs are multicellular,” and those which are
produced not by a new formation of hairs, but by hypertrophy
of the normal trichome. Frank reports an "Erineum" of the
last kind (loc. cit. p. 48) on Quereus Aegilops. Similar form
ations occur elsewhere also.

Since Fee, we have become better informed concerning
the etiology of the Erinea and know that their formation is to
be traced back to the colonigation of the plants by Phytoptus
mites. Undoubtedly the stimulus, causing the abnormal growth
of the epidermal cells, comes from a poison which the gall in-
sects produce, concerning which nothing more is known. The
Substance given out by them geems often able to filtrate from
one epidermal cell into another and thereby to stimulate those
cells to hair formation which were not directly infected by the
mites. If the mites affect the underside of a leaf, their
virus can penetrate the whole thickness of the leaf and incite

1. Compare also Meyen loc. cit. p,. 243, who observed the
embossment of the leaf and traced it back to enlargement of
the single cells,

2. Neger, Ueb, einige durch Phytoptud hervorgerufene gal-
lenartigen Bildungen. Verhandl. D. wissenschaftl. Vereins,
Santiago 1895, Bd. III, p. 149,

(116)

a LOS *

the epidermal cells of the upper side also to the phenomena
of growth here cescribed, In this case corresponding areas
on bothe sides of the colonized leaf are covered with Erineum
turf (compare fig, 38). ‘This action on the sice of the leaf
opposite to the surface primarily stimulated seems to be come
evident especially abundantly on the leaves of Tilia, on which
Frank had clrendy fomnc ther, I observed the same phenomenon
on the rough, uvper leaves of the linden inflorescence, If
we overlook the eases in which mesophyll cells alse cre incit-
ed to a wealenead growth, ve my assune thet, in the form tion
of Erinea, those poisons are active, ahich incite only the
epiderrnl cells to intensive growth?,
Microchenio methods, making possible the proof of
the sprecd of gall-poison in the plant body, are not at
our disposnl, ‘e oxn recognize its diosmotic distribution
orly in its‘effeets on the cells of the host plant. As
noted ahove, the cylindricsl hairs of the Erineum gells
form thickly closed masses, sinch each single epidermal
cell crows out into = hair, The assumption that the gall
nites work so exactly and infect each cell separately is
less probable than the one that the peisonous substance
given out by them can diosmase from one cell to another,
The hair formations on the side of the leaf not infected
support this assumption. On the other honmd the Erineum
“ hairs aré isojdteda if -club-like os: mushYoom-Lrké Torus
are involved, The possibility that for each individual
hair an especial act of infection is necessary may be con-
Sidered here, and also that the poisonous substance of the
mites can not diosmose from one cell to another, or at
least not in a sufficient amount. To my knowledge, there
is no case known in which mushfaom-like Erineum hairs had
been formed on the side of the leaf not infected,

“Me question as to whether tne epidermal celis wz ary pervs
of plants have this capacity for transformation may be ans-
wered only incompletely by a consideration of the materials
offered in nature. Apparently a}l parts of the plants bearing
Erinea, which are above ground, are capable of forming ab-
normal trichomes, so long as a living epidermis is present on
them, To be sure most of the Erineum forms are found on
leaves, but if the mites colonize on young petioles or parts
of the stalks, the hypertrophies described are produced on
these also, Most of the Brineum forms prefer the underside

of the leaf, in the case of Fagus, Tilia, Prunus Padus and
others, however, FPrineum hairs occur on the upperside also.
Cuboni*® observed Frineyn turf on bunches of grapes, . Further,
in many blossoms galls’, trichomes often develop which omm-

~_ = =
— ww meet _— ee a oo =

1 compare Kuster, Gecidiol, Notizen I, Flora, 1902,
Ba. XC, De BT.

2 te stazions speriment, agar. ital, Roma 1886, p. 524.
Quoted from Frank, loc, cit, p. 49.

9 Compare also Molliard, Cecidies florales, Ann, Sc.
Net, Bot, @™° ser,, 1895, 7. I., pf 67.

109

pletely resemble Erineum hairs (Compare also fig, 44). The
fact that the forms of the Frineum hairs sometimes occur dif-
ferentiy on different plant organ. is worth notice and de-
serves further investigation, (Compare Frank, loe, cit, p,44).

Only experiments will give ao reliable ansver to the

“question whether the epidermis of al] plants oon be stimulated

(117)

to the pfoduction of heirs by means of certain poisons, Dis-
ooveries in nature make it seem very probable primarily thet
the peculiority of the epidermal cells nov under discussion is
at least very widely distributed, since Erineum galls are to
be found upon representatives of the most varies plant fan-
ilies, The most numerous of the mtive Erineum golls ore
found upon deciduous trées;- among herbaceous plents the
preference for the Rosescece is strikingly noticeable,

Of the trees ané shrubs bearing Eruneunm, I will mention
the following;

Acer Quereus
Alnas Rubus:
Betule. Salix
Cratcoegus Sorbus
Evonynus Tilda
Fagus Viburnun
Prunus vitis
Pirus

As examples of the herbaceous plents bearing Erineum:

Geraniun Poteriun
Geum Salvia
Mentha Scutellaria
Potentilla Veronica

Yore detailed summaries are to be found in thg work of
Unger+, Frank (loc, cit. p. 47), v, Schlechtendal“, Neger
(loo, cit,), Darboux and Houard’ and ethers,

Fina}ly brie? mentian must still be made of the hair-like
outgrowths which are formed on different kinds of plants under
the influence of Cyanophyeeaé, In the case of Axolia, Nostoc
colonies always settle im the Hollows at the base of the upper
leaf lobes, A few of the epidermal cells covering the hollow,
grow out into long hairs, In the leaf ears ef the liberwort i
Blasia, dolonized by Nostoc strings, may be foun d similar uni-~
cellular, much branched hairs, In the Anthocerotacese also
the wall cells of the mucus hollows inhabited by Nostoc grow

¥ -_— ek
me ee eae ee ee a

Loc, cit, p, 372, ‘herein also references to the
older literature and some remarks on the plant geographical
distribution of the Frineum galls.

2 toe, cit, Compare further: Uebersicht der bis, Z, &.
bekannten mitteleuropaischen ' Phytoptocecidien und ihrer Litt,
zeitschr. f, Naturwis., 1882, Bd, LV, p. 480.

4 Catalogue sustem, d. Zoocecidies le 1'Burope et du
bassin mediterraneen, Paris, 1901,

(118)

| 110
out into delicate, much branched and intertwined threads?

b. Ground~-Tissue

The ground tiscue of plants partioipates differently
in the construction of the galls, In many-gall forms its ©
elements are only enlerged, without division (Hypertrophy),
in otbers very abundant cell divisions usuully follows grovth,
hy ae goncerned at present only with chenges of the first
Nd,

It is easy to name a large number of fungus or insect
galls in the production of whieh, for example, we find that
the mesaphyll of the leaves recot by developing abnornelly
large cells but to the exclusion of a11 processes of! division,
In clmost 211 cases, how6ver, those galls ore not inyolved
here, the ohsraster of which depends upon the products of
purely hypertrophic changes, but those in which the ission
of o611 division is to be observed only as indication of an
tnoomplete development ef the diseased form,©: UndermMmore fav-
orable"Cexternsl soenditions gall hyperplasias instead of gal}
hypertrophies would have been produced by the same parasites”,
We will defer the consideration of these galls to the next
ohapter and limit ourselves in the present to those in which
dn accordance vith the specific poisonous effeots - only
hypertrophic cell-changes are always concerned and only
through these is produced the characteristic structural form
of the gall-tissue, Phenomena of growth of the kind described
Can be caused by animal as well as by vegetable Symbionts,

As first instance, I will name those changes which arg
oaused by Anabaena Cycsadearum on the roots of the Cycadeae™,
In a definite zone, the cells of the fundamental tissue grow
out into sacs elongated like palisade cells, which leave

‘free large intercellular spaces, The Anabaena threads re-

main in these. (Compare fig. 41}.

Of the native Zoo~cecidia two fly~galls demonstrate
excellently the process of growth here described,

we tm mmm wm tem tent tom em te re

a Leitgeb, Lebermoose, Bd, V, p. 16.

& Similar considerations were given above (p, 97) in
the diseussion of callus hypertrophy.

3 Most important literature: Reinke, Morphol, Abhandle,
pe 22, fwei parasitische Algen, Bot. Zeitg, 1879, XXXVII
ps #¥2, Schneider, A, Mutualistie symbiosis of algae an
bacteria with Cycas sheen BO ee ee mee

. 25. Goebel, Organographie, * Ve » Life, Tuber-
Vike rootlets of cease revolute, Bot, Gaz, 1901, Vol, XXXI, 7.
p. 265, Pampaloni i, e, Nostec punctiforme nei suci rappor ti
coi tubercoli radicali delle Cicadee. N, Giorn Bot, Ita.,

1901, N, S. Vol, VITI, p. 626.

(119)

(120)

iad

, figure 42 shows part of a crass-section through the
So-called window-gall of the maple”; a roundish spot of
the leaf blade is appreciably swollen, since the cells of
several layers of the mesophyll have been greatly enlarged
and stretched at right angles to the upper surface of the
leaf. The epidermis and usually also the cells of the
uppermost palisade layer remain unchanged, the others have
become thick, delicately walled sacs, rich in albumen, which
usually do not show any chlorophyll content.

More widely distributed than the window-gall of the
maple is the reddish brown bladder gall dccurring on the
Leaves of Viburnum Lantana which is produced by a Becid-
omyine. 250 far as I know, this has not yet been thearly
defined, The leaf seems to be distended lense-like on
the infected spot. A cross-section shows that the gall
surrounds a cavity lined by greatly enlarged mesophyll cells
and occupied by the larva. (Compare fig. 43). The changes
in the mesophyll are about the same as those of the maple
gall already described. The cells of all the mesophyll
layers are soon elongated to about an equal extent, In other
cases, the growth of the palisade cells or of the spongy
parenchyma cells predominates, Thus rather irregular cell
forms are often produced, as shown in the illustration. In
all cases thé chlorophyll’ content of the hypertrophied cells
is extraordinarily scanty, or almost null, but their protein
eontent is very large. Often abundant formation of anthoo-
yan-in occurs which makes the galls visible even from a dis=
tence. Calcium oxalate glands are not infrequent in hyper
trophied mesophyll.

Even the pith is able to develop gall~hypertrophies.
In leaf blades of wheat, attacked by Chlorops taeniopus, the
cells of the pith grow out into long thick villi “Whose
free ends are much twisted and bent and remind gne, by their
length, of the papillae of many stigmae”. Cohn.

The list of known gall~hypertrophies is not exhausted
with those here described. 4An especial group is formed
first of all by the giant cells ~ in which not only the
protein content but even the number of nuclei increases wpa
ing cell growth. Multi~nuclear elements are produced, whic
will be eSpecially discussed in the next division, as tran-
sitions between hypertrophxe and hyperplastic forms.

A number of other hypertrophies, produced under the
influence of foreign organisms, will be mentioned in the
following “appendix”.

(Gt Real tees red Gad tos on fad pet fed ns ed ed Wee et NE EN em woe Uy ee Goer er) — pve me

1. Thomas; Fr. Fenstergalle des Bergahorns. Forstl. Nat=
urw, Ztschr., 1895, Bd. III, pe 429.

er ed Oe me gs te Np I

2. V. Schlechtgndal, Die Galbildungen ({Zoo-cecidien)
der deutschen Gefasspfi. Zwickau 1891, N. 1150.

3, Ueber die Bandfiissige Halmfliege (Chlorops taeniopus)
Ber. Schles. Ges, Vaterl. Kultur. 1865, pe 776

(121)

112
APPENDIX.
ca

Purely formal Correspondence with Erineum hairs already
described neccesitates the mention at this point of a number
of other hypertrophies and formvariations which are pro»
duced by the most varied causes, showing neverthelees a nat~
ural relationship. In the cases here Summarized, in the
first place, growing cells are concerned, which assume an
abnormal form under the influence of abnormal life~conditions
In the second place, cells with apical growth’ are constantly
involved, root hairs, fungus ‘hyphae, Siphonae, pollensacs,
and the like, In the third place, the same forms are re~
peated in all cases, even those which have been already
described for the Erineum hairs, Further, we will be able
to prove that the internal formation of the cell abnormally
formed does not vary from the normal, if we do not include
here the loss of cytoplasm, which cells often undergo in hy-=
pertrophy. Regular thickenings of the wall, formation of
the cell-organs, such as chlorophyll grains, etc. aré never
found. Also, cell division never follows cell growth, nor
is anything knovm of an abnormal nuclear increase. The :
Shanges are therefore only of a kataplastic nature, Forma=
tion of irregular cellulose accumulations is not infrequent}

The formal similarity of the roothairs to the cylindric-
al Erineum hairs is forthwith obvious; in both cases unicel-~
lular, almost always undivided, derivations of the epidermal
cells are concerned. The differences between the two lie
especially in the fact that the root hairs are always much
more Slender and often appreciably longer than the hairs of
Erineum Bypes. <A comparison between the two is made especial-
ly important by the fact that under abnormal conditions root=
hairs can assume the forms described above as characteristic
of definite felt galls. On their apices round or wart-like
processes are produced, wavy rifts become visible and here
and there even the beginnings of ramification,

Thorough investigations of this subject may be found
in the work of Fr. Schwarz”, who has furnished some informa-
tign on the conditions under which abnormally formed root=
hairs may occur, Schwarg experimented with nutrient salt
Solutions of 1 to 10 per cent. "since only the osmotic effect
produced by the salt is concerned here, even solutions of
cooking Salt, calcium or potassium nitrate may be used, The
plants, however, are more easily injured by these than by _

& solution of nutrient substances." “A concentratéd solution
arrests the growth of the root hairs very markedly, however

aps ne Wik tee ee tee ee ee et het ie te ee ee ee fee ee

1. Die Wurgelhaare d. Pfl. Tubinger Unters, Bd. I, Heft.
2, 1882, pe 185. Compare further, Wortmann, Beitr. 2. Phys.
d. Wachstums. Bot. Ztg., 1889, Bd. XLVIT, p. 283 and Rein~-
hardt, Das Wachstum der Pilshypken. Pringsheim's Jahrb. f.
wiss. Bot., 1892, Bde XXIIIp p,. 557,

(122)

113

process may be repeated many successive times, (loc, cit.,

p. 183). The same changes in form may be obtained by trens-
ferring the root-hairs from moist air into water or into con-
centrated nutrient solutions, t is even possible by these
methods to nroduce branched root-haits, occasionally mentioned
in the literature on this: subject,

The illustrations here shown should be convincing as to
the sinilarity of the Erinewm heirs to deformed root—hairs,
In figure 44, the hairs of an Erineum of Acer campestre are
shown side by side with club-like root-hairs, beginnings of
branching showing on their distented Meads, Further, in
figure 45, three irregularly waved hoirs from a blossom gall
of Phyteuma are shown side by side with root-hairs, which
Schwarz obtained by the methods desctibed above and which
show very Similar elterneting constructions and distensions,

As Schwarz has shown, these abnormal] root-hairs °rée pro-
duced after changes in the esmotia pressure of the oell,
through retention in solutions which withdrev cater from then,
as well as by transferring from air to water, It does not
seem possible that, besides the notion of withdrawing water
produced by the effective solutions, even specific poisonous
action, proceeding from these solutions may influence the
formation of irregularly deformed root-hairs, For comparison
with those above described, root-hairs of Sinapis seedlings
are also shown in figure 46, whichwere growm under treatment
with very dilute sublimate solution. As may be seen the
formal diversity is very great, even in adjacent hairs.

Hypertrophies occur further on yhizolds end root-heirs
after infection by foreign organisms”, The abnormol pro-
gress of apfeal growth is connected supposedly with some ef- .
fect on the turgger in the cell. The same forms cs in Erineun
and root-hairs Are found in a number of other tube-like cells,
which are similcrly.enlarged by apical growth. In the fol-
lowing fungus hyphae the S iphonene and pollen tubes may be
briefly discussed, The deformations of the fungus hyphae
are best known, They are extraordinatly abundant and in
fact are present in any fungus-culture, The hyphae here and
there form isolated boil-like spherical distensions or places
with alternating narrow and wide lumina, corresponding to the

a ie

ee eo a one

7 Examples in Magnus, Ueb, Chytridium tumefaciens n. Sp.
in d, Wurzelh, v, Ceranium flabelligerum u. acanthonotum us.
w, Sitzungsber, Ges. Naturforsch, Fr, Berlin 1672, p. 87,
Goebel, Morph, und biol, Studien. Ann, Jard, Buitenzorg, 7,
VII, p. 77, Boebel, Archegoniatenstudien, Flora, 1892, Bd.
LXXVI, p. 106 (Boob. an Polypedium obliquatum u, Trichomanes
rigidum). Marchand, 5, une nostochinee parasite, Bull, Sec,
Bot, France, 1879, Bd, XXVI, p. 336 (Obsesvations on infected
moss-rhizoids, especially Riceia). Nemec, Die Mykorrhiza Bs
einiger Lebermoose. Ber, d. D. Bot. Ges, 1899, Ba. XVII, p. <
(Observations on Calypogeia). Borzi, Rhizomyea, nuovo Ficbmi-
cete, Messina 1884(swellings on the root-hairs of many mono-
cotyledons and dicotyvledons after infection with Rh, hypogeea).

123)

114

above figures. Besides these, abnormal ramifications may
occur.

The variations in form already described have been
mentioned occgsionally. in works on mycology on account of
their conspicuousness, but have only rarely beeen studied
thoroughly. Reinhardt's redearches on the conditions of
their proéuction should be considered first af all. Slight
fluctuations in the concentration of the nutrient solution
fluctuations of temperature, or action of poisonous substan~
ces aause these deformations. If the disturbances are of
& permanent kind, the growing hypha tip is rounded up into
a ball. "The growth oe stops with this spherical
swelling, if resumed immediately, the outermost ball-calotte
grows out agins to a thp, of larger er smaller diameter, ace
cording to whether a more luxuriant or a less extensive
growth of the hypha ensues, Only in this way~ the process
being repeated successively~ all the wavy profiles produced,
while the completed condition shown in the growing hyphe
gives primarily the impression that the parts just back of
the tip are swollen through turgor into cap-like forms.'

In the case of more extensive disturbance, the bali is flat-
tened in front and the apical growth stops first, while the
parts lying next to the sides grow still further end extend
beyond the dormant tip like s circular wall, until the growth
here also eomes to a standstill. Often, after a few minutes,
4t is resumed not by the tip but by single points of this
circular wall, which as et grow out epically inte :
hyphae, (loc. cit., pe 496, 497)." I have given Reinhardt’ s
descriptions in detail since they apply not only to the ab
normal forms of hyphae, but also of other cells growing
apically which are described here.

Growth in to a spherical form which Schwarz studied tn
rootehaiys , occurs also in fungus hyphse and was observed
by Llebe+. He sawed spores of Mucor regemosug in 3 per cent.
citric aotd solution, In this “spores 0 e fungus swell
up te bladdérs, which may be said to be enormously larger in
proportion to the original size of the spore (0.01)gm., since
they can reach at times a diameter of 0.5 mm, ‘These giant
Gelis, however, are not elways spherical, but often pear~
shaped, or tubular,~ at any rate very differently formed.
When germinating, many spores first put out in different
places short germination tubes, which then swell out 66 : e
Spores themselves have done, so that whole groups ef suc
connected bladders are produced, Such a giant cell Bee O
thin cell-wall, a thin brownish the Lasmic wall layer an a
very abundant Cell-sapy. Such sells themselves, apedea
out pocketings, which at timese are cut off by a crosswall.
After a jittle time the @ells disintegrate." The tendency
of mcor spores to swell greatly through the additiog of
citric acid had been previously observed by Brefeld.

a eT tad
Sates we wan en tap then ae! Bly ate ates Yate ion Oe Taft wad cate me AO ee Nee wr Ee Ste ops soe MOP emp gs eer Hae mm vee wr ome Sm Kw e ete nw eae vb

1. Beding, der Fortpfl. b. einigen Algen u. Pilsen, 1896,
Re 519 a

2. Brefeld, Mucor racemosus u. Hefe. Flora, 1873, Bd. LVI,
pe 385, 392. :

124)

(125)

a

115

By the action of forei organisms deformations are
also sproduced, just as In the rhizoids discussed above,
whether the foreign living creatures remain outside of the
hyphae celis or be colonized inside of the m. Bladder~like
swellings and abnormal ramifications occur, for example, in
the mycelium of Pezzia, through the action of an adjacent
Aspergillus mycelium.” Intumescenses are produced also by
the action of bacteria, etc. On account of jtheir, biologic-
al significance, the deformations found by Moller® in the
fungi cultivated by tropical ants are especially interesting.
The. sterile myoeliun of Rozites gongyloxhera, formed by the
fungi gardens of the tugging ant (Atta) shows regular, ball-
like swellings on the ends of the hyphae, United into thick
groups they form the "kohl-rabi mounds which serve the ants
for food. (Compare fig. 47). Essentially the same is shown
by the fungi cultivated by the hair ond hupp ants (. Aptero-
stigma and Oyphomyrmex) although their kohl-rabi mounds do
not consist of such recularly formed hyphae-heads as dq those
of the Atta species, Moller{s cultural experiments with
Rosites gongylophore prove that the mycelium forms diverse
Setlings Sotreordinarsly easily. He succeeded in producing
the kohl-rabi movnds evor, on artifickal nutrient media. It
is not known what “actors 4n the nest of the tugging ants
are effective in causing the formation of the hyphae swell~
ings. Finally, hypertrophies of the fungus hyphae shoubd
be considered, which are produced after colonization by

parasites, They offer gothing essentially new for our ana~
tomical considerations,

. Intumescences, cells with wavy outlines etc. sccur
also in the Siphoneae. Bryopsis and Udotea are faverable
ebjeots and may be cultivated easily often forming in
cultures the deformations described, Thus they repeat onte-
genetically all the details which Reinhardt had described
for fungus hyphae (spe above.).

The fact that even in Siphoneae, intumescences can be
produced by the action of foreign organisms is proved by
eet Coen ye Sis beer YOR rer et a we tat eh tena mr the ew fee age cay Dine fees mee Hae ee et pw tee Yale ae ae ote ne Wem eee tn ase Pre an nats BOO iy ek met om ten eer Sew wa em Br Bane dar re on ee ae Dee

1, Compare in detail the statements of Reinhardt, Loc.
cit. p. 502, 519,

2, Moller, A.. Die Pilzgarten einiger sidamerikanischer
pera Jena, 1893. (Schimper's Bot. Mitt, aus dem Tropon,
Heft 4.

3,Bxamples in Cornu, Monogr. d. Saprolegniees, Ann. ae
Nat. Bot. 1672, V™°, Serie., T. XV, p» 145. Cornu, Bers .
D. Bot. Ges., 1889, p. 255. A. Fischer in Rabenhorst's ae
ptogamenflora, 1692, Ba. I, 4, p. 34, 37, and other places.
Zopf; Zura Kenntnis a, Phycomyceten. Nova Acta Acad. Leop.
1884, Bd. XLVII, p. 168, 173, and other places. Raceborski,
Pflanzenpathologisches aus Java, Ztschr. Ee Pilekvew ss
1898, Bd. VIII, p» 195. (The so-called conidia of Bactri-
dium flavum are enormously enlarged cells of an own
Fungus host plant (Pegiza?) in which lives an amoeba like
parasite (Rozella? Woronina?).

: . 116

the galls of different Vaucheria species, produced by a
rotifer (Notommata Werneckii)+ In the tubes of this alga,
terminal, or lateral, wart-like, pear-shaped, or spherical

ouches occur, which bear several horn-like outgrowths.
compare fig. 48). Each of the galls contains 2 mother~
animal besides numerous eggs or young.

The_polien tubes which are capable of forming similar
deformations should still be mentioned. In artificial cule
tures, intumescent forms may be obtsined.©

As has been stated for root-hairs and the fungus hyphae,
it may also be assumed that, in the Siphoneae and in pollen
tubes, changes in turgor in the,growing cell cause the var~
ijations in form here described.

Finally, we must pention here the involution forms of
bacteria, which Nageli* first observed and named. By the
action of unfavorable external conditions— for example. of
an unfavorable nutrient medium, or too high temperature
many bacteria, especially the vinegar bacteria gfow out into
extensive diverse monstrosities. They become, long, often
twisted filaments, bladder or spindle-like tubes, often
having wavy outlines. Branched forms are also abundant, as
in the case of deformed root-hairs; etc. The bacteriods of
the nodules in the Leguminoseae illustrate such branched _
forms. In short, it is the same structural=repertoire, which
Pe ye I ee ma fare Me em ee te ee ne ne ee Oe ee oe thee wo a oor er eaten hes lemduenleeataediscielanends atondinateeiaatanl pr some ee ee a ote oe ae ewe wee
1. Compare especially Rothert, Ueb, d. Gallen der Rotatorie
Notommata Werneckii auf Vaucheria Walzi n. sp, Pringsheim{s
rbe, te WiSS, Bot., 1896, Ba. XkIx, p. 525. Citation
of literature also in Trotter, La Cecidiogenesi nelle Alghe.
Nuova Notarisia serie XII, 1901.

it

2. Of the literature I will name Tomaschek, Eigentuml. Um-
bildung der Pollens. Bull. Soc. Imp. Nat. Moscou, 1871, T. IT
The same, Kulturen der Pollensbhlauchzelle. Verhandl. d. Nat=
urforsch. Ver. Brunn, 1872, Bd. XI, Halsted. Americ. Natur.
1886, Vol. XX, pe 261. Bot. Gaz. 1887, Vol. XII, p. 139, 285,
Acqua, Contribuz. alla conose. delle cellula veget. Malpighia
1991, Vols V, De Bs

3. Just aS in the cell~sacs already described, thick and
thin places alternate with each other, according to whether
-growth takes place chiefly in length or in thickness, in
multicellular organs, thick and thin places can follow one
another like a string of beads, if, in their development,
the external conditions alternately arrest and favor growth
in thickness, For roots zesembling strings of beads, com-
pare Sachs, Gesamm. Abhandl., Bd. II, p. 801.

4. Die nied. Pilge in ihren Bezieh. zu. den Infection-
krankh, 1877.

(126)

LL?

wea see repeated everywhere.+ The correspondence of degener~
ate bacteria with the cells of Higher and lower plants
described Above should be demonstrated by figure 49, which
gives involution~forms of Bacterium Pasteurianum, and by the
illustrations given earlier. Involution-forms of Khe bacter~
ia are oharacterized by their Small cytoplasmic content. Yhe
deformed cells finally disintegrate through loss of power.

Monstrosities occur also in the case of other unicel-
lular living creatures, when cultivated under ahnormal life
conditions. These are produced in the same way by abnormal
increase in volume’ and processes of growth taking an abnor~
mal course, Algae, fungus Spores and vegetative fungus cells
also form such "involution-forms". Algae cells, conspicuous
for irregularity of form and tendency to form branches, were
observed for example in Stichococeus by AF. Klercker, Matru-
chot and Molliard, by Kruger in Chiorothecium saccharophilum
Beverinck in Scendesmus acutus, etc, May name here also
the giant algae cells, Which are produced by the action of

guschita. Einwirk ¢ d. Kochsalzgehaltes des Nahrbodens ant

: die Wuchsform ad, Mikrooroganismen, Ztschr. f. Hyg. use In-

fectionskrankh, 1900, Bd. XXXV, p. 495, of temperature, Han~

‘gen, Rech. Ss. 1. bacteries acetifiantes, Travaux du [ebor de

Carisberg 1894, Vol. III. Michaelis, Beitr. 2. Kenntnes de
thermophilen Bakt. Arch, f. Hyg. Bd. XXXVI, p. 285, of_Sub-
stances eliminated by foreign organisms Potts, Zur phySi0l-

gie des Dictyostelium mucoroides. Flora, 1902, Bd. XC, P- 281.

&. Af. Klecker, Ueber zwei Wasserformen von Stichecoccus,
Flora, 1896, Bd. EXXXII, p. 90. Matruchot and Molliard, Var~
jiations de-struct. d'une algue verte sous l'infl. du milieu
nutritif., Rev. gen. Bot. 1902, 7. XIV, p. 113. Kruger, W.
Kurze Characteristik einiger' nied. Organismen im Saftflusse
d. Laubbaume. Hedwigia, 1894, Bd. XXXIII, p. 241. Bpeyerinck
Kulturversuche mit Zoochlorellen, Lichenengonidien u. and
nied. Organismen, Bot. Zeigg. 1890, Bd. XLVII, pe 724. Com
pare also Richter, Ueb. ad, Anpassung @. Susswasseraigen an
Kochsalglosungeh. Flora, 1892, Bd. LXXV. pe 4e Lockwood,
Formes anormales chez les Diatemees cultivees artificielle-
iment. Arch. Micrographie, 7. X. pe 5. Miquel. Rech. experim.
8. la phys. morph. et pathol. des Diatommes. Ibid. pe 49.
The latter obtained abnormal forms in older, exhauseted cul-
tures, especially if they were contaminated by other algae
(Scenedesmus and others). It must remain undecided, whether

ossibly the irregular, many armed forms described by Bohlin
Ueb, Schneealgen aus Pita-Lappmark, Bot. Cbl. 1895, Bae
LXIV, p. 42) as Cerasterias nivalis, the strikingly variable
forms described by Schmidie (Ueb. drei Algengenera. Ber. d.
D. Bot. Ges., 1901, Ba. XIX, p. 10) as Coccomyxa dispar and
Similar algae forms might also be included among the path
ologically deformed ones,

(127)

: 118

fungus-hypjae in the formation of lichens.+ Gamaleia®,
Matzpschita (loc. cit.) and otherg observed "involution

fcrms in yeast. Schostalkowitsch® gathered sausage-like or
obated spores from Mucor proliferus,

The question whether the deformations here described
are connected in all cases with an injury of the cells in-
fected, i. e., in the organisms hevé concerned, -may not be
decided definitely. In any case the injury is often only
Slight and is felt only temporarily. In many cases indeed
root-hairs and fungus-hyphae continue their growth normally
after the formation of some distended places, intwmescences,
In extreme cases the injury is unmistaxeble. In involution-
forms of bacteria and in the deformations of Mucor mycelium
described by Klebs, the cells ¢radually lose their cyto~
plasmic contents and literally srow until they’ die,~ com-
parably to the cells of the hyperhydria tissue, discussed
above, Thus in these too we may speak of a decided kata-
plastic hypertrophy. t

7. Muitinuclear Giant Cells,

Multinuclear cells have already been mentioned. If
cells of Spirogyra filaments, or the like, continue their
growth normally, if the nuclei divide regularly but for some
reason the formation of cross-walls becomes impossible, i&
then results in multinuclear cells. (See above p. 69). In
the following, cases are to be described, in which cells of
any kind are stimulated to abnormal growth, and their nuclei
to division, without the formation of eross~walls. We can
designate cells of the latter kind as transitions between _
hypertrophies and hyperplasias. To this must be added the
fact that many giant cells subsequently form septa, after
repeated nuclear division, just as we could prove above for
giant cells produced by a continuation of normal Savas
tivity. It mst be added further that, simultaneously with
the production of mltinuclear giant cells, abnormal cell
divisions take place in adjacent tissues, by which nuclear
division and cross-wall formation are related to one

1. Stahl, Beitr. z. Entwickelungsgesch. d. Flechten, 1877,
Heft 2; Compare also Lagerheim, Ueb, eine durch d, a
ung v,. Pijazhyphen entstehende Varietat. Vv. See tat Bee
illaris Nag. Flora, 1888, Bd. L&XI, p. 61. Bonnier ae
ation 4d, lichens s, 1. protonemas d. mousseS. Reve geNs a
Bot., 1889, T. I. p. 165), obtained irregular, swollen ce
forms on the moss protonema plants colonized by fungi.

2. Quoted in Jahresber f. Mierchemie, Bd. XXVI, be 923.

n 3+ Einige Versuche tb. d. Abhangigkeit a, M. Pre ve be
auss. Beding, Flora, 1897, Bd. LXXXIV, p. 88,

(128)

(129)

9

another! as usual, We will not discuss further the question
as t@ whether giant cells are to be classed with hypertro-
phies or hyperplasias, but will speak of them here as a con-
necting link between the two.

Only those hypertrophies can become multi-nuclear
giant cells, in which the ineresse in cell volume is not
produced predominantly or exelu.ively by wall growth and ab-
sorption of water, but is connected vith an abundant in-
crease oF the cyvoplasmic content. In hypertrophies of
the first kind; for instance, in bark exerescences, I know
of only uni-cellulor forms. It does not seem impossible that
in these or similer hypertrophics, {further investigations
will be able to prove phenomena of degeneration and decay of
the mucleus. However, increase of the nuclear substance
and division of the nu@éleus in one of two known ways (karyo-
kenesis and amitosis) will undoubtedly zemain restricted
to those hypertrophies, whose cytoplasm is abundantly in-
creased. Accordingly, giant cells occur predominantly in
pelise On the other hand, it is necessary to call atten~

On again to many gall~hypertrophies in which in fact very
abundant cytoplasmic increase occurs, but no nuclear division.

Most frequently observed and most exactly investi-
gated are the giant cells of the nematode galls (produced
by Heterodera) occurring on very different host plants ana
Showing everywhere a similar inner structurg (Coleus, Circaea,
Plantago, Beta, Daucus, Cucumis, Saccharum)”.

1. At the first glance, iti may seom foreed to discuss in
two different places the abnormal multi-nuclear cells, which
as is well known, are formed in animal and human bodies through
different causes. In the cases gathered together in the first
section (the simplest cases), the multienuclear condition of
the cells is caused by the fact that growth and nuclear di-
vision are continued normally, the formation of cross-walls
being omitted abnormally. As remarked above, it wes possible
to justify the conception that giant cells of this kind re-
present “arrested development", in which the process of eross=
wall formation is completely or partislly "arrested". In the
other kind of giant cells, they have the character of unmis-=
takable hypertrophies; the cell is incited to abnormal grown

‘and the nuclei to division, without che simultaneous fa

ing of the conditions necessary for division of the cytoplas=
mic body and for the formation of cross-walls, This concep-
tion is possibly hetter suited to explain the processes en-
acted in the plent body, in the formation of giant cells,

than is Ribbert's essumption that in the abnormally enlarging
cells, "the injured protoplasm was unable to divide, while the.
nuclei had suffeved. less". (Lehrb. d. allgem. Pathologie u.

a. allg. path. Anat., 1901, pe 198).

a, According to the statements of the following authors:~
Treub,Quelqu. mots. s.l. effets du parasitisme de l'Heterodera
javanica d.l. racimes de la canne a sucre.Ann. Jard. Buitenzorg.
1887 ,T. VI,p.93. Buillemin and Legrain,Symbiose de 1l'Heterodera

vadicicola avec l.epl. cultivees au Suhara. C.R.Acad.Sc. Paris

1894, T.CXVI1I,p. 549. Molliard, Sur quelqu caracteres histo~
log. des cecidies prod. par lfHeterodera radicicola, Rev.gen.
Bot. 1900,@. XII, pe 157.Tischler,Ueb. Heterocera=-Gallen an
d. Wurzeln.v.Circaea lutetiana L.Ber. d.5.Bot.Ges. 1901,

Bd. Sky De Ge

a

120

According to Tischler's observations on the nematode
galts of the roots of Circaea many celis of the pleroma are
Stimulated to abnormal growth. Large, irregularly formed giant
cells rich in cytoplasm are produced, many of which remain
uni-nuclear, the rest becoming multi-nuclear. Figure 50 shows
a group of multi-nuclear giant cells from an older Circeae
gall. The cytoplasm of the giant cells has begun to dis+
appear. Figure 50 ¢. shows a single giant cell with numerous
nuclei, 50 b. isolated nuclei in one phase of division (am-
itosis by "budding").

Multi~nuclear giant cells occur also in other kinds of
galis. Toumey~ found them in "crown-galls" and in root ex=
creseences, which in America infect various woody growths,
apple, pear, peach, cherry, plum, chestnut, poplar, black-
berry, walnut, etc. According to his careful investigations
bhe digease is produced by a Slime-~fungus (Dendrophagus glo-

(130) bosus}* The infected tissues are stimulated to abentent cell
division; thus producing the multinuclear giant cells, These,
however, do not differ so noticeably from cells normally con-
structed, such as the giant cells of Heterodera galls. Giant
cells are usually segmented subsequently by cross-walls, So
that uni-nuclear cells are again produced, (compare fig. 51).
Judging from Toumey's drawing, these differ but little from
the normal ones. Figure 51 shows, side by side with cells
still multi-nuclear, Some which have been divided by segmen-
tation tnto uni-nuclear elements. Subsequent formation of
cross-walls is noted also by Vuillemin and Legrain for the
giant cells of many Heterodera galls. (Loc. cit.)

_Multi-nuclear giant cells have been found_further in
the galls of the blood louse and in mite galls.

Giant cells very similar to those found in galls are
produced also by expeximental interference. Prilleugz ~ pro=
duced multi-nuclesr giant cells in seedlings, which were cul-
tivated at an abncrmui’y high temperature. The number of the
nuclei, however, raroi; exceeded three. They were often ir-

1. An inquiry into the cause and nature of crown~gall.
Arizona Exper. Sta., 1900, Bull. XXXITI, pe 5l.

2. Compare also MUller-Thurgau. 2 Jahresber. Versuch~
station Wadensweil.

3. Prillieux, Etude des alterations prod. dans le bois,
du pommier par 1. piqures du puceron langiere. Ann. Inst.
Agron., 1877~1878, p. 39 (Bot. Chl. Bd. I, p. 436). Prillieux
might well have been the first to observe multinuclear giant
cells in galls. Molliard, Hypertrophie pathol, des cellules
veget. Rev. gen. Bot., 1897, T. IX, ps 33. Sur les modifica~
tions hastol. prod. ad. 1. tiges par l'action des Phytoptus.
C. R. Acac. Sc. Paris, 1899, T. CXXIX, p. 841.

A, “Rrillieux, Alterations prod. d. 1. plantes par la cul~
tures d. un Sol Surchaufie. ANN. Sc. Nat, Bot. 67° SeFey
1880, T. X. pe B47~

(131)

»

121

i
regularly qobatod and contained several nucleoli. Further
Raciborski~ produced the formation of multi-nuclear giant
cells in Basidiobolus ranarum by cultivating the fungus at
30 degrees C., in 10 per cent. glycerine. At first cell
division followed nuclear division, later the former was
omitted and giant cells with from 2 to 20 nuclei were pro-
duced. (Compare fig. 52) . The last named cases make it
evident at once that no sharp boundary may be drawn between
the hypertrophies here named and those cited under l.

Aside from enrichment in cytoplasm, no further changes
are enacted in general in cells enlarging abnormally. The
walls of the multi-nuclear giant cells usually show no var-=
iation from the normal. In regard to the statements con-
cerning thickening of the walls in Heterodera galls (Viul-
lemiin and Legrein Loc. cit. ) compare Tischler's teports
(loc. cit., Pe 105).

Tischler investigated multinuclear giant cells from
the cytohdgical side, Attention has been called already to.
“amitosis through budding" which he observed. Reference
must be made to the original work, in reggrd to the chromat=
in structure of the nuclei, the "pseudo-nucleoli” etce
Amitotic nuclear division occurs also in the giant cells of
the germinating seedlings studied by Prillieux. In these,
those nutlei are noticeable, which often divide without any
Spearation of the individual pieces from one another: “fn
bl noyau multiple et hypertrophie presente a peu pres l'as-
pect @' un petit corps pluricellulaire." Figure 53 illus-
trates a nucleus of this kind, in which seven pieces may be
distinguished. Raciborski proved positibely that the nu-

clei of the cells which he studed are produced by karyokin~
esis,

CN rs ad en ee ee Ns ane? ala
ona Bypede® found in the stew of |
cells (multienuclear?} which exceedéd the volume of normal
cells by "une centaine de fois", Parasites do not seem to
have taken part in their formation.

ok noe ey eee or
O08 Ms ey ees Wee pase ree vee tame edd Mitts pets anes lee Med pegs teem tenes cae: foe eat TED wo pee oe to aot wns howe Hees Vase gee Oa pag coo Mowe women deme A Yee MERE ep Sek te

1, Raciborski, Ueb. d. Einfl. auss. Bedingungen auf die
Wachstumsweise des Basidiobolus ranarum. Flora, 1696, Bd.
LXXXII, ps 113,

2. Notes de pathologie veget. C. R. Soc. Bot. Belgique,
1897, T. XXXVI, pe 249.

(132)

(133)

CHAFTER V 122
HYPERPLASIA

+
1
With Virchow’, we will term hyperplasia all abnormal quan-
titive increase, which is produced by ¢sll-division,

A sharp, unbroken line may not be drawn between the formal
spheres of hypertrophy and hyperpjasic without dissolving many
of the "natural" groups of abnormal tissue formations which we
have olreedy estcblished, We thus term as "naturel", those
groups of which the members aro identified as belonging together
not on account of onlr one oharecteristic, but of several,- his-
tologic, ontogenetio, etiologic, In order jot to break up
groups of this kind, we spoke in the previous chapter of some
abnormal tissue formations, which are produced not only by cell

growth, but also, uncer tr?‘ain circumstances, by cell-division.

Reference is mde to the places here concerned (especially pp.
86-109). In the present chapter we will have to consider a thor-
oughly uniform materisl, since only. forms af disease will be dis-
eussed in it, which are produced by abnorml cell-division,

In the phenomena termed hypertrophies, it was often left
undecided whether they are produced by the supplying of nutri-
tive substances and "over-nutrition", or were accompanied at
least by processes of this kind and, not infrequently, it had to
be stated as absolutely impossible that such processes could pro-
duce them. In hyperplasias, however, there is nothing against
the assumption that the place of abnormal tissue formation is al~
ways the goal of an especial nutritive current; that therefore
an abnormally abundant supplyving_of nutritive gubstances alwayR
precedes the process of Hbnoenae cell-division’. Therefore the
sap currents, lying at the base of hyperplastic processes, can
correspond very well to the currents in the normally developing
plant so far as their direction and strength is concerned. If,
for example, the vessels are broken at any point of the plent
body, it may be assumed that the normal continuance of the trans-
fer of substances will result in an accumulation of material et
the place of interruption. Just as we have previously traced
metaplastic changes to such accumulations of foodi-stuffs (com-
pare p. 59), we will try in the following pages, to explain hy-
perplastic processes also by a similar over-nutrition. From
these cases those others differ but little in which, as a regnlt
of the breaking of the vessels or the non-use of mterial, a
preat quantity of food stuffs is brought to places, to which,
under normal conditions, only moderate amounts would have flowed.
Thus, by cutting back growing shoots, dormant axillary buds may
be forced to break, indeed even the leaves algeady present may be
stimulated to a more luxuriant growth, Sacks’, having remove
all eprouy tte points from Cucurbita plants, caused the embryonie
root cells adjacent to each petiole to grow out into extensive’
tubers, even as large as walnuts. In cases of the latter kind,
we will speak of "correlation-hyperplasie"™.

In other cases the abnormal eacecynulation of material which
precedes hyperplastic changes in tissue may not be explained thus
Simply by an interruption of the normal nutritive streams, or by

1 Cellularpathologie, 1858, p. 58

'

2 yrom a medical point of view, Cohnheim (Vorles, ud.
allg. Path., 1882, Bd. I, p. 703) has referred especially to the
connection between abnorml] formation of tissue, and increase
in supply of food stuff,

3 sesamm, Abhandl., Ba, II, p. 1172.

(134)

123

the non-ase of their material, For example, in meny gall-form.-
tions, extensive tissue excrescences are produced, into whieh
astonishing quantities of food stuffs wander, without the exis-

‘tence of any previous injury to the plant body, even the very

slightest one, which could have led to an abnormal accumulation
of material. We must assume that, in cases of this kind, the
production of definite currents of food stuffs in abnormal di-
rections which are surprisingly large arises from the action of
stimuli, noticeable in the infected cell of the host plant after
infection by parasites and under the influence of some unknom
poison given out by then,

Among vegetative hyperplasias a number of well-differentic-
ted groups may also be distinguished according to their etiolopy.
Many are produced by chemical stimulation, others arise after in-
jury, ete. In many the proliferation of the tissue may be traced
back to the clogging of normal currents of food stuffs, in others
to an abnormal bringing in of food, resulting from a local non-
use of building materials, In still others, we must assume the
existence of special stimuli, which bring about an abnormal sup-
ply of food, thus making possible hyperplastic tissue-formotions.

When considering etiological conditions, we generally find
ourselves in @ more favorable position than do human patholo-

gists, to whom the cause of remy new formations of tissue is
still unknown,

The abnormal tissues even show a diversity among themselves
which is not found in any of the chief groups previously dis-
cussed, The outer forms of the excrescences, as well as their

Life history and their histology offer a profusion of not eworthy
differences, the study of Rich will be our task,

It Will suffice first of all to sketch hastily the most im-
portant points of view.

Abnormal new formations of tissue deform the plant. organs
either as localized, more or less sharply defined excrescences,
as diversely formed protuberances, as loosely attached "gall
apples", ete, or they change a whole organ im such a way during
the formation of the abnormal swelling, that the organ itself is
at the same time completely consumed and thus, morphologically
as well as physiologically, completely gives up its peculiar
character. Figures 54 and 55 demonstrate this for a few galls.
In the piece of an elm branch shown in the first figure, the leaf
at the left has been causéd to form an enormous, pale green pouch
by Schizoneura lanuginosa, but has not been taken up as a whole,
The form of the leaf has been kept pretty well and a large part
of it has not lost the possibility of performing its functions.
The same holds gtied in the galls shown in figure 58 and in many
others, ;

Figure 55 illustrates two different Cynipides galls, in
which buds of the oak have assumed a striking conical form (Cynips
polycera) or have been grown out into long spindle-like struc-
tures, (Cynips aries). The infected organs have thus lost their
normal form and function.

While, in the eases shown in figures 54 and 55 and in numer-
ous others, the new tissue formation assumes a definite, usually
very elastic form and definite size proportions are regularly re-
peated in the same kind of galls, there are Still other hyper-
plasias, intihe development of which - speaking figuratively -
nothing of this morphologic striving towards a goal can be rec-
ognized,- hyperplesias in which o11 specific formal character is

: ie4

Lacklig and whose period of growth has no definite limitation,
Examples of this second case are furnished by wound-tissue
Tungus-galis and others, ,

In studying the life-history of hyperplastic excrescences,

the ceil-division producing them will have to be tested first of

(135) all as to their direction, We will find extensive tissue excr:s-
vences, of which the cel. walls show a perfectly regular arrange-
ment. tn others a definite orientation ean be found only in the
Larst ceil-divisions, When considering galls, the difference
between ceil divisions parallel to the upper surface of the or-
gan, bearing the gall, and those perpendicular to it wils be
proved worthy of attention,

Further the tissue material, from which hyperplastic excres-
cences come, needs more exact testing from various points of view.
The excrescence may be traced either to meristematic tissue or
to permanent tissue, In the first case the direction of the di~
vision, characteristic of the meristematic cell under normal -'”
conditions, must be compared with that recognizable in norm1
tissue formation.

df the tissue excrescence arises from an organ or part of

an organ of which the tissues are already differentiated, the
further question arises as to whether all the different kinds of
tissues of a normal organ are equally adapted te the production
of abnormal tissues masses. It will be possible to determine
conformably in hyperplasias of different kinds that the cells of
the different tissues possess different degrees of capacity for
abnormal division; thus, for example, the epidermis remains con-
Siderably below the mesophyll and bark tissues in its produotive

power, |
(136) Pinally the histology of abnormal excrescences will have to
be studied. One of Our chief tasks therefore will be a compari-~

Son of structures of abnormal tissue with the normal ones of its
ground tissue, i, e. if deformations of the whole organs are e¢on-
cerned, to compare the structure of the organs deformed hyper-
plastically with that of the corresponding normal ones,

In all cases when judging of any tissue excrescence what-
ever, we will have to determine first of all, whether the abnor-
mal tissues resemble the normal, corresponding parts of the
plant, or whether they differ from them im any way, This ques-
tion is of fundamental significance for our anatomical consider-
ations; indeed, we will divide all hyperplestic tissues into hom-
coplastic and heteroplastic ones according to the answer found,
We will speak of an homooplasm if the cells produced in a tissue
execrescence resemble the selIs underlying them or adjacent to
them and of an heteroplasia if the abnormal excrescences are com-
posed of cells differing from the corresponding normal ones.

Heteroplastic excrescences are of especial histological in-
terest, As might have been expected from the beginning the aif-
ferences between normal tissue and the abnormal derivations, de-
viating from it in structure, are very diverse. For example,
there is often a striking difference in size between normal and
abnormal celis. The difference in tissue-differentiation, how-
ever, is of greater importance. In very many cases the product
ef the heteroplastic tissue formation is but little differentia-
ted. So far as the form of the separate cells and the differen-
tiation of the different tissue layers is concerned, we meet here
with primitive conditions simiiar to those found in hypoplasia,
In othér cases, extensive differentiation occurs in the tissue,
which,- corresponding to the character of the heteroplasias,~

125

differ from the normal and often exceed them in complexity.
Therefore, in all heteroplastic tissue formations, we will be
obliged*to prove what the nature of the difference is between
normal and abnormal tissue differentiation, If less differen-
tiated tissue is produced by abnormal cell-division we can,
wihhout regard to the abundant increase in cell numbers speak
Similarly of a degeneration in the tissue formation, as we did
above (p. 867) of a degeneration of the cell, which was combined
with great increase in volume, We will. speak here too of
Kataplasy and term Kataplasmas the products of kataplastic pro-
cesses+. If, on the other hand, new kinds of differentiation
processes make themselves felt in the formation of abnormal
excrescences, which are not known in the life history of cor-
responding normal tissues, we will speak of prosoplasia and
prosoplasmas, Further differences between kataplasmas and
prosoplasmas will be discussed later,

Kataplasmas will be exclusively involved in most of the
tissue forms, with which we shall be concerned when discussing
heteroplastic tissue. It will be shown that prosoplastic tis-

(137) sue formations may only be found among galls, but not that,
conversely, all galls belong by any means to prosoplasmas, just
as this very extensive and varied group of abnormal tissue for-
mations is proved to be a homogeneous group, only etiologically
and not histologically.

As was done in the preceding chapters, we will here base
the division of our material upon etiological and histological
characteristics:

Group 1, Homooplasia., The abnormal tissue is composed
of the same elements as the original one,

Group 2, Heteroplasia, The abnormal tissue is composed
of other elements than is the original one, Those
heteroplastic products come under consideration as
the most important, which sre produced after injury
(callus-formations}, and those, which are caused by
parasites (gali-formations),

Before we pass to the detailed discussion of different hy-
perplastic tissues, we must emphasize the fact that division
not infrequently takes place in plant cells, which we must term
abnormal although no hyperplastic tissues whatever are produced
by it, The variation from the normal may consist in the abnor-
mal direction of the newly formed cross-walls, or in the forma-
tion of the new cross-wali at a "wrong place", so to speak,
while keeping to the direction, so that the normal size propor-
tions of the daughter cells are not produced, Of course, onjy
those abnormal cell-divisions belong in hyperplasias, by which
the cell-number produced, is abnormally Brge for the tissue
or organ concerned, Since no opportunity will arise later for
returning to abnormal processes of the first kind of cell-~di-
vision, a few examples may be mentioned here.

Cell-division in abnormal directions may be studied espe-
cially easily in those organisms or organs, in the normal cell-
division of which, one definite direction is constantly repeated,
Raciborski© observed on Basidiobolus ranarum that, by increased
concentration of the nutrient solution, the direction of the

® Reciborski, Ueb. a, Einfl. duss. Beding, auf. a, Wachs-
tumsweise des Basidiobolus ranarum. Flora, 1896, Bd. LXXXII,
Pe 113.

126

cross-walls is displaced more and more until it finally can
occur at right angles to the normal direction. Schostakowitch
observed similar phenomena, He found that Dematium pullulans
cgn be developed in the form of small tissue bodies by the ac-
tion of a higher temperature, Figure 56 shows a thread of

(138) Hormidium nitens of which cells pave been, irrégularly divided
under the influence of Congo Reda“, Kny's° investigations throw
light upon ‘the influence of mechanical pressure and strain on
the direction of cell-walls.

Miehe4 observed cross-walls which are not formed at the
piace where they would appear under normal conditions, As has
been known since Strasburger, the mother-cells of the stomata
in the leaves of rany monocotyledons are produced on the apical
end of the dividing epidermal cell. By different kinds of 6x-
g imental interference Miehe has succeeded in reversing this
polarity" in such a way that the mother cells of the stomata
are cut off on the basal end. Klebs (loc, cit) observed un-
equal cell-division in Oedogonium etc,

A. HOMUOPLASTIC TISSUE

We will term homooplgsia each abnormal tissue for mation,
which is produced by an increase of the normal elements, It
Should be noted here, that "homooplasia", in, our sense of the
word, is not present in every increase of the normal elements
nor in every abnorm@l increase in volume of any ergan whatever,
Through the eutting back of growing shoots, it is possible in
many plants to produce especially large leaves on the stump of:
the shoot. ILuxuriant nutrition leads often to the same result,
as demonstrated by the side leaves of many root sprouts which
have developed similarly to foliage leaves, Further, side 1
leaves may be brought to abnormally juxurient development by
the yemoval of the foliage leaves which belong there, as shown
by Gobel. Now, since abnormally large leaves of this kind are
composed of cells approximatsiy as large as those in the small
normal ones, the large organs must without question be produced
vy an overproduction of normal cells. It is clear, however,
that abnormal formations of this kind can not be the object of
our anatomical consideration, since, in the cases cited and in
analogous ones, anatomical variations from the normal are not
necessarily connected with the increase in volume, The abnor-~-
mally large leaf shows the same anatomical structure as does the

erm

: Klebs, Beding. d, Fortpfl. bei einigen Algenpilzen, Jena
1896, p. 338. Congo red often exerts an arresting influence on
the longitudinal growth of the membrane, Klebs therefore as-
sumes that the cells treated with coloring matter only swell
out like balls, but cannot be elongated, "the further result of
this spherical form is, that, in the capacity for division, at
fifst not arrested, new walls are laid on to the old cell wall,
according to the principle of the least possible surface, and
divide the content of the ball, independent of the longitudinal
direction of the thread". For oblique division in Oedogonium
compare the same author, loc. cit. ny 288.

S xny, Ueb, a, Einfl. v. Druck u. Zug auf a, Richtung der
Scoheidewand in sich teilenden Pflanzenzellen, Pringsheim's
Jahrb. f. wiss, Bot., 1901, Bd, XXXVII, p. 55, Further litere-
ture references there,

4 ved. Wanderungen ad, pflanzl., Zellkerns, Flora, 1901
Bad. UXXXVIII, p. 105,

(140)

127

small normal one. Homooplasiea is opposed to the phenomena of
the giant growth here described in so far that its products ae-
cording to the definition always bear the character of abnormal
tissue--formations. The latter will be the case, if the over-
production of the normal elements occurs only in narrowly limi-
ted places, or if only one of the tissue forms, or scattered
forms, composing, a leaf, a stalk, etc., are developed in ab-
normal abundance”.

From the gutset it must be noted that here, just as in the
other groups which we have set up, no absolutely sharp demarca-
tion can be drawn and that abnormal formations are not lacking,
which furnish at the same time a transition from the phenomena
of giant growth, the study of which is the task of morpholo-
gists, to homooplasias, which will be reported more closely
in the following.

1. Localized tissue excrescences of an homooplasticchar-
acter, composed of the same histological elements as the orig-
inal, are rare. A cross-section through a sugar beet (Beta
vulgaris) is reproduced here, which continued its growth in

ickness @bnormally even in the second year, thereby develop-
ing several ridge-like tissue excrescences extending longitud-
inally. These extensive ridges are composed of normal layers
of tissue, In figure 57, the concentric normal cambial rings
are indicated in the center as well as those newly produced in
the ridges. In a case closely investigated by de Vries® the
formation of new cambial rings outside the latest ones of the
first year, coincided with an arrestment of activity. The
rings of the first year as well as the accessory ones of the
second year were also only slightly lignified. The causes of
the excrescences lie supposedly in an abnormally increased sup-
plying of material.

Similarly the tissue excrescences, occurring on the leaves
of Aristolochia Sipho and others, have been known for a long
time. On the under side of the leaf blade, along the ribs,
wing-like ridges, no thicker than the leaf, are produced, which
like the normal leaf-blades are composed of epidermis and meso~
phyll and are traversed by vascular bundles. The question as

-— — ew oe ee eS elle le =~ om tlle ll mele eee

1 Virchow, (Cellularpathologie) uses the word hypermetry
in a Similar sense.

w

® Ueber abnormale Entstehung sekundaret Gewebe, Prings-
heim's Jahrb. f. wiss., Bot., 1891, Bd. XXII, p. 45. There also
statements on some of the tissue forms subsequently discussed
by us and on the results of the "lengthened pam ta ea
Further Rimpau, Des Aufschiessen der Runkelruben, Landwirtsch,
Jahrb., 1876, Bd. V, p. 43.,, Briem, Strohmer and Stift, Wurzel-
kropfbildung bei d, Zuckerrube. Oest,-Ung. 2tschr. f, Zuckerin-
distrie etc., compere also Ztsehr, f. Pfl.-Krankh,, 1892, Bd.,
II, p. 239, . Caspary observed on Brassica Napug (Eine Wrucke
mit Laubsprosgen aus knolligem Wurzelausschlag. Schriften Phys.-
Oeken. Ges. Konigsberg, 1873, p. 109), tuber-like swellings upon
which were buds and which could @evelop bunched shoots with
malformed leaves, The disease is hereditary as Caspary has
shown. (Nvpels described swellings on Beta of apparently vary-
ing structure. Notes pathologiques, C. R, Soc. Bot. Belgique,
1857, 7, ZXCVI, p. 183. Therein citations of literature regert-
ing paresitic svellings of a similar kind.

(141)

‘ 128

to the conditions under which they cre produced? has not been
answered satisfactorily and would renay experimentation. Sim-
ilar formations of ridges are already known in other plants;

in the case of more vigorous development, they furnish a trans-
ition up to a duplication of the blade,

Hottas® produced experimentally on the roots of Vicia Fabre,
similar formations of lesser extent and simpler compoSition, if
these roots were put in plaster casts, so that only little holes
here and there above the tip made possible eny further disten-
Sion; these holes were filled by "correlative" growth in thick-
ness of the roots, The form of the homooplastic excrescenees
corresponded to the form of the space at its disposal, It is
possible in cases of this kind to speak of correlation-homoo-
plasia, (see below),

Because of their external similarity to those above men-
tioned, the peculiar gbngrmel tissue excrescences may be men-
tioned here, which Namec” observed on the roots of Cardamine
amaru, They are produced exogenously and are connected with
the central bundle of the mother-organ by a procambial cord,
without, according to Nemec, its leading in them to the forma-
tion of a true vascular bundle, Sometimes they bear root-hairs.
Similar pathological structures occur also on the roots of
Rordpa, The conditions, with the fulfillment of which their
formation is connected, are not yet known exactly,

II. The homdoplasias named in the following are character-
ized by the fact that only single tissue forms of an organ are
super-abundantly developed and no production of local excrescen~
ces, by which means the histology of the organ is altered. In-
deed each tissue form can, under certain circumstances, under-
go a homooplastic formation, :

1. A group well characterized physiologically is shown in
those forms, in which the abnormally abundant formation of tissue
is caused by some increased demand made upon it. Tissue foyma-
tions of this kind which we will term work, or activity homoo-

lasias, (or hyperplasias), have long been known to physicians,
iaecies of which more and more is required become enlarged, ap-
parently by increase of their elements; es are also blood ves-
sels upon which especially strong strain is put, after stoppage
of other blood vessels, and the like,

We must make investigations to leern if plants are also
capable of forming o ctivity-homooplasias,

‘yvidges, Literature on these and similar structures is to be

found cited in Sorauer, Handb. d. Pflanzenkrankh., 2. Aufl., Bd.
1, p» 239. Investigations made by Magnus (Sitzungsber. Prov.
Brandenburg, 1877, Bd. XIX) show that with tissue excrescences
may be united also phenomena of arrestment in the adjacent parts
of leaves (Arrestment in the development in size of single meso~
phyll cells, scanty development of chlorophyll, and the like),

In the cases which I investigated, the latter were always missing:

“ veb. d. Hinfl, v. Druckwirkungen ouf d. Wurzel von Vicie
Faba. Dissertation Bonn, 1901. :

3 Ueber schuppenformige Bildungen an a, Wurseln v. Carda-
mine amara, Sitzungsber, Kgl. bohm, Ges. Wiss,, 1901, WN. Vi,

(142)

c 129

In the first place, mechanical tissues as well as fibro-~
vasvulay ones deserve our attention, because they seem better
fitted than other kinds of tissue for experimental action
through increased demand upon them, Hegler was the first to
attempt to onuse the formation of mechanical tissue by incteased
mechanical demand”, The result of his investigations are the
following: the working power of plant organs is favored by me-
chanical strain since the mechanical elements are then more
abundantly formed than under normal conditions. Further, ace
cording to Hegler, the production of mechanical elements can be
excited by mechanical strain even in those organs which normally
develop none, I have mentioned already that these statements
of Hegler, at least on the plant organs which he investigated -
petioles of Helleborus niger - are founded upon an erro#, since
these even in mormal individuals are not absolutely free from
mechanical elements, as he thought them to be,

In order to be able to furnish a clear picture of the al-
teration and strengthening of the mechanical tissues, I have
tried especially at different seasons of the year to influence
tissue formation in Helianthus seedlings by constantly effective
mechanical strain, - but unfortunately always in vain, so that
I cannot report upon the amount of strengthening which the me-
chanical elements undergo according to Hegler. A thorough test-
ing - the supplementing and correction - of his statements would
be most desirable, and would undoubtedly lead to interesting
conclusions, I wish, at this opportunity, to refer to the fact
that increase in the trachae capacity of any plant part whatever
can be produced in other ways then by increase of the mechanical
¢lements alone or a better formtion of the separate ones, As
is well knowh, mechanical demand upon the strained plant bogy
can change essentially the conditions of cohesion within it’,

It does not seem impossible, that mechanical demand can also mod-
ify the specific conditions of cohesion, in the cellulose wall,
in the sense of an increase in mechanical effectiveness.

Wiedersheim* has recently investigated this thoroughly, He
let a heavy weight (as much as 1.2kg,) act for months on branches
of different species of weeping trees and compared the formation
of the mechanical tissue in the strained and unstrained branches,

an increase of the stereids be proved in the strained branches.
1 pfeffer, Untersuch, R. Wegler'’s ub, a, Hinfl. v. 2ug-
kraften aut, die Pestigkeit und die Ausbildung mechan, Gew, in
Pfl, Ber/ Sachs, Ges, Wiss,,1891, p. 638.
® Beitr. z. Anat, d. Gallen Flora, 1900, Bd.LXXXVII, p. 117.

5 Compare for instance, Villari, Ueb, 4. Elasticitat 4. Kaut-
schuks, Poggendorf's Annalen d. Phys, u. Chemie, 1871, Bad.CXLIII.

4 veh, a. Einfl. a. Belastung auf die Ausbildung v. Holz-
und Bastkorper bei Trauerbaumen. Pringsheim's Jahrb. f. wiss,
Bot., 1902, Bd. XKXVIII, p. 41.

5 the stone cells do not participate in the strengthening éf

_the mechanical tissues, "We found stone cells formed in the same

way in the laden as in unladen branches of Fraxinus, Fagus, Cor-
ylus (Widerscheim)", I' cannot find in the negative results of
the attempt to incite an increase of stone cells, any proof that,
as Wiedersheim assumes, these cells possess no mechanical signi-
ficance at least over against tensile strength.

(143)

2 130

Hanging gourd fruits, which develop more abundant mechani-
cal tissue in their stalks than do the varieties which lie upon
the grovind, and the like have made it seem probable that an in-
crease of mechanical tissue can be called forth by increased me-
chanical demand upon it. Wiedersheim's experiments have fur-_
nished exact proof of this, Future research will have to deter-
mine whether the tissues of different plant organs are equally
suited for the formation of activity-hyperplasias, whether fur-
ther only a few varieties are capable of it and whether finally
by means of special conditions the organs, of which much is re-
quired, can possibly be made capable of an abundant development
of their mechanical tissues, ¢

4 contribution on the last named case may be given here.
Kochting* reported recently on experiments with stalks of
Brassica oleracea var, sabada (savoy) which were placed horizon-
tally and strained at the tip by means of hanging weights. On
the upperside of the branch, under. the influence of the mechan-
ical requirement, an activity-hvperplasia was produced by @bnor-
mally lively growth in thickness, In the present case ohly one
side of the object under experimentation was taxed by the ~
strain, - it would be conceivable that the very inequality of
the conditions under which the different parts of an axis develop
favors the production of an activity-hyperplasia,

t

Vochting's researches have shown savoy to be a plant in
which hyperplastic tissue changes occur on the side strained by
bending, Future research will certainly make known other ob-
jects, in which the side taxed by the pressure reacts in the same
way to the mechanical demand made upon it. In my opinion the
formation of the red wood (bois rouge} of spruce and hemlock
trunks favors this, This modification of the strengthening tis-
sue, characterized by a red-brown coloration shays broader annual
rings, richer in cells, than does the normal wood, It consists
chiefly or exclusively of thick walled tracheids, which are some-
what shorter than the normal ones, often leaving perceptible in-
tercellular spaces between them and conspicuous because of the
spiral structure of their thickening layers, Hartig saw redwood
regularly produced on the underside of horizontal branches and
further in tree trunks on the side opposite the one exposed to
the wind, when they were especially exposed to its action be~+
cause of their position in the open, in short, in those places
which were especially strongly taxed by mechanical pressure. In
regions in which westerly wipds prevail, the Potnont Side is al-
ways the one facing the East”,

fr 1 Zur experimentellen Anatomie, Nachr. K. Ges. Wiss.,
Gottingen, 1902, Heft 5.

-2 as the most importent literature on redwood, compare
Hartig, R., Das Rotholz der Fichte, Forstl.-Naturw, Zeitschr,,
1896, Bd. V, p. 96; further Holzuntersuchungen, Altes und Neves,
1901, Compare also Mer, De la formation du bois rouge ‘dans le
sapin et 1fEpicéa. C, R, Acad, Se, Pgris, 18687, T. CIV, p. 376.
Cieslar, Das Rotholz der Fichte, Cbl. ges Forstwesen, 1896, p,.
149, Anderson, Ueb, abnorme Bildung Vv. Harzbehaltern und andere
zugleich auftretende anat, Verand, im Holz erkrankter Coniferen,
Forstl,-Naturwiss, Zeitschr,, 1896, Bd. V, p. 439. Observations
on the influence of the wind on the unequal increase in thick-
ness of trees extend back as far as Knight (1803), according to
whose statements, the annual rings on the sides taxed mechani-
cally (by bending) are broader thay on the others, Compare fur-
ther Busgen: Bau u. Leben d. Walgbaume, Jena, 1897, p. 67, ard
the literature there cited. :

(144)

131

The branches of conifers are known to be constructed
hyponagtically, i, ©., excentrically, in such a way, that the
horizontal underside of the branches is more strongly developed
than is the upperside. I would like conjeoturally to call at-
tention to a connection between the excentric growth in thick:
ness of normal parts of-trees and the tendency toward (one-
sided) avtivity-hyperplasia under abnormal conditions, If in
conifers, the horizontal branches of which are developed more
strongly on the underside,- the one taxed by pressure,- than
on the upper side, it can be proved that the trunks also are
developed hyperplastically on the side espeoially taxed by the
pressure under abnormal conditions, then it may be conjectured -
that among plants provided with opinestig branches, whose bran-
ches therefore are more strongly developed on the side of the
strain we may search for such as will, under experimentel mot+
ification of the mechanical requirement, develop 6 reinforce-
ment of the side strained, Trees with diplonastioally construc-~
ted branches will possibly be able to react in the same way to
the strain and pressure, due to a bending of their trunks, by
reinforcing their tissues, It would be very deSirvable if, in
connection with our knowledge concerning the formation of red
wood, corresponding experiments could be made on deciduous
trees and if some one would prove the influence upon growth in
thickness caused by a bending continuea over several years.

Besides mechanical tissues, vascular tissues also have an
especial interest for us,

In order to increase the eff&ctiveness of vasenlar bun;
dles, which under normal ¢onditions - to conclude from their
extent, provide only for the transfer of modérate amounts, I
cut through the mid ribs of young leaves of numerous dicotyle-
dons which are pinnately ribbed leareess fig. 58) in the expeo-
tation that possibly the anastomoses well adapted for taking
over the water connection between the upper and lower halves,
(fig. 58a), would undergo a more vigorous formation than under
normal conditions, The expected did not take place, In most
cases the side ribs and their anastomoses are not capable of
compensating for the intersected midribs nor of providing suf-
ficiently for the upper half of the leaf. This either perishes
entirely, or becomes discolored, or the leaf-development pro-
gresses abnormally, since leaves with disproportionately wide
bases and stunted, tips are formed (Populus pyramidalis), How-
ever, @ more luxuriant development of the side ribs as mbar fa
hyperplasia never took place in the plants which I investigated”.

Further, I made girdling experiments with plants character-
ized by medullary phloem bundles (Eucalyptus, Nerium) but I
could not prove that in girdled branches the latter had under-

1 In spite of the, at present, negative results, perhaps
a continuation of similar experiments might not be undesirabdle.-~
At any rate, nature itself often makes experiments which, agree-
ing with what has just been described, prove that after removal
of definite conducting paths, any provision on the part of the
adjacent ribs and anastomoses does not take place. In leaves of
the beach the holmet«like galls of Hormomyia fagi (compare fig.
58) which are produeed on the side or midribs are aften found
very abundantly. The part of the blade provided for by the rib
bearing the gall always bleaches very noticeably above the gall.
If the gall is on 4 side rib, bleached stripes are produced; if
on the main rib, a pale green, rhomboidal field is produced at
the tip of the leaf,~ a proof that the intact adjacent ribs and
anastomoses are not in condition to provide shfficiently for tho
areas lying above the gall.

(145)

132

gone an especially strong development, or had become fitted to
replace the lost peripheral phloem bundles*.
a

The observations of deVries and Véchting furnish valuable
conclusions. DeVries (loc, cit.) describes a peculiarly abnor-
mal potato tuber, from which three well-leaved sprouts were pro-
duced, which, however, lacked stolons, MTwo other eyes of the
mother tuber, however, produced stolons without the requisite
leaf-shoots, "The nutritive substances formed in the leaves did’
not find on the bark of the stalk the usual place of deposition,
and were used successfully only in those tubers which bore sto-
lons. Apparently for this purpose they hod to transverse the
old tuber”, The vessels here mide use of had undergone a strik-
ingly vigorous development:+ "but had not attained to the form-
tion of a continuous woody-layer, although several bundles had
united into groups, Each single bundle, however, had been devel-
oped to a degree not otherwise attained in potatoes,-- The wood
consisted of wood-fibres and ducts arranged in rows, which usu-
ally showed a very distinct reticulated w3ll-formation. The
phloem bundles showed a corresponding development, but did not
noticeably differ in structure from the primary phloem", This
description by deVries does not decide the question whether an
activity-hyperplasia is actually present in the hvperplastic
vascular bundles which he observed, or not; i. e., whether in-
creased demand has caused the abnormal development of the vas-
cular tissues, or whether probably some other reasons, unknown
to us, have caused the abundant formation of their vascular
bundles before the sprouting of the tubers, Occasionally even
in ungerminated tubers one happens upon powerfully develaped
bundles or groups of bundles, which only with difficu]ty may
be proved to be activity-hyperplasias,

Voehting's” experiments furnish supplementary data, since
they prove.that by means of a definite kind of experimental in-
terference, .hyperplustically ddveloped vascular bundles may ac-
tually be produced... He succeeded. in interpolating the potato
tuber as an element in the potato plants grown from it. The
tubers were planted upright in the ground, to half their depth,
and either developed leaved shoots above the ground and stolons
with abundant roots below it, on which new tubers were formed,
or thé parts above ground were caused to form roots, by suit-
able expedients; the formetion of stolons, however, was possible
only. on the parts under the ground. In the latter case the cur-
rent of the assimilate flowed through the tuber to the newly
formed stolons and daughter tubers; in the former the current
of water flowing from the root-bearing stolons to the leaf-
shoots traversed the old tuber the length of life of which was
in both cases appreciably increased; The anatomical changes
in the vascular bundles of the tubers correspond in #1]. essen-
tials to deVries’ discoveries, Like the potato tubers those of
Oxalis crassicaulis may be interpolated in the main stock of
the newly produced plant.

Vochting assumes thet, in the abnormally constructed tubers
which he investigated, the current of water and of nutritive
Substances caused the increase of the vascular elements, that
further the increased mechanical demand also caused the increase

® veber die Bildung der Knolign, Bibl. Bot., 1887, Heft 4,
ps. ll ff. Zur Phys. der Knollengewachse, Pringsheim's Jahrb,
f. wiss, Bot., 1900, Bd. XXXIV, p. 15 ff.

—ww

of the mechanical elements,- the tubers interpt: ated in the main
stock of the plants had to carry the weight of whe parts of the
plant above ground, Accordingly, the tissue-formations here do-
scribed would have to be added to the list of activity hypér-
lasias, This explanation is undoubtedly very interesting, yet,
it Seems to me that still other possible explanations should

(146) come under consideration here. The peculiar method of experi-
mentation lengthened the life period of the potato tubdr,-al-
ready emptied,- far beyond the normel one, so thet a demnnc was
made upon the different tissues of the tuber for a very much
longer time than under normal conditions, Evidently continued
demand does not of itself mean the same as increcsed demand, Lt
might well be possible that even "continued” demand is enough
under certain ciroumstances to inclfe the abnormal formntion af
secondary tissue, as observed by "Vochting,

I would jike here to call attention again to the experi-
ments of Meer* who found leaves cut from Hedera helix forming
roots and living for years, Secondary tissues were formed in
the petioles by which the vescular bundles originally separated
were united into a cord of tissue, It is absolutely not pro-
bable that the new formation of @uots ete. is here to be traced
to an increase of the use of water, eto, To me the supposition
seems better founded, that the continued demand made upon cer-'
tain tissues, as a result of an abnormally long period of life,
caused their hyperplastic formation. Yet do we not find that
many perennial plants in the normal development of their parts
under ground increase regularly, by cambial activity, their.
tracheal and mechanical tissues, corresponding to a "continued"
demand made upon them, although the extent of the shoots devel-
oped yearly by them and the functional demand made upon them
by these remain approximately equal”.

In Vochting's experiments, the conditions are in so far
the same that tissues determined by them were kept alive longer
than is usually the case under normal conditions, Here also a
"continued demand" is made, with which there is also connected
an "increased demans", The conditions are therefore extraor-
Ginarily complicated, It will not be easy to decide whether the
reinforcement of tissnes observed by Véchting in Solanus tuber-
osum, etc. are to be put on an equal footing with those des-
Cribeé by Mer or whether the "increased" demand was the deter-
mining factor of their production.

Conditions are much Simpler when it is possible te bring
about an abnormally abundant formation of vascular bundles in
organs without lengthening the period of their life beyond the
normal, Vochting made experiments of this kind on dahlia tubers.
These were planted in an upright position and, in spite of the
unusual conditions, they rooted well, developing shoots in which
a part of the stem was replaced to some extent by a piece of the
root, Tubers, forced in this way to a greater mechanical work
and through whose vascular bundles the whole amount of water

mew meme ttm mt more
s

1 Bull, Soo, Bot. France, 1879, Bd. XXVI, p. 18.

2 Increase of the tracheal and eventually also of the me-
chanical elements, as a result of continued (not increased) re-
quirements, will occur probably also in those one-year 014 plants,
whose shoots, used as stock, below the scion become two or several
years old. (Compare Lindemuth, Das Verhalten durch Kopulation
verbundener Pflanzenarten. Ber, d. D. Hot. Ges,, 1901, Bd. XIX,

p. 515). Unfortunately no suitable material has been accessible
for me to test this question,

(147)

(148)

134

necessary for the shoot was conveyed, contained abundant ducts
ani libriform fivres and thick-walled, pitted wood parenchyma
wells, A comparison with equally old "normal" root tubers de-
monstrates that in this present case "continued" demand can not
have incited the abnormal formation of tissue. In the abnor-
mally developed dahlics which Vochting described there clearly
exists ‘an effect of “increused" demand upon the tissues ~ an
activity-hyperpiasia,

Simibaz compiieations, making more difficult an under-
standing of the 2ffective factors, may be found in many galls,
If these are produced on petioles, the vascular tissue below
them in the stem is often inoreased., In our native oaks var-
ious cynipides, most frequently Spathegaster baccarum, cause
large, round goils on the staminate inflorescences, The axes
bearing the galls not only live longer than normal ones, but
are also distinguished by a secondary coalescence of their vas-
eular tissue. The assumption that the increased mechanical de-
mand and increased supply of materials and water have given
rise to the described changes in tissue, is especially clear
here; nevertheless, the possibility exists that the same secon-
dary tissues would be found also if, in some other way and with
out a simultaneous increased functioning of the tissues con-
cerned, it were possible to lengthen the life period of the
inflorescence axes.

The histological structure of the abnormal tissues just
described, remands us that no sharp boundary may be drawn be-
tween homooplasias and heteroplasias. Holding more strictly to
the proposed principle of division we would have had to defor
many & hyperplasia discussed in this section to the next one,
As mentioned already the red wood, for example, does not con-
sist of entirely normal elements since its cells are somewhat
Shorter than normal ones. jn the vascular bundles developed in
abngrmal abundance, which Vochting studiéd, tracheids of short
eylindrical or barrel-like form occur, the libriform fibres are
rather short etc, The abnormal coalescence of the tissues is
therefore composed of elements which remain below the normal in
their size development, They show the same variations from the
normal cell structure that we shell find later coming into ef-
fect more strikingly in "kataplasmas",

On the other hand, Vochting proved that in the abnormally
fleveloped vascular bundles of Oxalis crassicaulis, elements
may be found in this tissue concrescence which are foreign to
the normal tuber. Besides wood parenchyma cella, libriform
fibres are also produced. In this case therefore the abnormal
tissue displays a more abundant differentiation than does the
corresponding normal one. We will find many differences of a
Similar kind in prosoplasmas,.

If, in spite of the degeribed structural differences, I
have included all under homooplasias, it was because the exist-
ing differences seemed too slight for me on their account to
have wished to disorganize a group, well characterized physi-
Ologically. We find, however, often in & normal development of
the vascular bundles, tracheal elements develop first of all,
and then, by continued growth, wood fibres and wood parenchyma
cells. .

2. We spegk of correlation-homooplasias when, as & result of
locally effective arrestment in growth, its logalized further-
ance takes place elsewhere, which leads to homooplastic changes

{149}

135

af tissue, Boirivant's? experiments on defoliated shoots are
very instructive, The assimilatory tissucs of the bark wer
increased “correlativoly" in the shoots, Recently K, Browne
has made similor experiments gnd proved in Aconitum Stoerkianun,
Syrineo vulgeris, Corvlus avellona vir, atropurpured, Rosé
ati rolin and others, an increrse of assimilctory tissue, the
number of iayors of which at times was doubled, In Lamium
orvelg nd others there was a striking increase of chlorophyll
grains”,

3, The abnormal tissves occurring on injured plant organs
are usunlly of an heteroplastie sharncter, I know of only one
oase of onllus homooplesic., Schilherszy* succeeded in stimules
ting on increase of tho vascular tissue in stalks of spe scopes
multifiorus through injury, This occurred beeause "the cell ;
groups, lying close to the phloem bundles, therefore, those ade
jecent to the innermost leyers of the parenohymetiec primary i
bark, beecme adjusted for division, after some preeeding tnjury,
(by on interruption of the veseular bundle cylinders, gloaine
upon one snother ldke rings), Thus they took the form of secon~
dery meristem," The newly produced meristematic zona sots Like
the eambinl, producing zylem end phloem, Figure 59 shows part
of & Orose-Section through a Pheseolus stalk, Outside the hard
bast bundle are visible the newly produced xylem and phloem,

We arrenged the material of our lest three sections from an
etiological point of view, but dn them surely have not named ald
the factors, hy which homooplaastia formations of tissue cen be
dneluded in any one of the three previously named groups, the
products of which, ar I suppose, might have shovm an homboplastie
character, In places on the laterelly compressed internodes, the
cells of the permanent tissue vere incited by the force of conm-
pression to a growth perpendicular to the direction of the prese
gure and also to repeated cell division,

Kny observed similar abnormal division under similar condi-

_ tions, in the pith of Bryophyllum ealyvcinum and Begonia”,

I know of,no positive case where, by the action of foyeign
organisms, homooplastic excrescenees of tissue - "gall-homoo-
plasias" «= would have been produced, In all galls produced by
abnoymal cell division, ve are concerned with heteroplestic tis~
sues, differing from the corresponding normal tissues in the
nature of the differentiation and the volume of the separate
elements,~ hen the fundamental tissues are simpler histologi-
cally, this may often be the only differenae.

Boirivant, Rech. 3, 1. erganes de remplacement chez i.
pl. Ann. Se. Nat, Bot., 1897, VIIZ, Ser., 7. VI, p. 307.

e Ueber Verand, {m Gewehe entlaubter Steng) u. Zweige.
Dissertation Erlangen, 1899.

5 one may conclude upon 2 correlation-effect in the abune
dant formation of trichomes on the inflorescence stalks of Rhus
Cotinus, whose bloom has not been fertilized, Indeed this Fors
ation of tissue should not be designated as “abnormal”,

F # xbnst ich hervorgerufene Bildung sekunddrer (extrafasci-
cularer) Gefassbundel bei Dikotyledonen, Ber, 4, D. Bot. Ges,
1892, Ba. X, po 424,

5 Ugb, 4d, Einfl. v, Zug, u. Druck auf 4, Richtung a,
Scheidewande in sich teilenden Pflanzenzellen. Pringsheim's
Jahrb, flr wiss, Bet. 1901, Bd. XXXVII, p. 55,

(150)

B. HETEROPLASTIC TISSUES 136

Wg term heteropiasia each quantitative increase of an
organ, in which, by abnormal cell division, tissues are pro-
duced, the single elements of which do not resemble normal
ones, Thereby either whole orguns, leaves, shoots, etc,- are
transformed, or only parts of them, so that new tissue for ma-
tions rest Like an appendage upon the mother organ,

If the tissue of the heteroplastically changed organs amd
parts of organs be sompared with corresponding normel tissues,
differences wii] be found in more than one sonnection; the ab-
normai tissues vary from uormai ones in regard to size of the
Singie elements, us welki as to the degree and kind of differ-
entiation.

So far as the size of the single eell is concerned, it is
easy to assume that &bnormal increase of the cell numbers takes
place at the expense of the cell size, in such a way that single
elements of heteropjastic tissues do not attain their normal
Size. In fact, relations of this kind seem to exist in many
cases, Hartig~ observed that broad, many-celled annual rings,
consist of smaller (shorter) cells than'do the inner ones with
fewer oells. The callus, produeed by abundant cell division
after injury to living plent tissue, is composed at times of
smaller cells than those of the ground tissue, etc. We shall
not venture to attribute especial significance to this connec~
tion between cell number and cell size; in a very large number
of cases the abnormal tissue is composed of larger cells, often
aa Mery much larger, than the normal tissue of the ground

issue,

Much more important are those differences, which make evi-
dent the differentiation of tissue in normal and in abnormal
parts, AS shown above, we Shall be concerned with some tissues,
which ar@ more simply constructed than the corresponding normal
tissues and with ators in whichwe may recognize processes of
differentiation in the formation of their single cells and the
distribution of their different elements; which processes of
differentiation, however, are not manifest in the development
of the: corresponding normal tissue, We will term heteroplastic
tissues of the first kind kataplasmag, those of the second
presoplasmas.

Kataplasmas and prosoplasmas are not only distinguishable
on the basis of an histological consideration, but are charac~
terized also as independent groups by their external form.
Kataplasmas show no constant proportion of size and form, the
same abnormal tissues occur now as deformations of the whole
organs, now as localized excrescences, In prosoplasmas, how-
ever, we find the "diseased appearance” always characterized
by the definite size and form of the tissue excrescences; forms
conspicuous because of & high, ever recurring organization, are
not at all rare, The difference in form is connected most
closely with the developmental period of the heteroplastic tis-
sues, We find many kataplasmas Of Which the developmental per-
iod vacillates within very wide boundaries, in many cases we

Speak of it as (theoretically) unlimited, In prosoplasmas,

however, the duration of the development of each single form
may be most exactly determined as to weeks and months. ‘The .
differences ,named, for their part, may be explained, at least
in a measure, by theetiolcgy of the various abnormal tissues,

which are partly caused by long persistent or permanent stimuli,

partly by stimuli of a short duration constantly effective.

ee | i ee ee

1 Holauntersuchungen, Altes and Neues, 1901.

: 137

Besides histology, we will have to trke etiolo -
pecially into consideration in the detailed deconiption of the
aifferent heteroplastic tissues and in the subdivision of our
material. In this we shall be able, repeatedly to mke the

,

same groups as in the treatment homooplastie tissues,

4otivity-heteroplasias of course will not be described,
All hyperplasias have boon disposed of above which are pro-
duced by a greater cmount of action anda indicate a relation to

heteroplesics through their slight histological vari
from normally constructed tissues; Eeeyson

Qorrelation-heteroplasias, produced after local arrestment
of growth, wiIT need at Least c short chapter,

Callus-heteroplesiss (in the widest sense of the word) i.
6, all those heteroplastic tissues thich are produced by wound -
(151) stimuli,are,vory diverse chd demand thorough discussion. We
will have to describe in order the undifferentiated, homogene-
ous wound tissue or the callus (s, str,), the wound tissue re-
anil aad pods the wound-wood, ond that resembling cork, -
wound~cork,

4&4 new group must be taken into consideration here, for
which no andlogy exists among homooplasies, that is the gall-
heteroplusias produced hy forevigh organisms, the multiplicity
oF which 6€xcécds that of all other tissues disclosed by the
study of pathological plant anatomy.

There are various other heteroplasias - and doubtless fu-
ture investigation will disclose still further forms - which
may not be included in any one of the above named groups, based
upon etiological considerations, Since we have learned nothing
as yet of the causes of their production, I have set aside no
separate chapter for them, but have discussed them in connec-
tion with those of the above named tissues, with whieh they
best correspond histologically,

If we now ask, which role the kataplastic and prosoplas-~
tic processes of differentiation play in the groups just dis-
tinguished, the following becomes evident, The corrolation-
heteroplasics so far as yet known have the histological charac-
ter of kataplasmis, The same is true ofcallus, wound-wood and
woundscork, Among galis, we find kataplasmas and prosoplasmas
which we shall hove to discuss separately.

An equal considerction of the histology and etiology re-
sults in the following subdiwision of the material;
1. Correlation=heteroplasmas )
2, Calluses i
3, Wound-woo
4, Wound-cork )
5, Gaiis (

Xataplasmes

a, Kataplasmes
( b.« Prosoplasmas

l, Correlation-heteroplasmas

We speak of correlation-heteroplasmas if the normal growth
of any plant is arrested at its vegetative points by any factors
whatsiever, wherever under the ihfluence of the unused nutritive
materials, some part of the plant body is incited to abnormal
growth, to the production of abnormal tissue,

138

The simplest process by which we can arrest the normal
ercvthein plants consists in destroying one or all parts of
the vegetative tips of their shoots, If correlation-hetero-
plasmas are then produced, their formation results after the
injury to be sure, but not because of it, No doubt exists thet
the same heteroplasmas are also produced when the normal vege~
tative points continue to live, if these are kept from further
development, perhaps by being put into plaster casts, They my
a be associated thorefore with the callus formetions nemed

ater.

(152) Voohting_ has published valuable date on correlation-
heteroplesmas+,

. If tho inflorescences and all axillary buds were removed
from vigorous kohl-rebi plants (Bressica oleracea f. gongylodes)
the leaf cushions swelled gradually to extensive bodies, possi-~
bly to 2om. wide, which "had becn formed from the perenohyma of
the bark of the cushion end from the vesculer bundles running
through it, These were formed in an unusual way and had devel-
oped partly to round, vigorous bodies covered all over with
cambium. In the vascular parts, the tissue produced frbm the
Gambium consisted of thin walled elements, through which passed
rows of small ducts, The abnormal tissue was distinguished from
normal tissue by the absence of mechanical elements and the
narrowness of the lumine of the ducts,

In cutback Helicnthus plants cnalogous conditions my be
found, "here too a significant development of the parenchyma
and a retrogression of the mechanical elements is found in the
stalk," especially in the upper part of the stem, In the lower
part hollow celis are also produced after the operation but
these are shorter than normal ongs, On all sides a bending and
twisting 1s frequently found. Vochting found tuber-like swell-
ings produced on the roots of decepitated Helianthus plants.

In the aerial runners of Oxalis crassicaulis, which are
filled with reserve stuffs, aré robbed of their @pical celis and
all axillary embryonic sprout cells, heteroplastic dwellings are
produced by the swelling of the leaves and internodes, Accord-
ing to Vochting the cells of the fundamental tissue participate
in the new formation chiefly by enlargement; the vescular bun-
dles have fewer ducts than normal ones, but the sieve tubes are
richly developed and at times extensive parenchyme outgrowths
lie between xylem and phloem. Vochting at times observed bi-col-
lateral bundles in the abnormal tubers®, The development of col-
lenchyma was absent in the stan, which had become inflated to &
‘tuber, the mechanical eleménts usually accompanying vascular bun-
dles were few or entirely lacking. I will return later to the
noticeably large and irregularly formed starch grains, which
fill she"Yeaf tubers" in especially striking forms, (Chapter VI,I).

It seems possible that cells of a permanent tissue my also
be "correlatively" incited to growth and division,

1900, Bd. XXXIV, p
K, Gos, Wiss. Gottingen, 1902. Math.-naturw. Kl,, Heft 5.

2 Abnormal ¥Yascular bundles of the same kind'may be found
in many galls (prosoplasmas), see below chapter V, B, 5.

(153)

° 139

From the statements of Vochting here quoted, it is ob-
vious that the tissue excrescences which he observed should
be ascribed to kataplasmas.

Sachs! Was the first to produce correla tion-heteroplas-
mas experimentally. "If all vegetative sprout points be re-
moved from vigorously growing pumpkin plents (Cucurbite mixima) °
a very remarkable phenomenon occurs which is aS yet unexpifined,
the embryonic root Golls, present in the tissue of the stom
at the right and left of each petiole, grow out into short
stalked tubers as lerge es hazel or walnuts, in which the root’
cap disappears and the vegetative point becomes irrecognizable,
while the axillary fibro-vascular cord (the axillary evlinder
of the root) is resolvod into a cirele of isolated vasouler
bundles, separated by ground tissue which contains chlorophyll."
Sachs calls attention to the similarity between the norml
Structure of the axis cnd thet of the abnormal Cucurbita tuber;
I think thet no speoial conclusion maybe darewn from this 28
to the character of the new formation, ‘Thet roots my become

reen is c. wide-spread phenomenon, clready deseribeé above

pe 56), The other histological cherecteristics, distinguish~
“ng the tubers from normal roots, seem to me connected vith
the overproduction of undifferentiated parenchyma, recurring
in so many heteroplasmas,

Further investigations will show whether all plents can
at will be brought to the formation of correlation-heteroplas-
mas or whether those plants tend especielly to this kind of ex-
crescence which form parenchymetic, little differenticted tis-
sue-masses ("tubers") even im & normal course of development.
That the ability to develop correlation-heteroplasmas is not re~
stricted to tuberous plants is shown by the cases just disoussed.

C, Kraus” using Helianthus, attempted to influence the
processes of growth by removing the apices of the plants under
experimentation, According to him, wart-like petiole excres-
cences are formed on the stalks which have no inflorescences,
C, Kraus also makes dome statements concerning the anatomical
structure of the plants operated upon, In similar experiments
Wollny® found that the axillary buds were transformed into
tuber-like rolls,

It must be left undecided whether the "gnarled tubers",
occurring on various Eucalyptus species, are to be reckoned
among correlation-heteroplasmas., Some notes concerning these
may be found in section 3, which treats of wound-wood,

2, Callus

Leaving out of the question the products of the processes
of restitution, we have termed all cell and tissue forms, pro-
duced after and as a result of injury, callus formations in
the widest sense of the ward and have spoken of them repeated-
ly. In many plants and plant organs only a metaplastic change

1 Gesamm, Abhandl., Bd, II, p. 1172.

® ulinstl. Beeinfl. des spectt ieonen Bildungsganges von
Helianthus annuus durch Entblétterung WU. s. w. Forsch, Seb.
a. Agrikultur Physik, Bd, IV.

: Einfl. d. Entgipfelns der Pfl. ‘auf deren Entwickelung
und Produktionsvermogen. jJbid,, 1885, Bd. VIII, p. 107. *°

. 140

of the existing cells was incited by the injury (ccllus-met-
aplasia); in others the cells laid bare showed an abnorml
ante and were changed into voluminous vesicles and sacs
oxllus-hypertrophy), In the preceding section A, it wos

shown that even ¢n increase of the norm:l tissue can result
from wound stimuli (callus-homooplasia), Those cells are most

(154) abundent in which after injury a heberoplestic tissue is pro-
dueed by cell division (cnllus~heteroplasia),

In the majority of cases of exllus hypertrophy (see above
p. 92) it was proved that the resulting large cells rem ined
below the normal cells of corresponding tissues in internal
form.tion; the chlorophyll content being usually lost 4n hyper-
trophy. In rare cases the oceurrence of new characters was
associated with the abnormal growth (p. 95).

Similar conditions exist in heteroplasias incited by in-
jury. Excrescenees arise, which are composed of cells of the
simplest form, very little differentiated, and are distinguish-
ed by this means from the ground tissue. They are all chnrac-
terized therefore as kataplesms,

Kataplasmas, produced after injury, differ very greatly
among themselves, Either tissues resembling cork are produced,
termed wound-cork, or those similar to wood, called wound-wood,
or nearly homogeneous perenchyma masses which are composed
mostly of very thin walled, undifferentiated cells, often ab-
solutely irregulerly connected, We term tissue of the last
king simply callus, Also all plants and organs are not capable
of producing ALL three tissue forms after injury.

We will begin our description with the homogeneous, par-
enchymatic "callus",

We find representatives of very different plant groups
eapable of forming callus tissue; algae and fungi often form
it, the vascular cryptogams less often, The callus tissue of
the phanerogams is of great significance; gymnosperms, monocoty-
ledons and dicotyledons, herbaceous and woody plents may form it
after injury. We shall have to study especially thoroughly the
eallus tissues of higher plants,

First of 211 some examples my be given, from the list
of cryptogams.

Algae, at least the larger tissue-forming marine species,
form Tissue excrescences of Simple histology, besides the well-
known adventitious shoots, The tubercle-like callus in these
consists mostly of cells of one kind or of cambium and bark
layers with little evident difference, The cells are often
arranged in radial lines; at times they are somewhat larger than
the cells of the mother-foundation, fubercles of this kind oc. ur
in Fucus, Polyides, Dellesseria, etc. I found swellings in
Laminaria which grew out to the size of peas, possibly attrib-
utatle to injury. I consi ger it very possible that the tuber-

-@les, described by Schmitz*, which he traced to bacterial infeo-
tion, have been produced by injury and cicatrization and that

1 Kuster, Ueb. Vernarbungs -u, Prolifikationserscheinungen
bed Meeresalgen, Flora, 1899, Bd. LXXXVI, p. 143,

a eo

2 Ueb. knolichenartige Auswichse an 4, Sprossen einiger
Floriden, Bot, Ztg., 1892, Bd, lh, p. 624.

141

(155) the, bacteris wandered subsequently into the porous callus tis-
sue", The cells of the algae tissues when wounded are very fre-
quently stimulated to cell division without the formation of
extensive swellings, The cleatrization tissue farmed on the
"leaves" of Sargassum shows some correspondenee with the
ec.lius of higher plants,

Fungi clso form golluses, but, as it seems, less ensily
than aigce. Hennings* observed in xylaria 2 ball-like callus-
swelling on the stroma,

Among vasculer ory pte sens verious species of Selaginella
may easily Be brought to e formation of callus, The cells

of the perenchyma, filling the passage surrounding the vesou~,,
lar sheath, are inoited to abundant division by wound stimuli”.

Woody plants, especially among phanerogams, have been
studied often and thoroughly as to their formtion of callus.
If cuttings of rose, poplar or willow branches of any length
whatever are made and Ie ft undisturbed in moist adr end under
sufficiently high temperature, after © few days a ring-like tis-
sue excrescence is formed on the cambium on the cut surface. —
This enlarges rapidly, Spreads out like a roll on the out sur-
face and wnites eventudl ly with the same kind of new formation,
which grows out from the pith and bark, ‘These rools of tissue
have been known as gallus for a long time, This is true also of
their tissue construction as stated sbove, Sooner or Inter the
callus discontinues its growth and in many species produces new
vegetative points, - favorable outward conditions being taken
for granted, Thorough gnatomic studies were made especially by
frecul Cruger and Stoll. .

—_—
ee | Pr a

1 iso in the swellings observed by Barton (On'certain
galls in Furcellaria and Chondrus, J. of Bot,, 1901, Vol, XXxIx,
p. 49) a callus tissue mylke involved, which was produced through
the grazing of animals end is inhabited by them, (N. B, Barton's
statement that Florideae starch, occurring in the "galls" of
Furcellaria, is lacking in the norm tissues of the alga, 1s
based upon an error),

: Ueber Pilzabnormitaten, Hedwigic, 1901, Bd, XL, p. 136,

@ Molisch Zur Kenntn, 4. Thyllen nebst Beob, ub, Wundheil-
ung in d, Pfl, Sitzungsber, Akad, Wiss, Wien, 1688, Bd. xXeVII,
Abt. 1, p. 264,

: Mrécul, Reproduction du bois et de 1'écorge. Ann, Se.
Yat, Bot., Serie IJI, 1853, T. XIX, p. 157. ~- Oruger, Einiges
uber die Gewebeveranderungen bei der Fortpflanzung durch Steck~
linge, Bot, Ztg., 1860, Ba, XBIII, p. 369. - Stoll, Ueb, die
Bildujg des Callus bei Steck}ingen. Bot, Ztg., 1874, Bé, XXXII,
p. 737, ~ Rechingar, Unters ub. ad. Grenzen d. Teilbarkeit im
Pflanzenreich, Zool, ~ Bot, GeSs Wien, 1698, Bd. XLIII, p, 510.
Compare further the summarizing leports ‘by Sorauer (Handb, 4.
Pflangenkrankh,, 2, Aufl; Bd, I, p. 561, 658) and Frank (Krankh.
d, Pfl, 2, Auf. 1, Bd. 1, p. 63} as also the authars named in
later notes, The new work by Lockell (Die ersten Folgen d, Ver-
wunduhg ad, Stengels dikotyler Holzgew. u. Ss, f. Jahresber. 10.
Realschule Berlin, Ostern 1901) may boast of but Jittle cleare
ness,

(156)

Externcl form of the callus 142

The prominent eotivity of the cambium in enallus forme-
tion, determines the fact that the callus, at least in its
first stages, usuelly cppears in the form of = ring on the
cross section of the shoot. In cuttings of many plants, the
production of callus is relatively scanty, so that in them it
never passes beyond the stage of < flat, ring-l4iké roll, In
others, as Populus, Rosa, Crtealpe and many others, the oellus
continues tog row for a longer time, esvecianlly if the cuttings
are kept in moist sir, The fact that callus tissue never has
a specific form is also important, The luxuriant new forma-
tions, produces, for example, on cuttings of Populus pyremid-~
elis {compare fig, 60) assume very different forms, even when
allowed to devclop freely, and are covered with large and ©
smell protuberences, irregularly distributed, Besides this,
from the very beginning, the production of callus in miny ceases
does not take place equally strongly on oll parts of the cut
surface,- often indeed it m.yke entirely lecking in places,

The space conditions of the erllus often determine its form;
the callus messes fill out all splits in the wood of the ot-
ting, ete, Figure 605 shows a callus which was developed un-
der a glass plate, Since development in a longitudinal direo-
tion was.thus prevented, it spread out sidewise without being
distinguishable in any way from callus tissue which develops
undisturbed, The seme is true of the callus tissues of herba-
ceous plants, Figure 61-shows the callus from a stalk of
Lamium orvela, the plent which among herbaceous plents produces
the Largest cellus-robls of which I know, ‘The irvegular, wex-
yellow callus masses, as lerge as one centemeter which are pro-
duced on cuttings of Catalpa syringaoefolis dre very striking
and resemble coralloid branches cones,

In'rere cages the eallus eppears in the form of algae-Like
thrends, as Stoll for example has observed in Tradescantic. At
this point, I would like to mention the hair-like structures
found by Sorauer in the core of "woolly streaked" apples,
(loc, o4t, p. 296), which might possibly be attributed to in-
jury. (Compare fig. 68). Massart also (loc. cit. p. 56) ob-
served the same structures, I will return later to these.

The period of development of the callus varies with the
controlling external conditions and the nutritive condition
of the object under in¥eetigation.

Origin of the callus

4

‘Gallus tissue can be produced on all organs, on roots,
axes, and leaves, Yet all parts of all plents are not capa—
ble of forming it.

Further, ell living elements of exposed tissue can be
incited to growth and division through injury so far as their
membranes have note become lignified, and therefore incapable
of surface-growth. An exception to this is made by wood par-~
enchym: cells which, as seen cbove, are incited enly to growth
by wound stimuli, overlooking some very rare division, Usu-
ally in wounded orgens and isolated pieces of organs of any
definite plant species, only single tissue forms are caused
to form callus,

The productive pover of different kinds of tissue varies
grently. In those rore cases in which the epidermis gcts at
all it produces only very small amounts of tissue, The chief

(158).

143

amount of callus is produced by the cambium on pieces of stem
or stalk”. In meny cases indeed this is the only tissue
which js able to produce it. Next to the cambium, the prim-
ary and secondary bark tissues, as well as the pith, come un-
der consideration, which can also furnish considerable amounts
of tissue - often the activity of the bark is scarcely less
than that of the cambiun,

dhe formation of ca}jlus therefore furnishes proof that
@hrough injury, not only meristematic tissues, such as the
cambium, ban be brought to an increased and abnormil activity,
but the celis of the permanent tissue as well, such as bark
Aira, can be incited to extensive growth end abundant
vision,

Life history of the callus

The life history of the callus will have to be studied
separately in the various t issues producing calluses, As a
basis of our description, we will take first of all the phen-
omena observed oh cuttings of woody plants,

The important part played by the cambium in the callus
formation which has just been mentioned, has been thoroughly
investigated by Stoli (loc, cit.) with cuttings of Passiflora

uadrangularis, “After the lapse of 24 hours the Gross walls
ores SEaDIET cells, bordering the eut surface and previously
flat wt beoome curved outwafd,- when not cut to pieces. A
stretching parallel to the long’axis took place simultaneously
with this outward curving, and after 24 hours more, a division
over the cut surface by means of two or three cross walls", —
Further, “in the cambium a region of cells, capable of contin-+
ually forming others by tangential and cross-division, Ha

been differentiated over the cut surface, which formed. the
point 3 departure for all further growth from the cambium,

‘The celis lying below this point undertook no new division,

and were pushed away little by little toward the outsida”.

The investigations of Stell (loc. cit.), R. Hoffman” and
others, 88 well as my own, show that the cambial cells when
dividing after injury, are not restricted to the mode of norml
division but are capable of growth and division in every direc-
tion. It is certain therefore that the changed pressure condi-
tions are of great significance. On the other hand it is
Scarcely possible to explain by these alone the phenomena of
growth which follow injury’. The cell divisions leading to
the formation of callus are very regular in those woody plants
which form it quickly and abundantly. Therefore the processes
are in detail as follows,

If cuttings of Populus pyramidelis and others are pleced
in water and covered wth a fstt flass, so that the upper end

-— - ov
a i ee a a co!

i ‘i Hoffman, Rob, Unters, Ub, d, Wirkung mechanisch,
Krafte auf a, Teilung, Anordnung und Ausbildung d. Zellen u.s,
w. Dissertation Berlin, 1885, - Schumann, Dickenwachstum u.
Cambigm Dissertation Breslau, 1873. ;

: Compare R, Hoffman, loc, cit,

144

extends above the water into the moist air, division takes
place wery soon in the cambial cells near the upper wounded
surface”, ', They are divided by walls perpendicular to their
long axis, producing thereby short prismatic elements. ‘These,
for their part, divide in an extraordinarily lively mane r by
forming tengentiol walls, causing en abnormally intensive
growth in thickness of the cutting near the injury, although
‘the berk pressure remains unchanged even in these places, or
may actually increase as a result of the growth in thickness,

Pigure 62 shows a longitudinal section through the upper
end of © cutting made slantingly. <A powerful callus ring hes
been developed on its cut surface, The cambium has been in-
eited by the injury to extreordinarily ebundant cell division.
Not only directly on the cut surface, but even at a considerable
distence below it, on ebnormlly lively gorwth in thickness has
taken place, which nets most strongly at the cut surfcce, grad-
ually decreasing ‘toward the lower part, so that the cuttin
seems forced out to a club-like form at its upper end. With
Th, Hortig, we con term the wedge thus formed between xylem end
phloem the "Lohden Wedge", Above, on the out surface, the new-
ly produced tissue {C) is forced out in a ring-like roll.

(159) Anatomical investigation shows that, in the production of
the new structure, the cambiel cells have divided just os uncer
norm:1 conditions, The Lohden wedge consists of radial rows of
cells the developmentcl homogeneity of which maybe seen every~
where except in the upper cell layers ond the convex ring-like
roll. In this cell divisions may usually be seen in every pos-
sible direction but no longer with ony regulor arrangement in
rows, Sections through very young callus tissue show, however,
that no deviation from the normal is presaxt, so far as the di-
rection of the first divisions is concerned, The segmented
cambial cells divide in a tangential direction parallel to
their long axis, Cross walls arise later an the products of
their division and are variously oriented, Figure 63 illustrates
that has been said, The cambial cells directly at the cub sur-~
face (B) have perished, those following next have produced Some
few cells- by tangential division-, the next have divided very
abundantly, The arrangement of the products of division makes
it still possible to follow the life history. The outer ports

(160) of these complexes which are formed in rows, -~ in which cross
division takes place in very different directions = help to mke
the outer visible callus roll; their inner parts, adjacent to
the xylem, show regular rows with only parallel walls, Of the
succeeding cell complexes - at the left in the figure - only
the inner, regular sections are show in the drawing. The dllus~
tration shows at the same time that the cells of the meristem of
the medullary rays can participate in the formation of the callus,
in the same way as do the adjecent segmented cambial cells.

The next illustration shows in longitudinal section the
luxuriant] developed "Lohden wedge" (C) of an élm, The cells,
90 fer 668 argangod in oloarjy roeogrigs-tic rews, ere indicated
in the figure as curves in the "Lohden weage", The Lowest’ (in-
nermost) of these curves are bent only slightly, if at all, the
upper ones (outermost) on the contrary, are bent very strongly;
Since the cells of the "Lohden wedge" not only grow in a radia

1 whe investigations of the cambial products is made |
easier, if cross-sections are also made on gbliguely cut cuttings
(Compare fig, 62 and 63).

2 nehrb. f, Forster, 9 Aufl., Bd. I, p. 227.

(161)

(162)

145

airection bnt also in the direction of the long axis, it is
evidnnt that the radial cell rows curve out foray d rie ae
surface, until they finally tear apart, as at z in the figure,
Befond jhis point of tearing, the cell divisions are very ir-
regular”. .In the callus of the elm here Shown, however, the

cell rows may be clearly recognized alth
toward the outside, en. although they are turned

The further increase of the callus tissue is often brought
about by the appearence of a new meristematic’ zone, the posi-
es ee vary. In figure 64, at a-a, such an one is

ed,

In addition it Should be emphasized that the youngest
bark layers act just as do the cambial cells, - from which they.
may not always be sharply distinguished,- furnishing the same
Short-celled parenchyma as do the cambial elements, The coni-
fers, so far as investigated, assume an unique position, in
that the latest, unlignified elements of the wood-body are also

incited to an analogous change by wound-stimuli. They divide
and furnish parenchyma cells”,

Figure 65, a tangential section, made above a girdling
wound in Abies ecphalonica, shows in its upper part normal ‘trach
eids with bordered pits, in its lower, parenchymatic cells,
produced by segmentation of the young woody elements which Ive
unbordered pits.. The transition between the two zones furnish-
es Some cells which show the character of tracheids in their
Bee parts, but in their Lower ones, the pitting of parenchyma
cells,

Not only the youngest elements of the secondary bark, af
which we have just spoken, participate in the formation of cal-
lus, but at times all of its layers or at least the growths of
the last few years, Of all the cuttings which I have investi-
gated, those of Populus form the most abundant bark callus,
Here, as from the cambium, regularly radial rows are also pro-
duced by tangential cell division, whieh curve out on the cut
surface Like robls, as was stated above for cambial callus.
(Compare fig..66). The bark callus usvally merges with the
adjacent cambial callus into an homogeneous tissue roll, so thet
it is possible to determine only by microscopic investigation
which part of a callus pertains to the bark or to the cambium
an@ whether the former was at all active”.

In plants with fixed medullary phloem, its cells may be
incited by injury to division and the formtion of callus,
(Observations on Eucalyptus}.

The primary bark, especially in Salix, passes over easily
to the formation of callus. Only a few days after the injury,

ee ee ed

Co ad a ne

1 the changed tensile and pressure conditions might not
be without influence on the direction of the cell division,

Maule, Der Faserverleuf im Wundholz., Bibl. Botan,, 1895,
Heft, XXXIII,

3 Also in Populus, the participation of the bark in the
formation of callus varies greatly in different examples; often
it is entirely lacking. In one case, I saw the cambial callus
only weakly developed, and the bark callus therefore excessive-
ly richly increased,

4163')

wn

146

if kept in moist air, a glittering crystalline covering is
formed from the callus tissue, which, in comparison with the
new formations already described, does not exceed a relative-
ly moderate amount, The cells, lying under the cut surface,
sre stretched perpendicular to the surface of the wound and
divide repeatedly with irregniarly oriented walls, Rows of
cells belonging together developmentally generally are not
formed here, I observed at times © predominant tangential
@ivision in the bark of young Sambucus sprouts,

awe

lus, In these from 10 to 12 days after the injury, a shenth- ©
like knobbed collus mass, usually star-shaped, becomes visible,
above the pith and is often greatly increased; the wounded sur-
face of the xylem grows out toward the cembium like e wall and
is united to it, It is clear from longitudinel sections that
the uppermost cell-layers of the pith died after the injury end
that those immediately ynderneath have been elongated perpen~
dicularly to the wounded surface and have divided repeatedly.
From the very beginning any definite direction of division is
ec nae here;- generally well arranged cell rows do not
exist,

The epidermis becomes active only in rare cases, Stoll
thinks it doubtful if it can ever participate in the formation
of callus. Hansen observed divisions in the enidermis, how-
ever, Which led to sallus formation (Begonia), Further obser-
vations are reported by Massart, who proved e division of the
rie ie cells in the stalks of Ricinus and Tinanthia [loc,
Git.

Any ability to form callus may scarcely be spokem of in
connection with the cells of the wood-parenchyma, As was
thoroughly discussed above, the wood purenchyma cells, incited
to growth through injury, slmost always remain undivided. Ac-
cording to Molisch, division is known only in the tyloses of
Cuspidaria pterocarpa and Robinia (compare above p. 102). This
does not exclude the fact that tyloses occasionally become en-
larged and, like the products of the cambium, the bark, otc.
can curve out over the cut surface. In the cuttings of Pla-
tanus the cells grow out ffom the cut ducts in the form of
gigantic pouches, The statements of Stoll éhat in Passiflora
quadrangularis the tyloses grow out only from the ducts, and
divide repeatedly outside these, producing a many celled callus,
which unites with the callus of the cambium and of the pith,
are based indeed upon an error and need testing. Tompa's
study throws light on the participation of the wood parenchyma

Cd a ee -— we we wee Reel

und Blattfall, Pringsheim's Jahrb. f. wiss, Bot. p60, Ba.XII,
p. 133), in which theepidermal cells of the Clivip leaf divided,
a formation of cork exists as the author emphasiges; perhaps
similarly also in the cell division observed by ‘ assart on

the leaf of Banisteria argentea (loc. cit., p. 49%.

,2 Soudoure de ln greffe' herbacee de la vigne. Ann. Inst.
Ampelol. Budapest 21900, T. 1, flo, i.

{164}

147

of Vitis in the formation of callus. Also in roots rich in
parenchyma, cases are not lecking in which the ‘700d parenchyma
after “injury takes part in this formation, I have never cs yet
been able to observe division in the wood parenchym. of roots
of Taraxacum.

If we again look over what has been said, we ean make
certain that, after injury, the cambium and secondary berk,
corresponding to the normal dividing activity of the oambicl
cells, strive to forma tissue radially arrenged, In the
pith and primary bark of the objects investigated such a ten-
dency was not found.

Petioles and leaves also often form abundant cellus from
their bark tissue and 6Specially from their mesophyll. To me
the callus excrescences formed on the petioles of Populus
Seemed especially striking becguse so abundant, The colorless
tissue formed on the edges of wounds of leaf bledes (Acer,
Syringa, etc,) bears but slight resemblance to the normal epi-
dermis with which it has been compared at times by various
authors, The life history of the eallus on leaves discloses
nothing mew. The extensive callus rolls deserve especial men-
tion, however, which are produced in the legumincceous cotyle-
dons, rich in starch, after their removel from the axis, I
found them becoming highly multicellular in Vicia*, Here the
cells. below the cut surface are also elongated perpendicujerly
to it and divide repeatedly without noticeable reguicrity™.

In fleshy leaves, the burrows eaten into the mesophyll
by insect larvae are not infreouently filled by o mubticelluler
callus, containing chlorophyll, which distends the epidermis.
Thus, in later stages, instead of the burrows, ve find ridges
on the leaf which are filled with ocllus. (For excwygle, in
Sedum spectabile, Brassica, etc).

A thorough investigation of the ohenges to be found
in leaves injured by mining insects might well be sorth
while. The conditions aoting here on the injured tissue
differ essentially, hovever, from those which oome thto
effect after somewhat cocrse interference on the port of
the experimenter. Perhaps the recotion of the plent tis-
sues is also correspondingly different,

The filling of the burrovs vith callus tissue 15
shown also by the tender masses in the wood of different 2
trees, long known as Mmoon-rings". According to sent 8
description, they are composed of irregulatly pores )
parenchyma cells with thick pitted walls arranged aa
ubarzy. On account of their similarity to medullary - ie
sue, Nordlinger called them ™medullayy spots”, Their his-
tology, the irregular arrangement of their elements, and
~ "1" g3 Van Tiegham (Rech, 8, 1. germination, Ann. Bc.
Nat. Bots gine nbn, 1873, 7, XVII, p. 208) whose statements
should be compared here, the fate of the isolated cotyledons

has been eSpecially investigeted.

-“— == =e re re = eel er

2 leaves also in Massert
Further statements on callus in
loc, cit,, Blackman and Matthaei:~ On the reactien of leaves to

é tion, Ann, of Bot,, 1901, Vol, XV, p. 553,
Meno, cL Sprueh -u, Duerrf eckenkrankh. 4. sheinovetes ,

Landw. Jahrb., 1901, Bd, XXX, p. 7” and many others,
3 vergl. Anat, a, Veget. - Org,, Be 507.

(165)

148

their passage-like course favors the explanation of M,
Kignitz’, who recognized in them, at least for Salix,
Sarbus and Betula, callus filled passages of the larvae

of some Diptera, Of course, even after other kinds of
injury, the cavities produced in the cambium cen be filled
with similar tissue,

Histology of the callus

is has been already emphasized, callus ticsues are chor-
acterized histologionlly by the slight differentiation of their
cells. In many kinds of cuttings the enllus rolls consist ..
throughout of the same kind of cells; they cre construoted per-
fectiy homogeneously. The separante sells ore always thin-
walled, filled with a olear cytoplasm ond an almost always
colorless cell sap, In slow growing callus excrescenoes the
tissue is usually small-celled and close, lorger interstices
are visible only in thé outer cell layers. In those growing
rapidly, the cells are usually lorge, loosely layered, sepnra-
ted especially in the outer layers by large intercelluler spaces.
In the callus of Cydonia japonica and others, I found thet the
tissue connection of fen became so broken, that the cells were
almost completely loosened from one another, If callus tissues
are left in the light, they become green; their sie eth pene
however, are always few in number, small and poor in pigment,
on account of which the callus rolls are always a pale green,
at times even more yellow than green, as in Catalpa.

No definite laws determining the proportionate sizes be-
tween callus cells and those of its mother tissue may be recog-
nized, In Populus, for example, the cambial callus consists
of cells, which are ee aa | lerger than those of its mother
tissue, while the products of the pith are smaller than those
of normal medullary cells.

A difference between the single cells. is caused very often
by the fact that some of them, - especially in the inner layer

-of the callus,~ are chanfed to tracheids by reticulated thick-

ening and lignification of their walls, Their formation may be
traced especially clearly in the callus of poplar euttings,
Figure 67 shows part of a callus of Populus: - the delicate
walled, irregularly arranged parenchyms cells with wide lumina
enclose a tracheid with reticulated walls, Although in the
"Lohden wedge", especially in its lowermost part, very many
cells assume a tracheal character, tracheids are relatively rare
in the upper callus rell, They are trregularly distributed in
the undifferentiated tissue, Moreover, the under layers near
the place of origin of the roll are usually more abundantly fur-
nished with tracheids than the outermost ones, By the union

of many tracheids, primitive vascular bundles and a wood-like
tissue ore produced, which will be spoken of ln ter as wound-
wood, The cells of the superficial layer of the callus never
become tracheids.

It is now worth noticing, that not onlyd derivatibes of
the cambium may become tracheids, but that callus from the

Hartig, Kraus, etc,).

& Compare also Sorauer, Handbugh der Pfjanzenkrankh.,
2 autl.s, Bas 1, ps 362,

(166)

ha

: 149

secondary bark end from pith also produces elements of the

same kind. The same differentiation is undergone by the callus
of injured cotyledons (Vicia, etc,), of petioles (investigations
on Sakix and Populus) and of roots (Taraxacum),

Next to the formation of tracheids, the development of an
epidermal tissue is the most striking process of differentia-
tion in the callus, This too may be studied in the callus tis-
sue of poplar cuttings, Its outermost layers differ from the
inner ones first of 411 by the greater volume of the single cells,
These are forced out into the form of pouches or long sacs,
Their walls, so far as they come in contact with the air, ‘give
the reaction of membrane -coverings which have become cork,
since they take up Sudan III~ abundantly and at the same time
are colored with phloroglucin and hydrochloric reid, like lig-
nified membranes, I do not doubt that the same substance for
a Similar one) is the cause of these re&ctigns, just as occurs
in the "wound-gum" of very different plants”. On closer obser~
vation, delicate, pouch-like or semi-spherican, convex promin-
ences become noticeable on the outer wells of the calls, which
may consist entirely of a gum-like mass, the reaction of which
we have just mentioned, Mellinok has also obgerved these in
callus formations on the petioles of Nymphaea”, An a
good object for this investigation might be furnished by the
"woolly stripes” of apples, which Sorauer* has described, The
woolly stripes are praduced on the innerside of the core; def-
inite cell groups grow into thick little bunches of cell rows
lengthened to look like threads, (compare fig, 68), "which dif-
fer from thase surrounding them in their thinner wall-fermetian
and neee over very gradually into the tissue of the fruit's
flesh", On these cells, wart-like or knob-like "thickenings"
of the cell wall gppear, as is shown greatly enlarged at the
left in figure 68°, The tissue described by Sorauer of which

Loin using Sudan III, I generally proceed thus;- after
leaving the sections some minutes in @ dilute solution of the
coloring matter, I then boil them in glycerine on the slide,-
During the boiling, the membranes which have become cork are
colored a strong red,

e Compare especially Prillieux, Et, s. 1. formation de la ©
gomme a. i, arbres fruitiers, Ann. Sc, Nat, Bot. 1875, 67° ser,,
T.1, p. 176, Frank, Ueb, die Gummibildung im Holze u, deren phys-
iol, Bedeut, Ber. d. D, Bot. Ges, 1884, Ba. II, p.3@1, Tamm,
Ueb, Schutz-u.Kernholz, seine Bildung Be Golbive 108 ters tana
u,Kernholgz ad, laubbaume, Pringsheim's Jahrb. f. wiss, Bot, 1888,
Bd, XIX, p. 52. Molisch, 2, Kenntn, d. Thyllen etc, Sitzungsber.
Akad, Wiss, Wien, 1888, Bd, XCVII, Abt, 1, p. 264, Lopriore.
Ueber dje Regeneration gespaltener Wurgeln, Nova Acta Leop,Carél.
Aoad, 1896, Bd, LXVI, Kieler, Die gummosen Verstopfungen des
Zuckerrohrs, Beitr.,wiss,Bot.1698, Bd, II, p.29 and many others,

° gur Thyllenfrage, Bot, Ztg., 1886, Ba, XLIV, p. 745.
I think it more correct to place the often multicellular forms
observed by Mellinck, in wounded leaf stalks of Nymphaea among
callus forms, rather than among tyloses.

4 wonab, a. Pflanzenkrankh,, 1886,2 Aufl., Ba. 1, p. 296.

5 Apparently the same forms can occur also in normal tis-
sue, Jost found them in the aerial roots of Phoenix spinosé,
(Beitr, z, Kenntn, d, Atmungsorgane d, Pfl. Bot. 2tg., 1007, Bd,
XLV, p. 601), Noack in the intercellular spaces in the roots of
various orchids (Ueb. Schleimranken in d. Wurzelintercell. ein-
iger Orchideen. Ber, 4, D, Bot, Ges., 1692, Bd. X, p. 645),

150

(167) the original causes_of production are not yet known, resembles
many callus tissues! (see above), On this account I ventured
to mention it at this point.

In the outer cell layers of most callus formations a cork
meristem is produced sooner or later, the products of which
will be termed wound-oork, We will return to this later.

Crystals - ~ isolated crystals like glands,- thay often be
met with in Gallus (for example, in Populus, Fagus, Corylus,
end many others); usually, however, in lesser quentity than in
normal tissues, Raphides may be found (according to Sorauer)
in the callus of Fuehsic, According to Stoll (loc, cit.) stone-
cells are formet in the oallus of Camellia japonica, "gum
passages” in Hibiscus reginne, I observed the form.tion of
anthocyania, Tor exemple, in the eallus of Populus, According

0 Rechinger© the cellus of the roots of Armoracia rusticana is
sich in stargh. Vaouoles of tanic substances are very notice-
able in the callus of many foliage trees, I found letex tubes
in the callus of Taragacum roots, Differentiations my, there-
fore, be found in ¢allus similar td those which we are aecus-
tomed to find in the normal tissue of the plants conce¥ned
only very much more weakly developed - - corresponding to the
character of all kataplastic tissue,

Massart (loc, cit.) was the first to treat the ques-
tion of nuclear division in callus tissue, which, in the
cases investigated, Only exceptionally contaired more than
one nucleus of each cell. In Ricinus, Cucurbita and
Tradescantia he found that, in the majority of cases, di-
rect nuclear division took place after injury. His suppos-
ition that the nuclei in all wound-tissugs divide amito-
tically has been disppoved by Nathansohn*, Nathansohn
found that only mitosis occurs in the callus of halved
roots of Vieia Faba, but mitosis as well as amitosis in
thet of poplar cuttings,

Conditions of callus formation

It seems a matter of course that different plants shoulé
b&have very differently in regard to the production of cgllus,
The time which the injured plants need to develop it, as weil
as the amount formed in different plants fluctuates within
wide limits,

The callus on young plants of Pisum develops very rapidly
in cotyledons of Phaseolus and Vicia, under favorable conditions,
it attains a considerable size even a few days after the injury.
In cuttings of woody plants, this formation is slower. Sorbus
develones abundant callus within the course of the first week;
Populus, Salix and many others also react relatively quickly,
while months elapse before cuttings uf Ostrya show a moderately
strong callus ring on the cut surface,

Soraver assumes that the "woolly stripes" are produced
by excess of water,

2 Unters, ueb, d, Grenzen ad, Teilbarkeit im Pflanzenbreich,
Verh, Zool.~ Bot, Ges, Wien, 1894, Bd, XLIII. p. 310.

= Physiol, Unters. ueber amitotische Kernteilung. Prings-
heim's Jahrb. f, wiss, Bot., 1900, Bd, XXXV, p. 48.

(168)

{169)

151

Similar differences exisf, in regard to the quality of
the callus tissue produced, Populus heads the list of the
many woody plants with cuttings of which I have worked. In
moist air masses of tissue often more than one centimeter high
and wide grow out on the cut surface, Cuttings of many other
woody plants produce ohty & low callus ring (Ulnts, Salix,
Ostrya, Quercus, etc), Further, in Ulmus ond Populus, the
stimulus proceeding from the place of injury also makes itself
felt at a considerable distance from the cut surface, Through
abnormal cambial activity, the bark is distended until it may
at times even rupture, In most other woody plants abundant
cell division takes place only in the immediate vicinity of the
place of injury/

We will have to trace these and similar differences in the
formation of callus to specific peculiarities of the plant
species concerned, when & closer analvsis of the causes may
not be possible.

As may be surmised, the nut#itive condition of the object
under investigation will influence the formation of callus, If
we compare the organs of one plant which are rich in food
stuff with those of the same species poor in food stuff, we
find that the former develop wound tissue more abundantly than
the latter, The difference between the action of the cotyle-
dons of many Leguminoseae is most striking. (Vicia, Phaseolus,
etc,), Rich in proteins and starch, they proliferaté the tis-
sue on the cut surface to an extro-ordinary degree, but the
thin leaf blades of the same plants develop only weak callus,
We find the same difference hetween cotyledons and foliage
leaves of the Cururbitaceae, (Luffa, Cucumis, etc,) and others,
The fact that a more luxuriant callus is formed in injured
leaves (cotyledons) in the immediate vicinity of the stronger
ribs than between them, may likewise be traced to unequal nu-~
trition. No investigation has vet been made as to whether sup-
plying food stuffs artificially from without, treatment with
sugar solution and the like, might promote the callus formation
of organs, poor in food stuffs,

Concerning the "external" conditions which may be mofidied
as one wishes jn the experiment and their effect studied, the
following should be emphasized,

The influence of necessery moisture on the injured tissue
iz a condition preliminary to every callus formation, whether
it be in a liquid or gaseous form; callus may be formed under
water as well as in moist air, but not in dry air. Many plants
indeed form callus, only in moist air, and the callus formation
in all plants is much more abundant in moist air than under
water - supposedly because the absorption of oxygen and trans-
piration are hindered under the latter conditions, Gravity
and light are not decisive in the formation, or, rather, the
non-formation of the callus, Indeed it developes often more
abundantly in cultures. in the dark than in the light (for in-
stance, in Populus); perhaps the humidity of the air, increased
in the dark, is the cause of this, Of course, there is no fore
mation of chlorophyll in the dark,

If a eutting be left with both ends in moist air, it de-
velops abundant callus on both cut surfaces, If one end is in
dry air, which, as previously state¢, prevents all callus for-
mations, the callus tissue can develop only on the other end,
where conditions are favorable. If one end is in water or sand,
the other in moist air, the latter is then preferred and de-

. 152

velops callus. JI know of only a few cases in which callus is
formed simultaneously on the end under water, A very small
"water-callus” is produced in cuttings of Populus pvramidalis,
in the formotion of which, in my experience, only the cambium
participates while bark and pith remain inactive, I found
callus produced in Sambucus end bigustrum under water by the
activity of the bark tissue, when the conditions were similar,

If, in the lnst nemed case, the cut surface fails to form
callus in sand, the arrested respiration and trenspiration my
indeed be to blame for it. However, callus may be formed in
the end in the sand, if the notion of,the dry air mkes its
formation impossible at the other end*, Phat portion is there-
fore preferred for this formetion which is at the time under
most favorable conditions,

Also, if the formation of callus in outtings is temporar-
ily arrested by unfavoreble conditions, the tissue does not on
‘this account lose the ability to form it. I found callus tis-
sue produced to the usual amount on poplar cuttings, which had
lain about four weeks under water, after they had been brought
into a moist room, Titmann obtained the same result, He put
the cut surface in plaster oasts and then, after removal of the
plaster bandage, found them developing callus. Titmann calls
attention further to the fact that poplar cuttings, with scars”
left on the main axis by the falling off of dead side branches,
form callus on these already healed wound~surfaces through the
action of a moist atmosphere, "Therefore the scarred wound
acted in this just as a fresh, unscarred one would have done.
The results of the injury therefore allow a continuance of con-
ditions, which later make possible the formation of the callus",

Correlations exist further between the formation of callus
tissue and the development of side shoots.on the cuttings. No
case is known to me, in which the production of a callus would
have been completely suppressed as the result of an abundant
_ formation of side shoots (favorable conditions heing presup-

posed), but indeed its development is often retarded to the ben~-
efit of the side shoots. ;

In conclusion, still a few words concerning "pobarity”.
An object suitable for the study of this is again offered by
the oftnamed poplar cuttings, Even under equal external condi-
tions, the capacity of both cut ends for forming callus is not
perfectly equal, If a nugber of cuttings are placed in water,
some upright, some inverted, with the upper cut surfaces favor-
ably arranged for callus formation, it is found that the in-
verted examples develop a more luxuriant callus than do those
normally oriented; the basal poles are capable of a more abun-
dant formation of calus than the apical. JI observed the same
phenomenon in Rosa. Frém the observations of other authors,
on girdled stems and the like, it takes place also ina number

-— el
Ce ial ~ meme ew

i Compare also Tittmann, Physigl, Unters. ueb. Calluse-
bildujg an Stecklingen holziger Gewachse, Pringsheim's Jahrb.
f. wiss, Bot., 1895, Bd. XXVII, p, 164.

. 153

(170) of other plants}, In most of the woody plants, whose cuttings
I investigated, an obvious difference between basal and apical
poles could not be proved, As yet, no case is known to me, in
which, the apical end of Sprout-cuttings of any certain spe-
cies, was the one preferred, However, I do not considér it at
ll impossible that further investigations may make known ex-

ae of this kind (compare thot said below, concerning
roots),

In Populus, Rosa and others, polarity may be
in the tissues dsrivotives of the aoen nthe Mor ae
to whether other kinds of tissue may show the same difference
in their callus products deserves still closer investigetion,
As yet, in the formation of bark callus, I heve nbticed © pre-
ference for the basal pole only in cuttings of Alnus,

; Polarity as found in pieces of the stem mmy also be proved
in other organs, Petioles of Populus forme more prolific ceal-
lus on the pole nenrer the place of insertion of the leaves
than on the pole toward the leaf blede, Among leaves, the r 6-
viously mentioned cotyledons of the Cucurbitaceae (Cucumis,
Luffa and others) have been proved well adapted for this, If
the seed leaves of the young plants are removed, cut across
and kept in moist air, they form abuydant callus tissue on the
wounds of the ribs, The difference between the basal and apié
cal pole is unmistakable at the place of the cross sectioning;
the injured surface toward the base forms callus very abundant-
ly, toward the apex very Sparsely.

Among roots, I have investigeted especially those of the
dandelion (Taraxacum officinale) which, as is wellknown, may
easily be propagated by root-cuttings®. If pieces of roots, 2
to 3 cm. in length, are put into a moist place in such @ way
that both cut surfaces remain exposed to the air, an effect of
Speen is evident in the formation of the callus taking placé
soon, Since almost all pieces of the roots develop callus masses
first of all on the basal part, i. 2. on the side toward the
root neck, while the apical end remains for the present free
from callus, and participates only later in its formation,
Rechinger (loc. cit.) also proved polarity of the same kind in
other kinds of roots, According to his investigations, root
cuttings of Medicago sativa form a striking exception, a power-
ful tuber-like callus is produced on the root end, while the
callus on the sprout end remains smell.

ammeter eme

, ..} De Vries, Ueb. Wundholz. Flora, 18676, Bd. LIX, p. 2.
Vochting, Organbildungen im Pflanzenreich, 1884, Bd. II. Barth-
elemy, De 1'infl. de la tension hydrostatique et de ses varia-
tions s, 1, mouvement des liquides 4. 1. yeg. et. Mem. Acad.
Se, Inscr. Bell. Lett. Toulouse, 1881. Muller, N. J. ¢., Kul-
turversuche an Weidensteckl. Ber. d. D, Bot. Ges., 1885, Bad,
III, p. 159, Kny, Umkehrversnche mit Ampelopsis quinquefolie wu.
Hedera helix, Ibid., 1889, Bd, VII, p. 201. Tittmann, who |
worked also with poplar cuttings, Seems to have overlooked this
polarity. If itis a question in any investigation of obtaining
the most luxuriant callus excrescences possible in a short time,
it is advisable to place the cuttings upside down. The callus
formations described above (compare fig. 60) originate from
cuttings inversely oriented.

= Compare Wiesner, Hlementarstruktur, 1892, p. 112.
Rechinger, 1 oc, cit,

(171)

(172)

154

The phenomena here described are most closely connected
with the action of unlike external conditions already discussed,
The "po¥arity" expressed in the callus formation of Taraxacum
roots does not rest entirely upon the fact that the apical cut
surface was permanently, or at least at the beginning of the
experiment, incapable of forming callus, If root cuttings of
Taraxacum are inverted and pleced in vater, in such & way
that only the apical poles extend into the oir, soallus is form-
ea on the latter while the basal surface rem:ins free from it
just as when inverted specimens are put in send, or in plcster,
ete, The polarity then seems to be "reversed", Poplar cuttings’
behave similarly. If they ore put in water in a normal position,
the basal pole is not only unrible to develop a more luxuriant
ecllus, then the epiccl one but its eallus, if developed at all,
is less than that of the other pole. If both poles ore placed
uncer the same externc] conditions lend one pole nevertheless
seems to be preferrec, or if only one of the two develops ogl-

-lus, this proved only that the internel conditions, likewise

effecting the formetion of callus, are unlike at both poles and
thet, as always, that pole shows the most abundont tissue pro-
duction, in which exist cond4tions more favorable for tissue F
formation, It is difficult ta say, what these internal condi-+
tions are, I suppose that here, as is so often the ease, in-
equalities in nutritive conditions decide the matter, end I re~
turn to the old assumption of a decreased flow of the sap, in
order to explain the reference of the basal pole in pieces of
the stem, heaves and petioles, Taking this kind of sap current
for granted, an accumulation of food substances on the basal
pole may well be conceived. Analogously, a stream directed
toward the upper end, must be assumed in roots, in order to ex-
plain the superior nutrition of the upper end of the cutting.

The processes of tissue differentiation depend also
on definite external conditions. We can study the action
of arresting factors in abnormal tissues, as in normal
ones, It is a mattermof course that the cells of the cal-
lus roll remain free from chlorophyll, when shut away from
light. In Populus the wound tissue remains snow white, in
others it assumes a yellowish tone, The fact that I could
find no tracheids in the callus of cuttings of Amygdalus,
Carvlus and Forsythia is undoubtedly connected with the con-
ditions under rhich the callus was produced (too slight
transpiration?), A more exact testing of the question
was not undertaken.

It should be noted in conclusion, that callus tissue can
be produced in the plant body even in the "normal” process of
tissue formation, Such a case occurs if the "mechanical ring”
in shoots of many plants ig finally broken by continued secon+
dary growth in thickness, The "physiological" wound thus pro-
duced is soon closed by an in-growing parenchyma, comparable
to callus.

Formation of organs in the callus

In very many woody plants, organs of aifferent kinds are
stimulated. by injury to the form tion of adventitious vegeta-
tive points - adventitious shoots and adventitious roots. These,
vegetative points are thereby produced directly from cells of
the permanent tissue of the wounded plent organs, or a callus
is first formed and from this the gegetative points. Laventi-
tious structures of the first kind exjst in many ferns, in the
leaves of many monocctyledons etc, Adventitious structures of
the second kind in leaf-cuttings of Peperomia, in the shoot

155

cuttings of the poplats, elms etc., which usually develop
numerous "Lohden vedges" fram the %llus+, Further, there
are plants which produce new veget. tive points directly from

the cells of their permanent tissue as well as by the mediation

(173)

of calius tissue; for instance, Begonia leaves after removal
from the stalk and injury to their ribs, produce new shoots
and roots dirsotly from the epidermal cells as well as from
the gellus tissue, produced on the edge of the injury on the
jeaf?. It has never es yet been observed in higher plants
that the cells exposed on the surfece of the wound would have
been able to produce a new vegetgtive point, without the in-
terposition of callus tissue,

The consideration of these regenerative processes is only
loosely connested with "pathological anatomy", in as much &s,
in the formation of root or shoot vegetative points, the pro-
ducts of abnormal tissues is stopped by the formation of nor-
mal ones, Nevertheless a few remarks concerning the forma-
tion of tr7.p8 in callus may well be added here. The fact
that meristematic complexes in the form ef shoot or root wege-
tative points can arise from the cells of the callus t issue;
is one of its most important characteristics,

Callus occurring on injured roots may be just as capable
of forming organs as that on pieces of the stem and on leaves.
Yet in most plants not all organs seem to be able to form new
vegetative points from their callus; in many othegs the ability
to do this is lacking in the callus of al1 organs*, - or per-
haps we are ignorant of the conditions under which the callus
tissues of these plants may develop vegetative points,

Up to the present the callus tissues of poplar cuttings
have been the most carefully investigated as to their ability
to form adventitious organs, If they are placed in the usual
way in water, in a few weeks a large number of adventitious
shoots are developed from the callus. Thus it is shown, that
light has no influence on the formation of the latter. Natur-
ally adventitious shoots sprouting the hark have the character
of etiolated ones, Further it is shown, that cuttings, of
which the apical ends are immersed, form adventitious shoots
on the basal poles, which extend into the air, According to
Tittmann roots may be produced from the basal poles of poplar
‘cuttings, when placed under water,

The root-pieces of Taraxacum which form callus behave sim-
ilarly in regard to the formation of shoots, As has been said;
when kept in moist air, they form their callus preferably on
the basal pole, (the one toward the root neck). Placed inver-
ted in the water, sand or plaster, the apical. pole as well
forms callus and adventitious shoots with equal luxuriance, It
is indeed possible to cause these pieces of roots which lrve
formed callus-and adventitious shoots on the sprouting pole,
supplementarily to form a second callus and a second series of

o
ee ee er ee |

3 In leaves which grow roots after separation from the
axis, these roots are very often prodpced nof from the callus,
but above the cut surface,

(174)

156

vegetative points by placing them inverted in w

plaster, so that in this way root cuttings aa eras
which develop adventitious shoots On hoth cut Sunendsee The
development of new organs, like the farmation of callus. takes
plece af that end which is placed under the more favorable con-
ditions’, In Taraxacum the production of roots from callus
fails far below the formation of Shoots,

The development of adventitious shoots from c -
rested by the formetion of side Shoots in the ee ae
carry it; on the other hand, a luxuriant formation of callus
often hinders the production of adventitious roots on the cut
surface, Soraver has already referred to this.

_ The investigation of conditions under which vegetative
points are formed in callus and under which shoots, or rather
roots, are produced, promises many interesting results. I re-
fer again to Sorauer's statement according to which eallus
tissues of conifers, Ericas and other plants do not produce
roots until after artificial incision.

Wound-wood

Besides a thin walled, homogeneous callus rench ,» man
plants, after injury, produce tissues of other kinds, wnigh ee
come Similar to wood tissue through a develpment of tracheal
elements, The tissue resembling wood, which is formed after
injury, is pore het from normal xylem by its simple his-
tology. We will term it wound-wood and for this reason ada it
to the list of kataplasms,

The fact must now be emphasized that tissues of the kind
described, resmmbling wood, are usually produced not only af-
ter wounding but also by the action of other injuries, In the
present chapter, we will speak not only of the wood formed on
the wounditself hut also of other tissue products resembling
wood, whatever may be the interference to which they owe their
production. Those products will be described in a later sec-
tion which arise after infection by foreign organisms, - tht
is "gall-wood",

We described above the case studied by Kny and others, in
which young shoots split lengthwise can fill out anew the in-
terrupted cambium ring in both &alves by means of callus tisxzue,

‘. om

Se ol oe a

lL Wiesner (loc, cit,) observed as exceptions some Taraxa-
cum root cuttings, which had formed sprouts on both sides, It
would be interesting to follow the further development of such
root pieces and to prove whether possibly and in how far the
double development of shoots influences their histology. Fur-
ther literature on Taraxacum in Wakker, Onderzoekingen over Ad-
ventive Knoppen. Amsterdam, 1885; Goebel, Ueb. Regeneration in
Pflanzenreich, Biol. Chl., 1902, Bd. XXII, p. 385.

© In the process of rgot formation and bud-development
in willows, described by Vochting (loc. cit.) the polar con-
trast seems to be independent, to a high degree, of external
factors, Its reversal has not yet been possible. The same
holds good in my opinion for the polar Bryopsis, with which
Winkler worked, (Ueber Polaritat, Regeneration und Heteromor-

‘phose bei Bryopsis, Pringsheim's Jahrb. f. wiss. Bot., 1900,
Bad. XXXV, p. 449,

5 Populdre Pflanzenphysiologie f, Gartner , 3891, Pe 269%

(175)

*

157

this callus is produced from the pith. bark and cambium of

the split shoot and from it a new canbiug, which is attached
at both sides to the ends of the normal cambium halves (see
above p. 20), Similar conditions exist in older branches of
woody plants, in which the wood, body is exposed by some in-
jury and the thickening ring interrupted. The cambium fur-
nishes the above discussed cellus and a new eambium is pro-
duced from it, which attaches itself to the normal one, By
means of its capacity for division, the roll lying upon the
surface of the injury chnstantly becomes larger, the cembium
produces bark tissue on the outside, wood tissue oh the inside.
This we must term wound-wood because of its structure, since

it varies from the norme1, All possible transitional stages
exist between those cases where the new cambiun produces normel
(or nearly normal) tracheal eleménts and those in which it pro-
duces typice1 wound-wood, Just as we found 2 production of
undifferentiated tissue termed callus, not only atthe place of
injury itself, but mlso at a considerable distance from it in
the form of a “"Lohden wedge" between the wood and bark, so
under the influence of increased stimuli an abnormal wood oc-
curs ot some distance from the place of injury, near the normal
xylem nlready existing. Although the wood appearing on the
wounded surface, by which the exposed places are “covered over",
Seems to have some especial significance, this seems lacking

in the wound-wood of the second kind named, When considering
the matter anatomically, we will refer simultaneously to both
kihds of wound-wood, ti

In the liferature on this subject, the investigations of
de Vries and Maula come especially under consideration jn re-
gard to inquiries concerning life-history and histology”, Be-
Sides these, referencés may be made also the statements on life-
history in the preceding chapter and the literature there cited.

We will consider first of all those wound-wood tissues
which may be produced developmentally by the cambium of wounded
shoots and roots.

Histological Composition and Gourse of the Fibres
in Wound-wood

The deviation of the wound-wood from the normal differs
according to whether its formation is brought About by cross
cuts into the cambium or by longitudinal wounds, The wound
wood is characterized in longitudinal wounds by a wide-celled.
structure and more numerous ducts than under normal conditions.
The libriform fibres are less prominent,

The action of cross wounds must be described more in de-
tail.

De Vries proved that in Caragana arborescens it was possi-
ble to demonstrate the action of wound stimuli on the formation
of wound tissue, even at a distance of Yom. from the wound it-
self. The deviation of the wound-wood from the normal becomes
less, the more distant its formation from the place of injury.
The difference is the gréatest directly at this place. The
cambial cells dévide repeatedly as described above, perpendicu-
lar to their long axid, thus furnishing only short memhered
cells as ef result of a continuation of their normal tangential
activity, The nearer the cambial cells are to the place of

On eo on
, . 2 De Vries, Ueb, Wundholz, Flora, 1876, Ba. LIX, p. 2.
Maule, Faserverlauf im Wundholz. Bibl, Bot., 1895, Heft 33.

. 158

«

injury, the more cross walls are formed. fsa result of this
the "short-celled zone" of the wound-wood is produced near the
place of injury, at a further @istance, transitional forms
which finally pass over into the "long-celled zone" of the’
wound-wood, which is produced from tndivided cambial cells.

The cambial daughter cells of the short celled zone pro-
duce, near the edges of the woundp a wound-wood composed of
polyhedric parenchymtic cells, whose separate elements gen-
erally resemble the cells of the medullary rays in normal wood,
only a few becoming parenchymatic tracheids through character-
istic thickenings of the walls, At 2 greater distance from
the wounded surface the daughter cells of the cambium are
Slightly pointed to a spindle form ,

In the long-celled zone the cells usually retain the char-
acter of wood-parenchyma, Between them narrow vascular cells
are produced which are united into cord-like groups; but wood-
fibres and broad ducts are lacking,

After the formation of the elements described, which, with
de Vries, we may term «<yrfxarywound-wood, there follows, in the
Short celled zone as well “aS in the Tong celled one, a forma-
tion of a secondary wound wood. The cells newly produced grad-
ually assume a normal form, the tissue regains its normal com-
position, This transition is especially worth noticing in the
short celled zone; in which the short membered cambial zone
must be gradually replaced by the normal long-celled one, Ac-
cording to de Vries, ea few of the short cambial cells grow in
length thereby crowding upon the others.

If we roenondider the histological results.as a whole, we
can prove in all cases, in cross wounds as in longitudinal
ones, that the wound wood remains below the normal so fas as
any differentiation of tissues is concerned, The libriform
fibres are either entirely absent, or are very insignificant,
the parenchymatic elements advance into the foreground and in-
deed so much the further, the more energetically the wound
stimulus acts on the cambium. Concomitant with the predomin-
ance of parenchymatic elements, full of sapiSthe fact that
wound-wooé is less resistent to injuries of various kinds (frost,
parasites} than is firm normal wood.

De Vries found typical wood parenchyma in the wound-wood
of Caragana arborescence, al though it is entirely absent in
(176) the normal Wood of this plant+, Still more striking is the
formation of abnormal resin ducts in wound-wood, De Vries
found that they are often,more numerous in wound wood than in
normal wood, and Vochting@ proved for Picea excelsa that,
reckoned on the surface content, seven times as many occur in
wound wood as in normal wood, In fact resin ducts occur abun-
dantly in plants which normally do not develop them, for in-

Co el ela oe el

1 That the elements in question illustrate "real" wood-
parenchyma "and have not been produced possibly by cross-divi-
Sions which had already taken place in the cambial cells, fol-
lows on the one hand from the direct observation of the cambiun,
which lacks divisions at this height", -the long-celled zone
of the wound-wood is here concerned,- "and then from the ob-
servation, that in exactly radical sections an undivided com-
pensating fibre frequently lies on the outer side of such a
parenchymatic fibre", (De Vries, loc. cit, p. 24).

@ veber Transplantationen am Pflenzenkorper, 1892,
p. 139, 140.

{177)

: 159

stence, in Abies cephalonica, which Ma d
investigated thoroughiyt, ule (loc. cit. p. 18)

Wound wood does not always appear as stratified tissues
to be considered as a direct continuation of the normal wood.
In the cambial callus of cuttings, which swells out over the
place of injury, separate cells often assume the eharacter of
parenchymatic tracheids as described above, In the produetion
of these we may recognize the beginning of the formation of
wound-wood, Not infrequently, tracheid--like cells lie in the
callus, united into ball-like groups. In both cases the abnor-
mal tracheal elements remain separated from the normal wood.

In the further course of development independent cambial, or
meristematic tissues are formed in the periphery of the tracheid
groups, through whose capacity for division these grou may be
greatly enlarged, The new ebnormal cambial tissues can elso
remain permanently separated from the normal cambial ring.

In spite of the universal similarity in the structure of
wound wood in different plants, differences may also be proved
in the individual species, Besides the different quantative
proportions between tracheid-like elements and those resembling
medullary ray parenchyma, besides the formation of the resin
ducts already mentioned, etec,, the irregular, waved course of
the fibres of wound wood elements comes under consideration
and has been clearly recognized in macroscopic investigation.
48 is-alrendy known, the structural appearance, conditioned by
the irregular course of the fibres, has been termed gnarled

Co an ae ol ee ee ee ed en ee ee ee a ond

It is well to observe here thet these abnormal resin

containers do not exhibit the structure of normal resin ducts
in conifers; "in particular, the epithelial cells lining the
ducts are lacking in these. The longitudinal course of the
Single reSin containers was always parallel to the course of
the wood fibre;- besides, this course was often interrupted
by a bridge, several cells wide, of parenchymatic elements,

so that there was not present an actual resin duct, but a con-
tinuous row of resin containers, the length of which esceeded
three or four times the wide#h", In addition to this, many
circumstances point to the fact, "that they do not serve for
the continued secretion of resin, but only as store rooms for:
resin, which was formed in the wound callus, the transference
of which to the bark has become impossible on account of the
wood mantle lying on this", (Maula, loc. cit. p. 18, 19.
Gompare also the further statements on abnormal formtion of
resin ducts in the discussion of gall-wood). Just because the
formation of the characteristic epithelium is not present in
the abnormal resin containers and because we are concerned in
them only with “ordinary” parenchyma cells, which have been
filled with resin, every reason is lacking for seeking new
kinds of differentiation processes in the occurrence of the
abnormal resin ducts, as wiJl be observed in prosoplasmas,
The game holds good for the wood parenchyma cells, which de
Vries found in the wound wood of Caragana.

160
wood (veined or grainea)*,

It may be seen from microscopic investigation, that def-
dnite groupings are regularly repeated in the irregular course
of the fibres, In vertical longitudinal sections, especially
Af the wound wood has already attained some Size, fibres ap-
pear which have been cut slantingly and crosswise, "Just as
the elements already produced may vary in length, considerable °°
disturbance in their normel perpendicular course is found which, ,
always qae en age at the edge of the callus, spreads upward and

__. downward", (Mula). Among many irregularities the frequent

(178) recurrenos of V-, O-, or W- like twisted eells is very notice-
able, Thése are’united into groups like balls of thread,
(compare fig, 69) a8 well cs context for fig, 202), All ele-
ments kh? wound wood cen participate in the construction of
these bells, Zn those piotured in figure 69, taken from the
wound wood of Abies cephalonica, parenchyma cells as well as
trecheids are Tound, Tracheids olways ploy the chief role,
As Méula has proved, the wound wood of different plants is
characterized by the different size and the different distri-
bution of ifs ball-formtions, Figure ¥%0 throws light on the
form of the separate cells which odmpose these balls, It rep~
resents « few strikingly twisted tracheids, here and there
branched, from the wound wod of Gyaonia japonica, The middie
one of the three conteins a spiral band. “Besides the slender
tracheids, short, bgrrel-like ones are produced and parenchy-
matic elements often of wonderfully infleted brancheé forms,
According to Véchting (loc. cit. pe 136) similar forms are
found also in the abnormal bark-formed after injury, which
we can term "wound-berk", In this oecurs aiso the formation
of balis as in Wound-wood (Cydonia japonica).

Voehting (loc, cit. ps 132) deseribed this ball-Like ar-
rangement of the wood-elements in the wound woad of Cydonia
joponicn, which was formed in grafting experiments in whic

he bark rings were inserted upside down, ‘These ond other ab-
normal tissue formations after grafting on Beta vulgaris and

other objeets led Vochting to the assumption That @ individe
uhl elements of the ong axis are constructed with a polar re-
lation, and that their poles are drawn together or pushed away
according to whether we brivig the unlike or the like into con~

ee ee ee

but also in abnormal tissues of other origin. We will have to
Speak repeatedly of "gnarl tubers" and gnarl structure, Compare
also Frank, Krankh, da. Pfl., 2. Aufl., 1895, Bd. I, pp. 80 ff.
At this point I would like to call attention casually to the
fact that an irregular course of the fibpes can even occur
where there is no question whatever of hyperplastic formation
of tissue, R, Hartig has proved recently, that the “waved or
grained structure" in trees is often to be traced back to the
tongitudinal pressure, "which a side root, growing much thick-
er towards the top, exerts on the bark and cambium of the lower
end of the trunk, or which the branch, in becoming thicker

/ exerts above and’below on the bark of’the ‘tree, This longi-
tudinal pressyre causes foldings in the bark of thin barked
trees, and in. the wood produced from the cambium., These run’
in.a longitudinal directions. In trees with thick bark (oak,
chestnut, bleckwalder), en accouht of longitudinal pressure,
the elements of the innex bark and of the wood are wound in
wavy-lines, running tangentially. In conifers, waved wood o¢-
eurs rerely in the trunk", (Holzuntersuch,, Altes und Neus,
1901, p. 5¢, Ueber die Ursuchen d. Wimmerwunchses (Wellenhol-
zes) der Baume. Chl, £, ges, Foretwesen, 1901, April).

(179)

{180)

161

tact", (loc. cit, p. 151). wlith the help of these data
on the polarity of cells, Maule has tried to explain
those balled formations which oecur so abundently in
wound wood without any previous grafting, Although
Maule's attempt at explanation does not seem to me ex-
actly convincing nor tenable without many auxiliery hy-
potheses, I will nowlet him speak for himself.-

Méula starts with the supvosition tirt in new form-
tions of different kinds,- even in wound wood,- the devel-
opment of the separate elements 1s unequal, since some ate
formed early, others are #etarded in development. Fibres,
pushing forward, will not be able to maintain their strug-
gle to stretch downwards since the enllus of the girdling
wound here concerried is closed on the under side, The ©
fibres will therefore hove to bend. According to Miule
the fact, thet most fibres are bent tangentially along the
upper surface of the body of the wound and not radially,
may be explained on similar grounds (resistence of the
wood). Accordingly, the rootpole of fibre in the edjacent
diagram (fig. 71) at first grows out approximately hori-
zontally. "If the resistance also becomes too powerful in
this direction there results « further bending downward,
if possible; if not, then upward, Thereby its rootpole
Wl pushes directly on the rootpole of W2 of another fibre,
which may possibly have been somewhat retarded in growth.
As & result of this direct contact of two homologous
poles, We is obliged to deviate, either towards the oute
side (left) (as in tho figure) or towards the inside
(right). There We is pushed along on fibre 1, until any
further extension is impossible, or the growth in length
of this fibre 2 is ended, The next fibre 3 then pushes
on We with its rootpole Wg and must also bend, carrying
its rootpole end along fibre 2,--- It is evident that the
fibres 6, 8, etc., which at last are entirely inclosed,
have only a very small space for their extersion and that
finally, necessitated thereto by the pressure of surround-
ing fibres, two homologous poles can come exactly together.
This, however, does not in any way contradict the polarity
of the cells, It is only that the power here forcing the
ends apart is less strong than the external pressure,
even hohologous poles of two rod magnets can be bro ht
together, if the free nobility of the rods is preven ed*,

Tracheid-guares on balls resembling in all essential points
those balls described above, are to be found not only within
tho wound wood formed by the natural cambium, or by newly
formed cambial bayers but also isolofed from these, in the uh-
differentiated callus tissue. In the luxuriant cambi6é1 callus
of poplar cuttings, ball-like tracheid groups are produced here
and there, as already described, In these, as in those des-
cribed earlier, we find irregular forms. Mhe root too may be
able to produce the same forms of wound wood, a8 are produced
on acillary parts, The same "balis” may be found in the callus
of roots as in that of organs above ground, I investigated

‘more closely the callus products of Taraxacum roots. ‘In the

basal callus rolls of the cuttings, woody cores are produced
composed of long and short tracheal elements, The cells, how-
ever, are differently arranged and in such 4 way that in every
section one meets here and there with groups of cells, cut
lengthwise, and side by side others cut crosswise or slanting-~
ly. In the middle lie the strongly bent tracheids, such as
described above. Round about this woody core there lies a
pall-like cambial covering, which on the outside produces con~

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162

centricnlly layered bark tissue with abundant latex tubes,
The sqparate balls are usually connected with one another
and with the cambium of the cutting by means of cambial
bridges,

The cases here described prove at the samt time that
the formation of the balls is not connected with advance é
stages in the production of wound wood, but my also indicate
the beginning of its formation,

Tissues furnishing wound-wood

Just as the cgambium, to the #erivations of which the pre-
ceding statements chiefly refer, can produce wound wood or
products similar to 1t, all other tissues, furnishing callus,
can also produce wound wood under certain circumstances, The

ith is concerned here more thin all other tissues, In differ-
ent plants, for instence in Populus, it is highly capable of
forming callus, In the medullary callus, tracheids and groups
of tracheids are also produced very early, on the periphery

of which are formed new meristematic tissues, The formation
of tracheal elements which Prillieux@&tudied in the pith of
different cuttings (Coleus, Ageratum, Achytanthus and others)
should be mentioned,

A cese described by Maule (loc. cit, p. 27) is of inter-
est for severel reasons, In Evonymus europaea, cambial form-
tion was brought about in the pith when it had not been direc-
tly injured, In several branches, from which rectangular
pieces of the bark hed been cut the cells of the round tissue,
resembling parenchyma and containing chlorophyll, which lies
between the pith zone and the pith, was incited to division
beneath tho place of injury. From the new tissue thus pro-'
duced, & cambium was differentiated which, extending pike ‘an
arch, produced xylem on the inside, phloem on the outside, alsa
& new bark zone and & new cork layer, "so that therefore, all
the zones of a regular woody-trunk are formed within the old
woody body", "It must still be noted that the beginning uf
the formation of wound-wood in the pith did not coincide with
the beginning of its formation on the external, directly in-
jured, part of the branch, As a result of the exposure, the
wood under the places where the pieces of bark has been re-
moved, begen to turn yellow, i. e. to be changed chemically.
This change progressed slowly towards the centerg especially

along the medullary ray until the entire old wood body had

been altered as far as the injury extended, If the trans for-
mation in the medullary rays had penetrated as far as the pith,
cell division then began in the latter, There existed here
therefore the remarkable case, that the pith was not directly
brought to the formation of wound-wood by the injury, not even
by the wound stimuli, but only by a secondafy phenomenon’ con-
nected with the injury". We will later find other cases,
which make it seem probable that living elements adjacent to
the dead cells can be stimulated to division by the products
of decomposition in the latter.

The isolated wood bodies, which Vochting and others?

ee eee

é Vochting, foc, cit, p. 141, 142. Tschirch, Pflanzena-
tomie, p. 396, Mauie, Der Faserverlauf im Wundholz, Bibl,
Bot,, 1895, Heft. 33, ps 23s

(182)

162

found occurring in processes of cicatrization and coales-
cence in the bark, seem to correspond in all essential pointe
with the tracheid groups described above, In them also an
independent cambium is formed around the core of the wood,
The ability to form this kind of isolated wood-cores of larg-
er or smaller compass might well be peculiar to very many,

or indeed to all plants which form wound-wood.

Tissues resembling wound-wood are produced also in the
callus developed from the ground tissue of injured leaves,
At any rate, so far as my experience goes, it must generally
end with the formation of isolated parenchymatic tracheids in
them. More extensive quantities of tracheal elemonts occur
for exmmple in the form of isolated spherical groups of cells
in the callus of detached Vicia cotyledons, Here too we find
again the formation of gnarls of moderate size,

Outer Form and Perigd of Development of Wound-Wood.

Conditions of its Formetion.

Wound-wood has no definite outer form, Its form is de-
termined in the first place by the Swollen rolls occurring on
the surface of the wound, the form of which depencs naturally
on the naturo of the injury. hus a differently formed wound -
wood body is produced after cross or longitudinal sectioning
then from girdling or spiral wounds ond the like, The wound-
wood body always adjusts its form to the space conditions
granted it. Therefore it is immaterial for ovr consideration,
whéther the cambium is incited to the formation of these rolls
by injury, by accidental or intentional mechanical interfer-
ence with its integrity, or forms them after local injury from
frost. If the frost causes the death of the cambium in places
of any indefinite extent and if the dead@ plece is later sur-
rounded by rolls of wound-wood, then we speak of cank¥r (frost
canker). If the so-called frost tears are caused by 8 split-
ting of the wood, the masses of wound-wood produced by their
healing are called frost ridges. The manuals of phytopathology
give more exact information congerning the significance and
distribution of these phendmena-.

R. Hoffman® has shown how the course of the medullary
rays in the covering rolls is determined by mechanical incidents,

The period of development of wound-wood varies with con-
ditions wnd within wide limits, as does that of callus, It
is known that the rolls of "canker" (frost canker) are destroy-
ed every winter by the action of cold because of the greater
delicacy of their tissues, so that in the following year the
injured tree "tries" to heal its wounds by a new overgrowth.
Under these conditions wound-wood can be formed for many years,
the rolls of which are laid one above the other like terraces,

The conditions necessary for the formation of wound wood
#équire still closer investigation, as do those of callus for-
mation, AS stated above, there has been as yet no successful
analysis of the "wound-stimuli” effective here. The dependence

ee oe To a

Ba. 1, p. 207 ff,

2 untersuch. ub, d. Wirkung mechanischer Krafte auf die
Teilung, Anordnung und Ausbildung der Zellien etc. Disserta-
tion Berlin, 1885.

(183)

i 164

“upon external conditions of wound-wood formation and of its

histology has likewise not been closely tested, Undoubtedly
the structure will be influenced by nutritive and transpira-
tory conditions, as is that of normal tissues, Compare also
the statements on callus page 171.

The fact that the conditions giving rise to the formation
of wound-wood are not only effective, directly at the place
of injury and in its immediate vicinity, but also at a con-
siderable distance is of great importance, De Vries! eyperi-
mentS on Salix, Acer, Evonymus and others (loc, cit. p. 113)
prove that, when the outer bark layers are wounded, no wound
stimuli are produced, which would cause the production of
wound -wood,.

Tissues resembling Wound-wood,

Aside from the different forms of gall-wood, to which we
will return later, there are abnormal wood tissues which do
not arise after injury but from the actian of some other fac-
tors, These, however, are more or less similar to wound-wood
so far es their histology is conce rned. Besides these, tis-
sues of the same composition must be considered in the follow-
ing, concerning which no decision has been reached as to
whether their produetion is due to wound or to other stimuli,
We will defote a few lines here to their discussion.

The production of tissues resembling wound-wood proceeds,
as does thet of wound-wood itself, either from the normal cam-
bium ring or from newly formed, independent cambium,

Apnormel tissues should be considered first of all, which
are produced by the activity of division in the normal cambium
ring. In all cases, the deviation from normal histological
conditions consists in a lesser histological differentiation
of the wood tissue produced. The deviations described above
are approximated first ef 211 when the parenchyma of the med-
ullary ray increases in places at the expense of the other
formal elements of the wood, Abnormally broadened medullary
rays are not infrequently found in fasciated branches, The
factors, leading to the fasciation and thereby to the change
in histology here named, are still unknom, The occurrence
of abnormelly broadened me dud lary rays in non-fasciated
branches is also not unusual”,

In other cases normal differentiation is lost to the
secondary woody-coalescence in all its parts. <As,Sorauer as-
sumes“, slightly differentiated wood is produced, for in-
stance, in the fruit spikes of Prrus communis, as a result of
rich nutrition and abundant supplying of water, and as a sign
of the "weakening of the branches through cultivation". In-
stead of libriform fibres, predominantly parenchymatic ele-
ments are produced in the wood and generally remain unligni-
fied. Besides these, a luxuriant development of the bark
takes place, which causes it to rupture here and there, Un-
differentiated wood is produced also in the "dropsical"

Wor tse

2 Nachweis der Verweichlichung d. 2weige uns, Obstbaume
durch d. Kultur. Zeitschr, f, Pflanzenkrankh,, 1692, Bd. iI,
p. 66, .

(184)

: 165
branches of Ribes*.trected of earlier, Still more exemples
of this kind might be etted; an crrestment of the processes
of differentiation end an increase of the parenchyme con-
tained in the wood is olmost always assoocinted with over
production of wood,

Those eases must still be mentioned in which new onan-
bial layers are produced, leeding to on chnorm.l form.tion
of wood, dust cs in wound tissues described cbove, isolated
wood cores of varying size are produced by the activity of
their division, :

Sornuer hes given thorough anatomical descriptions of
the "tuber-like gnorls" of the stone-fruit trees, and Krick
of similar formations in beech bark®,

Sorauer found tuber-like woody bodics in the bark of
Pirus malus, In their centres lay one or two hard bast bun-
dics, separnted by lignified perenchyma, About these "are
layered in a ray-like arrengement, first of o11 approximete-
ly iso-diametrie cells of wood parenchyma, lying bluntly up-
on one another, and usuclly contraining starch", Little by
little this zone passes over into narrowef, thicker-walled
wood parenchyma cells, already somewhat elongated end running
horizontclly or diegonallyp between them are scattered short,
broad simple pitted duct cells. These groups have oclready
been divided into numerous circles of bundles by approximate-
ly cubicel medullary ray cells, lying possibly from 1 to 3
rows thick, The further the celleelements ere separated from
the centrum, the more marked is the difference between the par-
enchyma of the medullary rays and the elongated fibro-vascu-
lar tissue, Near the centrum, begins also the phenomenon
which makes itself felt throughout the whole wood body, that
is divided into different annual rings,- viz., thot the ele-
ments of the fasciated partlying between two medullary rays
show a different course than do those of the parts lying near
it. While the razor cuts through the cells and ducts of one
bundle almost in cross section, it strikes those of the adja-
cent bundle longitudinally". Many tuber-like gnarls vary from
these here described, in that the hard bast bundle is lacking
cs a centrum; instead of this is found a group of bark paren-
chyme cells.

The isolated wood bodies which Sorauer (loc, cit, p. 185)
found in 4 branch of Pirus communis resemble in all essential
points those described, - in which a one-sided flat swelling
was conspicuous. "The cross-section through the middle of the
swelling showed new, isolated, wood bodies almost touching one
another, however, at the sides, which were entirely separated
from the central wood cy}inder of the Branch by a normal cam-
bium and secondary bark zdne. Each of these wood bundles bore
in the center a hard bast group and had also the structure of
the centrum of the tuber-like gnarl of the apple, only, the
wood cells and ducts were not arranged cone-like on all sides
about the centrum but extended parallel to the length of the
branch, There were, therefore, no wood tubers, but short
wood-cords, which traced further downwards became steadily

-— > -~ -_-_ - aa _— etme

1 Soraver, Wassersucht bei Ribes aureun, Freihoff(s
Deutsche Gartenzeitung, 1880.

2 Sorauer, Die Knollenmaser der Kernobstbaume, Lana-
wirtsch, Versuchsstat,, 1879, Bd. XXIX, p. 173, Handb. da.
Pflanzenkrankh,, 2, Aufl,, 1886, Bd. 1, p. 726. Krick, Ueb,
d, Rindenknollen d, Rotbuche, Bibl. Bot,, 1891, Heft 25.

. 166

thinner until they showed a simple, weak, ring-like bast
circumypllation, formed of lignified parenchyma", Toward the

top, the cords approached the central wood-body more and
more closely and were finally united with it.

’

The eonditions under which tuber-like gnarls are pro-
duced are not yet sufficiently understood, Sorauer states
that they are formed "readily near the outgrowing wounded
surface"; which ergues in favor of the supposition that some
of the conditions created by the injury become the cause of
thas formetion,

The isolated woody kernels of tissue which lie in the
bark of Fagus silvatica (fig, 72) and which have been thor-
oughly described by Krick as "bark thbers", show a still
greeter diversity in development end histology, They are
either produced in connection with preventitims buds or short
shoots which have been separated from the wood body of the
mother stem,- their oambium this being descended ontogeneti-
cally from the normel cambium ring, in as much es it was con-
nected with it, at least at the beginning, or they are inde-
pendently formed of buds and short shoots without having eny
connection with the mother stem, In the later case, Kriok
distinguished between tubers with central wood bodies and those
which enclose cork tissue at their centre, The formation of
these bark tubers seems to hava nothing to do with any in-
jury and its results.

Krick has collected the statements of earlier authors
coneerning bark tissues (loc, cit), As one of, the most im-
portant works may be named here that by Gernet~.

1185) The gnarl-tubers of different Eucalyptus types, e8l-
ready repeatedly studied, are of eSpecial interest, They
occur in the, ames of the first pairs of leaves and, ac-
cording to Jénsson“, are produced under the influence of
unfavorable nutritive conditions, The dependence of
their growth upon that of the whole plant reminds,,one of
the correlation heteroplasmas mentioned above. JoneHan
could bring about the production of ri-tubers by cuf- |
ting off leaves, buds, or branches, 41, ¢,, he cowld nteten:
their growth, According to Vuillemin, the Eucalyptus
tubers are produced under the influence of a parasite,
Ustilago Vrieseanea, which is said to cause tuber-like new
formations of other Myr$agoae (Myrtus, Acmena, Tristania,
Melaleuca, Callistemon)°>*,

Pe ee od

- Ueb,, 4,Rindenknol len von Sorbus aucuparia. Moskau, 1860,

Ytterligare bidrag till kannendomen om masurbildningar-'
na hos Myrtacerna, sorskildt hos sligtet Eucalyptus. Bot, Not.,
1901, p. 181, further bibliographical citations there in.

‘ 5 Vuillemin, S, 1, tumeurs ligneuses prod. p. une Ustilag-
inee Chez,1, Eucalyptus, C, R. 4cad. Sc, Paris, 1894, T,CXVIII,
yp. 933, Les broussins d@ Myrtacees, Ann, Sc, agron, Franc, et
etrang., 7. Il; compare Zeitschr. f, Pflanzenkrankh, 1896, Bd,
Iv, p. 167/

4 purther data on gnarl formation may be fouhd also in
Andreae: Abnorme Wurzelanschwellungen bei Allanthus glandulosa,
1894, v. Kolb, Abnorme Wurzelschwell. bei Cupressus sepervir-
ene; Arcularius, Fall v. Wurzelkropf bei Abies Pichta, etc.
T6897 (Erlanger Dissertations),

(186)

167

, The "Chichi" (Nipples) of Ginkgo biloba atte gnarl
formations which arise after injury but originate like
many bark tubers of the Beech from definite buds, They
are leafless, branch-like excrescences which, on the
shoots and roots, can grow out into adventitious buds,
even becoming 2 meters long, Keniiro! calls them "cylin-
der-gnarls" on account of their form, The arrangement
of theirt racheids is irregular, like gnarls.

4, Wound-cork,

After injury of different organs,- roots, tubers, rhi-
zomes, stalks, leaves, inflorewcences,- several layers of
cells are often formed arranged in rows, and generally in
immediate adjacency to the place of injury, Since the newly
produced walls react to known reagents (sulphuric acid,
chior-iodid cf, zink, Sudan III, etc.) as do those of cork,
Since the abnormal tissue corresponds to cork in the arrange-
ment of its elements and since further the dependence of its
production upon the abnormal conditions created by the injury
is unmistakably, the products described have for a long time
been called wound-cork,

Wound-cork is generally formed on all parts of the
wound and at its edges conndécts directly with the normal mem-
brane of the injured plant organs,- epidermis or cork, The
new cork formation thus seems to close the wound. Since
wound-cork doubtless reduces the transpiration of the exposed
tissues and may indeed in other respects be able to compen-
sate for the normal membrane, we may assume that, by its fors
mation, the continuance of the exposed tissues and of their
functional activity is assured and we may speak of a healing
of the wound by the formation of cork,

There is not mach to be said concerning the life-his tory
of wound-cork. A number of celldivisions takes place in
either one or in more cell layers under the surface of the
wound and parallel to it, Not infrequently an obvious meris-
ten zone is thus produced and the wound cork is increased
through the activity of its division. The ground tissue is
here, as in many other cases, by far the most efficient; the
thin-walled, parenchymatic parts as well as the collenchyma
fibres are capable of producing wound cork. Besides these,
the cambium and the bark produced from it come under consid-
eration and finally the epidermis also, If the last becomes
active in the formation of wound cork, each cell generally
seems to be capable of very few divisions. In Wounds off the
stems and leaves, the derivation of the epidermis and of the
ground tissue form together a homogeneous wound cork plate,~
It is known that the place of production of the normal cork
of the trunk (epidermis or ground tissue) is, however, usu-
ally constant in genera and families.

The histology. of wound cork is characterized by the ar-
rangement in rows of its sheet-like elements, The walls of
wound cork are always thin and often folded. I found thin
walled wound cork even in Cytisus, the normal cork of whose
trunk is known tobe made up of thick walled cells, Differen-
tiations of any kine whatever, formations of zones, lenticels
and the lika, entirely absent in wound cork, Its cells gre

-— ear eee

1 On the nature and origin of so-called "chichi” (nipple)

of Ginkgo biloba. Botan, Magaz, 1896, Vol. IX, aueh Zeitschr,
gf. le rank e 1896, Ba, VI, De 2e5.

‘ 168

usually larger than those of the phelloderm, It is worth
noticipg that even those plants can be capable of forming
wound cork which, under normal conditions. develop no cork
on their stalks, (Experiments on Viscum)?,

Nearly relatec to wound cork is the multicellular tis-
sue, which often grows out from the wounded bark on the’
places of insertion of roots and buds, If, for example,
Salix branches ure placed in water or brought into a room
saturated with water vapor, numerous roots develop on them,
at the base of which a smull, porous, whitish mound of tis-
gue is noticeable, which has the greatest similarity to out-
growing lenticels, (@ompare p. 75). It is founf in cross-
section that a meristem is produced near the wound in the
bark, the derivatives of which resemble elongated colorless
bells or scas, Between the individual cells, which are often
entirely detached from one another, lie large intercellular
spaces filled with air, Therefore the structures described,
also histologically mesemble hypertrophied lenticels., Mohl
has called attention to this similarity and warned others
against confounding the forms. The same tissues are also
produced as in the places of insertion of the roots, if buds
injure the tissues of the bark during their development.
(Fig. 73). The walls of the wound tissue described do not
become cork,

As fur as the conditions are concerrsa, under which
wound cork is produced, the relation of its formation to the
(187) injury and to the conditions created by it, first come under
consideration, Each break in the continuity of the tissue
can cause the formation of wound cork, no matter if the wound
lies on the upper surface, whereby the surrounding air has
direct access to it, or if "internal" injures are inwolve
such aS are produced perhaps by twistings of stalks, etc.”.
A preliminary condition of its production, however, is that
at least | small degree of transpiration must be possible fa
the exposed tissue, On this accowmt no wound cork can be
produced in the sting canals made by parasites which produce
Qics, but only callus tissue (hypertrophy and hyperplasia).
n the succulent, juicy gall of Nematus vallismerii upon
whoee innermost tissue voracioussinhabitants of the gall cav-
ity constantly graze, a richly outgrowing callus is produced,
but wound-cork only in exceptional cases (in injured galls).
Tissues which seem incapable of forming callus, such as the
parenchyma of the potato tuber, develop wound-cork after in-
jury,only when transpiration is pogsible, There is no forma-
tion of the wound-cork under water*, Of the many changes in
conditions usually caused by injury, apparently the abnormally
1 Damm, Ueb, d. Bau ad, Entwickelungsgeschichte u, d, me-
chan, Eigensch. mehrjdrh, Epidermen beimd, Dikotyl. Beih, 2.
Bot, Cbl,, 1901, Bd. XI, p. 219.

—_— = oe

Quoted above p. 75, note l.

3 Compare v, Brefeld, Ueb, Vernarbung u. Blattfall.
Pringsheim's Jahrb, f, wiss, Bot., Bd. XII, p. 133, also
above p. 162, note Z,

4 on the causes of the formation of wound cork, compare
@lso Frank, Krankh. d, Pfl, {2 Aufl,, Bd. I, p. 61 ff. Kny,
Ugb. a. Hinfl, v. Druck u, Zug auf die Richtung der Scheide-
wande u. S. W. Bef. d. D. Bot. Ges., 1896, Bd, XIV, p. 378,

169

increased elimination efwater from the exposed cells and
tissnes comes first of all under consideration in the forma-
tioy of wound cork, It is certain that "wound-cork” can also
be produced independently of any injury, if only the elimin-
ation of water is in some way abnormally increased, A case
(188) of this kine seems to me to be present when the large celled,
thin walled, strongly transpiring intumescences of Hibiscus
ore cep.rated from the normal mother structure by e layer of
wound cork”. It is well known that wound-oork is formed
sooner or ater in callus excrescences, which grow out on
the cut surfaces of cuttings etc, It is difficult, to decide
whether the formation of wound-cork should be considered as
a delayed effect of wound-stimuli, or as 8 result of the
strong transpiration, to which the callus tissue is exposed,
Similar conditions are present in the intumescences shown
above (fig. 23), the formation of which is preceded by a
dissolution of the normal cell-continuity ond the foundation
of which is often connected directly with wound-cork, In
these, o8 in callus, it does not seem to me improbable that
the abnormelly increased transpiration of sbnormal tissues
can call forth the formition of wound-cork entirely indepen-

dently of the dissolution of the tissue continuity and of
*"wound-stimuli"©,

Up to the present, it has not been proved dsfinitely
that under certain circumstancds factors other than abnor-
mally increased transpiration car also cause the formation
of wound-cork; but there is much in favor of it. Wound cork
is often produced when separate cells or cell-groups die in
the inner part of the tissue; a more or less ztrong cork
mantle is formed urovhd this center of disease, It does
not seem to me very probable that the transpiration of the
cells left in the center of the tissue has been abnormally
increased, and that the formation of wound-cork has been
caused by this; rather we should not Peject the supposition

1 Compare above p. 86 note,

2 ‘the production of cork in thé letives of Ribes grossu-
laria seems to be comparable with the cases named, in a Low
lying past of hisexperimental garden, Sorauer (Handb, d.
Pflanzenkrankh., 2. Aufl,, 1686, Bd, 1, p.222) observed
gooseberry bushes with groups of branches entirely gray
jeaved, Sorauer designates the disease os cork-sickness,

The individual leaves were either covered only with two cush-
ions or cork, spreéd out like wings, or were coated over and
over with cork, I think it allowable to deduce from Sorauer's
statements concerning this disease, which I myself have ned

no time to investigate, that the formation of distended in-
tumescences precedes the abnormal production of cork - hhe
palisade celis stretch and burst the epidermis - then follows
the formation of wound cork.

3 veber Transplantation am Pflanzenkorper, 1898, pp.
113 ff, The cells connecting directly with the destroyed
parts always become cork; "those following next, however,
often the majority present, are still unbrowned and of a
cellulose nature, This is then retained even if all pro-
cesses of growth have long ceased", The turning to cork is
almost always absent, even "if thickened walls turn brown
in the zone of contact and delicate walls occur in the ele-
ments belonging to or adjacent to these”. Yf is an open
question whether these cells also can serve for a covering

170

cicatrizations of the bests upon which he operated; but cork
had been formed only in the vicinity of those enclosures which
ned turned brown, in which therefore some products of disin-
tegration hed been produced. In different succulents which
Showed an especial "tendency" toward a vigorous formation of
(189) wound-cork softer injury, I repeatedly observed strongly de-
veloped formations of cork ‘in the region of dead parts of
tissue, and, as I suppose, undor the infiuence of unknown
chemical combinations, In this connestion elong perhaps
the "cork excrescences" studied by Bachmann”, whioh make. pos-
Sible the »~roduction of extensive tissue protuberenoes or which
in places aan chinnel the organ concerned or completely per-
forate it, (Ilex, Zamia, Ruscus eto,) while division of the
parenchyma cells end the suberization of their products of
division progresses further and further into the interior of
the leaf. Histologically ond ontogenetionlly the oork ex-
cresocences described and illustrated by Bachmann correspond
throughout with typical wound cork.

The manuals of phytopathology should be consulted
on potato scurf or scab, Nobbe produced cork exoress
cences on potato tubers by cultivating them in water”,

Gike callus (see above), wound cork ¢an be produced also
on "physiological" wounds,, Many plants develop it, for ex-
ample, on their leaf sears”,

5. Galis

We have termed gall-farmations all abnormal tissues pro-
duced by the acticn of vegetable or animal parasites, The
great majority vf these arise either through ce}l growth
alone (gall-—hypertrophy) or through ceil @ivision (eal 1 -nyeees
plasia): Since, in the latter case, the newly produced tis-
Sues differ more or less strikingly from normal ones, we are
concerned only with hyteroplasms in such gall-formations.

The number of heteroplastically constructed galls is ex-
traordinarily large; even the diverse gall hypertrophies re-
_ “1 veo, Korkwucherungen auf Blattern, Pringsheim's Jahrb,
f. wiss, Bot., Bd. Xif, p. 191.

@ Die Kartoffel als Wasserpfianze, Landwirtsch, Versuche-
Stat., 1864; Bad, VI, p. 57.

- Compgre further Tison, Rech, s, la chute d, feuilles 4,
Dicotyl, These, Caen, 1900. This tissue becomes of interest
for pathological plant anatomy only when it arises at the
wrong time as a result of abnormal conditions, I would like
to refer at this opportunity to the fact that the "tissue of
separation", which makes possible the’ freeing of the leaf from
the axis, is produced prematurely if the leaves are robbed of
their blades; the axis then lets the petioles fall off, Ths
question whether the resuits of wound stimuli are to be recog-
nized in this needs supplementary testing; it is more probable
that the reduced transpiration determines it; a]so branches’
left in moist air are known to drop their leaves, (Wiesner,
Untersuch, uber die herbstliche Entlaubung ad, Holzgew. Sitz-
ungsber, Akad, Wiss, Wien, 187i, Bd. LXIV). In these and sim-
ilar cases, the wound produced by the fall of the leaf ‘is no
longer a “physiological" one, The question as to whether the
tissue uf separation produced on mutilated leaves and by ac-
tion of moist air corresponds with the normal one, needs
supplementary testing.

(190)

py 2

main far below these in number, Heteroplastie gall formations
occur in very different kinds of plants, appear on all plant
organs and may be traced developmentally to very different
normal tissue-forms, A few general notes might be in order
before we proceed to a descrintion of the different fall forms,

One generally terms galls, or Cecidia?, those variations
in form which are caused by foreign organisms, ‘Thomas, whose
definition of the conception of the poll has received the most
approval, expicins aS a Ball, ‘every variation in the form of
plants which is caused by © parasite”, “and adds: "in this ex-
planation the word formation is to be taken directly in the
sense of the process (therefore active), not merely in the
sense of its result, Each leaf eceten or mimed by caterpillars
Shows a formal variation. No one will associate such changes
with cecidia. To the nature of these latter belongs active
participation of fhe plant, its regotion agninst the siigulus
then experienced”,

I have attempted ot an egrlier opportunity” to define
more sharply the definition given by Thomas and have advised
a closer consideration of the biological conhection between
the plant bearing the goll and the foreign organism producing
it, in the formulation of the definition. Clearly there are a
number of variations of form which are caused by stimuli given
by the foreign organism and in which abnormal tissues are pro-
duced, without one's venturing to call them galls, Such a
case is met with perhaps when a"mining path" is filled with
callus (examples above p. 163). No one will contend that such
cases present gall-formations. The abnormal tissues show no
connection with the foreign organism,- aside from an etiologi-
cal one. In our opinion one essential of a gall is that the
abnormal parts of the plant affected bring about symbiotic re-
lationship between these and the parasites producing the gall.
These symbiotic relations are primarily of a nutritive physio-
logical nature; the abnormal tissues furnish food for the par-
arsites, Additional relations exist since the host plant not
only furnishes sufficient maintenance, but also as good shel-
ter. The galls are thus formal variations of the plant which
promote the development of the parasites and are in this sense
"expedient" for them, Now, since according to ghe above sym-
biosis with the producer of the gall always signifies a loss
of nutritive material for the host organism, the part which
bears the gall often dies a premature death and further, since
in all cases as yet known the parasite producing the gall per-
forms in return no service to the host, as one is often in-
clined to assume in so-called mutualistic symbiosis, we are con-
cerned in cecidia with formal variations which are injurious
to the development of the organism bearing the gall,

Of all the variations in form satisfying the demands of our
definition, we will naturally treat. in the following only those
in which abnormal tissues are produced. To present the doubling

— = -_ CO ee ee - a - - = ~-— me ee eee

2 toe. cit, pe 513, 514,

3 Kuster, Ueber einige wichtige Fragen der pathol. Pflan-
zenanat. Biolog. Centrabl.. 1900. Ra. XK. n. 29.

(191)

(192)

172

of infloreseences, ceused by gall-inseets ana galleplants, a

turning green of tissue
task of the morphologist. abnormal brenching etc, is the

Galls form a oup, well i
ogically, In theif histology “Rowever’ He ear pT ond, bio}:

one feature, which i8 common to &ll., Even when considerin
only gfll-hyperplasias we will find no common i obsess eS -
ae oe ese Nata — heteroplastic tissue is involved °
P £38 either extraordinarily simple his vy
showing little or no differentiation, aw ae a aoe ae
same chiracteristics as met with in "arrested developments"-
or Specific differentiations which bring about strhotures en-
tirely different from those known in normal tissues, We will
call tissue formations of the first kind kataplasmatic galls
or kataplasmas, and galls of the second kind prosoplasmatic
g6lls or prosoplasmas, We will base the division of our
abundant material upon the given differences between the for-
mer and the latter, Even with the help of this principle of
division we will not be able to set up two entirely distinct
groups, but with its use we will only rarely be uncertain as
to whether the separnte gall forms belong to this or that
group, One could perhaps add to those galls, conceived-as
transitional between kataplasmes and prosoplasmas, the others,
which, in spiteof their verv simple tissue structure, develop

¥

"new" characteristics - in that the cells show abundant anth-

,ocyanin content, instead of being colorless or containing

chlorophyll, or cells occur in them abnormally rich in cyto-
plasm, starch content etc, We will observe here that "typical"
and unquestionable prosoplasmas often contain other cell-forms
than those of the corresponding tissue of normal plants and
that further the different kinds of elements participating in
their construction are united into well-defined zones,

It is to the interest of a natural classification to con-
Sider the morphological characteristics of galls together with
their histology. We will show that galls with kataplasmatic
tissue characterintics haze no definite outer forms «and no def-
inite size, Heteroplasmatic galls show varying sizes and forms
just as do callus tissues, formations of wound-wood and the
fields of Erineum galls. We find, however, where galls of
prosoplasmatic tissue structures are involved, that the outer
appearance of the galls assumes "new" characters, being char-
acterized by definite proportions of size and form, Kata- ©
plasmas are often produced by the action of parasitic fungi,
which in the inner part of the host plant take up @ field of
distribution of varying extent, or aftor infection by animals
which live freely on the apper surface of the diseased organ
and by their wandering can indefinitely enlarge the field of
their stimulation, Prosoplasmas are produced by the action of
domiciled organisms, the extent of the field of stimulation re-
maining the same under all circumstances, Further, the differ-
ent effective periods of the stimuli,which produce the galls,
must be considered, The stimulus caused by producers of proso~
plasmas is felt only in definite phases of their development,
which, in various species, is enacted in a certain number of
weeks and months, while many constant period of stimulatory
action seems absent in kataplasmes the producers of which can
often grow to be many years old and still be effective. We.
will be able to explain the histological differences between
kataplasmas and prosoplasmas only by the specific quality of
the effective gall-stimuli, But we vill venture to trace the
constancy, or rather the variability of the form and size pro-
portions in different gall-products to the temporal and local
extent of the effect of the stimulus,

{193)

173

Finally, a few words more concerning the etiology of
galis. «Naturally, nothing at all coneerning the qacters act-
ually effective is indicated by the statement that these galls
are produced after the infection of vegetable tissue by any
parasites, Usually injury to the plant organs goes hand in
hand with infection, Indéed many galls very strikingly re-
Semble tissues produced after injyry. This phenomenon becomes
elearly evident in those cases, for instance, in which are in-
volved diseased products of the cambinm, influenced by para-
sites. In very many other galls, the structure of which ex-
ceeds the kataplastic character of wound tissue, at least the
first stages of development resemble callus tissue, The fact
that, in the production of prosoplasmatic galls, new processes
of differentiation and formation must be added to those known
for cal lus, proves satisfactorily, however, that still other
stimuli besides traumatic ones must often participate in the
formation of galls, Besides this, there are many galls in
which it can be demonstrated that infection takes place with-
out injury to the vegetable tissue, in which therefore all
traumatic influences are excluded even from the beginning,

The gali stimuli are undoubtedly of a chemical nature; some un-
known substances, excreted by the parasite, incite tho colls

of the host plant to ggrowth and cell-division and undor certain
conditions the products of division to difforont processes of
differentiation, We know as yet nothing definite concerning

the chemical character of the substances acting here, Up te

the present, all attempts to cause gall formation by artificial
inoculation with substances of known composition have failed.
Unfortunately experiments, made with the contents of the "poison
sac" of the leaf wasp in the endeavor to call forth ragti ficial"
gall formations, have as yet given no positive results*,

Disregarding the fact that the wound stimuli, preceding the
formation of various galls, enclose within themselves a complex
of many factors the Significance of which is still but little
known, 48H analysts of the factors active in the formation of
galls was not perfected even with the discovery of traumatic
Stimuli and of the action of gall poisons. It is to be hoped
that future experiments will throw lnght on the question as to
Whether the tissues of the plant in their normal condition are
always susceptible to chemical stimuli or whether, in the for-
mation of galls, they are often made susceptible to stimuli of
other kinds only by traumatic interference and its results, It
will be necessary to test further the questions as to whether
the stimuli or contact proceeding from the larvae, which wan-
der about inside the half-grown gall, are not also kmportant
in the further development of the gall, or whether it is pos-~
sible, and in which cases it is possible, for the larvae to
bring wound stimuli into affect by grazing upon the innermost

tissues, thereby causing a new production of tissue;- whether

the excrement balls, thrown off by the inhabitants of the
galls, can act as 9 fertilizer, whether new stimuli proceed

from these, etc,

We know but little, at any rate, about the capacity for re-
action against gall poisons possessed by definite plents and
definite tissue forms, because, in judging of this, we are
still dependent upon the investigation of the new formation of
tissue produced in nature ané because the gall-insects cause
their virus to act onby on a definite substratum. On this ac-
count the question, as to whether tissues other than the ones

1 Beverinck, Ueb, ad. Cecidium v. Nematus Capreae auf Salix
amygdalina Botan, 2tg., 1888, Bd, XLVI, p, i.

(194)

174

preferred by them cre clso expable of reacting in the same way
must remain unenswered, We will be fully informed es to many
of the auestions referred to here onlyvhen it is possible to
produce galls artificially on various plants and parts of
plants under varying external conditions. Then ve will be

able to test experimentally ell parts of plants as to their
sepecity for the formation of galls as we are now able to do

in the formation of callus,

Looking back at the speculations of the nature-phil-
osophers (Redi), we find that the assumption of an ex-
pecial poisonous action has always played the ohief role
in the attempt at expe ining the genesis of the galls.
Malpighi* assumed tha @ insect producing the gall ex-
cretes a poison which causes a fermentation of the content
of the infected plant; this fermentation exciting the ab-
normal growth which leads to the formation of galls.
Reaumur”,.to whom the secretion furnished by the gall in-
Sects seemed too scanty to cause such extensive new forma-
tions, thought that a kind of suction was produced by the
gall-producers end inhabitants, which caused the juices
of the plants to flow toward the place infected, Accord-
ing to him, & rise in temperature takes place at the place
of stimulati on- which Pavers tissue growth, and the theory
stated by Malpighi has beep proved capabie of further de-
velopment; Lagaza-Duthiera”’ returned in every detail to
Malpighi's theory and explained galls as the products of
the action ,of different kinds of poisons, Darwin and
Hofmeister” later expressed the same opinion about the
formation of galls, If the traumatic stimuli, which un-

doubtedly participatefin the formations of many, galls,
were overlooked or given too little importance by the

authors named it maybe explained directly by the fact
that their attention was directed first of all to the com-
plicatedly constructed prosoplasmas. We will be obliged
to return often to the similarity of many simply construc-
ted galls (kataplasmas) to wogjnd tissue; which favors the
theory that traumatic stimuli participate in the forma-
tion of galls.

All previous attempts to produce "artificial" galls
by inoculation with different poisonous substances have
failed, Compare, besides Bacerinck (spe above), reports
by Kny; Kustenmacher, Laboulbena, ete,

2 Réaurmr., Mém; ps servir. A l'hist, a@, insects. 7, III,
mem, IX u, X,

Lacaza-Duthiers, Rech, pour servir a l'histoire des
gajles, Ann, Sc, Nat. Bot., 1853, 3™° ser., 7, XIX. p. 273,

4 Darwin, On the origin of species, 5th edit., 1869, p.
572, Hofmeister, Allgem. Morph. d, Gew., 1868, p. 6354,

6 Kny, Ueb, kunstl, Verdoppelung des Leitblndekreisés im
Stamm, d, Dikotyl. Sitzungsber, Ges, natur®. Fr{, Berlin, 1877,
p. 189. Kustenmacher, Beitr. 2. Kenntn. d. Gallenbildungen eta.
Pringsheim's Jahrb, £. wiss, Bot., 1895, Bd. XXVI, p. 82,
Laboulbene, Essai d'ume theorie sur la production d, div. galles
veget. C. R, Acad, Sc, Paris, 1892, T. OXIV, p. 720.

c . a 175

The parasites, under whose influence abnormal tissues
are produced, are drawn from the plant and animal kingdoms,
("Phyto-cecidia" - "Zoccecidia"), The higher plants take
part here by means of the Loranthacese, while among the lower
plants fungi especially come into consideration as ineitors
of gall formation. The animals which produce galls bebnng
among the worms and the Arthropoda - the greatest majority
by far among the Intter, Mites ond insects especially pro-
duce the most diverse galls on the most widely different
kinds of plants, The Piptera and Hymenoptera play the most
prominent role and emong the latter belong the gall wasps
(Cynipida) which oan produce the most complicated of all gall
formations, Further the Hemiptera should be named, among
which are found many gall-producing leaf lice and shield lice,
and finally the butterflies and beetles, of which, however,

peer a small number of representatives are known to produce
ga Ss

_In out histological observations, we can enter only very
bréefly into the nature of the producers of galls, At times
it will be demonstrated that parasites, closely inter-related
can produce the most different kinds of heteroplastic tissues,
At any rate, fungi galls belong almost entirely among the kat-
aplasmas™, on the other hand, the galls of the Cynipida belong
predominantly among prosoplasmas, while gajls of both kinds
are produced in large numbers by Diptera and Zymenoptera, Also,
among prosoplasmas themselves, fixed relations between the
quality of the abnormal tissues and the systematic position of
the producers of the gall are neither very numerous hor strik-
ing; thus, for example, the leaf-wasps which produce galls of
@ simple structure are most closely related to the Cynipida,
whose complicated products will fully occupy our attentions.

Plants capable of producing galls, are found represented
in all groups of the plant kingdom, sometimes more abundantly,
sometimes less so, Cryptogams, in comparison to phaneroggms,
nust be distinguished as being especially poor in galls and
tho few which they develop have a simple histolegy. Among
phanerogams, the dicotyledons form the group which has galls
most abundantly, the representatives of which are capable of
developing kataplasmas and prosoplasmas in equal quantities,
The galls on trees and shrubs are universally more varied in
form than are those of bushes and herbaceous plants. Quereus
and Eucalyptus apparently belong to the plant genera which
have most abundant galls.

Gémpare for exceptions or disputed cases p, 211.

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j-
16)

‘ ae Kataplasmas.

We will term Pataplasmas those galls of any origin what-
ever,which are distinguished from the normal tissue of the
corresponding organs by the small amount of their tissue dif-
ferentiation. The differentiation of the Single cells cor-
responds to that menvioned above in callus and vound=-wood
tissues. Yhe tissue of kataplasinas consists often of abnormal-
ly large cell elements, the union of which usually gives a
thin-walled, often entirely homogeneous varenchyna. or ap-
proxinates it, Further, kataplasmas are characterized by
their lack of any definite characteristic form or regularly
recurring Size. .

Anong kataplasmas belong first of alb almost all Phytoce-
cidia; Since, anong the plants which produce galls, only a very
few are Imorm as yet through the action of which prosoplasmae
tic structures may arise.

We should mention as the most important gall producer
among Myxomycetes, the producer of the club root of cab-
bage,=_Plasmodiphore Brassicae., Ballelike swellings of
various forms and Sizes are produced on the rpots of
Brassica and other Cruciferae. According to Gobel, Tet-
romyxa parasitica, produces tuberlike swellings on
Ruppes.,, Sorosphaera Veronicae Schiroter moterately strong
outgrowths on the roots and peviclos of different Ver-
onica Species. According to tne recent investigations by
Toumay, the goitres of many ‘ruit trees etc. are the

products of 2 slime-fungus - (Denirophagus globosus).~°

Le The most important literature on myxomycete galls,— Wor
onin, Plasmodigphora Brassicae, Pringsheim's Jahrb. f. Wiss.
Bot., JO78 5 Bd. Ms Pe 548. Nawascrin, Beobe Ub a. feih. Baw
u. Umwandle. v. Plasnodiophora Brassicae ue Ss. f. Flora, 1899,
Bd. LXXXVI, p. 406. Gdoel Tetramyxe parasitica, Flora, 1834,

/ Ba. LXVII, pe 517. Schroter, Phytomyxinae. Engler-Prantl's

Naturl. Pflanzenfam. I, 1, pe 56 Toumay, An inquiry into the
cause and nature of crown-gall. Arizona Exper. Station,
1900, Byil, XXXIII. Muller-Thurgau. Il, Jahresber. Versuchs~
stat. Wadensweil.-- The disease of azave leaves (Tylogonus
Agavae, Athens 1888) described by Miliarazis might well not
be traceable to parasites. In investigating microscopically
the brownish cushions, occurring extraordinarily numerously
on the leaves, I found no traces of a slime fungus (Professor
Miliarakis most kindly sent me the material). Rather I believe
that the swellings, just like the well known black buttons on
the leaves of Gasteria and other succulents, are related to —
"hyperhydric" tissues (see above p. 83). Among the abnormally
enlarged cells there results a vory abundant formation of
Wound cork, by which the diseased parts of the leaf tissue
are separated from the healthy ones, Further investigation
would be desirable.~ The agave Gisease studied by Miliarakia
not only occurs in Mediterranean countries but also in Ger-

man botanical gardens etc.

96)

ee

Certain bacteria are known to incite the roots of
‘the Leguminoseae to the production of extensive tub-
ercles, consisting of parenchymatic, undifferentiated
tissue. We will not stop~ to consider the question,
whether this is to-be included among the new patholo-
gical formations, or not. We will Speak later of the

® Swellings caused by bacteria on Pinus halepensis and
Olea europaea. ?

Of the Bumycetes, all the chief gcoups come under con-
Sideration here; numerous Phycomycetes, Uredineae, Us-
tilagineae, Ascomycetes and Basidiomycetes develop kat-
aplastic plant galls. The galls of the Synchytriae
(Phyconycetes) were mentioned above (p. 108). Among the
Uredineae, I refer, for example to the Aecidia galls
of Viola, Berberis, Rhamnus, Urtica, to the branches of
Vaccinium Vitis Idaea attackek by Calyntospora Gopper=
tiana, to-those of Juniperus infected by GymnoSporangium,
to the products of Peridermiun Pini, which resemble wound-
wood, etc, and to the bizarre branching, produced by
Cacoma deformans on Thujopsis, Of the galls of the Us-
tilagineae, I will name only the smut boils on maize in-
florescgnces, (Wstilago Maydis) the galls of usta leRe
Treubii*, those of various Urocystis species above and
below ground. Of the Ascomycetes, especially the prim
itive forms (protomyces, Exoascus) come under consider-
ation aS producers of galls, Besides these, still a few
representatives of the Carpoasci which produce canker-
like woody excrescenees (canker of the larch produced
by Dasyscypha Willkomii eto.) of the Basidiomycetes,
various Exobasidium_species ere of interest to us as
producers of galls.

Tissue exerescences caused by Algae are kmown es="
pecially for Cystoseira opuntioides and C, erigoides,
upon which according to Valiante? and Sauvageu Streb=
lonemopsis irritans and Ectocarpus Valiantei live par-

Of the higher plants the Loranthaceae are almost the
only ones coming under considération here. They often
produce enormous gall formations, the so-called wood
roses, on their host plants. The infected branch of the

1. Compare Frank, Lehrbuch der Botanik, 1892, Bd. I, ps 266
ff; Therein also many further literature references. For var-
iously formed "tubercles" compare the dissertations by 0. Schwan,
Ueber d. Vorkommen vy. Wurzelbakterien in abnorm verdickten Wur-
zeln ve Phaseolus muitiflorus. Erlangen, 1398. = On the tubercle
outgrowths inhabited by bacteria, found on many marine algae,
compare above pe 154, note 2.

2. SolmsLaubach. Ustilago Treubii. Ann, Jard, Bot. de Bui-
tenzorg, 1887, T. VD, ps 79. We will speak again of this gall

in the section on prosoplasmas.

3. Compare especially the text book by v. Tubeuf, Pflanzen-
krankh, , durch ery ptogeme Parasiten verursgacht, 1895, Further
literature will be named later.

4, Valiante. Sopra un Eetocarpea parasita iella Cystosetts
opunticides - Streblonemopsis irritans. Mittle. Zool, ep ge
Neapel, 1683, Ba. VI, p. 489. Compare the illustrations in Eng
ler-Prantl, Naturl. Pflanzenfam. Bd, I, 2, Pe 199. | y, de
5. Sauvageau. Sur quelqu, algves phbosporées parasites. Je
BOts, 1692, Ts VE, pe 57, |

178

host grows out in a ridge around the clasp shieid of
‘ the parasite (Phoradendron etc.) , thereby producing

radiated cup-like excrescences, corresponding to the
form of the perasite.t : / .

The Zooceéidia, which may be classed among kataplasmas are
produced especially by worms (Nematodes) and also by mites
and insects,

Nematode galls, produced by Heterodera and Tylen-
chus, are found on’ the aerial and underground parts
of the vary many different plants, H. radicicola is
important because of its distribution; it produces
Hee galls on the roots “f monocotyledons and

icotyledons, Nematode galls (produced by Tylenchus
fucicole)are said to occur also on Ascophylium nodosum

Of the mite galls, I consider as belonging here
the fleshy (hyperplastic) curlings of the leaf edges
of Tilia, Crataegus, Pirus and many others, the bud
swellings of Corylus avellana, the galls on the tips
of shoots, which aré composed of swollen leaves and
the so-called pustule galls abundant on Pirus communis
on Sorbus and many others, many "Erineum’ galis, con-
sisting of multicellular cones and. ridges, such as
the so-celled_Erineum populinum,and still others.

The Diptera often produce complicated galls with
a prosoplasmatic structure; the kataplasmas called
forth by them repeatedly have the form of fleshy
cuttings of the leaf edges (for example, on Polygonun,
Populus tremvla and others) and swollen tips of shoots
(for example, on Glechoma) or there are produced by
a uniform swelling of numerous leaf bases or inflor-
escence stalks, clustered forms, resembling pine-
apples, termed pinapple-galls. Cecidia of this kind
have been found on various Crueiferae (for example,
Nasturtium, Barbarea) and others.

ee ee ee ee em tee eee eet tr meee ae te tee ne eee me in ae me eee cae ee a tee et ee ee en ee tee te ee ee te ee me

1. Gompare the illustrations in Engler, Loranthaceae,
Naturl. Pfl.-Fam., Bd. III, I, p. 61.

2. Statements concerning nematode galls are to be found
especially in Frank,,,Die Krankh. ad. Ppfl., 2. Aufl., 1896,
Bdeygell, pe 12. C. Maller, Mitteil. ub. de UNS. Kulturpfl.
schadlichen, das Geschlecht Heterodera bildenden Wurmer.
Landwirtsch. Jahrb., 1884, Bd. XIII, p. 1. Ritzama Bos,
Die Aelchenkrankheit d. Zwiebein (Allium Cepa). Landw. Ver~
suchssta#t., 1888, Bd. XXXV, p. 35. Atkinson, Nematode
Root-galls, J. Elisha Mitchell. Scient. Soc., 1889, Vol.
VI.-- Many new statements in Soraver's Zeitschr. f. Pflan-
zenkranki.- For Tylenchus fucicola compare Murray, Phyco=
logical Memoirs, 1892, Part Il, p. 21.

17°
The Hemiptera musi oe mentioned because of the salle

pe Aphids (leaf-lice) and Psyllodes (leaf-fleas).
leve too we find thickened, curled or swollen leaves
(for example, on Crataegus, Fraxinus ) kmot-like swell-
ings on roots (Phylloxera vastatrix on the roots of the
grape) ani canker-like woody-excrescences, for example
on Firus malus and Fagus silvatica after colonization
by Schizgoneura lanipera (the blool-louse) and Lachnus
exSiccator (the beech-tree louse). The shield lice, in
So far as they cause the fornetion of galls, produce ka~
taplasmas in the form of canl:er-like excrescences and
the like (on oaks and beeches, Coccus Cambii and C. Pagi)
ae ee ee Significance, Purther, the role

vy e bugs 7% G : s Co: tere a
Lepidoptera as eet dapecte Ge pauerdiugte: one domed
optera (leaf wasps and gall wasps) almost exclusively
produce gllas of a prosovlasmatic character and will be
discussed later, Finally I will mention the gall of
a. Copenod (Crustaceae) on, Rhodymenia palmatat

We find plants in all groups of the plant king@g@om , capable

of producing kataplastic galls. I+¢ is noteworthy that the

lower plants bear sells exclusively of a kataplasmatic character,

while on higher ones, kataplasmatic end prosodlasmatic structure

abound. The above-named galls on marine algae are of very

Simple structure end indistinguishable histologicelly from the
(198) excrescences produced after injury, (See ebove p. 154). The

Same i8 apperently true of the galls of fungi, if I may include

here the abnormel tissvnes of Agaricus caripestris“produced by

the excitor of the "Molle", The galls of woods and ferns, so

far as known, are predominantly (or entirely?) of a kataplasma»

tic nature.4

Kataplasmatic galls are found on all parts of plants: roots
and sprouts, stalks, leaves, inflorescences and fruits are de-
formed by them. Proportions of size and form, as above said,
vary within wide limits in galls of the same kind; sometimes
whole leaves are transformed; whole initlorescences and large

eaves eee ee
en eee eee ee ene ee eee ee ee ~e ae

1. Barton, J. of Bot. 1891.

2. On diseased mushrooms, Mycogone rosea end Verticillium
are found as parasites. See also Gostantin and Dufour: La Molle,
Maladie de ch, de couche. C. R. Acad. Sc. Paris 1692, T. CxIV,
p. 498, Costantin: Sur quelques maladies du blanc de Ch. Ibid.
Re 849, There also further literature references.- For galis on
rungi com-are algo Vogler, Insekten auf Polyporus, Illusir.
Zeitschr. £. Entom. 1899, Bd. IV, p. 345, and others.

3. For the forms of galls occurring in different Pteridophy-
tes, Darbpux and Houard. Catal. systém de Zoockcidies (Paris
1901) should be compared, It must remain open to doubt whether
the meny chembered gall of Pteridium aquilinum (not well Imovn
to me) produced by a Cynipide, also belongs among kataplasmas.
The "“pseudo»bulbils (Strasburger's, Einige Bemerk. ub. Lycopo-
diaceen, Botan. Zeitg., 1873, Bd. XXXI, p. 105) produced on
Selaginella pentagona by ea diptera, are apparently kKavaplasmas.
For their morphological charecter, compare Strasburger's work
-already cited.

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: 180

sections of shoots are brought to hyperplastic development;
sometimes more or less extensive parts of Single organs. Ball-
like ‘swellings are often produced, or isolated galls, often
clustered comphexes. Since the area of infection in the case
of different gall producers has no constant size, tiny pus-
tules are often produced or often extensive deformations,
corresponding to the amount to which the parasites are dis-
tributed on or in their host plants.

The histology of kataplasmas needs no detailed descrip-
tion, Almost universally, aside srom 4 slight tissue differ-
ehtiation, the compostion of kataplasmas is made up of abnor-
mally large cells.+ As in ull gall-fornations the cells of
the kataplasmas also Show an abundant albumen content. They
often contain red cell-sap pigment. Especially striking is
the accumulation of starch which we find again in very dif-
ferent kinds of galls,- in the rupture of the cabbage as in
the tubercles of Leguminoseae roots, in aphid galls etc. Since
the anatomical structure of Katavlasmas shows essentially ©
everywhere the same Structure forms, in their slight differ-
entiation, it suffices to explain the essential points by a
few examples.

1. Primery Tissues,

The difference between normal and infected tissues is
very obvious, when leaves and parts of stalks are involved,
which if undisturbed, would develop diversely differentiated
tissues in well-separated layers.

In leaves etc. infected by fungi (Mycocecidia) the other-
wise very evident difference between epidermal and ground tis=
sue cells is often only weakly defined. In the mesophyll it-
self the difference in formation between palisude parenchyma
and spongy parenchyma is often entirely lost. In other cases
a Slight differenece in the celle of the upper and lawer meso-
phyll layers is retained. It is often the case that the cells
of the spongy parenchyma are prevalently incited by infection
fo a rich proliferation. The illustration by Woronin, re-
produced here, shows very clearly the difference between
normal and diseased mesophyll: the parts of the leaf of Vac-
cinium Vitis Idaea infected by Exobasidium Vaccinii are great~

‘ly distended(fig. 74a) developing a tissue composed of very

large cells, poor in chlorophyll or “‘ree from it (fig. 74»);
the uppermost cell layer of this corresponds to a hypertro-
phied palisade layer. The tissue continuity of the cells is
the same in all parts of the leaf, a difference between thick
and porus spongy tissue (fig. 74b- aot the left) being scarce-
ly recognizable in the part of the leaf infected. In some
cells of the gall a red coloring matter is developed. That
even the mesophyll o? the conifer needles,may be brought to
excrescence by, fungi has been proved by Wornle, in the leaves

1. It was mentioned above(p. 117) that in cases of weak
infection, or unfavorable developmental conditions, the cell
divisions are absent, and instead of hyperplastic excrescences
only hypertrophic changes can occur,

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181

of Juniperus communis attacked by Gymnosporangium juniperinun
(the form living in the needles) .+ ca dane

The same arrestment of tissue differentiation is found
in Zoocecidiae. Figure 75 shows a cross-section of 4 leaf of
Crataegus oxyacantha after colonization by Aphis oxyacanthae,
a leat~louse. On the infected swollen planes, uSually Strik-
ingly red&enec, the mesophyll is increased several cell layers ,
any distinet formation in the upper and lower layers is entire~
ly lacking, and the epidermal cells are approximately as large
aS those of the mesophyll. Its cell walls are often pretty
thick and apparently very rich in water,

In all cases the hyperplastic cell increase is limited
to the mesophyll while the epidermis participates only in so
far as its cells are often considerably enlarged, cross-divi-
Sions taking place only exceptionally. That the sround tissue
tends to a greater proliferation than does the epidermis has
been repeatedly confirmed above and will be reaffirmed later.

While, in most cases, in the proliferetion of the meso~
phyll as in pure hypertrophic changes (see above), the chlo-
rophyit content degenerates completely or in great part, there
are ~“ a few exceptions among galls in which the chloroplasts
are retained. Such exceptions are shown by the go-called
pustules of Pirus, Sorbus and others, Through the action of
gallemites mesophyll is forced out into elliptical swellings, ~
the single cells are g reatly elongated and many times divided,
their content retaining its normal green color. In the places
infected the leaf tissue consists of porous green, confervoid
rows of gehks. The excrescences of the assimilatory tissue in

1. Wornle. Anat. Unters, der durch Gymnosporangium-Arten
hervorgerufenen Missbildungen. Forstl.~Naturwiss, Zeitschr.,
1894, Bd. III, p. 68. Of the other literature, compare es-
pecially, Woronin, Exobasidium Vaccinii. Verh. naturforsch.
Ges. Freiburg i. Br. 1867, Bd. IV, p. 597. Wakker, Unters,
tb. 4. Hinfl. parasttcher Pilze auf ihre Nahrpfl. Versuch ein-
er,pathol, Anat. d. Pfl., Pringsheim's Jahrb. f. wiss. Bot.,
1892, Bd. XXIV, p-, 499. Further Fentzling, Morph. ws anat.
Untersuch. der Veranderungen, welche bei ecinigen Pfl. durch
RosStpilze hervorgerufen werden. Diss. Freiburg i. Br. 1892,
Peglion, Studi anatom di alcune ipertrofe indotte dal Cystopus
canidus in alcuni organi die Raphanus Raphanistrum. Hiv. Pat.
veg. 1692, Vol. I, p. 265. Smith, W. G., Unters.d. Morph» U.
Anat. der durch Exoasceen verursachten Spross- u. Blattdeforma-
tionen. Gorstl.- Neturw. Zeitschr., 1894, Bd. III, pe 420.
Therein a number of graphic illustrations, Molliard, Ubcidies
florales. Ann. Sc. Nat. Bot, 1895, 8@& ser., T. I, pe 67.
Strohmeyer, 0., Anatom. Untersuch. der durch Ustilagineen her~
vorgeruf, Missbildungen, Dissertation Erlangen, 1896, Geneau
De Lamarliere, S. 1. mycocecidies du Roestelia.s Rev. gen.

G5 Bot., 1890, ©. Ke ps 225

2. In contrast to the many cases already described of chip -
rophyll ‘degeneration and its non-development, the present cases
are of eSpecial interest since there is no lack of food sub-
stances here for the colorless cells, or those poor in pigment.
The cytoplasm is rich in protein and the cells are usually
abundantly provided with starch meal. The causes determining
the utilization of the food substances for the formation of
chlorophyll are unknown.

Lge

the a he emergences on the leaves of Crataegus oxy-
acantha (after colonization by Cecidonyia Crataefsi) may also
be included here. 2)

The vaScular and mechanical tissues undergo the same re=
duction in kataplasmas as does the assimilatory tissue. The
vascular bundles in the parts infected are often only of very
moderate extent; the single ducts often retaining the narrow
lumina. The mechanical tissues, which under normal conditions
protect the vascular bundles, are not developed (compare fig.
74). According to Wakker (loc. cit.) the collenchyma is lost
in the infected stalks of Vaccinium Vitis Idaea (Exobasidium)
in the stalks of Rhamnus frangula {Aecidium Rhanni) and.
Crataegus oxyacantha (Rosstelia lacerata). In the same cases,
the sclerenchyma also is lacking.

Finally, the hyperplastic excrescences of the pith should
be mentioned. One eSpecially conspicuous form is found in
those produced by Aecidium Englerianum on clematis branches;
parenchym atous cone-like protuberances are developed from
ae ae Which break through the ring of vascular bundles and

ée bark. ,

While in prosoplasmas all the cell divisions or at least
the first ones, accompanying the formation of the gall, often
Show a definite orientation and produce regular cell rows,
in kataplasmatic excrescences of the primary tissues regularly
oriented cell rowS are almost entirely lacking.

In very different kinds of galls, as in wouhd tissue (see
above p. 166) bead-like structures occur on the outer surface
of the cell-membrane, but nothing positive has been discovered
as yet concerning their chemical composition.

2. Secondary Tissues.

Of the secondary tissues, only the products of the cambium
come under our consideration. In the formation of galls, eith-
er the living derivatives of the annual ring already formed
are incided to division, or its own cells are used in the pro-
duction of the kataplasmatic tissue; as described above in
the formation of wound-wood. After infection with different
fungi or after colonization by gall-animals, swellings are
produced in wood and bark usually knob-like in form, or clus-
tered (compare fig. 76), which resemble the canker formations
produced after injury or frost, ("gall-wood"), or even brush-
like excrescences of the branches develop,known as "witches-

-_ ne we
(em ee sem mee Siem i tee ape meen ee mim em Oe es ee ee nee ee ne en BD howe AD ce eh Me fy Ge em coin be wy Go Cony RS OP mee ee mee en Mee ee ve re sw

1. Lindau, Bemerk. ub. Bau wu. Entwickelung von Aecidium Engler~
ianum. P. Henn and Lindau. Engler's Jahrb., 1893, Bd.XVII, p. 45.

2. Compare also Noack, Ueb. Schleimranken in d. Wurzelinter-
cell. einiger Orchideen, Ber. d. D. Bot, Ges., 1892, Ba. X,
p. 645. Nypels. Notes de Pathologie véegétale. C. R. Soc. Bot.
Belgique, 1897, T. XXXVII, p. 246. ("prolongements de la mem-
brane cellulaire").

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(204)

185
brooms",

*

Abnormal Wood.

The numerous woody-galls produced dy many ‘fungi (Gymnos-
porangium, Peridermium, Dasyscypha, Nectria, Agalaospora,
etc.), parasitic phanerogams (Loranthaceae} end insects
(Schizoneura, Lachnus, etc.) have been subjected tn part to
closer anatomical investigation. So far as known, all woody-
galls are characterized by the abnormally abundant parenchyma
development, recognizable in the structure of wound~wood.

Increase of the parenchymatic elements can be produced
here and there by segmentation of the young derivatives of
the twambium, which thus furnish groups of parenchymatic cells,
instead of growing out into prosenchymatic xylem elements,~ or
by the corss-division of the cells of the cambium itself and
éhé production, after further division, of parenchymatic pro-
ducts. Hither the cambial cells are only changed in places
as described, so that the cambial rays are broadened and their
number seems increased,- or the cells divide over the entire
ar@a of infection, so that extensive, continuous masses of
parenchymatic wood are produced. No difference in principle
may be proved between Myoocecidiae (fungus-galls) and Zooce-
cidiae fenimal=pelis)

We will begin with an example from the list of Mycoce-
cidiae.

As is well known, ‘the gymndsporangia produce spindle-
like or ball-like woody~galls on different Species of Juniper
(J. communis, Sabina, etc.) Wornia* has studied their
s tructure thoroughly. According to his statements, the dif-
ference between spring and autumn wood is not expressed nor-
mally in diseased wood, the annual boundaries are scarcely
recognizable. Besides this, the parenchymatic elements in
the wood require themselves a noticeably broad space. Instead
of being only 2 to 10 cells deep, the cambial rays in the
parts of branches infected by Gymnosporangium clavariaeforme
are often 10 to 20, even 60 cell layers depp, and as many as
3 cells broad. Still broader cambial rays are found in the
tangential longitudinal section through the woody-gall of
G. juniperinum shown in figure 77. Further variations from
aA HoOkMAL GON@ITLOH are found in the hypertrophied parenchyma
cells, Which assume a "Shapeless form" and disturb the radial
arrangement of the tracheids (Wornie, loc. cit. p. 146) and
further in the occurrence of distended paxenchyma-cell centers
which Wornia in one case found broadened to one sixth of the
whole size of the branch. They extend partly in the direction
of the cambial rays, partly in the vertical direction of the
parenchyma of the cord. In cross-section it is clear that
they are separated only by slender, tracheid-groups, often
consisting of: ome row.:of cells. Wornle's discoveries do not
throw sufficient light on the development of these abnormal
tissues, Yet I would like to assume that the first named, ab-
normally broad cambial rays are brought about by segmentation
of the cambial cells, the last named parenchyma centers by

1. Anat. Untersuch. d. durch Gymnosporangium-Arten hervor-
gerufenen Missbildungen. Forstl.-Naturwiss. Zeitschr., 1894,

Bd. II, pi 68,

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184

@ uniform division of the young cambial daughter cells. In

my opinion, the occurrence of isolated tracheid-groups favors
this supposition. The parenchyma centres (G. juniperinum) are
often followed, toward the periphery, by abnormally short and
a tracheids, furnished on all sides with numerous bordered
pits.

Naturally, a division of the parenchymatic ele~
ements and the over=-production of a woody=parenchyna
can also occur without abnormal widening of the annual
ring. Woody plants with fungous diseases furnish num-
erouS examples of this. I wish to mention at this
point the production of ebnormal resinecanals which
are known to be surrounded always by parenchyma tissue
alone. Hither the number of resin-canals is increased
beyond the normal or they occur in wood which normally
remains free from them. (cf. the abovesaid concerning
wound-wood, page 176). Hartigl produced ah increase of
the resin-ducts in the diseased places of conifers, in-
fected by Agaricus melleus. Anderson” produced the
interesting proof, that the resin canals are increased
not only in the places filled with the fungus mycelium,
but in the whole plant, outside the infected areas.
(Picea, Pinus, Larix).

In Abies pectinata, the wood of which is known
to develop no reSin—canals under normal conditions,
such canals are developed after infection by Phoma _
abietina even above the constricted place of infection
ain the xylem;° this also occurs in Abies pectinata and
Picea excelsa after colonization by Pestalozzia Harti-~
gii. The abovesaid (p. 176) is supposedly true also
of the structure of these abnormal resin-canals.

The transftimation of wood into parenchyma is performed

even more energetically by some Zoocecidiae,. ~

Instead of a formation of parenchyma rays and parenchyma. _
centres, we can prove a production of parenchyma to the great-
est extent, in the case of many Hemiptera galls. Just as in
the case of callus and wound-wood formation, all the cells,
or, in'the latter, the youngest daughter cells in extensive
areas of the cambial mantel divide and furnish a tissue com-
posed of isodiametric elements. While th the ease of injury
corresponding to an abrupt interference in the normally a
tinued development of the tissues, the parenchymatic woun
tissue directly joins the normal xylem, we find in the oie
of many galls, that the weak but continuously poids ig ee
uli given out by the parasites make possible a gradua
sition from the normal xylem to a homogeneous gall parenchyma.

ae
ee ee ee

1. Krankh. 4. Waldbaume, p. 13.

W
@. Ueb. abnorm. Bildung von Harzebehaltern u. andere zug-
leich auftretende anatom. Verand. im Holz erkrankter Koniferen.
Forstl.- Naturwiss. Zeitschr., 1896, Bd. V, pe. 439.

i du sapin,
3, Compare Mer, Rech. s. la maladie des branches

causee par le Phoma abietina. J. ae Bot., 2696, Us Vil,

p. 364, also Anderson, loc. cit.

185

«The structural conditions to be stucied in the galls of
the blood louse of the apple are very instructive. (Pig, 76)
First of all, the mechanical elements are absent in the ab-
normal wood; instead of ducts and woody=fibres, numerous
parenchyina cells are produced by division of the prosenchy-
matic elements, which in longitudinal sections show their
developmental relation to the regular longitudinal rows.
(Pig. 78a). As shown in the illustration, the single cells
have pretty thick walls which are pitted. In the layers of
gell-wood produced later, the Sincle parenchyma cells are
noticeably larser while a regular arrangement is no longer
recognizable, and their walls remain delicate, (Compare fic.
78b). Instead of normal ducts, only isolated parencnymatic
tracheids or others united into Groups are formed, distin-
guishable from the delicately walled parenchyma cells by
their size. Their membrane is pitted like that of a trachea,
but often unlignified; the tissue structure reminds one of
callus. {Fig. 67). In its entirety, the thin-walled woody
parenchyma furnishes a soft swelling, wich in water, which
can increase to Such an extent that the bark is ruptured and
the gall tissue laid bare+. The fact that the delicately
Walled woody parenchyma cells are multi-nuclear, as discovered
by Prillieux (loc. cit.) is noteworthy.

The conditions in galls of the beech-louse, (Lachnus_
exgiccator) are similar to those of the blood-louse. Rk. Hart
ig” studied them closely. Here also is found tha same grad-
ual trensition from normal wood to homogeneous, parenchy-
matic gall-tissue. ‘

Abnormal Bark.

While in many cases (galls of Schizoneura lanigera,
etc.) the bark remains practically unchanged, in other gall-
formations extensive bark excresences are produced, whereby
the changes in tissue, essentially the same as in the forma-
tion of woody galls, consist of an abnormal production of
parenchyma. .

The Mycocecidia which should be named here, are pro-
duced by Eumycetes and bacteria.

It is seen in the galls of many Gymnosporangium_
varieties that the bark and the wood form excrescences Sim-
ultaneously. According to Wornle (loc. cit), in weakly
grown branches of Juniperus communis, Gymnosproangium clava-
riaeforme incited the bark rather than the wood 66 a tissue
production. Hand in hand with the superabundant formation of
parenchyma, proceeds an arrestment in the formation of the
parenchymatic, mechanical fibres. They remain thin-walled
and decrease in number. Therefore in a comparison of normal
with abnormal barks, essentially the same points of consid-

1. Prillieux, etude des alterations prod. d. le bois
du pommier par les pigures du Puceron langiere. Ann. Inst.
Nat. Agronom,, 1877, ©. Ii, ps 39

2. Die Buchenbaumlaus (Lachnus exsiccator Alt.) Unter-
such. aus d. forstbot. Inst. Munchen, 1880, Bd. I, p. 151.

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LOO

eratipn exist as in that of normal with abnormal wood.

An especial class of tissue excrescences of a kae
taplastic nature, usually produced from the bark tis-
sue of the branches, more rarely in other places, is
formed by the parenchymatous, wood-like excrescences,
occurring on the olive. (Olea europaea)” and on the
Aleppo pine {Pinus halepensis) and, according to the
unanimous statements of Freuch and Italian authors,
caused by bacteria, Provided that the present state-
ments , concerning the etiology of the swellings hola
true,” an eSpecial significance accrues to these
"tumeurs a bacilles" in so far that, according to our
present knowledge, the action of pathogenic bacteria on
phants consists chiefly in dis-organization and ne-
crosis and is not connected with formative stimulatory
effects. Besides the bacteria tubercles here named
only those of the Leguminosae and the leaf gwellings
on tropical Rubiaceae observed by Zimmerman® come into
‘question. as exceptions to the rule,

The bacteria galls of the olive are mostly produced
on branches 1 to 15 years.old, more rarely on roots,
leaves or fruit and indeed in such a way that, in the
case of branch infection, a colony of bacteria is first
visible near the cambium or in the bark tissue, by
which the adjacent cells aré incited to division. The
proliferating tissue cases the rupture of the super-
ficial cell layers and grows out gradually to a knot,
aS large aS 2cm. in diameter, The swellings consist
primarily of predominantly thin-walled parenchyma, in
which are scattered thick+walled cells with woody and
pitted membranes. This becomes woody later and groups
of irregularly arranged, short-membered ducts are
formed, reminding one of the histology of wound-wood.

1. Literature:- Arcangeli, Sopra la Malattia de 11' olivo
detta volgarmente "Rogna". Pisa, 1886. Savestano, Les mal-
adies de 1{ oliveir et la tuberculose en particulier. C. R.
Acad. Sc. Paris, 1886, 1. CIII, p. 1144. Savastano, Tuber-
culosi, Iperplasi e Tumori dell’ olivo. Amnuario 4. R. Scuola
sup. d'agricolt. Portici, 1887, Yol. V. Fasc. IV (Therein,
also full literature references.) Prillieux Les tumeurs a ,
bacillies des branches de l'olivier et du pin d'Alep. Rev. gen.
Bot. 1889, T. Ie pe 293. Vuillemin, Sur une bacteriocecidie
ou tumeur bacillaire du pin dtAlep. C. R. Acad. Sc. Paris,
1888, T. CVII, p. 874. Sur les relations des bacilles du
pin d'Alép avec les tissus vivants. Ibid. p. 1184.

2. Savastano (Les maladies de l'olivier, hyperplasies et
tumeurs. C. R. Acad. Sc. Paris, 1836, T. UIII, p. 1278) de-
sctibes very similar swellings on the olive which are pro-
duced without the participation cf any parasitie whatever.

3. Ueb. Bakterienknoten in 4d BlAttern einiger Rubiaceen.
Pringsheim's Jahrb. f. wiss. Bot., 1901. Bd. XXXVII, p. 1.

Brzczinski attempted recently to trace canker-like éxcres-

f a Sip ap back to the activity or bacteria
es of she apple (Nectria : oo ia
ee cnancre et de la Somme des arbres fruitiérs.

NPAT

Cc. R* Acad. Sc. Paris, 1902, 7. CXXXV, 9. 106)

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: 187

They show a tendency to the "gnarl formation" de-

* scribed above in detail.4 In old age, a disinte-
gration of these knots takes place, in such a way
that a depression is formed in the middle of the
swelling.

The bacteria swellings of the Aleppo pine, fast
becoming a m@nace to wooded districts of the maritime
Alps, are still larger than those of the olive and
more regularly rounded. No disintegration of the
central parts takes place later. According to
Pfillieux the formation of the knots proceeds from
the bark tissue; histologically they also resembke
wound-wood.

: AS an example from the list of Zoocecidia, I will men-
tion the gall of Chermes fagi, the beech wooly louse, which
Hartig has closely inveStigated. The gall-formation here
begins directly beneath the cork and can advance even to the
woody-body; all parenchymatic elements of the bark, includ-
ing the tissue of the cambial rays grow out extraordinarily
vigorously and divide actively in a tangential direction, so
that long, multicellular, regularly radial rows are produced
(compare fig. 79), by which the stone cells and the prosen-
chymatic elements of the bark are pushed from the normal po-
Sition. He found in the bark excresences of Goldribes
(p- 80) that similar changes may also be produced by hyper
trophy of the parenchymatic bark elements.- The case of the
beech=Chermes gall again illustrates very distincly the great
correspondence between kataplasmatic galls and callus tissues.
The abnormal bark tissues illustrated in figure 79 show the
greates similarity with the bark callus excrescences de-
Scribed above for Populus. In both cases a constancy of
direction of cell-division and a lack of differentiation of
tissues is common.

Bark excresences, the cells of which display no regular
arrangement, are produced by different Ceutorrhynchus species,
especially C sulcicollis, the "kohlgallerrusselkafer" (cab-
bage weevil) on the roots of various Crucifera (Brassica,
Raphanus). The wood too is developed abnormally abundantly

on the side infected.

Witches Brooms and Stag Head.

An especial class of galls is formed by the so-
called witches-brooms (or Thunder-bushes), branch-
1. Prillieux, loc. cit. p. 298--"des faisceaux sinueux de
bois traumatique a cellules courtes, qui s' enroulent autour
de centres de formation. Ils apparaissent ca et la dans la
masse du parenchyme, au voisinage des points ou se montrent
les colonies de bacilles. Ces enroulements de fibres lig-
neuses sont tout a fair comparables ceux des madrures des
bourrelets qui se produisent au bord des plais des arbres et
au plancher ligneux qui s' organise dans la moelle, a la
base de certaines boutoures." (Compare above p. 180)

2. Die Buchen-Wollaus (Chermes fagi Kltb). Untersuch aus
ad. fortsbot. Inst. Munchen, 1880, Bd. I, p. 156. .

os Prank, log. Git., DP. 206.

188

excrescences of shrub or nestlike habit of growt |
Which is involved an over-production of whole peetual
Questions of morphological interest are especially con-
nected with these, {Compare Goebel, Organographie) ,

Among them we find Mycocecidia,

produced on Alnus, Betula and Prunus, Weer ees
ious ferns after infection by Exoascacerke, on Abies species
on Acacia and Berheris by the action of vardous Recidiae
Thujopsis dolatbrata by Caeoma deformans ete, Anong the
etapa for instanee, the abnormal ramifications of
the Syringa shrubs attacked by the mite-disease bear a
great similarity to the above mentioned fungus galls,
ze Senbogen has shown that the formation of witches-brooms
oes not always proceed from normal buds but can also be
peoraeee from leaves as adventive formations, (Taphrine on
porns), Studied macroscopically, many forms of the witohes-
rooms may be recognized as "arrested developments", Thus,
according to Tubetf, the witches broom of Caeoma deformans
Sune tats of leafless branches“, According to Giesenhagen,
floshy, wart-like or antler-like forms, always entirely
leafless, which are traversed by a vasculor-bundle. cord,
He loss by Zaphrina Cornu cerv4 on the leaves of
‘Spidium aristat » dnvestigated microscopically, all
Witches -Broons show the characteristics of kataplasmatic
galls, The different tissue forms, of which the abnormal
branchlets and their leqves are composed, remain below the
corresponding normal tissues in differentiation,

Some arrestment phenomena correspond to those already
described (p, 32). The witches-brooms of the pitch pine
caused by fecidium elatinum bear needle s, the hypodermis
of which remains undeveloped and the mesophyll homogeneous,
The de¥etopment of bark fibres in the trunk is retarded,
but that of the parenchymatic elements, om the contrary,
is greatly favored, The pith is abnormally abundant, the
bark perhaps twice as thick as in normal pgrte, also the
number of resin-canals is abnormally large*, Resin-canals
may occur even in wood, which in the spruce would have
none normally, through the action of ‘the witches-broom
fungus”, The anatomical conditions of the Exvasceae-wit-
ches brooms® are of a similar nature, The parenchymatous
tissues,- pith, hypodermis - are greatly increased, wood

-_— = ow om

ee emma ee
°

1 Yeb. Hexenbesnn an tropischen Farnen, Flora, 1892, Bd.
LXXVI, p. 130. ;

e o
In this they resemble the cyhinder-gnaris of. Ginkgo,
described above p. 185,

2 The antler-like malformations described by Miquel (Lin-
naeg 1853, Bd, XXVI, p, 285) are, according to Solms-Laubach,
deformed leaves of a Hemiptera gall (Ann, J. Bot, Buitenzorg,

1887, Vol, VI, P, 88). .

* According to Hartmann, Fr. Anatom. Vergl. 4d. Hexenbesen
ad; Weisstanne mit den norm, Sprossen derselben. Dissertation
Freiburg i, Br.,1892, Anderson, loc,cit.also DeBary, Ueb, d,
Krebs u,d.Hexenbesen ad, Weisstanna, Bot. ztg.,1867,Bd.XXV,p. 257,

5 Gf, Mer and Anderson loc, cit.

6 Cf, Rathay, F., Veb. da, Hexenbesen ad. Kirschbaume, etc,
Sitzungsber. Akad, Wissensch, Wien, 1881, Bd. LXXXIII, 1. Abt,
p. 267 and especially Smith loc. cit. :

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189

and bark are traverged by abnormally broad cambial rays,
the ducts have short members, the wood-fibres wide lumina
and are often cross-divided and thin-walled. The bast ;
fibres are few or entirely lacking, Tubeuf found in the

(210) irregularly forked branches of the Caeoma witches-brooms

on Thujopsis, a woody structure characterized by a paren-
chyma formation, similar to thet found by Wornle in the
galls of the Gymnosporangia,

According to Giesenhagen, the leaves of the fern-
witohes-Broom are distinguished from normal ones by a sim
pler tissue structure, For instance, the stomata are lack~
ing in the abnormal leaves, proguced by Taphrina Laurencia
on Pteris quadriauriga, Tubeuf+ also verified Similar ar-
restment sRenonsan in the diseased buds of Syringa shrubs
bearing witches brooms,

In many respeots, the stag head of the willows, pro-
ducéd by leaf-lioe (Aphis amenticola), are similar to wit-
ohes~brooms, These have often been described since Mal-,
phigi and were recently thoroughly investigated by Appel”,
In them, aauliflover-like, ball, or tuft-1ike accumulations
of brenches are involved, which gan become 10 to 20 cm, and
more long, The branchlets, of which these are composed, are
always short and richly set with small, often somewhst
thickened leaves, The axes are soft and rich in parenchyma,
the leaves contain undifferentiated mesophyll, - therefore,
the characteristics of kataplasmatic galls are repeated
here, The stag heads originate either from normal wads, or,
a8 Appel has shown single thickly massed new vegetative
points, produced on the pistillate infloresceneez in the
interior of the ovary, as well as outside the carpel -
leaves on the gland spots and on the stalklet of the ovary
and grow out to the above described abnormal branch-excres-
cences, On account of the adventitious character of their
origin, stag heads are comparable to the witches-brooms on
fern-fronds, which Giesenhagen described.

b. Prosoplasmas

We will tern prosoplasmis those galls which are character-
ized first by the fact that their tissues, in their differentia-
tion, do not show the histology of arrestment-formentations nor
of callus tissues, but form new kinds differing entirely from
the normal,- and'then also by the fact that definite proportions
of form and Size, cheracteristic for the species, ore always
repeated in them, Therefore, in this external form, prosoplas-
mas display something independent, well-defined, distinguished
Obviously from the organs of the normal plant-body; some th ing
"now" and independent, however, is shown also by their inner
structure,

If we compare the histology of prosoplasm:s with thot of
the above described kataplasmas and callus-formations {in the
widest sense of the word) we cen define prosoplasmas as those
(hyperplastic) new formations. of pionts, in which occur ©2180
histological characteristics other than those known as yet in
arrestment and calius formations, Hyperplastic tissues of this

nd have been found up to the present only in the excrescences

1 pie von Milben erzeugten Hexenbesen der Syringen,
Flugblatt,

cx z uote Paree. und Zoomorphosen, Dissertation Wurzburg
Konigsberg), 1899,

; 190

produced by parasites, They cre the most richly differen
of all known abnormal tissue formations, ae ee sa
take them up at the end of our consideration,

The goils to be treated of in the present section cre ol-
most exclusively Zoocecidia, Of the animals producing galis
only the arthropods come under consideration here, since the’

golls produced by worms (Nematodes) always have c kataplastic
structure,

The study of the animals which produee galls brings us
but little information of Importance for Boner aeration: since
we are concerned only with the diseased products of plant er-
gans, It will becone clear thet the systematic position of
the gol onim.1 in one or another Group of the nrthropsis eon
determine no regular connection betveen the form end strueture
of the galls produced by them,

The mites, mentioned as producers of different kinds
of kataplasm:s must be considered «lso under prosoplcsm.s,
Their products are very simple in form, as in structure,

The dipters produce very many prosoplosmes, the form
end structure of the galls heing very different and often
very complicated,

The hemintern also produce numerous, usually very

Simple prosopinsm é

The hymenoptera produce almost entirely prosoplasmas,
those produced $5 the gt11 wasps (Cynipida) are especially
Striking becouse of their size, the diversity and complex-
ity of their forms ond the difference in their internnl
structures, In describing the histology of prosoplasms,
we will heve to examine especially thoroughly the struc-
tures ocaurring in Diptere and Cynipida galls,

Of the Coleoptera and Lepidoptera, only a few proso-
plasmatic gclls are known; eir structure is relatively
sinple,

Among the Mycocecidia, there cre varions galls which re-
semble prosoplasm:s in the regular arrongenent of certain ele-
ments, for instance, of the calls of the membrane tissue which
contain anthocyanin, Their cel) forins, however, ore no other
than those which we are ccceustomed tO meet with in arrested de-
valopments and in ecllus tissves, An especial position is t ake
by the goll, produced on Polygonum chinense by Ustilago Treubii™..,
This may perhaps be included mmonf the prosoplasmas on cocounk ks
of its peculiar fibres which are Jike capillitia.

At least we my think that the trunsition from kata-
plasmas to prosoplusmas if furnished by the gall of Ustil-
ago Treubidi. According to Sotms-Laubach, this fungus,
like so many others, canses the production of canker-like
excrescences here ond there on polygonum stems. The ex-"
erescences consist of spongy, parenchymatous wood-tissue,
on which account, this same fungus was referred to earlier
(p. 196), These sprout out from the canker swellings which
correspond entirely to the «bove described kataplasmas,
"fleshy, succulent, ensily breakable excrescences", "the
irregularly bent, cylindrical and often longitudinally

Solms-Laubach in Ann, Jard, Botan, Buitenzorg, 1887,
Yol. Vi, pe 79.

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391

furrowed stalks of which are broadened at the top, like the
head of a sail, and closed by flatly convex, smooth apical
surfcoes", The fungus forms its spores in this part of

the exorescence - the "fruit-gells", These fruit-galls
Show a certain similarity to prosoplasmeas (the size-propor-
tions seem to vary); because of their characteristie form
and still more in their peeulior differentiation, Suoh an
one is produoed by the outgrowth into long filaments of the
cells of the host plant, lying at the fruiting spot of the
fungus, Solms~Laubach sompares these filaments, in their form
and function, with the fibres of the myxonycetes-capillitic,

Still another fungus gall, closely related to proso-

plasmetic galls, despite ite simplicity, is that produced

on the leaves of PotentillaaTormentilla by Synchytrium pili-
ficum, Here and there are formed Small, roundish, flat pro -
uberences which are beset over and over agein with very
long, wnicelluler thick-walled hairs, Akl gall individuels
are equally lerge and similarly formed, The small gall,
which seems to be pretty rere, is of especial interest- be-
cause through it vas 4llustrated the relations which were ox~
plained above, between constancy (and variability) of form

(213) and the constant (or changing) extent of the stimulatory

field, The infecting organism does not extend beyond its
nutritive cells; the field of stimulation is therefore al-
ways of uniform size, Also the developmental period of the
parasite and the character of the stimulation varies in the
Synchytriae within narrover limits than in many other fungi,
which produces galis, Figure 80 expleins the histology of
the gall. In the centre is the nutritive cell, adjacent to
it the parenchyma, and the epidermis with its many hairs,
distinguished from normal ones by their size and the den-
Sity of their growth,

In the following, we will first report on the external form
and the course of éevelopment of the prosoplasmas and later in-
vestigate more closely the histological details of their develop-
ment and the structure of the matured gall,

1, External Form and Course of Development of Prosoplasmas

fhe external form of galls varies greatly, In all cases they
display extensive masses of tissue, which enclose a more or less
Spacious hollow cavity, in which the gall animals remain, While,
in kataplasmas, the animal parasites live superficially or in
cavities imperfectly closed, as in leaf roll galls, the proso-
plasmatic galls are characterized by well enclosed cavities of
definite form,

Prosoplasmas may be subdivided into four groups according
to their form and course of development®.

1. The simplest prosoplasmas are produced by the turning
down or inrol}jing of the edge of the infected leaf,/ A leaf
fold gall arises, which bears a marked similarity to many kata-
plasmas already named. A comparison of prosoplasmas and kata-
“1 mhomas, Fr., Synehytrium pilificum, Ber, a, D. Bet. Ges,
18683, Ba. 1, p, 494, T owe the herbarium material to the kind-
ness of Professor Thomas (Ohrdruf).

= Compare here Kerner Pflanzenleben, 1898, Bd, II,

(214)

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192

plasm:s aequires espeoinl interost directly in the golis which
res Seperate ae contrast to those discussed pen

6 prosoplostic leaf-foldings ate set off absolutely short®
from the healthy pert of the Lect (galls of Bemphd ous eee
flexus and others on Fistncic), The charcaeteristie oroscent
form of the gcll is conspicuous in the products of Pemphigus
Senilunulcrius, Further, ell gells produced by the same
Bpeoles ore Of the seme size, Finclly prosoplastic leaf-fold-
ings, in contrast to those rbove uentioned, show o peculior
tissue differentiotion, (Pig, 108 G,),

2, If, through the uetion of cny'goll poison whatever, ©
small part of the leaf-blade is stimulated to abnormally aa-
tive surfnod crowth, en outward ourving of the lea? meas
erises, Whether the ourving in this is upward or downward de-
pends upon whether the apper or the uncer side grows most in-
tensively, Obviously the side which portioipates in the more
eetive grovth will become convex in the eurling back of the
leaf, The side growing most 4s always the one eway from the
gell animls; the one emposed directly to the irritation grows
relatively little, so thot, in this rolling of the infected
leaf-area, the gall cnimis come to lie within the cavity thus
produced, Figuren8? illustrates dingrammatically the produe-
tion ef this king of leaf gall, The displaced part of the —
lemina {4s curved upwards ond encloses,.after further growth, ©
Spacious cavity, which serves as n dwelling plece for the gall
onimels, We term golls of this kind,- sac galls, It is evi-
dent that the cavities in which the gall animals here live can
not be closed on all sides, An entrance pore always remains
Open, However, this cnn be extraordinarily nerrowed by sup-
plementary grovth in thickness of the leaf-m-ss or my be
stopped up by hairs,

In connection with sac galls we my also recall some
eorlier statements. Not a few forms are found among kataplas-
mis in which cavities are formed for the pnrasites by a curling
and folding of the lexf., The same is true of momny felt galls
in which (compare nbove p. 115) hypertrophy of the epidermal
cells conbimes with surface growth of the infected leaf, pro-
ducing vesicular projections, In cases of this kind, however,
the galls do not hrve the characteristic form and constant
size proportions found in prosop]esmis, In them too the "sac"
remains very primitive, in as much as the closing of the open-
ing lying on the under side is either very incompleté or does
not take place nt all. Besides, in kataplastic sac galls new
kinds of tissue forms never occur,

Soag-falls sre produced especially by different kinds of
mites, «lso by Hemiptera (leaf-lice) ord Diptera (for instence,
Cecidomvia bursarin on Gleohome), Their size varies greatly.
The leaves of difrerant maple species are often covered with
am.1l1l, reddish nac-gells, the smallest of which mensures about
1/2 mm. in breadth, The gnlis of the aphis Tetraneura Ulni,
whiéh livds on elms, become more than one centimeter large.

The pale green sac of Schizoneure Jenuginosa (on elms, compare
fig. 54) becomes seversl centimeters Targe. The single galls
are often spherical, as, for instence, the Phytotus galls on
the maple, The well-known nail galls ef the linden are slender
and conical, Tetraneure Ulmi produces pocket-like gnails, with
Slencer bases and brond ends, Tetraneure compressa (on Ulnus
effusa) coxcombelike sac-galls, Schizonenra Lanuginosa often
Tobatea and knobbed forms, Large sac galis, for Instance/ like
those formed by Pemphigus marsupialis stand in isolated posi-
tions on leaves [Populus) those oF Tetraneura Ulmi and others
are united into groups of a fow galIs,; the Small sacs of many

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193

Phytopti (on Acer Negundo, Til@a ete.) not infrequently into
groups of hundreds on the same leaf,

At tines the folding of the ero-ving leaf surface is more
coxpliceted thor in the cases discussed as yet, Figure 82
illustrates «a Phytoptus gall, occurring on leives of Prageria
vescn, We often sce bslow the sac « ring like fold, protruding
from the underside of tho leaf, by which the entrance pore into
the seo-orvity is mde smcelier, At times these and other mite

gells show further, often irregulrr complications in the fold-
ing of the leof mass,

Seo galls sinil:r to these found on leeves occur also -
but much oro rorely - on Stalks end petioles, Under the irn-
flucnoe of the gtll stimuli, tho bork tissue mekes c« strong
surface growth, brevks. away from the tissue leyers lying more
deoply ond furnishes a tissue fold of definite form, Examples
of galls of this kind cre foynd in the brench gall produced

by Phytoptus of Prunus Padns*, as eleg in the epidermal fold
gclle which Thomas observed on Gallium”,

3, We will term the third clcse walled galls because of
the neture of their production.

Walled galls of very different form and size are produocd
by Diptern, Homiptern ond Hymenoptera (Cynipides), During the
produetion of the gail, the tissue lying directly beneath the
gell anima], or rether the egg of the future gull-inhabiteant,
grows tut little, if ct cll. The parts adjacent, on the con-
trary, grow out oxtreordincrly strongly. Figure 83 illustrates
diogrematioally th. development of a walled gall, Ina, the’
round egg is visibie on the vegatative point of a bud. In Bb,
tho edges of the young wali mey be recognized, which in ¢ in-
cline toward each oathor over the egg ana in a ere united.

Gaile of this kind can be produced on widely different perts of
the plant, on vegeuctive points, on steme ond stajpks, on leaf
blades and on roots, The provesses of growth ors fiways essen-
tially the sume, even *hen mony eges cre deposited near one &n~
other and each one becomes wa.led separately. Figure 84 illus-
traivo the production of the well-xnown bright red spring gall
of Cynips terminalis on tne Sips of nok branches, Seven eggs
are visible which wére deposited near one another, fA shows

the first stoge; ab B-G the eggs, still partially provided with
their long epg stolkS, may te secn to disappecr gradually in
the outgrowing tissae, With Beverinch, we will term "gall
plastein" the rapidly groving “embryonic” tissue, which the_
gall produces. In the finished gall its own larval cavity is
reserved for cach larva, While the developmental course shown
in figure 83 led to 2 one-chambered goll, a multi-chambered
form is produced in the memner illustrated in figure 84.

The "typical" welled galls here described ate connected
with the "typical" seo galis, moreover, by numerous transi-
tional forms, Betveen the two stand the sac galls, which eré
provided with a so-called orifice wall such as are produced
by various Phytopti snd others, Figure 65A gives a cboss
section through the sac gall of Eriophyes similis (on Prunus
spinose)which origincted in the Tee?. The lerger, upper part
of the gall shows the sac produced by superficial growth of

-_—

“ ie
Se ee ee -— = ee eee OPO ele

l Pronk, loc. cit, p. 56.

z Aeltere u, neue Beob, uebex Pnytoptocecidien, Zeitschr.
ges, Naturwiss, 1877, Bd, XLIX, p. 351.

(217)

(218)

(219)

‘ 194

the infected part of the leaf. On the entrance pore, however,
we find besides this as a local outgrowth of the leaf-laminea,
a ring-like tissue wall by means of which the ontrance into 4
the gcll-cavity is considerably narrowed, According to Frank
this orifice-wnill is produced errlier then the actual sac.
Similar conditions exist in the case of the mite gall of Salix
Caprea shorm in figure 85B, only here the orifice-wall is ex-
tensive and fleshy, the sco remaining greetly below it in sizé.
The gcll cnimsle remnin in the cavity enclosed by the “orifice
wall",- they heve been "welled in" by the outgrowing tissue of
the lecf-lemina, Similar conditions zlso exist in the helmet-
liko beech-leaf gell of Hormomyie fegi (compare figure 58),

Two dovelopment:l stages are illustretec in figure 86, The
larva, remcining on the underside of the leaf, is "walled-in"
(to the left in the figure), leter the pert of the leef-lemine
which Jics cbove it makes en extraordinarily active growth in
murface cnd thickness and furnishes the peaked, helmet-1ike,
pert of the gall, which enoloses an extensive icrval eevity”,

(to the right in the figure), It is difficult to decide in

ecacs like these deseribod, whethor a sae gcll or o walled gall
is present, Hovever, wo will not lingor longer over this
tcchnical question of subdivision,

Even the "typiogl" unmistakable wolled gglls, in‘the pro-
duction of which no sae formation comes into question, very
greatly among themselves, The oxterns] form as wall as the
noturc of the closing of the entrance pore mekcs possible the
recognition of mcny verients, Not infrequently the surrounding
wells grow together snd complete the closing of the lerval.
cavity, (many Cynipides galls) in others the edges of the roll
remcin froc (mmny Diptera galls); - to be surc, they lie close
upon one cnother, but do not grow together, Anatomicsnl strue~
tures of especicl kinds may at times prodube a firm cogging of
the contact surfaces, In their outer forms, the walled galls
often resemble spherical, wart-like, or egg-shaped bodies, or
conicrl and bottle-like structures, The latter occur frequent-
ly among the products of the Hemiptera (for instance Pomphigue
bursarius) and of the Diptera (Cecidomyia Corni and others).

Walled galls which, in their production, vary some what
from the type described, are not rare cnd are often represen ted
in our nature flern, Among the most striking of these belongs
the spirally twisted petiole gall of Pemphigus spirothece,
which often extensively deforms the foliege of popler trees.

At the infected points, the petioles grow out into fleshy,
brond bands, which twist spirally and finally touch one another
on their edges, The contact is so close thet a lodging cavity,
well enclosed on 411 sides, is formed for the enimals which
produce the galls, clthongh no coalescence takes place,

Finally, the beech leA# gall of Hormomyia piligera de-
serves a special description. While, in the case of the se P
ana walled galls described above, we have taken it for soon .
that tissues lying above the infected place - epidermis, bark-
even mesophyll - ean be incited to (at least approximately)
equal intensive growth, we now find in leaves infected by Hor-~-

-monyia piligera that the upper epidermis can not participa

- - Pr ad
ee -— = oo Pe - -— =

w
Concerning developmental history sce especially Busgen,
Zur.Biol. d. Galle v. Hormomyia fagi, Forstl.-Naturwiss. Zeit-
schr,, ,1895, Bd. V, p. 9 and Appel, Ueher Phyto-und Zoomorpho~
sen, Wurzburger Dissertation (Konigsberg 1699).

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195

in the growth, It is therefore ruptured by the stron e
liferrting mesophyll, and 2 gall is mrbauced. the Aen Shee
ing of which - just as that of side roots produced endogenwors-—
ly or the like ~ does not originafe developmentally. from that
of the normal organ, Figure 87 illustrates a very young de-
velopmental stage of the gall. On the underside are visible
the broad walled edges, by which the larval chamber has been
formed; on the upperside, through active growth of a circular
roll (aa),the epidermis (e) hes been pushed up and ruptured,
Under the covering thus pushed back, a flat tissue head, thick-
ty beset with hairs, is produced, through the intensive growth
of which the old epidermis already ruptured will later be
Stripped back and torn off, The greater mass of the nature gall
may be,traned back to this medial tissue head, With Kusten-
macher”, we will term “free galls" those which, like the ones
here describdd, are not enclosed by normal tissue, or rather,
its derivatives, but by a newly formed membrane-tissus, We
will return to these in the next section,

4. While, in the forms az yet discussed, the gall animils
persistently remained on the upper surface of the plant organ
Which produged the gall, or only later, by coalescence of the
wall rolls, were enclosed on all sides by tissue masses; ~ we
find in the representatives of the fourth group, that the en-
tire development of the gall animal from the very beginning is
enacted in the interior of the organs, bearing the gall.

If the eggs of the future gall-inhabitants are deposited
by the mother animal in the interior of any plant organ what~
ever and the infected tissues are stimulated to outgrowth,
cambiaj] galls are produced, Representatives of this fourth type
are found among Diptera and Hymenoptera galls,

While in sac galls the abnormal growth took place predon- .
inantly parallel to the upper surface of the infected plant or-
gans and in walled galls the direction of growth was so deter-
mined by the egg and the larval body, that the tissue increased
most actively tangentically, we can call the radial direction
the one preferred in the growth of cambial galls, Round about
the larvae or the eggs a large tissue knot is produced, of a
Spherical, ogg-shaped or elliptical form, which appears as a
thickening of the infected stem, or as an embossment of the ina
fected leaf, or may be attached to the leaf, stem, root etc,
as an independént appendage, while the outlines of the organ
which bears the. zall_ would not be essentially altered by it,
With Lacaza-Duthiers*we can call the first kind internal galls,
the second kind external ones, ‘That numerous transitional
forms are found is directly evident. Further, we will have to
distinguish between one and several-chamberod galls, es in
walled galls,- For instance, the galls produced on Salix by
nematode species (leaf wasps) contain only one chamber {(com~
pare for example figure 88). The large stem knot galls of fulax
Hieracii on various species of hawk-weed are many chamhered.

_ Further, the difference between "free" and “enclosed” gells
(Kustenmacher) deserves especial consideration, In cambial
galls it frequently happens that only the tissues which lie in
the closest proximity to the egg can increase abundantly,- the
cell layers lying above participating little or not at all in
the outgrowth, The inactive tissues are ruptured by those

Pre ree a OR a

Oo ee ee an!

1 toc. cit. p. lie,

é Rech, pour servir 4 tihistoire ad, gajles. Ann, Sc, Nat.
BOtes iil serie, 1853, T, ARIZ; [.« aye *

(221)

. (222)

194@

growing so strongly and the new formetion pushes outwrrd,
While in the eambinl gall of a Nematode shown in figure 88,
the epidermis persistently surrounds the luxuriant tissue ex-
erescenoe, we find in other galls that the covering tissue holds
its own only at the beginning so that in the end tears are
formed, 4n which the more deeply-lying goall-tissue is exposed.
Tho galls of Aulex Hicrecii, Lasioptera and others cre "cen-
closed" by a modcrate development of the gall-excrescence, In
the onse of cspocially luxurinontly de¥eloprd specimens, however,
tha normal soovering tissue is ruptured here and there and the
form.tion of wound cork is eventuclly necesscry, In mny Oyni-
pidos gealis (in the autumnal galls of Neurotorus lonticuleris
n, numismotis cto,) from the very beginning only B Snell tissue
complox in the interior of the organ, producing the gell, is
ecpable of increasing, "gall-plestom"}{ The outgrowth progresses
apddly, brecks through the inactive outer tissue layers and de-
volops its ovn covering tissue,- just cs the "frec” walled gclis
ef Hormony4e piligerg cre formed (see nbove, figure 67), Figure
89 Shows in cross-section the free oembial goll of Biorrhize
aptera (the winter generation of the above-named gynips termin-
eis) Which abounds on the roots and yaung branches of Quercus.
The endogenous origin 46 made alosr by the drawipg, without
further explanation,

The nammer of production of "free™ galls necessitates the
feet that they usunlly appear om more or less independent appen~
dages of the plant orgen beering the gall, However, it would be
abselutoly unsaaed Eletie to wish to drew conclusions from the
oxternal appearances of a mature gell as to the ontogeny of this
goll, which, like that of Biorrhizn aptera, rests Jike an inde-
pendent organ upon its substratum, Thus, for example, the gall
apple, produced hy Spathegaster baccenrum (on Quercus inflores-
eenees and loaves) as a willed Boil, covered round ubout by de-
rivetives of the normal opidermis, and the dainty goll-apple of
Nematus gallorum (on willow lecves), disregarding its mor phologic
Indépendencé, fre canbial golls with the same development as the
one shown in figure 88, ,

The description of the much ruptured gall of Lasioptera
picta, or of Aulcex Hieracii proves further thet no Sharp bound-
ary toy be drawn botween free and enclosed golis, I would like
finally to mention one more type of cambial geil, in which, os
in the ense of the walled gnll of Hormomyin piligera, regulerly
defined portione of the new formetion remain covered by the nor-
mal epidermis, while others become exposed, In figure 90 is
shown 2 cross-section through an otherwise undertermine d (Dip-
tera?) gall from the leaves of Parinarium obtusifolium (Chryso-
balances) which will interest* us in many ways, in a short,
Cylindrical gall is produced by a local outgrowth of hr arbeg
phyll. Thus the strongly proliferating portion of the t ae
ruptures the epidermis which lies above it and, by growing fur-
ther, elevates it, Similer processes are repented on the oppo~ —
site side, We find here 9 tissue ring increasing reletively ‘
weakly, in the development of which & circular rupture is cae i
the medial field of the epidermis remaining at its origina

level while the adjacent parts are raised by the outgrowing
tissue ring, However, no new, real epidermal tissue 1s pro-
duced on the exposed parts, I know s1so0 of similar processes

in other galls.

-— -— =
Pe ee ee ee ee ee el

A Unfortunately, only herberium material of this interesting

gall was at my disposal, (Herbar. Monncense),

197

I would like to call attention to the fact that the
formation of “free” galls is not met with in prosoplasmes,
alone. If, by the action of Schizonevra lanigera (com-
pare abova p. 205), = kabaplnSmatica woody-excrescence is
produced, which distends the bark and then splits it, the
developmental process is ovidently similar here to the
prosoplasmas just described, Also, other stimuli besides
gall stimuli enn ¢all forth Similarly outgrowing, endogen-
ous formations, In the intumescences illustrated in figure
£0, only the mesophyll increases in this way, finally
rupturing the epidermis,

Further reference should be made to the fact that the
developmental diffsrence, proved between walled galls and
medullary galls, is expressed clso in the gall products,
which crise only through growth of the cells without sub-
Bequent division (gall-hypertrophy). In Brineum galls,
the gell anim-1ls are "walled in” more or less completely
by the growing epidermal cells, In the vesicle gall oc-
curring often on Viburnum Lantana (figure 43) a typical

pa gall is produced by growth of the ground tissue
cells, i

The forms of the various medullary galls differ greatly.

The elliptical is most frequently repeated. Where leaf galls
are concerned, the gill is either visible on both sides of the
leaf as calotte-like swellings (fugure 88) or it is attached

on one side by a small, thin stalk, In the former case, cithéer
both sides are equally or approximately aqually developed, as,
for instance, in the gall of Nematus vesicator. N. Vallisnerii
etc,, or there is prosent a decided dorso-ventrality (compare
figures I1I and 112), The upperside displays o different form
from that of-the under side, Not infrequently, the dissimiler-
ity between the upper and under sifes may be recognized only by
considering the anatomical conditions (figures 108 and 93),
Next to the elliptical, the spherical form is usual, (Nemntus
allarum etc.). More complicated forms with divorse outgrowths,
constructions etc, may he found emong the Cynipides galis.

Although the prosoplasmes hove a peculiar character-
istic form, small variations, corresponding to external
conditions, ore not rare, It seems a matter of course
that the form of the gall varies from the usual one, if
unfavorable spacial conditions arrest its development;-
this case abounds in those galls which are developed in a
small space, in closely congested groups (Neuroterus len-
ticularis etc.) and are thereby united into extensive
fasses (Cecidomyia Corni).

+ $§til1 more interesting is the fact that many of the
galls, capable of developing on different organs, assume
different forms on different substrata, However, in all
the cases known to me, this formal difference is vary un-
essential. Diplosis botularia can infect different parts
of Fraxinus Teaves, If the midribs of the leaflets are
infected, roll-like leaf-foldings are produced, as shown
‘in figure 91A. But if the galls are formed in the leaf
axis, the slander leaf-blades of the rhachies swe}} out
into fleshy ridges, which enclose the larvae cavity —
(figure 913), The majority of the other gall animsia,
however, (Diplosis tiliarum, Spathegaster paccarum etc.)
which form their galls on different organs df the host

plant, always produce the same gall form - with but very
slight differences,

(224)

198

The eft-quoted statement that Rhinocola s j
eciosa
produeas other galls on the leaves Of 2 Spocioa oF popiis
n Germany than it does in Aragon*.needs more exact proof.

Besides, in the gall productions of Rhino
co ~_
mas are probably the ones concerned, la, kataplas

I have already called attention to the fact that t
ternal and internal peculiarities of prosoplasmatic ae ney
be traced back indesd to the quality of the gall stimulus and
the composition of the gail poison given out by the parasite,
while the constancy of the proportions of size and form cannot
be explained so well by the quality of the infection as by the
extont of its action and its type. In prosoplasmas, gall ani-
mols are invelved, which cannot at will leave or change the
Place dnfested as can possibly be done by wandering leaf-lice
ete, nor can they extend 1t irregularly, or indefinitely,as do
outgrowing fungi, only a narrowly limited field of infection
is produced, Further, the poison causing a production of the
gell is introduced into the plant only once with the deposition
of the egg - or it is effective for a comparatively short time -
thus the period of stimulation is evidently very limited, Like
this, the development of the gall soon ends. Although the galls
of the Gymnosporangia ete, continue growth for years, never r
reaching ony real final er"mature"stage, prosoplasmas reach
their last phase of development a few days or weeks after the
deposition of the eggs, corresponding to the rapid developmen-
tal progress ef the parasites.

In speaking of & limited period of stimulation, we think
indeed enly of the most important of the stimuli, td whose
action the tissues which produce the gall and the gall itself
gre exposed; i, «, of the chemical stimuli arising from the
gall poison, However, for at least some prosoplasmas, it has
become evident that another kind of stimuli co-operates in
their production and formation - wound-stimuli, Either the
gall mother injures the plant organ, before she deposits her
wee, thereby causing the production of callus tissue, or the
growing occupants of the gall gnaw its tissue, In the present
consideration. the second is the mere important case, because
there exist in it stimuli of long continued, ever repeated ac-
tion, We find that the tissue of the galls responds to the
atimulus of injury with the same reaction as wound normal tis-
sue, Callus ‘hypertrophies are produced (in the elliptical
galls of the Cynipides infecting oaka; see belew p, 254), or
callus hyperplasias fas in the galls of Nematus vallisnerii)
the formation of which can be continued jong after the form
and size of the gall have reached their last stage; the impor-
tant external characteristics of the gali are not influenced
by these supplementary, long continued phenomena of growth.

In kataplasmas, on the contrary, the chief role is played by
weund stimuli and by those of gnawing which proceed uninter-
ruptedly from the producers of the gall, ‘Their effect is de-
terminative for all the qualities of the gall and the assump-
tion is a propos, that possibly in many cases, no other stimuli
are effective,

i According to Eckstein, Pflanzengallen u. Gallentiere.
Leipzig, 1891.

(225)

(226)

II, Histological 199

Since we now understand clearly the external form of the
different species of galls, so far as of interest here, we will
now turn to the results of microscopic research; we will first
look more closely into the life history of the galls and then
investigate the different kinds of tissues in mature ones.

If we study the abnormal cell-divisions which usher in the
formation of the gall8; we can distinguish three thpes, accord-
ing to their direction: a regular orientation of the cross-
walls can not be recognized in young galls, or the cells divide
predominantly perpendicular to the upper surface of the organ
involved, or they divide chiefly or exclusively parallel to the
surface of the organ.

The galls of Cynips terminalis which consist of irregular
callus tissue (compsre fig, 84) furnish an example for the
first case in which all regular erientation of the cross-walls
is absent in the young galls, Wo definite direction of cell-
division may be found in the young walling-in rolls.

We find division predominently perpendicular to the upper
surface of the organ which bears the gall in the galls produced
by growth parallel to this surface;- in sac galls. In investi-
gating early stages of development, cell rows are often found
running tangentially which have originated from one cell by
anticlinal division. Figure 92 illustrates this case by a cepss-
section through the gall of Pemphigus marsupialis (on poplar
leaves). In most see galls, numerous periclinical divisions
are added to anticlinical ones; However, the galls of Cecid-
omyia bursaria (on Glechoma) for example, seem to be produced
practically exclusively by anticlinial walls. At least in the
examples which I have investigated, I could find mly here and
there an isolated periclinial wali,

Most medullary galls may be traced back to divisions par-
allel to the upper surface of the organ which bears the gall,
Instances are not rare here, in which extensive galls are pro-
duced exclusively by cell division in one direction, Even in
mature, ripe specimens at times tht regular arrangement of the
cells in rows leaves no doubt on this subject, Figure 93 shows
part of a cross-sestion through an undetermined (Diptera?)
gall of Banisteria*, Leaving the epidermis and upper palisade
layer of the mesophyll (P) aut of the question, all the cells
of the leaf tissue have divided extraordinarily actively and
have produced long, strikingly regular cell rows, Cell divi-
sion does not always take placé equally intensively in all
parts of the gall, rather, it is strongest in the middle and
weakest at the edges, In this way, many flat elliptical gelis
are produced on leaves (Cecidomyia tiliacea on Tilia, Hormonyia
Caprea' on Salix Caprea etc,). in Cross-section, the célis are
found to be arranged in regular rows, which, running in straight
lines at the center, are rolled up at theedges, turning their
concavity toward the periphery (compare fig. 94); the cell rows
and the outlines of the gall may be considered a system of
orthogonic trajectories,

The distinction between galls produced predominantly by _
anticlimal division and those others produced entirely by peri-
clinal division still has an especial significance, in so far
that the histology of galls of the first kind always remains
simple, while in the others, besides simple struetural condi-
tions, extraordinarily complicated ones also may be found.

a a en eS

From the herbarium in Munich.

(227)

(228)

200

Also, the external form of the galls ve 1@!
meke possible conclusions as to the Rind of i a ce
which they are producod, Figure 95 shows a very eariv stage of
the walled gall of Femphigas bursarius, which is active on the
stems of poplar leaves.” in cross section through the tissue
ring (fig. 953) 8 higher magnification shows that the cells of
the bark parenchyma, together with those of the epidermis, have
been much divided anticlinally, Near these may also be found
periciinal walls, which are greatly increased during the further
develonment of the gall. Figure 87 illustrates a young gall of
Hormomya piligera, Here too a similar tissue ring /a-a) has
been developed, Which is ;roduced, however, merely by division
of the mesophyll cells, parallel to the leaf surface. It is

ae to prove isolated anticlinal walls here and there in the
sue,

The question as to the tissue mterial, used in the forma-
tion of galls, may be considéred from several points of view,

Thomas has thoroughly tested the tissues of plants which
produce galls, as to whether they are capable in all stages of
life of reacting to the gall stimuli by cell division, His in-
vestigations proved that only those tissues,are able to form °
galls which are attacked during dcvelopment?. In other words,
permanent tissue is incapable of forming galls.

First of all, to keep to prosoplasmas, no case is known,
in which permanent tissue had served as material for the form-
tion of galls, This result is surprising in so far, that in
other pathological tissues, even the cells of permanent tissue
are found to react to stimu]i of differast kinds with most di-
verse phenomena of growth, I will call attention only to the
formation of callus from bark parenchyna which is several years
old and from medullary tissue,- to the production of callus en
old "ripened" Begonia leaves to the hypertrophy of the bark ef
Gold-ribes, to the formation of tyloses in old wood etc. But
what is the condition in kataplasmas, for example, in the bark —
gall, of the beech-wood louse (Chermes fagi??. Hartig's investi-
gatiohs (see above p, 207) prove that, in small trunks which are
meveral veard 01d, the bark cells are incifed to proliferation
and that the formation ef galls can extend even into the wood;
thus here old tissue,- permanent tissue- can obviously be
brought to excrescence and used for the formation of galls.

However, it has been emphasized above, that these very
galls of the beech woolly louse (compare fig. 79) possess the
greatest similarity to callus tissue, Therefore, the question
must be asked, are only wound stimuli concerned in the formation
of the beech-Chermes-gall, by means of which the permanent tis-
sues can be incited to the formation of callus, in the same way
as perhaps by girdling, or other somewhat coarse attacks? And
further, may the permanent tissues be distinguished from those
which have been attacked during development by the fact that they
can react with cell division to wound and many other stimuli but
not to chemical ones? I consider it very improbable that a pos-

Compare Thomag, Zur Entstehung der Milbengallen u. ver-
wandter Pflanzenauswuchse, Bot, Ztg., 1872, Bd. XXX, p. 284,
Beob, ueber Muckengallen, Programm Gympas, Ohrdruf, 1892, Other
investigators arrived at the Same results, Compare Sachs, Physis
01, Notizen, 1898, p. 84 (also Flore, 1893, Bd, LXXVI, p. 241).
Beyerinck,Beob, ueb, @, ersten Entwickelungsphasen etc, loc.cit.
p. 180, Appel, loc, cit. p. 52. For the older point of view,
compare also Hofmeister, Allg. Morph, a, Gew., 1867, p. 634.

20°.

itive answer can ever be given to the second question: There
is no reason for surmising any such difference in principle
between mature and immature tissues. between chemical and
“traumatic” stimuli, It would be ouite another auestion, as

to whether the chemical stuffs, furnished by the gall-producing
parasites, are the ones suitable for inciting the cells of
permanent tissues to division, :

It seems to me that a further point must not be overlooked
here. If prosoplasmas are produceé only from tissues attacked
during development, the explanetion may lie in the unfitness
for use of the permanent tissue, but may also be based,- in
some or in many cases,- on the fact alone that the gall animals
give out their poison only, to young organs and avoid the old
parts. Whether the permanent tissnes may perhaps be able to
proliferate, when it is possible to carry through infection in
them, is a question for the solution of which naturally exper-—
mentation is necessary, Unfortunately, however, as is well
known, all attempts with experimental cecidiology have failed,
up to the present, All my efforts to influence Phytoptes to
colonization and to cause them to form galls on permanent tis-
sue have miscarried, Still, I do not give up hope of coming to
positive results in later series of experiments. Perhaps it is
advisable to make use of organs, whose tissues are mature, but
have also remained tender, So far as their cuticula etc, are _
concerned, I plan 4t some later opportunity to take up again
my experiments with etiolated plants or with specimens from
moist cultures,

Many galls are produced from completely undifferentiated
tissue, from the primary meristem of the tips of shoots or from
callus tissue. Many others are produced from organs whose tis-
sues already show some distinct differentiation, It is now
necessary to make investigations as to whether all tissue-forms
of the host plant can furnish material for prosoplesmatic out-
growths and further, whether all participate to the same amoun
and in the same way in the production of the tissue outgrowths”.

(229) From the outset, cells and tissues with lignified walls
are excluded, since, as is well-known, they can not make any
further surface-growth, As for the. rest, all living cells can,
under certain circumstances, participate in the formtion of
galls - no matter if they belong to the epidermis, the ground
tissue or the vascular bundle tissue.

‘In stem-galls the vascular bundle tissue and especially —
the cambium palongiue to it, often participate greatly in their
formation, Indeed, many galls of the Cynipides winter forms
are produced exclusively from the vascular bundle tissue (com-
pare fig, 89). In leaf galls the activity of the vascular
bundles is less; and often no increase of its cells may be oo
noticed,- rather their development is often prematurely arrested,

In most cases, the grougd tissue produces the largest mass
of galas pith, bark, ane mesaphyil often proliferating pour
astonishing luxuriance, If, in jeaf-galls, the infected sind
of the leaf sttains ten or twelve times the thickness of Sih
normal leaf, in almost all cases it is the mesophyl1 along whi
has been active, Figure 96 gives = cross-section through the
edge of a gall of Cecidomyia tiliacea. Not only the ae of
the assimilatory tissue have heen enlarged and strongly | Se ge
creased, but even the colorless ground fissue cells, which con-

—_— =
wk ee ne Se eS HS eS

XO, ps 67.

(230)

(231)

: £02
nect the transverse ribs with the epidermis on top and under-
neath, ,On the other hand, cases are not lacking in which all
parts of the ground tissue of the leaf can not increase in
the same way. In many fungus galls, the spongy parenchyma is
Superior to the palisade tissue in its capacity for increase,
The same difference is evident in many zoocecidia; of a proso-
plasmatic character, Figure 93 illustrates a (Diptera?) gall
of Banisteria, in which the uppermost palisade layer has re-

mained inactive, while those lying deeper have divided re-
peatedly.

The epidermis always participates only moderately in the
formation of galls, Very often its cells, in contract to.
those of the mesophyll lying directly beneath them, do not di-
vide xt all; for instanoe, in the gall of Hormonyia piligera
(oompare fig, 87) the growth remains less than that of the
more deeply lying tissue-layers, so that the epidermis is ul-
timately ruptured. In the zac gall of Tetraneura Ulmi the
inner epidermis, lining the cavity of the gall, is not able to
keep pace with the growth of the outer epidermis and most of
the ground tissue layers; its cells are usually distended,
drawn out to "retort" cells with thread-like necks, and finally
torn apart (cempare fig. 97), The cells of the adjacent meso-
phyll layers act in places like this under epidermis, In-
Stances of this kind, however, are rare, Sac galls and walled
galls are usually covered with an uninterrupted epidermis, of
which only the supprifical growth has been active,

Epidermal growth in thickness is very much rarer in galls,
To be sure isolated cross-diviisions occur in many galls (Urtica,
Tilia fig. 96, Jaglans (Kuste#, loc, cit.), but only rarely a
many-layered epidermis from a single-layered one, The galls of
Spathegaster baccarum can be taken as examples, also the flask-
ike fly-galls of the elm (fig, 99) and especially the abundant
willow galls of Nematus gallarum, (Figure 98). In these, 4
Sheath of tissue of varying Size is formed from the thin epider-~
mis; at H, in figure 98, the epidermal tissue seems to be con-

structed, since no division in the hair cell has taken place et
that point.

I have already called attention to éhe fact that no con-
clusions as to the participation of the different tissue-forms
in the construction of the galls can be drawn from the nature
of the host plants and their normal histogenetic peculiarities.
In the Salix species, the cork is nee ke re ee ee the
epidermis, As we have found, the epidermis in man y
galls is many layered, To conclude from this that the epidermis
of Salix is especially inclined to eross-division would be ab-
solutely useless, Willow galls (Phytoptocecidia) may be found,
in the production of which the epidermal cells remain undivided,
On the other hmd, in the elm galls above named, we have found
that the epidermal cells divide extraordinarily actively, which
does not take place under normal conditions and that in Ulmus
the cork is produced sub-epidermally - and the like.

Galls have often been compared to tumors or swellings
of the animal and human body. In fact, in one as in the
other, a diseased new formation of tissue is involved,
which shows a moderate similarity in external form in all.
Further, in both cases, a similar connection exists between
outgrowth and substratum, In galls also, we may speak of
"malignancy"; since they often take appreciable amounts of
food stuffs from the ground tissue, in this, resembling
tumors which, like parasites, use up their substratum and
entirely exhaust it, Besides this very little correspon-
dence can be proved, :

(232)

w

203

_ Fortunately we are able 2n galls to inv i

slot Splat bee uopmental stages? the rete ee
bale as — hological new formations and the ground tissue
Baily te pena up beyond all doubt, Phenomena, explained
weed ees of germs, are Suppressed from the very
a typical infection provthy ike tet hich vei acral
mal cells to proliferation can oft oe ar une a
far and can ecnuse active hy er leet oe ee
Siderable distance from ees ine Race e pe
Galls enlarging by ineiidmation” ceo eee

Tumors consist principally of connective tissue

sorie of connective tissue and epithelium, or scene ok
Sue and fatty tissue and the like; we will leave the blood
vessels out of this discussion, In plants, the ground tis-
Sue is as significant in the formation of diseased ort growths
as is connective tissue in tumors, "Mixed swellings” occur
aoe frequently in galls, epidermal outgrowths and those of

he bark, or rather the mesophyll, uniting and forming an
homogeneous whole, ‘Thus we can prove at the same time that
in galls arising endogenously the fundamental tissue of the
plants can develop typical epidermis (with lenticels, hairs,
etc.) on its upper Surface and that the cells of this epi-
dermis can produce derivatives in every way resembling the
cells of the ground tissue, which in the mature galls are
no longer distinguishable from the descendants of normal
ground tissue, Therefore, we cannot speak of a "specifi-
city” of the epidermis ete, in plants, in the sense that,

in abnormal outgrowths, only new epidermal cells will be
furnished by the epidermis and that no epidermis can be pro~-
duced from the fundamental tissue. As i§ well known in ani-
mal tissues, such a difference between epithelial and cam-
bial tissue as here described is accepted as certain by most
histologists,

The histological structure of tumors even im "mixed"
swellings" may he characterized as very simple, when com-
pared with the higher ofganized prosoplasmas, No tumor is
known, which consists of characteristic tisgue zones of
such diversity as those of the gall products of the Cynipi-
des, the Diptera etc, Rather, in many tumors, the production
of but slightly differentiated cells may be confirmed. In
this, tumors correspond to callus tissues and galls termed
kataplasmas. In common with these, tumors may also have the
negative characteristic that they have no definite external
form nor definitte size proportions, In many tumors, aS in
many ketaplasmas, we may speak of theoretically unlimited
growth.

ed

> - el
e

1 compare especially Ribbert, Lehrb, a4, Allgem, Pathol,

Leipzig, 1901,

2 Infilgration growth often occurs elsewheré in the develop

mental history of plant tissues, The parasitic fungi, the "thal-
lus" of the Rafflesiaceae, the haustoria of many phanerogamic
parasites, grow infiltratingly oh
growth oceurs alse, for example, in unbranched latex tubes and
pollen tubes, the haustoria of embryo sacs and others,
never been able to observe that galls develop forms li
toria at their bases; future investigations, however,
make known phenomena of this kind. —

their substratum; infiltration

I have
ke haus-
may perhaps

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204

AS said above, the h
thei ; > 7 istology of pros ; ‘ 2 1 :
ment forms Oe aes os Pa acy heve the _ ee a cect
PL nd ° issue newly di sits cal pee ean -
a :
lly differing strikingly from the et ee eee

tissue and often grea i
edie GoLl forms Ee exceeding these in the abundance of

te Pahoa gg aiffer among themselves ag greatly in re a

aie ee form. Besides highly ein

PemhLe tiene _ hree, four or five kinds of easily distin

or Does ae orms, Simple ones may be found which also "

galis oan ene noe eiaies 4 oa ogee eet see
3 € a

as above mentioned, from those of the pond oe ae

-frequently only the inrer parts are formed with a prosoplasmic

h ry
histological character, the peripheral ones resembling kata-

‘plasmas,

A concentric structure is common t

ha If roll-galls, sac, walled or ee ge ie cee -
ie a a SO ean soon a rag different a tape
pave Son sorusd. surround the larval cavity as concentric
gate tissue ther, the innermost zone top a very firm i a

e simplest cases, only oie eee ae vacroe: provided with a
ally more complicated a peculiar dover mar be in Seber TT atrac ed
of sclerotic elements, or indeed several such layers, The inner
soft part of the tissue;—- for instance, in sac galls,- is formed
of delicately walled epidermal ¢elis and those of the adjacent
grouhd tissue, whtch are rich}y filled with albumen and starch,
In medujlery galls, the innermost layers, bordering the larval
cavity, are, as a rule, delicately walled and rich in cytoplas-
tic substances, Tissues of this kind just named give the galls
the solidity necessary for their occupants, the others furnish
the food necessary for the parasites. Alma ¢ all tissues, com—
posing prosoplasmas serve one or the other purpose”,- all others
“p11 far behind them. Protective tissue and nutritive tissue ere
not only universally distributed and make up the chief mass of
most falls, but also have in the different forms SO a@iverse &
formation, that we must devote & detailed consideration to them.

In this histological treatment, as above in the discus-

sion of external forms, we can affirm that the same cherec-

' teristics found in prosoplasmas may also be proved in the
very much simpler gall-hypertrophies (p. 107). In many
Erineum galls a protecting layer is prought about in @ very

gf ee ee eee eee

lgtatements in the histology of galls are to be found
abundantly in cecidiological literature. As compre hensive works ,
only the Following come under our consideration: Lacaze-Duthiers
Rech; pour servir 4 L'histoire d. galles, Amn. So, Nat, Bot. gd
ser., 1853, T. XIX, p. 275. Beverinck, Beob. veb, 4, orsten
Ls eee ar einiger Cynipidengallen. Amsterdam 1882.
Kustenmacher, Beitr. z. Kennts. ad, Gallenbildungen, ett, Prings-
heim's Jahrb, f, wiss. Bot., 1895, Bd. XXVL, p» 82. Fockeu, Rech,
anat. 8. l. gelles, Lille, 1896, (compare also Rech, S. quelqu.—
galies follaires, Rev. gen. Bot,, 1896, Tt, VIII, p- 491). Appel,
Ueb, Phyto - u. Zoomorphosen. Kbnigsberg. 1899, Kuster, Beitr.
g, Anat, a, Gallen, Flore, 1900, Bd, LXXXVII, P-» 117 and Ueber
einige wichtige Fragen a. Pathol, Pflanzenanat, Biolog. Chls
1900, Bd. XX, PD» 529,

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£05

Striking way by means of the rowi ‘

like ends of the hairs and the fiinranes oo ae oo

merfbraneous parts ; the nutritive tissue at any rate being
furnished by the hairs, the filling of which with steren
Oil etc, was discussed above. ‘The bladder galis of

Viburnum Lantana are for the most pant composed of nptxi-
ive tissue (compare p. 119),

Besides the differences separating kataplasmas from proso--

plasmas, some characteristics common for all galls should be
mentioned, — _

Above all, the tendency to form parenchyma is striking;
the galls are almost entirely par¥enchymatic structures, To
be sure, ducts may be found in them, but these ducts themselves
are composed of parenchymatic elements, The lack of libriform
fibres in all gall. formations, even the most highly organized,
is very noticeable”, In these negative characteristics, the
prosoplasmas conform to callus tissues, wound wood and kata-
plasmatic galls.

Further, the supppessed retropression in the formation of
tracheal elements Is conSpicuous; galls generally contain only
very scanty vascular bundles, the duets usually having narrow
lumina, Similar conditions are found in kataplasmas, where the
eae bea of parenchyma also retards the formation of tracheal
cell-forms.

The same is true of the scanty chlorophyll content of
galls, They are as pale a green as many fungus galls, most
eat he tissues, etc, In many the green pigment is entirely

acking,

We will herewith pass over to the discussion of the dif-
ferent kinds of tissue forms in galls and will begin with The
two most important, the protective and nutritive tissues. As
less inportant, the sparsely developed fibro-vascular, the as-
Similatory tissue and a few others will be named later.

1. PROTECTIVE TISSUES

As the protective tissues of prosoplasmas, there come un-
der consideration, the covering tissues and, also, especial
complexes of stone cells, We wil] term the latter mechanical
tissue, No absolutely sharp line can be drawn between both
forms of protective tissue because many peripheric cell layers
in galls, including the epidérmis, are often composed of simi-
lar elements, resembling stone cells,

Epidermal Tissue

At this point, the epssermes comes under our gonsidera-
tion, only in so far as performs the functions of & cover~
ing tissue and, by means of an unbroken covering, a strong
cuticle or because the productian of hairs gives protegtion to
the more deeply lying tissues, ‘The epidermis in sac and walled
galls, which lines the cavity of the gall, has other functions
and will be discussed later, Further, we will have to discuss
only those forms of epidermal tissues which in gall-production
are not carried over in an unchanged form from the normal parts
of the plant, bearing the galls, as is the case in many medul-
lary galls, but. which in some way vary from the normal in their

1 Compare here statements on p. 246 on the gall of
Synophrus,

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206

histology. For the present consideration, it is immaterial
whether the epidermis of a gall is derived developmentally
from the normal one, as in "enclosed" galls, or is to be con-
erived of as a new formation, as in "free" galls,

In sac and walled-galls the outer epidermis is composed
mostly of relatively large, but often very flat cells, which °
are proviced with only 2 moderately strong cuticle, At times,
ameny lcyered epidermis can be formed from one which, under
normal conditions, would have only one layer, Isolated ercss-
Qivisions may be found in various galls (see above), but such
& tighty epidermel shect as that found in the Diptera gall on
Ulmus* shown in figure 99 is rarely woduced, Here and there
eight, tén and more epidermal cells lie on top of one another,

The external gells (Lacaza-Duthiers galles externes)

Which appecr attached as special appendages to the organs bear-
ing then, at tines produce as meny layered epidermis and often
show a strong cuticle on'their ogter walls, In the ("enclosed")
gall of Nematus geliarum, the cells ere rather smatl and strong-
ly outiculerized, (compare figure 1004), in the gall of Andricus
qucdriiineatus they cre distended like papillae and hove rather
thick wells, (Fig, LOOB), Ine Californian Cynipides gall on
quercus Visiizeni, the outer walls of the epidermal cells end

e upper part of the side walle are thickened, so that an ap-
proximately conical cell-lumen remains free (compare fig. 114).
The gell of Acraspis macropteree (figure 106) has thick-walled
epidermal cells, with at tires a pit-like wall structure.

I found a very singular epidermis ine gall of Jacquinie
‘Schliedeana Mez, The rAPioveagonse stalks swelled out £5

thick, turnip-like bodies, the covering tissue of which is shown
in figure 101, The cells in the outermost layer eon not, for
any length of time follow the gall's continuous growth; they

are pressed into sheets, their walls are constantiy drawn out
thinner and finally tear apart, At the same time, the cells of
the layer lying immediately beneath this one assume the func-
tions of the epidermal tissve, since their outer walls are
greatly thickened and powdrfully cuticularized, Even the third
and fourth cell layers can be transformed in this way. In the
figuré, at a, is shown the overlapping of the wa11-thickening

and of the process of euticularization in the cells” lying

meaner,

So far as I know, cork as a covering tissue is one of the
rarities in galls, It is formed comparatively luxuriantly in
the gall of Neuroterus numismatis {On Quercus), the character -
istic form of which 18 Shown in figure 102a, In the central
depression on the dorsal part of the gall are formed several

ro nt aig Peet se es raga Oe ance) cat CY cat | eee eg Ae geo ee

Schlechtendal's Verzeichnis, Nr. 361.

2 So far as my Slight tests permit of a decision, a simi-
lar epidermal substitution does not take place on norm] axil-
lary parts of Jacquinia Schiedeana. Sclerdder (System, Anat.
ad, Dikotyl., p. 577) mentioned a Subepidermal formation of cork
in Jacquinia, Damm has ennounced recently that the celis of the
bark parenchyma in various piants form cuticular layers and
cause the production of a "cuticular epithelium" (Ueb. d.,,Rau,
die Entwickelungsgesch. v, a, mechan, Eigenschaften mehrjahr.
Epidermen bei d, Dikotyl, Beih. z. Bot. Chi. 1901, Bd. XI, p.
219. Cuticular epithelium may be proved in various Viscoideae.
A new example is illustrated by the gall treated of in the text.

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layers of thin-walled cork. Wound-cork is occasiona ly met
with in these galls, in which the outer layers are se
by the intensive growth, of the inner ones (for instance, in
galls of Aulex Hieracii+, Lasioptera, . :

The formation of bark is known as yet only in a few galls
(Aptera and Radicis galls). (Beverinck loc. aie. Pp. 64).

frichomes, which in structure and arrangement, may well
Serve 48 & protection to the covering tissue in its functions,
are not unusual in prosoplasmas, The @all of Nematus bellus
(on Salix) bears a thick covering of hair, as do those of Hor-
momyia piligera (figure 87) and Neuroterus lanuginosus) The
oak galls of Neuroterus lenticularis and N. numismatis -bear
heirs of a striking form. Star-like bunches of hairs are found
on the former, the single components of which are thick-walled
and filled with a brown content; in the others, we find a thick
at hair covering round about the edge of the gall (Figure
102a)., The hairs of the lenticularis gall are interesting since
the bunches of hairs of this stiff, short-membered form are
found on numerous Quereus varieties, but not on our native ones,
The hairy forms of the numismatis gall occur neither on the_
German nor on any other Quercus variety, They are long, uni-
cellular, sharpZy pointed and often two-armed, Both arms differ
greatly in length (compare 102c) and are always so oriented,
that the longer of the two seems to be centrifugally directed,
the shorter turned toward the central point of the upper side
(at a). When studying cross-sections, one cannot suppress the
thought that spacial conditions regulate predominantly the pro-
‘duction of the two-armed forms, To al11 appearances the hairs
become two-armed, because they fill out the Space at their dis-
posal. At b in the figure, differently formed hairs are shown;
some are bent sharply, like knees, another kind is bent twice
and provided with a "Shoulder" for a second arm, Forms ef
this kind and similar ones are produced only as a result of a
lack of space”,

By far the majority of prosoplasmas are naked or only
Slightly pubescent,

‘Many galls laok all covering tissue. The galls of Cynips
terminalis on the tips of shoots, produced from callus-tissue,
arg made up externa}ly of homogeneous parenchyme, the outermost
layer not being characterized in any way as epidermis or cork,
Moreover, the galls here mentioned belong to those, which
"srack open" in places and expose their inner tissue. In others,
the epidermis is lost inan early stage and is replaced by hypo-
dermal layers of stone-calls.

— ee lel eel lll lll ell el lll

lel

* Compare also Skrzipiet2, P., Die Aulazgallen auf Hier-

-aolumarten, Dissert. Rostock, 1900.

z While I trace the branching of the hairs here described
to the action of spacial conditions, I assume that even in Sin-
gle cells the same phenomena of "correlative growth" can take
place, as in some organs (for instance, roots, compare above
p. 140), I would like also to trace back to similar conditions
the production of abnormally formed tracheids in the gnarls of

wound-wood, especially the formation of branched forms. -(Com-
pare figure 70).

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Mechanical Tissue £08

We will term mechanical tissues those whith are composed of
stone-cells, This name is justified by the fact that without
doubt the layor of stone cells can’act mechanically because of
its firrmess. The larval chambers, which are composed of mechen-—
ical tissues, cand their inhabitants ere thus shielded from pres-
Suro and blows = and protected from the attacks of animal enamics.
Lacnze-Duthiers, who had recognized this community character of

the stonc-cell tissues in galls, termed the firm zone a "couche
proteotrice",

Compared with the formation of meeheniorl tissue in the nor-
mel plant body, tho strengthoning tissues of gnlls rey be of two
kinds: ocithor the gulls carry over their mechanical tissue from
the plant organ, which produoes thom, or they produce a tissue
of this kind for themselves, "A Pethological Anctomy® is natur-
ally goncerned only with a study of the latter,

The "externcl" galls only rarely leek all mechanicnl tis-
Bues 2s in the different nematus varieties on the willow, Te
find in most gells an extrnordinarily rich production of stone-
coll tissuos. We will study first of all the quclities of the
Singlc; thick-walled cells and later the form an@ distribution
of mechanical tissues,

~ 1, <ALL thick-walled colls, found in galls, are selereids.
Sclerenchym: fibres (stereids)rare absolutely lacking in galls.
The mmission of the prosenchymatic mechanical alemunts conforms
with the parenchymtic character peculiar to all] gall tissues
and also to callus formations.

Within the boundarics dravm for the forms of the mechanical
cells by their strongly retained sclercid-character, we find
nevertheless an abundant variation, The form of the stone cells
differs greatly in the different galls; their porosity and the
degree of lignification are also unequal. Finally, the stone
cells are very noticeable, which are produced by the unequel
growth in thickness of the cell-menbranes.

In the majority of cases the stone cells of the galls are
small, round, and iso-diametric, as shown in figure 93 (Banis-
teria gall). In other galls, however, we find angular cell forms,
stretched like palisade-cells and usually oriented perpendicular
to the upper surface of the gall body, Similar to the rod-like
sclereids of many fruit and seed shells. Figure 103 gives the
cross-section of a gall of Hormomyia fagi. ‘The greater part of
the gall tissue is composed of Glongated, thick-walled cells, the
walls of which are mich pitted. Here ond there little intercel-
lular spaces have remained free. Elongated sclereids, with a
distinctly radial orientation, are found in the galls of Cynips.
kollari C, tinctoria and many others, Occasionally palisade
Sclerenchym i8 produced forthwith in young galls by sclerosis
of the assimilatory palisade cells, or the cells of the latter
become enlarged before they have hardened to gee eben ae
The oak gall of Cecidomyia Cerris (figure 104) may serve as an
example of this case,

Even when the cells of the mesophyll divide abundantly,
their derivatives often retain the form of typical palisade é
cells (for instance, in the gall of Cecidomyia tiliacea). If
they have hardened near the gall-chamber into a couche protec-
trice", we find it composed of palisade ceils all oriented par-
fllel to one another, In galls having © different process of

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. 209

development, the sclereids in the Vicinity of the larvae cav-

ity are
oe distinctly radially, (the kéllari gall ana

It is interesting that in ga i
independent zone of mechan Gal eee ee ea
omvia Cerrig and very many others, the two mechanical coats
are composed of sclereids differing in form, The ober coat
consists usually of large ceils often elongated like palisade
cells, the inner one of appreciable smaller, iso-diametric ele-

ments (compare figure 104 We 7 j
ae A eel 2 ‘ will have to refer later to sim-

The differences in porosity of the sclereids is often ver
Striking, In many gclls the pembremes ef the stone cells Seen
yp eet closely dotted, the pits standing close to one another
a ale a Bag instance, the cynipides galls shown in figures
a a Lid), In other enses the pitting is relatively scanty,
rin me Aor in the oft--mentioned heech gail of Hormomyia

§*,~ in numorous galis the pitting of the mechanical cells is
completely lacking, at least in many layers, No vitting may be
tee ce in the upper anguler part of the mechanical. tissue,

g interesting Diptera; gall of Parinarium {Fig. 90);~- the
age of the lover, flatly arched part and the stone cells which

€ on the under surface of the lead (shaded in the figure) are
espocinlly porous, Numerous examples might be cited to prove
thet the me chanical tissues, which surround the larval chambers,
are composed of colls with varying porosity and arranged in
zones, The side toward the larvae cavity {figure 105N) is of-
ten provided with delicate .sclereids, in which the thickened
ridges resemble slander bands, while in (105R) much thicker cell
walls are met with at some distance from the cavity. These dif-
ferences may be noticed very clearly, for example, in the gall
of Diastrophus Potentillae, In the fagus-gall (figure 103) the
delteate celts of the innermost tissue have pitted walls of a
kind similar to that known in the thallus of the Marchantiaceae,
in the illustration this meshed, most delicate wall-thickening

has been indicated in only a few cells. If an outer and an

inner mechanical coat may.be distinguishrd, the cells of the
first are often only weakly pitted, those of the latter very
abundantly so,

Finally those stone cells must be mentioned, which undergo
only a onesided thickening of the walls, thus remaining half thin-
walled, or in which the wall-thickening in different parts iF
noticeably unequally strong, One-sided or “horse-shoe" thick-
ened cells occur under normal conditions, for example,in the me-
chanical ring of the Laurineae;- so far as I know, they are com-
pletely lacking in the mechanical tissue of the Cupuliferae,

Likewise in vak-galls, we find extraordinarily often that all

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the mechanical cells, or at least the cells of definite zones and
layers, are thickened on only one side. In this way the deli-
cately walled vart of the stone cells in many galls comes to lie
toward the outside (Apdricus guadrijineatus, Dryophanta_folii,
Br. divisa, Neuroterus palftars and many others, compare figures
TOY and 114), or toward the center (as in the elliptical gall of
the oak, in that of Acraspis mecropterae and many others, conm-
pare fig, 106). It Seems rarely to happen that the cells, thick-
ened on one side, differ also in size and form from the adjacent
ones which have become thickened all around (as in the oak gall
shown in figure 107), In all ¢ases in which "horse shoe" scler-
eids occur negr others thickened on all sides, they form,as it —
were, & transition to the delicately walled tissue zones. The vy
lie either on the inner edge of the mechanical coat (figures

‘ 210

106 and 107), or on both this and the outer edge, furnishing
both the transition and the soft parenchyma (Fig. 114), On
the other hand, palls are found, in which stone cells, thick-
ened strongly on all sides, directly follow the delicately
walled parenchyma, Figure 119 shows finally that even complete-
ly isolated zones of sclereids, thickened on half their sides,
may occur. It irs a metter of course, that this thickening of
only half the sides daes not cxdlude the formation of pits, In
the gall of Gynips Lisnicoia and many others, the thickened
part of the wali is very Strongly pitted, We will have totre-
port later on the remarkable phoenomonr of secondary growth
which has been verified in many of the scloreids of Cynipides
galls, the walls of whish have been thickenéd on one side,

Uneauclly thickened solereidss, the lumine of which show
bottic-neck, pointod forms occur in various Oynipides galls.
Compare fig, LOY, also fig, 114),

The oolls in the gell products of other insects (Stefani-
ella Trinacriae on Atriplex and others), which are thickened un-
equaliy or on half their sides, are rarer and less striking
than those of tho Oynipides oak galls,

243) 11, Having discussed the qualities of the individual me-
chanical cells, it will be necessary to investigate the way in
which single cells are united into mechanical tissues and what
may be the distribution of the mechanical tissues inside the
gall body.

In most eases the mechanical cells of galls combine into 4
elose mechanical tissue, Not infrequently, however, a soft par-
enchyma may be found within this in which isolated stone cells
are scattered (compare figure 101). The manner in which the
mingle, thick-walled cells join on td one another, displays noth-~
ing unusual; either parallel rows are produced (as in figures
90 and 93) or irregular bands, Small intercellular spaces be-
tween the simple sclereids are very clearly recognizable. In
order to be able to describe the arrangement of mechanical tis-~-
sues in the gall body, reference must be made to the other tis-
sue forms.in galls.

Lacaze-Duthiers (loc, cit, p. 292), on the basis of his ob-

servations on highly organized galls, such as those of Cynips
tinotoria and aerara, differentiated the following tissue layers:

(:1. epiderme

( 2. tiseue cellulatre sous-epidermique
I, ( 3, parenchyme (spongieuse

( {dure

('4, vaisseaux
II, ( 5, couche protectrice

( 6, partie alimentaire

j : issue forms
verinck (loc. cit, p. 39): called the two last named t1isi
an tthe aad vali". the others (1) a1] together "the gall bark",

The different formation of the couche protectkice, in con-
trast to gall bark, makes possible’ the differentiation of the
following three types in mechanical gall tissues.

I. The mechanical tissues lie comparatively deep in the
inner part of the gall. An epidérmis and a bark formed ee
walled parenchyma is present which ean differ greatly in thick-
ness and histolggy.

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ell

4S an example may be named the gall of Aulex Hieracii:
internaldy each larvel chamber is found to be Stirrovrced by
a hard protecting layer while a richly developed gall bark
lics outside of a11. In other galls, the propo tion between
the fall bark end the "inner gall" varies, In the products
of Hormomyic oxnreae, for exanple, which exists on willows,
only a vewy fow dayérs of bark tissue lie between the mechani-
onl tissue end theepidcrmis,

2. In forns of the second type, the mechanical tissues
lie Gircetly bener.th the onidermis, The "gall bark", in Bever-~-
inok's sense of the word, is here recuced to the epidermis.

The oft-mentioned, undetormined Boanisteric gell (fig. 93) bears
on its upper side « tvo leyered ¢rll hark, composed of ene lgyer
of epidermis and 2 leyor of paliscd: tissue. On tho underside,
the mechanicel tissue lios directly against the epidermis,
Figure 90 illustrates siniler conditions: merely one layer of
epidermis lies above tho moechenical tissue gone. Further exan-
ples aro furnished by the leaf-eurling gall of the Pistaciae,
produced by Pamphigus pellidus, P, retroflexus and PF, semilun-
Qlarius, The gcll of Andrious coriaceus, abounding on various
Southern Europein oaks, consists, st any rate at the time of
ripening, only of epidermis and the"inner gall", The mechanicel
tissues are Strongly developed. In the Kollari-gall (produced
by Cynips Kollari) the epidermis is thrown off prematurely, s0
that the outermost tissue layers of the ripened gall are the
mechanical ones, (Beverinck loc, cit. p. 159); I found similar
conditions in the gall of Cynips Mayri and Kustenmacher (lot.
cit. p. 181) in that of C, ferruginea.

3. The third type is characterized hy the fact that the me-
chanical tissues extend to the outer surface of the gall, Even
the outermost tissue layer, like those next following, is formed
as a mechanical one:- an eSpecial epidermal laver or a “gall
bark" can scarcely be spoken of as in Hormomyia fagi (fig. 103),
Dryophanta divisa, etc, The outermost layers of the mechanical

issue often consist of cells elongeted tangentially, those :
lying deeper of radially oriented ones, En the ask gall of
Diplosis botularia, the cells of the epidermis take part in the

-sclerosis, at least in places (fig. 110). In this, as in the

fagus gall, "enclosed" galls oceur of which the epidermis is
derived developmentally from the normal one.

The form of the mechanice}] tissues, corresponds entirely
to its significance for the inhabitants of the galls. Speaking
teleologically, the question is one of preventing the collapse
of ‘the cavity inhabited by the gall animals, of insuring ifs
form and of closing the way into the interior to anima] enemies,
Accordingly, the mechanical gall tissue usually represents en
armor, closed on all sides, which in thickness and extent cor-
responds more or less ta all demands, The question, therefore,
whether the firm "mechanical mantel" is only a few.cell layers
thick or whether practically the whole gall consists of mechani-
cally effective tissues is of no importance for its formal
character.

The form of the mechanical mantel usually repeats in minia-
ture the form of the whole gail. In spherfeg}] galls, we again
find the ball form in the mechanical Pe (figure Loss), in.
the flat, ellintical oak-gall (B), of the Banisteria gall (EF)
of the short-cylindrical gall of Peringrium {figure.90) etec.,
the form of mechanical mantel always follgws that of the whele
gall, @he same conditions are present in gag and walled galls.
These do not represent a closed body s{ice an open ganrl unites

v

the larval cavity with the outer world. A mechanical mantel i¢

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. 212

also produced here round about the whole, (Big. 1087), In

the leaf-curling gall of Pemphigus pellidus enc in others, the
up-curled edge of the leaf is pressed so firni- ageinst the
lamina, that the shaft for exit scarcely comes under considera-
tion in the action of the mechanicul tismue develonec in the
leaf tissue (Fig. 108G), As an exception to the ruie, the gall
of Cecidomyia tiliaceae (Fig. 108C) should be nared. ‘While the
gall Itself resembles a bi-convex lense, its mechanicl mantel
has the form of a spindle or a helmet; its long -axis being
perpendicular to the medial plane of the gall.

The cases deserve special mention, in which the mechanicel
mantel is composed of tivo parts, Instead of a hollow ball, it
here resembles two hollow hemispheres with overlapping edges
or with edges almost touching each other. ‘The gall of piphosis
globuli, not rare on rspen leaves, opens on the underside by
means Of c narrow cleft, The lover port of the mechanic.) man-
tol (Fig, 108H) begins immediately ct the cleft and, like a
bowl set upright, oncloses the under h:l¢ of the larval chamber,
The secon half of the mantel lies somewhet bent over this;-
and, like a hemisphere, protects the upper part of the gall
cavity, Between these two parts of the mechenical tissue, lies
a thin-walled parenchyma, The galls reproduced in figures 90
énd lll show very similar conditious; in them the upper part of
the mechanical tissue has ascuned the form of a Fat 144,

Usually each gell possesses only one mechanical mantel: &
further advance is shown where a second one surrounds the first.
While the inner mante] is usually closed on all sides, the
outer one is often only half formed;- it then lies like a flet
pan over the inner one and over the central pall cevity. asere

04 and 108D). The structure of the ash gall of Diplosis bot-
ularia (fig. 1081) is espdcially firm. On the complete inmer
mechanical mantel is laid an outer one which is open only on
top, showing in cross-section a horse-shoe form, Often both
parts, lying opposite the gall opening, unite with one another.
In other cases, the outer mantel nlso forms a closed whole, as,
for instance, in the Banisteria gall (fig. 108E), or in tmt of

Ginips Maye (Fig. 109). In the latter we see cleerly that the’
outer

mechanical mantel repeats well the form of the whole gell,
while the inner one assumes a Simpler spherical form,

If two mechanical tissue mantets are formed in the same
gall, the two may almost Always be distinguished more or less
from each other by their histology.

A&A very peculiar kind of Cynipides gall is represented
by Synophrus politus, On branches of Quercus Super, etc,
A small inner cavity encloses the larva, Its anatomical
Strieture io vory. striking.’ The protective tissue of the
falls if formed of a thick woody-mantel which represents a
Zvlem kernel surrounded hy bark, but apparently completely
isolated from it, similar to the tuber gnarls spoken of
above, The galls also correspond histologically to these.
We find in abnormal wood, composed predominantly of pittec
parenchyma, that there are places with normally arranged
elements lying side by side with others whose fibres, in
the greatest "disorder" take first one direction, than an-
other, Also the beginnings of "gnarl formations" with
strangely bent libriform fibres are not lacking. We often
find large sclereids with large lumina and strongly thick-
ened walls in the immediate vicinity of the larval chambers,
Unfortunately in the dried materiel I investigated the for-
mation of the nutritive layer was no longer recognizable.

247)

(248)

213

If a well differentiated nutritive parenchyma follows,
on the inside, the irregular wood layers, the structure
must be considered to be a prosoplasma; the gall of Syn-
ophrus politus would thus be the only prosoplesmatic one
with layers of libriform fibres, -However, it shows essen-
tially the greatest correspondence to kataplasmas and we
may term it a knarl ball produced by gall animals, The
ievelopmental history of this gail, which fs not of rare
ocourrence in Sicily, could not be studied in the speci-
mens et my disposal. A Gloser investigation of the re-
markable structure would be very desirabic,

In meny galls the "tendency" to form thick walled paron-
ohyme cells is vory sreat ond is not thoroughly oxhausted in
tho produstion of the mechanicel mentels just described, Galls
which contcein sufficient quentities of thin-walled bark peron-
chyma in young end medial stages of dovelonment finally consist
only of sclereiis - at times after the daisappoaranee of the ten-
der nutritive tissue. An exemple of this is the large gall of
Cypips Mayra, in which tho luxuriant tisrue masses between the
outer end inncr mechanicnl mantels finally become entirely
thick-welled and lignified (fig. 109),

As in the consideration of normal parts of plants, it is
also not admissable to consider here all thick-walled cells as
mechanically acting parts which function expediently. Besides,
the sclereid tissue, produced late in many galls, is often so
porously constructed thit there can he no thought of a mechan-
ideally effective tissue.

Nevertheless, besides the above named sclerotic tissues,
we find still others which function very obviously as such and
deserve brief mention,

I would name first of all the closing tissues, I thus term
those tissnes which are used to assist in tightly closing the
entrance of the gall, because of their suitable cell forms, In
many walled galls, short, extraordinarily thick-walled papillae
are produced on both sides of the entrance to the gall cavity,
and form a cogging of the two contact surfaces, Figure 110
shows part of a cross-section through the gall of Diplosis bot-
wlaria, The papillae are short and rounded, apparently acting
Similarly to the same structures of the cone-scales in coni-
fers+. Since these peculiar hair structures in the botularia
gell are formed only on the surfates touching one another and
in their immediate vicinity, it might be well to make investi-
gations as to whether locally acting stiml4 (perhaps stimuli
of contact?) possibly cause their form:tion*,

Further, the mechanisms of opening deserve our attention,
Many gall animals free themselves from their enclosures by eat-
ing their wey out of their dwelling place, In others, the host
plant produces the necessary mechanisms which, at the time of
ripening, give the gall animals their freedom, The mechanism
is set in action as soon as the tissues of the gall begin tz

1 cuneut, Haarbildungen &, Koniferen, Forstl.- Naturwiss.
2eitschr.,, 1896, Bad. V, p. 109, Compare plate VI, fig. 3.

2 It might be possible that here, as well as in other gall
formations, the chemical stimulus, arising from the gall poison,
participates only indirectly in the production of definite
forms, since it only makes the tissues susceptible to other
kinds of stimuli,

. £14

Shrink,- the unequal water content of the mechanical tissues
and the soft parenchyma causes an unequally strong contraction;
thereby bringing about a rupturing of the gall tissue, The
undeterminable (Diptera?) gall of-an Anherstioce is very
Strikingly constructed, fh Cross-Section through the gall shows
(fig, III) that the mechanical mantel consists of two isolated
(249) parts, A flat, cover-like plate of tissue lies above the lar-
val chamber, the edges of which extend over and around the
flatly curved, bowl-like sclereia mantel lying beneath the cav-
ity. Between the two are a fer layers of delicate tissne, When
the gall dries, this tissue degenerates and the cover falls off
in one piece, thus opening the interior of the gall. The me-
chanierl tissue of the gall illustrated in figure 90 may indeed
function very Similarly, but my dried material did not permit
of any oeonclusion concerning this, Our netive flora furnishes
further examples, At the base of the gall of Hormomyia fagi
(compare fir, 86) a delicately walled zone of Separation is re-
tained, - so that at the time of ripening, the helmet-like
part of the gall lying above this zone is’loosened, In the
linden gall of Ceeidomyin tiliacea the sclerosized inner part
of the gall, which contains the larval cavity, is squeezed out
of the contracting peripheral tissue and the inner gall falls
to the ground. Later, as described by Kerner”, the gall animal
aw8 & vegular groove in the gall kernel and then pushes off
the upper part, like a cover, Figure 112 illustrates this pro-
cess, Further examples are describad in Kerner's "Pflanzenleben"..

Nutritive Tissues

Those gg11 tissues which are devoured by their inhabitants,
or the contents of which at least are of benefit to them, may be
termed nutritive tissues, The form of the single cells and the
Character of their walls are of less interest to us hbre than
is their distribution inside the gall body and the quality of
their contents,

The Significance of the nutritive tissue in the histology
of the gall formation and for the existence and development of
the gall animals even exceeds that of the protective tissues,
No gall is without nutritive tissues and these not infrequently
represent the chief mass of the gall body. In the discussion
of gall hypertrophies and kataplasmis, we have already become
acquainted with galls in which #11 the pathological cell pro-
ducts, without an exception, bear the character of nutritive

(250) cells. It is usually a question of the deposition of proteins,
of oil and of starch,- as stated above in the discussion of
Erinewn hairs, The fact is here of interest, that, in proso-
plasmas, the "divisdon of labor” among gall tissues produces
definite zones, the cells of which "serve" exclusively for the
storage of carbo-hydrates or of food stuffs containing pe oeety
Especially in the highly organized cynipides and diptera abe
the layers of the nutritive tissue are extraordinarily sharply
set off from the neighboring, mostly sclerosized zones, lacaze-
Duthiers, in his gall anatomy, differentiated an especial
"couche alimentaire" (see above),

- ~
- - —_-_ - -_ = - =m -
~~ -— = - ed
-— = -~ -~- -_- =
_— 9 = _-— = - = -

i r Ra 's kind determination,
Aecording to Professor Redlkofer's kin j
For the chapman t of material, I wish to thank Mr, Zenker in
Bipindi, :

® prlanzenleben, 1898, Bd. II, p. 484.

(251)

. | 215

In a "normal" develonment, the contents of these nutritive
sues aye devoured by the gall animals, Under abnormal con-~
ions, however, the nutritive materiol of the pient cells

vuomselves may be used, Galls of Pediaspis Aceris (cynipides)
freed from their inhabitarts and loft in solutions which are -
poor in food stuffs, or in ordinary tap water, remain alive for
weeks; but the contents of the nutritive tissues disappear, If
gells of a similor ind, ceteris peribus, are put in a sugar
Solution, the contents o: the nutritive tissues remain unused
or may even he slightly inereased,

ve Will distinguish two foms of nutritive tissues: the
nutritive cpidermis and the nutritive porenchyme, Nutritive
tissues of the first kind ere present, when, for example, in
8.0 gclls or walled galls, the spree occupied by the gall ani-
mals is lined with 9 clearly recognizable epidermis, which func-
tions as nutritive tiscue, Very often, delicate walled hairs,
which ore oxtraordin:rily rich in food stuffs, are produced on
it which we will term nutritive hairs, ‘ve speak of nutritive
pareneh mr. , “hen the well-filled celis belong to the ground tis-
sue. This forn of nutritive tissue plays a large part especi-
ally in medullary galls, The nutritive parenchyma usually con-
Sists of m.ny coll leyers, whieh ern differ greatly among them-
Selves, in the quality of their contents, A double "nutritive
mantel" may be often developed, just as in many galls the larval
cavities cre protected by a double mechanical mantel, The in-
ner nutritive zone is then enclosed by the mechanical tissue and
belongs to the inner gall; the other lies outside the mechanical
mantel and belongs therefore to the gall bark, Conditions are
very complicated, when two mechanical and two nutritive mantels
are present.

Nutritive Epidermis

We find a nutritive epidermis in many leaf sac galls, which
have been produced by Phytoptes and Aphides, The inner epider-
mis of the infected part of the leaf remains delicate, develops
only a thin cuticle and is usually richly filled with albumin-
ous stuffs, here is nothing unusual about the form of the cells,
so long as they do not grow out into hairs - nutritive hairs,

We find papillae-like structures in the larval chamber of
the: gall of Cecidomvyin Wimariae; the cells ere strongly curved
outward, their menbranes being often considerably thickened,
Nutritive hairs occur on the inner side of different mite galls
and in their simple form seem sinilar to certain Erineum hairs
in size as well as amount of cell contents (compare figures 85a
and l1l3a). Abbuminous substances abound in their lumina, such
as drops of fat and also small grains of Starch, Small papillse
or flask-like. hairs are found, on the galls of many Aphides (on

Populus Pemphigus spirothece)~ on Ulmus Tetraneura compressa
?ieire T16B) and many others.

Nutritive Parenchyma

It is evidént that no sharp line may be drawn between the
superficial nutritive tissues, which still bear distinctly the
character of the enidermis, and the inner ground tissue com-
plexes of the nutritive parenchyma, since many walled galls,
which, as we heve seen, are lined with epidermis, can grow into
completely closed balls etc., the cells of the epidermis then
often undergoing the same development as the cells of the bor-
dering ground tissue lsvers,

ro)

216

The distribution of the nutritive parench in galls

1s into various types, In the sarieaines ad wee fpanucnt
case, an inner nutritive mantel is formed only within the me-
chanical tissue, is at once «ccessibdle for the occupants of the
gall, and is usually unsparingly devoured by them, In more
complicated cases, abundant euantities of food stuffs are de-
posited outside the mechanical mantel, The cells of this outer
mantel, hovever, are not consumed by the gall animals, but
rather their contents become accessible for the larvae only by
breaking through the eclereid layer,

(252) The form of the simple nutritive cells shows little varie-
tion, Ustally iso-dinanetric elements are concerned here, elon-
goted, for example, into sac-like forms in the elliptical galls
of Neuroterus lenticulnris. I found very delicate, elongated
oe}]] threads, oomparable to branched algae, in the outer nutri-
tive mantel of an undetermined Cynipides gall of Quercus Wisli-
seni (figure 114 St), ‘hile the nutritive tissues in general
usually consist of e dense porench.ma, wide intercellular spaces
remoin free in the outer nutritive mantel of this gall. The
forn of the nutritive tissues, as a whole, ts connected in gen-
eral with that of the mechanice] mental, or of the entire gall.

‘In regard to the cell contents, tio different zones of nu-
tritive tissue usvally come under consideration in highly or-
gonized Cynipides galls.

The cells of the innermost lavers, on which the larvae feed,
contain regularly © cloudy, dense cytoplasma, in which numerous
small drops of fat are often mixed, We term this innermost
layer the protein layer, Figure 115 shows @ cross-section thraugh
the maple Teaf pall of Pediaspis Aneris; a}l the cells are thin
walled, the outermost boing rather small, the innermost strik-
ingly Barge. ‘The cells bordering directly on the larval cavity
are filled with a cloudy mixture of cytoplesma and fatty oil.
There cre here and there a few clear vacuoles in the emulsion.

(253) In most galls, several layers are found, the cells of which are
filled in the same way with proteins ete, Ife mechanical man~
tel is also developed, the nutritive tissue lies, af course,
inside the sclereid tissue.

_ Starch also should come under consideration. In any kind
of galls - in many kataplasms and in many Erineum galls -
atarch is usually present in abundance and always lies outside
the protein lnyer. We term it bricfly the starch layer. Hither
both the protein and starch layers belong to the innde gall, ly-
ing therefore inside the sclereid tissue, or the starch tissue
is deposited partially or entirely in the gall bark. The ellip-
tical galls of our native oaks (Neuroterne lenticularis etc.)
store np the greater pert of their farval rood outside the me~-
chanical mantel,- at times, almost the entire gall bark repre-
sents q gigantic reservoir of food stuffs, An especially com-
plicated case is that illustrated in figure 114; the starch
layer (St) lies about the inner mechanical mantel and on it a
second mechanical mantel.

It should )foted that the contents of the nutritive cells,
which contain starch, are dissolved before being used, and,
aceording to Beverinck's investigations, are converted into
proteins and fats,

(254)

217

In the nutritive tissue of many galls two striking
boddes are found, in the cell contents, which Hartwich

has thoroughly investigzuted, Besides balls of "tannic
substances", to which I vill return later in brief, cysto-
ligh-lixe forms cre olso found, which give the reaction of
wood and which we, with Uertvich, 411 term Lignin bodies.
According to Hartwich, they are produced at the corners,
where several cells come together, as local thickenings

of the walls (fig, 116a) svelling up to sphero-crystalline
tubers and finsily taking into reanisition the entire cell
(fig. 116b), ‘Also, in lnter developmentel stages, the con-
centric errangement of their levers is often very distinct.
"hey color red with phloro-glucin and hydrochloric acid -
not sll the Icyers equelly quickly nor equally intensively.

It is still uncertain whether the lignin bodies ere
of any sbecinl significarece for the oscupints of the gclls,
Doubtless they are consumed by the larvae, bug it seems im~
probable that they contain nutritive matericl , They have
been found as yet only in a limited number of galls, in
fast only in the Cynipides galls of various speoies of
Querous, ‘Hartwioh mentions them in the galls of Cynips

tinctoria, (on Quercus infectoria) of Cynips lignioola end
in an undetermined Texan gall on Qu. virens, ‘further, I

found the same structures in the galls of Cynips strobliana
and Chilaspis nitida (the letter on Qu, oer The celts
provided wi ignin bodies either form a continuous layer
in the nutritive tissue of the galls {as in the gells of

C, tinetoria etc.) or moy be found in groups here and there

outside the mechanical mantel, in the gall bark (ripe galls
of Chilaspis nitida).

Although the cells of the nutritive tissue are gnawed by
by the gall animals, secondary phenomena of grovth my at times
be enacted in them. RFither hypertrophic or byberp ier iie chenges
mey occur in them. Beverinck (loc. cit. p. 84, 1 3) has deter-
mined in the elliptical gall of the oak that the sclereids
thickened on one Side, which were mentioned above, may supple-
mentarily grow out to resemble tyloses, while the part of the
epidermis which has remoined delicate, undergoes a strong Super-
fioial growth, therehy causing the production of a secondary
nutritive tissve,

In other cases the cell material, upon which the gall ani-
mais feed is replaced by a nev outgrowth, regembling callus, @s
in the gnll of Nematus Vallisnerii - which Frank’ investigated
developmentally,- and still others,

wee Rem ee ee

Besides those tissues which protect and nourish the occu-
pants of the pall, all others in the galis play a very subordin-
ate part. Je may content ourselves with a brief description of
them,
sign ee Se Nae a ar ee ae ‘ae
1 veh, Gerbdstoffkugeln u. Ligninkorper in 4. Nahrungsschicht
der Infectoria-Galle, Ber.d.D. Bot. Ges,,1885, Bd. III, P. 146.

Recent investigations have m:de improbable my earlier ex-
pressed point of view (Reitr, 2. Anat, etc, lot, cit.) that the
lignin bodies like the carbo-hydrates and proteids of the nutri-
tive parenchyma furnish food stuffs for the gall-insects.

3 Krankh. &. P21., 2, Aufla, Bas Tit, De 201.

~ ao & we oe OS

(255)

(256)

&

3. Assinilatory Tissue 218

One characteristic of elmost .11 ealis is their poverty in
chlprophyli, Very meny prosoplicsm:s to be sure are © pole greén
such as the half-transparent products of Spathegaster baccarum;
Hormonyia fagi, etc,, but their chloroplusts cre scanty, smagl,
twisted and only weakly colored, In very many, such es the
verious elliptical geils, the Terminclis, Polii, etc, no chloro-
phyll et all may be found under the microscone at the time of
ripening,

The gall of Nematus Vallisnerii (on Sclix), for exemple,
should be considered on exception to the rule. When c gall of
this kind is broken open, the extensive deep green tissue con-
plex inside it is strikingly noticeable even mecroscopically.
The outermost leyers consist either of elements elongated into
& palisade form, or roundish ones as clear as ‘water, Then,
towards the inside, comes a thickly developed, cssimilatory par-
enchyma (compare also figure 88), which 4s for stronger thon the
normal mesophyll of the willow leaves,

The large galls of Aulex Glechomae, rich in water, which
deform leaves and stalks, develop superficially on ossimilcetory
tissue which is pale green in color and cbinsists of one or more
paldisade Isyers,

In the sac galis, whieh Phytoptus mecrorrhynchus usually —
produces very abundantly on the leaves of Acer Pseudo-platenus,
a large-celled, colorjess parenchyme. or one containing enthocy-
anin, is formed on the outer side (the morphologicrl1 upper side
of the leaf) end on the inner side (the morphological under side}
& cell layer which, pale green in color, resembles ¢ palisade
tissue (fig. 117).

Cases cre not really rate in which the galls carry over Un-
changed the assimilatory tissue of the organs which bear them,
(many stalk and leaf galls; compare, for example, figure 93).
Since products of pathological tissues cre not concerned in
these, we may pass them by.

4, Vasculer, Tissues

The reletion of the galls to the vascular bundles of the
plants which bear them is unmistakable, Many are produced di-
rectly from the tissue of the vascular bundles, others ore con-
neoted throughout with the neighboring vasculer tracts, The
vasculer bundles are usually very sparsely formed, and only 4s
delicate cords, inside the galls themselves,- in kataplesmas,
as in prosoplasmas,

The individual elements of the vascular bundles resemble
normal ones; yet the individual ducts usually have very narrow
lumina, Tracheids abound cnd, — their ae pee ae
form 6 the parenchyma cells, In many gélis,- 307 ;
that of esnthepaater baooarun © the composition of the vasculer
bundles and the rorm of the Separate tracheal elements resemble
throughout the corresponding cells of many callus tissues.
(Compare fig. 67).

The structure of the vascular bundles likewise in general
is Similar to the normal one, ‘The galls of jndricus albopuncta-
tus and Trigonaspis megaptera should be namef as exceptions, :
which, according to Beverinck (loc, cit. p». 128) have concentric

(257)

’ 219

Bi
bundles . The arrengement of the bundles in the gall bod -
ies greatly. They ara cither placed in a circle oe in ae
normal “axillary per ts of dicotvledons, thus turning the xylem
toward the larval cavity, the phloem toward the outerside of the
gell, (revoreed accovding to Beverinck, in the gall of Aphile-

“dhrix Meipigha) , or they pase through the bark of the gall ad a

cate net work es may be found in the fleshy pericarp of
mony fruits, Courchet* has explained the double vasculer bundle
ring in the gall of Perphiepus cornicularis by peculier processes
of folding ané copleSéense In he crear bearing the gall,

5. Berating Tissues

In general, the tissues of the galls are even more porously
construote¢ than are the likewise mostly porous callus tissues,
Almost everyyhere ct lecst small intercellular spaces are dis-
tinetly recognizable, so that provision of air is assured for
the gall tissues and gall occupants, The porous texture of the
bark tissue in many Cynipides galls is very striking, The single
cells are provided with long slender arms, by which they are con-
nected with one another;~ between the single cells lie extensive
intercelluler spaces, Figure 118 gives a few cells of this kind
of star-parenchyma from the Kolleri gall. In other cases, in-
stead of star-like cells, elements distended into pouches are
formed which are connected with one another only at their slénder
ends, or through especially short pointed protuberances, We find
the same conditions in the tissue of bark excrescences end lenti-
cel outgrowths;- of the native Diptera galis, that of Diplosis
tiliarum, for example, is esnecially rich in "aerating tissue"
of the kind described,

In the Kollari gail, the Argentea gall etc., the star-like
parenchyma cells lignify in the later develppmental stages and
take on an aburdant pitting. In the gull of Cynips Mayri,
cells of no Imconsiderable wall thickness are produced,

The question must remain open as to whether the air-reser-
voirs, furnished in these tissues which chound in interstices,
can in any way aid the well-being of the gall animals and in so
far be termed “expediently" functioning tissue forms. As al-
ready indicated, very similar tissue and cell forms also occur
in other kinds of pathological products (for example, bark ex-
crescences), in which fro m the very peginning the auestion as
to any "purposefulness" is known to be unfounded,

Tissaes which contain air occur also in other galls. ‘The
characteristic white markings of the gall of Andricus quadrilin-
eatus are produced by flatly raised ridges, which consist of
tissue ahoundirg in interstices, The ga}1 of Aulex Hieracii is
traversed meridionally by tissue stripes whieh contain air.

Pneumathodes occur in galls in the form of stomata and len-
tieols, In the "enelosed" galis, the stometa of the normal epi-
dermis are always changed in so far that they often lose their
ability to close, remaining open permenently;- for example, in
many Nematus galls, In the galls of Dryophenta folii, Dr. divise.
Dr. longiventris, etc., Kustenmacher found that the guard cells

Sia a i a

4 Vascular bundles with abnormal arrangement of the phloer.
occur also in correlation-heteroplasmes (p. 252).

2 ptude s, 1, galles prod, par les aphidiene. Montpeilier.
1879.

(258)

220

which touch one another at their tips, become pitted on the
contact, walls, "the walls are reabsorbed, the two guard cells
thus appearing later as es cells, which serve less in clos-
ing the air passage, but rather stiffen it", In general the
g211€ do not abound in stomata, I know of no case as yet, in
which, then the epidermis makes an active surface growth, ‘the
number of the stomate is increased in corresvondance with the
inorease in survece, Tho tissue lying directly unter the stom-
ata often shognds in interstices and forms, ut times, a snakt
cushion on the top of which lies the stoma,

Lenticels cre especially noticeable on the various Nematus
galls of the willow, The stom ata, together with the adjacent
parts of the epidermis, soon disintegrate and large, roundish
lenticels develop beneath then, rhich as brown dots, often give
the galls a very characteristic appearance, The lenticels on
the galls of Nematus gallertm on Salix prandiflora are especially
large and nunerous, In Wematus bellus one or (two especially
large lenticels are presént 6n that port of the gell which be-
longs to the upperside of the leaf, In moist air, lenticels d6-
velop the excrescences already described just like those of the
normal parts. Aphis gajls also are at times rich in lenticels,
especially those of Pemphigus epirethece ond P. bursarius, Not
only the galls themselves, But even the edjacent parts of the

petioles end the midrib swell greatly et tines cnd develop
numerous lenticels,

Ww
pick aud el has found holes in the epidermis of var-
ious galls which he terms carbondioxid fissures. The car-
bon dioxid fissures are simply epidérmal cells, which are
separated fram one another and between which the intercel-
lular space is open to the outer fir. - They usually have
small lunina and lie at points, where several cells touch
at the cornors, The upper opening is usually three-
cornered",

"T have named them carbon dioxide fissures, because I
think they have heen produced by aa inner pressure in an in-
tercellular space too far distant from other air passages,
which pressure is caused by the freeing of carbon dioxid
(loc, cit, p. 281)".

According to Kustenmacher, under certain circumstances,
pores in the membrane can also discharge the functions of
pneumathodes,

“The sieve hairs of the Cecidomyia gall, the normal
fascicular hair of Hieracjum and the hairs of the Ferruginea
gall, ere, according to Kustenmacher,- "organs which can
convey air into the interior of the cells”.

‘In these statements, of course, it is only a question
of hypotheses, and, as I believe, very improbable ones.

6, Secretions and Secretion Reservoirs

The secreting elements of the normal epidermis and those
conveying the secretions, are either found again in gall tissues
in an unchanged form, or a rich increase of the elenents fur-
nishing the secretions takes place, According to Kustenmacher,
in the formation 6f the Cecidomyda galls on Artemisia can estris,
the oil pores of normal plants act absolutely passively, Among
the galls of omg (tert of which I investigated herbarium rater:
ial, forms may be fowd which are practically free from secre-
tory pores, side by side with those whose parenchyme is penetrated.

SET RETE

‘ 221

throughout by theml. In many other galls also, as in the for-
mation of, wound-wood and g#11 wooc., the inerease of the inter-
cellular spaces containing secretions aleys én important >art;=
as for example, in many Pistcecic galls (such as thet of Pem-
phigus semilunularius and many others). —

less frequently, new forms 6f secreting cells and. tissues
occur in galls, which are not known in the anatomy of the nor-
melly developed host plants. I include among these a peculiar
gland, which I found in the interior of a Cynipides galls (on
Quercus Wislizeni). This galls may be illustrated here as an
xamjle of a riehly differentiated form (fig. 119). The se-
ereting suverficial cells are still to be mentioned;- such as
occur, for instance,,in the ge]l »roduced by Cynips argentea
(259)on Quereue pubescens”, in thet of Andricus Sieboldii, in the
Bassorah galls? etc. The galls of Cynips Mayri annear Similerly
"varnished!t, Unfortunately I could no longer recognize the

stbucturg of the secreting cells in the dry meterial at my
disposal~.

Crystals of calcium oxalate are not generally found in
abundance in galls,- and wé could verify the same scarcity in
many callus tissues. The entire absence of crystals seems to be
rere. Vantevelde® has published some statements on the scanty
crystal content of those plant organs, which have galls.- Like-
wise, cases are not lacking, in which, we may find a rich crystal
formation in the galls. Kohl has emphasized the fact, that forms
rich in sclereids often contain erystals®. In others the crys-

(260)tals occur as an accompaniment of the fibro-vascular cords. Cells
bearing crystals and united in radial rows are found in Tinctoria
galls and in others. In the »roducts of Cynips Hedwigii and
Dryophanta verrucosa, certain layers of the gall tissue are es-
pecially rich in crystals (according to Kustenmacher). I foue
in the fagus gall (fig. 103) that all the cells which bear
crystals and are at an equal distance from the sw face of the
gall had been united into a special layer, which lay on-the
boundary line between the lerge-celled outer tissue and the
small-celled inner one. The cells are often divided by exceed-
ingly delicate cross-walls; each division containing a single
crystal. In numerous galls we find that continuous leyers of
erystal cells arise through the abundant but localized »roductibn
of crystals, these cells layers, in many forms, lying in the
gall bark; in others, in the inner gall.

The diversity of Lucalyptus galls is surprisingly great.
The tests, which I had opportunity to investigate, lead me to
expect many an interesting result from a comprehensive treatment
of ee galls from a developmental and histological stanc-
point.

Compare Hieronymus. Gallen aus Sudamerike unc Italien.
Ztsehr. £. Entomol., 1892, Bd. iVII.

3 .Hartwich. Arch. d. Pharm., 1883, p. 829.

4 Investigations on fresh material woulc be very desirable -
the gall is abundant in Sicily.

2 Bijadr. tot de phys, der gallen, het aschgehalte ad. aange-
tocte bladeren. Bot, Jaazb. Dodonea, 1896, Vol. VIII, p. 102.

6 anatom.- physiol. Untersuch. d. Kalksalze etc. Marburg,
1889.

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222

‘Rinally the content in tannic substances should he consid-
ered, which, as is well known, makes many galls of practical
importance, Those galls are histologically interesting in
which the storage of the tannic substance is restricted to def-
inite zones, The bark of many Cynipides galls is strikingly
rich in this, In them the tissue, resembling star-parenchym
since it abounds in interstices, is filled with the substances.
The antiseptic action of the tannic substance may, under cer-
tain circunstances, he of significance in the development of
the galls end their occupants. Nevertheless, it is noticeable,
thet, "tannic substance balls"! may be found in the nutritive
perenchyma of many Cynipides larbae, and are devoured by the
gell animals, but are, according to Hartwich, thrown off egain
es excreta. According to Beverinck (loc, cit) and Hartwich,
forms which are at once conspicuous because of their very dark
color, occur in the various elliptical galls, in the products’
of Gynips Kollari, C. lignicole, C, insana ("Bassorah galls"),
Of tinctoria eto, Also they ore know Already to Lacaze-Duthiers.
For thé tannic substance in other hyperplasies, compare p. 167.

Finally, the anthocyanin content of many galls should be
mentioned, Many galls, just like normal fruits, get "red cheéks”
through the action of light (Nematus gallarum, Hormomyia fagi,
etc.); a reddish tone is thoroughly characteristic of mony
(Cynips terminalis, vefy many Phytoptus sac galls etc,), In _
many Others the fsnthocyanin content is restricted to definite
parts of the tissue, The red zones, ten or mare layers thick,
in the galls of Nematus Vailisnerii (on Salix) are very notice-~
able. On the upper Side (the Side toward the light) the cell
layers derived from the mesophyll become colored unusually high -
ly - those derived from the epidermis were colorless in the
examples which I investigated,

The present pages give indeed no exhaustive anatomy of
prosoplasmatic gails;- only the outlines of such an one - cor-_
responding to the task of our book - may he given here. What is

iven may well furnish sufficient material for a comparison of
the various pathologica} tissue forms with one another ,- which
we consider the aim of this exposition. New points of view Tor
our question would scarcely have been acquired by a deeper in-
vestigation of the galls, which have been studied up to the
present,

In conclusion, we should remember that the number of galls
which have heen closely investigated is still very small; we
know practically ae ee concerning the forms outside of Burope
or in the tropies, least of all concerning their anatomy and
development. And also a thorough study of the native galls is
in many cases still urgently desired,

(262)

Appendix 223

Our theme is exhausted with the discussion of the
various abnormal tissue forms, which led us from simple
hypoplasias to highly organized prosoplasmas, since the
many forms, furnishing information concerning abnormal
cytological struotures, and, further, all phenomena of
degeneration and all micro-chemi.cal conditions, varying
from the normal, must remain excluded from our presenta-
tion of this subject,

An active interest in oytology has brought to mtur-
ity in the last decade, a quantity of zoological and botaa-
ical publications, many of which either consider abnormel
structural conditions as well as normal ones, or treat of
the former exclusively,’ Of the zoologists and anatomists,
I till name only Arnold, Cornil, Denys, Hansemann, 0.
Hartwig, Hass, Schottldnder and Stroehe’, Instead of an
exhaustive survey of the botanical literature, I will give
below only a small selection,- especially in order to in-
dicate the various questions, with which attempts have

eps yade to approach the problems of "pathological cy-
ology’.

—-— =
— = - = - _— =_ = - —_— - - _— ~ ee ee -— - ~ =a lol!

1 gitations of literature in 0, Hartwig, Ueb, pathol-
og. Verand, a4. Kernteilungsprozesses infolge exper imentel-
ler Eingriffe, Festschr. f. Virchow, Berlin, 1891, Bd. 1,
p. 19%, Albrecht, Physik, Fragen der Zellpathologie.
Ergebn, a. Allg. Path, u. s, w., 1901, Ba, VI, p. 900,
1902; Ba, VII, p. 783. Ziegler, Allgem. PatBologie, Jena,
1901, p. 300 and places given.

2 Gontributions to the "pathological cytology" of
plants were furnished - besides by many others - by Andrews,
Wirkung der Centrifugalkraft auf Pfl, Pringsh, Jahrb. f,
wiss, Bot,, 1902, Bd. XXXVIII, p. 1. Bilazek, Einfl, yon.
Bensoldampfen auf pflanzliche Zellteilung, Abhandl. bohm,
Akad,, 1902 Ba, XI, Nr. 17, Buscalioni, Osservaz, ericerche
sulla cellula vegetale, Ann. R. Ist. Bot, Roma, 1898, Vol.
VII, p. 255, Cavara, Ipertrofie ed anomalie nucleari etc,
Riv, Patol, veg., 1896, Vol. V, p. 238, Dangeard et Armand,
Observ, de Biol, cellulaire. Le Botaniste, T. V., p. 269.
Dangeard, Sur le caryophysems. C. R. Acad, Se, Paris, 1902,
T, CXXXIV, p. 1365 (compare also Mem. s. ‘1. paras. du
noyau et du protopl. Le Botaniste, T. IV, p. 199). Geras-
simow, Die kernlosen Zellen der Konjugaten, Bull. Soc, Imp,
Natur; MoScou, 1892, p. 109. Grant, Multinucleated condi-
tion of the veget, cell ete, Transact, Proc, Bot, Soc,
Edinburgh, Vol. XVI, pt. 1, p.,38. Heidenhain, Einiges-
ueber d, sogen, Protoplasmastromungen. Sitzungsber. Mediz.
Phys, Ges, Wurzburg, 1897, p. 116. Hottes, Veb. d. Einfl.
von Druckwirkungen auf die Wurzeln von Vicia Faba, Diss.
Bonn, 1901. Huie, Changes in the Cell-organs of Drosera
rotundif, Quart, J, Mier, Sc. 1897, Vol. XXXIX. (Ann, of
Bot., 1897, Vol, XII, p. 560), and 1899, Vol. XLII, p.203,
Juel, Kernteil in d. Pollenmutterzellen v. Hemerocallis u.
s. f; Pringsheim's Jahrb. f, wiss, Bot., 1897, Bd. XXX,

p. 205. Klebs, Beitr. z. Phys, d, Pflanzelle, Tubingen
Untersuch,, 1888, Bd, II, p: 289, Kohl, Z. Phys. des
Zellkernes, Bot. Cbl., 1897, Bd. LXXII, p. 168, Magnus,
W,, Studien an der endotrophen Mycorrhjza yon Neottia

(263)

224

aoetnate 2 continued) :
us avis. Pringsheim's Jahrb, f, wiss, Ot, 9 b0.0.4'4
Pe - Massart, Cicatrisation ch.'1, Pear ag fate, ten.
cour, Acad, de Belge, 1698, T, LVIL, p. 37, Natruchot et
Molliard, Certains phenom, pres, par 1, noyaux sous ltaction du
froid. C. R, Acad. Sc, Paris, 1900, 7, CXXX, p. 788., Modific.
de struct, observ, d, 1, cell, subissant la’ fermentation propre.
Hbid., py 1203, Modjfications prod. ‘par le gel d. le struct, a:
coll veget. Rev, gon de Bot., (1902, T, XIV, p., 491. Molliarar
rie tag ae pathol, d. ce}1, veget. Rev, gen,s,Bot., 1897,

tT. I } Pe 33; 'S. ]. caracteres anatomiques de ‘Hemiptetocec.
folidires, Mem, ded. au prof, A. Giard, 1899, p, 489. S. qs.
caract, histol, d, cecidies prod, per l'Hetéerodera radicicole.
Rev, gen.cBot, 1900, 7. XII, p. 15%, Miehe, Ueb, wanderungen
d, pflanzl, Zellkernes, Flora, 190%, Bd. LXXXVIII, p. 105.
Mottier, Effect of Centrif. force upon the cell. Ann, of Bot.,
1899, Wol, XIII, p. 325, Nawaschin, Beob, ueb. d. fein, Bau, u.
Umvandl, vén Plasmodiophora Brassicae u. s. f, - Flora, 1899,

Bd, LXXXVI, p. 406. Nemec, Cytol. Unters, an Veget.-punkten

d, Pfl. Sitzungsber, Bohm, Ges, Wiss., 1897, Nr. XXXIII, p,489.
Ueb, abnormé Kernteil, in der Wurzel-spitze v., Allium Cepa.
Ibid,, 1898, N, IV, Ueb, Kern- u; Zellteilung bei Solanum tub-
erosum, Flora, 1899, Bd, LXXXVI, p. 214. Zur Phys, der Kern-
u. Zellteilung, Bot, Cb1,, 1899, Bd. LXXV, p. 241. Ueb. den
Einfluss niedriger Temperaturen u. s, f, Sitzungsber, Bohm.
Ges, Wis., 1899, N, XII; Ueb,; experim, erzielte Neubildung v.
Vakuolen u, 8 f, Ibid,, 1900, N. V.° Die Reizleitung'u, a,
reizleit, Strukt, bei d, Pfl,, Jena, 1901, Paratore, Ricérche
istol, sui tubercoli radicali delle 'Leguminose, Malpighia,
1899, Vol, XIII, p, 211, Prillieux, Alternations prod, 4. 1.
pli. par la culture a, un sel surchaufie.’ Ann, Sc, Nat. Bot.
1800, serie VI, T, X, p. 34%, Rosenberg, Phys.-cytol, Unters,
ued. Drosera rotundifolia, Upsala, 1899, Schrammen, Einwirkung-
en v, Temperaturen auf die Zellen da, Vegetationspunktes 4, ° ;
Sprosses v, Vicia Faba, Dissertation Bonn, 1902, Schwarz, Fr.,
Morph, u, chem, Zusammensetzung d, Pl, Cohn's Beitr, zur Biol,
d, Pfl., 1887, Bd. V, p. 1. Shibata, Experim, Studien ueb, °
d. Entwickelung d, Endosperms bei Monotropa, Biel, Chl, 1902,
Bad, XXII, p. 705, Strasburger, Zellbildung u, Zellteilung,

3, Aufl,, Jena, 1880, Ueb,. Plasmaverbind, planzl.‘Zellen,
Pringsheim's Jahrb. f. wiss, Bot,, 1901, Bd, XXXVI, p. 493.
Tischler, Ueb, Heterodera-Gallen u, s,'f, Ber, d. D. Bot, Ges.,
1901, Ba, XIX, p. (95). v. Wasielewski, Theoretische und ex-~
perimentelle Beitr, %, Kenntnis d, Amitose, Pringsheim's

Jahrb, f, wiss, Bot., 1902, Bd. XXXVIII, p. 377. Zimmermann,
Morph, us Phys, d, pflanzl. Zellkernes, Jena 1896, - Compare
further the critical work by A, Fischer, Fixtierung u, Bau d,
Protopl. (Jena 1899), in which is named a number of further
works, pertaining to this.

Ca i ied

In abnormal cytological conditions, there usually occur
variations of the following kinds:

1, It may be a question of an abnormal arrangement and
distribution of the cell elements - as a result of mechanical
interferdnce, for example, in the use of centrifugal forms,
or after plasmolysis and so forth, or as the especial effects
of stimulation, for example, in the migration of the nucleus
or ee of currents in the cytoplasm after injury and
the likey

(264)

: 2e5

&, Or it mey be a question of an abnormal form and struc-
ture of the cell organs - such as the abnormal form of the dor-
mant nuclei, the abnormal distribution of its chromatin, abnor-
mal figures in cell division, or of amitoses, pseudo-amitoses,
abnormzl cytoplasm structures and so forth,

3. Or there may exist variations from the normal condi-
tions of size and number = hypertrophies of the nucleus, in-
crease of the cytoplasm, definite kinds of cytoplasm, of vacu-
ate Boers nucleoli, contraction of the various organs, and
so forth,

Besides this, those various processes of degeneration come
under consideration, which might be separated only with diffi-
culty from many of the phenomena here described.

If Ihave given here no detailed treatment of cytological
questions, it was because our present knowledge of the normal
cytological processes seems to me still too little understood
to warrant an all inelusive discussion of the abnormal condi-
tions, I have therefore limited myself to calling attention,
here and there in the text, to changes in the nucleus, the
figures in the cell divisions and so forth, if the abnormal cy-
tological conditions seemed suited for completing the characger-
ization of any abnormal tissue forms, The short bibliographical-
summary given here will pverhaps suffice, for the present, for
further orientation,

The phenomena of degeneration and necrosis can be consid-
ered as physiologically well-characterized Sub-divisions of
those namdd above,

It is according to whether we take into consideration the
parts of cells which disappear during degenerative processes, or
those newly produced products of decomposition, that we «ill’be
able to distinguish various groups of degenerative phenomena,
‘hich I have mentioned only by way of suggestion tn the preced-
ing chapters and then only if they helped to characterize the
abnormal tissues which interested us,

Of primary interest is the degenerative disappearance of
the cytoplasm, of the nucleus and of the chromatophores in
starving cells (phenomena of inanition), in the parts of tissues
sucked dry by parasites, or in those cells \hich are incited to
abnormal (kataplastic) growth by some stimulus (hyperhydric
tissue p, 80, callus hypertrophies p. 93 and many others), The
protoplast becomes inpoverished, the nucleus disappears, the
chromatophores become paler and smaller apparently changing
back into leucoplasts, Many of the cases described above prove
that all the living parts of the cell degenerate equally qick-
ly and in the same way; that under conditions, which, for example
do not endanger the continued existence of the nucleus, the very
sensitive chlorophyll grains can disintegrate and the like; of
that the cytoplasm often can outlast the nucleus and the walls
of the vacuoles jn the former often prove themselves to be the
most résistant parts,

All parts of the plant cell can be changed degeneratively,
We oan distinguish, according to the products formed, a

slimy and y degeneration to which whole cells, includ-
ing their cellulose covering, may often fall victim (disenses of
"Liquefaction", gumming end so forth);

. 226

degeneration into vacuoles, in which the cytoplasm be-
comes fidied vith numerous vacuoles assuming a coarse foamy
structure; ,

fatty degeneration, characterized by the occurrence of oil
drops in the cells;-

cellulose degeneration, I believe I have found in those
sacs, in which (as the clearage product of decayed cytoplasm)
inter-cellular cellulose precipitates are produced, as in the

cases studied by W. Magnus (loc, cit) and those deseribed in
the third chavter (P, 63),

Besides the products of decay already nemed, the preeipi-
tates, "granula” of an unknown kind, should be mentioned, which
are often found in disensed cells, also, many of the artifacts

a eee here which oe: their production to vorious fixing
medica.

(265)

We may perhaps look for the results of o degenerative de-
cay of the cytoplasm in yhe abnormal processes of suberization
or lignification (p. 64)*,

The abnormal micro-chemical conditions lie outside of our
consideration, The conclusions to which micro-~chemi¢al facts
lead us are connected only very loosely vith anatgmy, but more
Closely with chemical physiology, Numerous «orks” have already
throvn light on abnormal acidity, on cbnormeal distribution of
tanhio substances, of sugar, nitrates, alkeloids, on the pro-
duction of foreigh matters, on the cbnormel composition of the
cell membrane and the like,- It is not our task to go more
into detail as to the contents of these ‘vorks.

-
Ce oad

of vound-~gum, compare also p, 165) note 2, Phenomena of disor-

é Thus for instance, R. Kraus, Gr., Stoffwechsel bei den
Crassulaceen, Abhandl, der Naturforsch, Ges, Hallg, Bd, XVI,
Timps, Beitr. z. Kenntn. ad. Panachierung, Diss. Gottingen, 1900.
Tschirch, in Bot. Cbl,, 1887, Bd, XXXII, p. 94. Kassner, Ueber
Solanin in Kartoffeln, D, Landwirtsch, Presse, 1887, Nrf 19.
(Just's Jahresber., Bd, XV, 2, p. 340), Strasburger, Ueb. Ver~
wachsungen uv. deren Folgen. Ber. 4, D. Bot, Ges., 1885, Bd, ITl,
p. XXXIV, Sauvageau, Infl. d'un parasite sur Jes plantes hospi-
talieres, C, R. Acad, Sc, Paris, 1900, T, CXXX, p. 143. Ritzema,
Bos, Over het ontstaan van giftstoffen in plantede@ien die door
parasitische schwammen zijn aangetast' etc, Hygien, Bladen, 1901,
Nr. 1-3 (Zeitschr, f, Pflanzenkrankh,, 1902, Bd. XII, p.'235). On
exidation enzymes, compare above p. 35, note (1). Mangin, 5. le
constitution ad, cystolithes et ad, membr, incrustees de carb. de
chaux. C. R, Acnd, Sc, Paris, 1892, T. OXV, pe 260, Boodle. On
lignification in the phloem of Helianthus annuus, Ann, of Bot.,
1902, Vol, XVI, p. 180. Compare also above p. 64. Koychoff,
Infi, d. blessures s, la formation d, natieres proteiques non
digestibles, Rev. gen, de Bot., 1902, 7, XIV, p. 449.

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a
CHAPTER Vi 227

GENERAL ORSERVATIONS ON THE FTIOLOCY JID DEVELOPMENT oF
PATHOLOGICAL PLANT TISSUES, DISCUSSIONS OF GENERAL
PLTHOLOGY, THEORETICAL MADTER

On the present, ond conolvding chapter ve will reeepitulcte
the results alrecdy ottained, arrenging the sccording to difer-
ent general points of view, In this, opportunity 1ill be offered
for meking reports on mony importent metters which ct the time
hed to be left uncongidered,

The diversity of the forns disclosed by tha study of plant
pathology is extraordinerily large. ‘le find smong representa-
tives of the same species, thet leaves, which under normel con-
ditions, are developed into extensive thin sheets of tissue, may
under abnormel conditions oecur in the form of slender insigni-
ficant seales, or swell out to fleshy tissue cushions; instead
of a lerge leaf-blade and e short petiole, we find thet c tiny
blade may appear on an immensely lengthened stem, or the leaf
may be covered with very different kinds of swellings, or it moy
be transformed into e single massive lump, which ean he termed
"leaf" only beeause of its position on the plent body and the
like, Hand in hand with these macroscopienlly noticeable differ-
ences come variations in enetomicel strvetme, While, in norm-
elly developed leavee of one and the sare species, the sane struc-
tural conditions are ajways recognizable in cross and surface
sections, abnormal examples show very creat differences, eccord-
ing to the nature of the disease, The repertoire of structures
is inconceivably extensive, especially in hyperplasias, produced
i the action of foreign orgenisms on leaves end other organs.
The capacity for diverse and brightly colored forms possessed by
the cells which make up the leaves is astonishing;- a consider-
ation of exclusively normal forms and structures would not lead
one to imagine such a diversity. We recognize the fact that m
many courses are poscible for the developmental progress of the
cells or cell groups and the cuestion forces itself upon us;-
what factors decide which one of the mary possibilities shall
ultimately be realized, It will be necessary to ask, for example,
why the cells composing the primordial leaf, do not furnish
those derivatives in the process of division which we are fccus-
tomed to find as normal components of “healthy” leaves;-~ or why,
in some cases, hesides the normal cells, still others are pro-
duced, which have some abnormal characteristics, Obviously the
action of variable factors is reflected in these distinctly dif-
ferent forms, which factors act on defirite kinds of cells and
thus influence the formative processes, Before taking up the
study of the factors at work and of their action, some general
remarks might be useful by way of introduction,

Without doubt, processes and qualities noticed in organisms
and in portions of organisms are influenced by very different
kinds of factors, to a still greater degree, than are those of
inentmate bodies. Various Finds of forces change the cells and
tissues in the most diverse ways, Mechanical pressure and
strain mould the form differently, loss of water through dios-
mosis or evaporation decreases the volume, increases the concen-
tration of cell solutions containing water, changes the ormotic
pressure and so forth, Resides changes and @ffeets of this kind.
and similer ones, still others of unequally greater importance
come under consideration, which ere not sufficiently explained
by the transversion of the amounts of energy supplied, hile
in the above mentioned processes of changes in energy equal

. 228

: {
amounts came into play in cause and effect. woe must conside
those processés and effects, in which there is ArUseS Beaton
able disproportion between the amount of energy firnished by
the stimulation and that expended in the effect, on the part
of the cells In this indged the amount of energy expended by
the cell is Pere than that dtought to ity We will term an
effect of the kind fitst tamed, the forte iafféct, one of the
Second kind the stinlus effect; The energy Supplied van ef~
-fect the organism oth ways, While the férce effect is in-
dependent of the energetic condition of the eell, no stimulus
effect can be produted. without a sufficient and available amount
of potential energy, whith, in the process of stimulation, can
be transmitted by the cell tere bee) energy. Each stimulus
effect is therefore dependent first of All on the energetic
condition of the cell and may in this sense be cénsidered as
having been accomplished by the cell itsel?,

Although the above+said makes clear the principal difference
between the force effect and the stimulus effect it will not
always be possible, when judging of single processes, to decide
which class of effect 1s concerned in each. If, for example, a
cell divides, under the influence of any factors whatever, we
will not be able to say whether the amount of energy furnished
is equal to that expended in the process named or not. Such
difficulties confront us also when judging of almost all the re-
maining processes of growth and formition. Since in this treat-

(268) ise these processes of growth and formation are concerned, it
wAll therefore be advisable in the use of the word "stimulus
effect" to make ourselves independent of any considerations re-
gording energy and its use and, with Herbst~, to speak of stin-
ulus effect in all those cases in which any cause whatever "may
induce a resulting phenomenon in some living organism", - "be-~
cause of the unexpected character which these resulting phenom-
ena always have", Accordingly, we will venture to speak of
force effects only when ve can understand in terms of energy
the ones observed on the organism or when they take possible
conclusions as to the proportionate amounts of énergy and in so
far have no longer any “unexpected quality". Stimulus effect
takes place in almost every case with which we shall be occupied:
all processes of growth and differentiation are the reaction of
the Firing organisms to some stimulus”,

Various types of stimulus effect may be distinguished, ac-
cording to the nature of the stimulating agent as well as to
the character of the reaction to the stimulus,

Every occurrence in animate as in inanimate nature involves
some change, We can, hovever, think of changes of #11 kinds
only as being Brought about as the result and effeet of some
other change, Also, each process of formtion and #ifferentiation
muy not he imagined otherwise than as the effect of Some change
in one of the many factors influencing the ‘cell life.

Cb1,, 1895, Bd, XV, p. 21,

2 It is possible that with a better knowledge of cell
physiology and the mechanics of the protoplasm, many a "stimulus
effect" vill lose its, to us, "unexpected" character and ‘ill be
shown possibly as a force effect, We are at present very far
indeed from having this insight into cell life.

(269)

£29

The effective factors, in which any a tera
the cause of stimulation, lic either ie te Sa ati
are prgduced in the interior of the orgenism by the activity
of the cells themselves, Accordingly, external and internal
factors must be distinguished:- in thcir action, we speak of
externol end internal stimuli,

: Fungus spores germinate when piaced in a nutrient s -
tion; a smoll germ tube growing out of the roundish a
This Phenomenon of growth and chenge of form is caused by the
alteration in the conditions, to the action of which the
Spores ore exposed. OGontact with the nutrient fluid end even
more the endosmotic absorption of water and nutritive sub-
Steances, not aS stimuli, the reaction of which is recognizeale
in the phenomene of germination, If the short germinating tube
is left under similer conditions, still further change takes
place; the smgll germinating thrend becomes steadily larger
and is divided by cross-walls into several cells. These forma-
tive processes are also stimulus effects, to be sure, the exter-
nal conditions have not been changed, but the factors aoting
on the cells themselves are different, Each enlargement of the
germ tube results in changes in it which may be found ina dis-
Placement of the separate particles, in chenges of the chemical
neture of the cell contents, variations in cirouletion and 0s-
motio pressure, in changes of tension conditions etc, The oon-
tinuous alterction in the internal factors furnishes an unin-
terrupted ohain of stimuli to which the organism responds ..
equally uninterruptedly with typical reactions, If we resolve
the processes of development of the growing germ tube into
innumerable differentials, each of these represents the reac-
tion to a definite stimulus: their sum furnishes a continuous
process of growth and formation,

Formative processes - among which we must unconditionally
include the continuance of a process of growth, which has he-
gun already - can therefore result fron external as well as
internal stimuli, Without a change in some factor, ~ external
or internal - no process of growth and formtion is conceivable ;-
nothing is produced "of itself", nor does it change "of itself".

Even if the beginning of a process of gravth, just as‘its
continuance, be conceived of as due to the stimulus effect,
still an essential difference exists between the two processes,
We will wish to mark this difference by terming "rectipetive
atimuli" those which'cause the continuation of format ive pro~
cesses already begun, and formative or morphogenic’, the ones
which quahitatively introduce new formative processes, Justi-
fication of this distinction mey be found in the importance of
the latter in the maturing of animals and plangs, On the other
hand, the near gelationship bet:-een rectipetive and formative
stimuli of formation are involved; they are 211 formative in
the broadest sense of the word, In rectipetive processes of
stimulation, the stimulatory cause apperently lies in the
changes in internal factors; in the formative ones it must usu-
ally be sought for in a change in the codperative action of
external factors, Without any change in the internal and exter-
nal factors; i. e. without some stimulus - this must be re-em-
phasized - neither a rectipetive nor a formative process of
growth is conceivable,

1 on this word compare Virchow, Ueber Reizung and Erizbar~
keit. Sein Archiv, 1858, Bd. XIV, P» ‘es Billroth, Uebd. 4,
Einwirk, lebender Pflanzen- und Tieyzellen aufeinander, Wien
1890, Herbst, loc, cit,

— le ema

(270)

230

In the broad meaning which we have given to the con-
ceptian of stimlation we will have to include also as s
stimulus effects those processes of growth, which, accord-
ing to Weigert” ad numerous other pathologists, can not
be traced back to the aetion of a formative stimulus, but
which are caused by the removal of any kind of hinderances
to growth. According toi/eigert we are concerned in all
abnormal tissue proliferation with phenomena of growth etc.
made impossible under normal conditions of itfe end a normal
cause of development by £11 kinds of impediments, The re-
moval of any opposition is evidently equivalent to the
change in the effective footors, (external ond internal).
According to our definition of the precesses ‘of stinuletion
and its causes, no reason exists for explaining the offests
of growth which are oonsed by the removol of impediments,
as other than the stimulus effeots,

Be will soon return to the question as to whether there
are normal plant tissues of whieh the formation mey be ex-
plained by the removal of any opposition to growth.

We have termed stimulus the change in any active factor,
but not every change Of external conditions causes reaction on
the part of the cells,- many a change, which acts as a cause of
stimulation in definite kinds of cells, does not come into ques-
tion at all as such in cells of a different nature. In short,-
each reaction presupposes a definite qualification of the cells,-
without a capacity for reaction there is no reaction.

The spores of the fern usually germinate very quickly when
strewn on & nutrient solution,- provided they are exposed to
the light. ‘The spores react by grosth to the stimulus brought
about by the absorption of food stuffs, after the light has
made the cells capable of reaction. AS has been shown, in this
case the capacity of the cells for reagt ion may be brought
about also by increases of temperature“. The spores of mosses
feel this same necessity for Light, - in them, this capacity for
reaction can also be produced” by a supplying with sugar. In
most cases we find that the reaction capacity of the cells is
dependent en definite conditions, The supplying of energy is
gzupposedly the chief cause in its production, and then pole
the consupption of energy in the reaction to stimulation. x
should be observed here that the energy supplied from withou
is not convertible in every form for the cells, nor transverti-
ble into potential energy.

Distinction must be made between an accidental incapacity :
for reaction, explained by & temporary lack of potential ie ie
and a specific incapacity remaining peculiar even ae ae ze
which are provided with potential energy. While Lael . ne
in the factors cause stimulation reactions in definite nds
- “l Neue Pra estellungen in der pathologischen Anatomie,
Ges, deutscher fatur?. u, Aerzte, Verhandl, 186964.

-
~ @ @ Ss ee Se SS ee ee

2 porest Heald, Gametophytic Regeneration, Leipzig, 1897.

3 . r tory" influence of light
Further examples on‘the “preparatory

and other factors in Kiebs, Beding. 4. Fortpfl, bei einigen
Algen u. Pilzen, 1896, ; *

(271)

23]
cells, they remain ineffective in others,- these cells do not'
react to thet kind of stimulte, Like so may other phenomena
we will not be able to explain capacity and incapacity for re}
action in other way than by the assumption of a Speottie pet e
of the cells which my be based on structural conditions, chem
deal peculiarities, phenomene of tension and of movement in the
cytoplasm and the cohesive and athesive action of its moleculgs.
Not only do cells of various plant speotes behave differently
in regard to this capacity for reaction, but even the oells of
verious organs and tissue forma in the some species and the
colls of different ages, In any onse we will hove to locate
the causes of each reaction or non-reaction in the cytoplasm,
Each formative prooess 1s caused by the specific peoulicrities
of the cytoplasm, set free or brought about by a chonge in some
internal or externnl factors,

Like hg he thet heppens, ve oan not picture to
ourselves oll formtive processes as otherwise than oasuelly
eonditions - which holds good for the variously changing
pathological formative processes ag well as for the norme 1
ones which in corresponding organs in the Sage plant species
Always lead to well-knovm structures, Each formative pro-
cess is oaused by the specific quality of the eytoplasm and
by the sum of all the ootive faotors, which bring about the
separate processes of formation, The mixed kingdom of nor-
med and abnorm.1 forms is thus far a wellterdered one; the
opposite is inconceivable, Each separate process takes
place as a matter of neaessiry and is the only one possible
under the conditions just then in control. 4¢ enormous
diversity among abnotmel forms can not lead us aye here, -
just as for the locomotive, when trevelling over @ much
branched network of rails, there is only one way possible,
which is determined by the sum of all the effeotive fas~-
tors,- in this case, by the placing of the switches,

If, in comparing normal and ebnormal tissue forms, Hs
speak of "arrested developments", of ao “tendency” to or of
ferentiation, which “exceeds” the normal degree and kind 0
tissue differentintion end so forth, these ore alj expres+
sions which are of course meant only figuratively cod have
been chosen because of their vividness, In the firm ceusy
system representad by the course of developre nt ot es oF
ganism, there is no reom for special "tendencies of the
cells and tissues toward any per ticular method of develops
ment. Where, however, no gendenoy exists, oe ean a1so
speak only figuratively of any "arrestment". There is ue
"normal" and "abnormal", no "tendency" and no "arrestment
for the organism which does not "strive" for any special
(ormal") method of development, but,as a natural apn
without will pover, is formed just as the sum of the exter
nal and internal factors may determine absolutely. Yet the
introduction of such terms is necessary in ow work sane
we can obtain clearness, and be understood only by a com 4
parison of the diverse forms and frocesse Ss amon thongs eve
and by the establishing of a norm, by which ve attemp
to standerdize all,

After these introductory remarks, 1t will be our task re
that which follows, to ascertain and analyse so far as poss2bis
the factors ective in abnormal tissue formation; we will fur- i
ther have to considér the reaction to stimulation, the ge hoe
formative processes, from generel points of View and then f ae
ally test the capacity for reaction in various plants end plen
tissues to response to def4nite stimuli.

(274)

A. Concerning the Active Factors 232

All abnormal processes of growth amd formation in plants
are ebviously caused by definite external life-conditions, In
the present section we will attempt to mention by name those
factors which become influential in the formation of plant tis-
sues and can cause the production of abnormal forms,- and clse
to study the way they act, The science to which we will en-
deavor to furnish some contributions by considerations of this
kind, has been called, since Roux, the developmental mechanics
of organisms,

‘We will enoounter many diffioulties. when busted with this
task,- so that it is avisable to become closely acquainted with
them from the beginning,

In the "introduction™ mention was made of the fact that the
investigator who works experimentally, will find himself, in &
favorable position for the "study" abnormel plant tissues, sinee
it is now possible to produce artificially and ot will most of
the forms of abnorm 1 plant tissues, We will not deceive our-
selves, however, with the thought thet we ean experimentally
cause definite processes to take placdé without having some knov-
ledge of the factors actually ot work:~ Even when we have recog~
nized definité factors as participants in the production of any
processes, it is especially difficult to ascertain the specific
action of each of these factors separately and to distinguish
it from that of the other active factors,

Callus tissues furnish a goed example of this, As is well-
known, they are produced "after injury", But in this, nothing
has been said about the active factors, Obviously, at the ¢ ime
of injury, definite cells and tissues are freed from the pres-
sure of their turgid neighbors, Therefore, the conditions of
strain and pressure are changed by the injury. If plants and
plant organs are involved, which are not covered with water, the
part of the plant exposed will undoubtedly lose more water thru
transpiration after the injury than before it, The esmotic
pressure in the exposed cells and tissues will be chamged, the
diosmotic exchange of substances from cell to cell being influ-'
enced thereby. Further, in the cells at the edge ef the injury,
the cytoplasmic fragments and the products of decomposition from
the destreyed, dead adjacent elements will exert ohemical ac-
tions, while contact with the new medium,- air or water - will
have an- unusual influence on the expased cells, It should be
recalled, from the earlier discussian, that each of the factors
here named can also have great influence on the tissue formation
of the plants, Therefore, it seems very possible that they are
alse significant in'the formation of callus tissws, How shell
we isolate, however, the different factors from one another, in
the case of injury to the object undew experimentation gnd as-
certain their specific method of effect in the comparative 6x~
periments? Our present methais do not always make it possible
to carry through this isolation experimentally. Besides, even
with the methals now at our disposal, there still remains much
te be investigated, At present we do not know what is the sig-
nificance of the above enumerated factors in the formation of
callus, nor whether perhaps the essential ones are still unnamed,

The conditions in many galls are even more complicated,
Many of those which we have termed prosopleasmas have been pro-

(273)

for4)

£33

duced after injury.- Yet the chief fa j i

Yew ec actor in their oduetio
eae undoubtedly to the poisonous matter npoinead be the :
gall animals. Besides the factors which hypothetically are te
be considered in callus tissues, the action of some special

oi i
earn ag have to be reekoned with, when analysing the "gall-

A comparisen of the abeve-nared tissue forms with the ka
eee @lready described leads to new considerations. see
bring forward proof thet kataplasmas correspond histologic-
ally in all essentials, often indeed in all details, ith wound
tissues, (callus, wound-wood), Therefore the interference pro-
coaddng from the infecting organisms cnd the conditions under .

which the tissue of the host plant is brought by those inter-
ferences are not forthwith to be put on an equality with the
ones which, 4n coarse injuries and mutilation of the plan} hody,
result in the formation of wound tissw , When; forexample, &
ghclige grows in some plant tissue and incites it to the forma-
Kos of abnormal excrescences, corresponding in every way with
hose produeed after injury, the reason for their formation can
scargely be caused by changed transpiratory conditions, At any
TUNG in many cases one can not speak of the ehemical action
of dead cytoplasm nor of any product of decomposition,- and it
is certainly not probable that changes take piace in the me chan«
doa] action of pressure and incite the growth of the abnormal
tissue in the kataplasmas produced by sucking parasites which
live superficially, (Hemiptera), The contact ef the inner
layers of tissue with atmospheric air should be taken into con-
sideration as © contributing factor in the production of this
kind of Zoocecidia and Phytocecidia. Hence the question follows,
as to whether factors of different kinds can incite the formation
of similar kinds of tissues, or whether perhaps injury and in-
fection make possible to the same extent the action of certain
factors, not found among those enumerated above and of whose
quality we can not as yet form any decision,

Formative processes simpler than those named here seem
well suited for explaining more particularly that which was
discussed above,

I would call attention first of all to Kleb's observations
according to which it is possible to incite Vaucheria tubes to
the formation of zoospores by various kinds of interference.
Further, I would pefer to the deformation of fungus hyphae and
the like, described above (p. }; abnormal processes of growth
take place if the concentration of the surrounding medium chan-
ges, if fluctuations in temperature become eftective, or if a
parasite in the interior of the cell, robs it of part of its
nutritive substances and so forth, We can either assume, in
relation to the question as to effective factors, that external
conditions of different kinds are able forthwith to bring about
the same effect in the cell, ond that the cell responds ta un~ —
like stimuli with the same reacti on,- or that, disregarding thet»
diversity, external factors directly accessible for our cansic -
eration and measurement resujt in the same conditions, which
would come under consideration only as causes of stimulation as4
bring about the phenomena of reaction studied here, If we could
ascertain the active factors, we must grasp the fact that be-:
tween the change in factors proved in the experiment and the

Pe ne oe A oe

Compare elso statement bejow under 5.

(275)

284

reaction to stimulus observed in the cells, numerous different
transitional stages can be meade possible, One or more of

these transitional stages can represent reactions to stimuli

on preceding ones, others can not be understood as due to stin~
ulus effect (in the above @iscussed sense), but as the effect
of the force of the energy supplied. The detailed knawledge

of these "chains of stimuli", whose end links in these cases
represent processes of growthcor formation, is still absolutely
closed to us;- in only a few cases are we at present in a posi-
tion to name a few links of the problematic chain of stimuli :
and to make probable any causal connection, The numerous works
whose authors have taken up experimentally the questions of
pathological plant anatomy, often throw much light on the ques-
tion as to how plants can be brought to a production of these
or those tissue forms, But any further dissection of the active
factors and the course of their action has been attempted only
in exceptional cases and not always successfully.

If we find in an experiment that similer formations of
tissue are produced through the action of unlike factors, from
what has been said already, we will have to make tests as to
whether possibly a dissimilarity of the effective factors has
only seemed to exist here, because of our scanty kno ledge of
the so-called "chain of stimulation", or whether, by more exact
proof, similar effects and reactions may not become traceable
back to similer causes, Only when a positive answer to this
question has been proved impossible, will we admit the suppos-

ition, that stimuli of different kinds can bring about similar
formation reactions,

When plants cultivated in the dark display tissue hypo-
plasia, as do those examples whith are matured under water or
in a scarcity of carbon dioxide, we do not venture to find in
this a specific action of scarcity of light or of contact with
water etc., but must look for the cause of the hypoplasia in
the tertium compsrationis, in snsmfficient nutrition, to the
results of which, the non-assimilating and weakly or non-trans-
piring plants are equally exposed, If fluctuations in temp r-
ature and changes in the concentration of the surrounding
medium cause the same abnormal processes of growth, we do not
find in them any specific action of the temperature or the
8olution as then present, but must think of the fluctuations of
turgor and of osmotic pressure, caused by the changes in tem-
perature and concentration, we must seek in them the cause of
the described processes of growth, If the same tissues are
formed after the mutilation of parts of plants, as after the
infection by funginetc. the question confronts us as to wh ther
there may not exist factors,- causally conditioned by injury.
or infection,- which in this case as in that become effective
and cause in both, apparently dissimilar, cases the known re-~
actions on the part of the organism, Since our scant knowledge
of the effective methods of external factors and the capacity
for reaction of cells and tissues for the present makes poss.:
ble the giving of any satisfactory answer only in a few cases.
naturally nothing can be said against the justification in
principle of my interrogation,

Since we tract certain kinds of arrestment formations back
to ingufficient nutrition and recognize in the fluctuations of
osmotic pressure the cause of certain abnormal phenomena of
growth and the like, we thus become acquainted with specific

235

gauses for certain abnormal formative processes, The fact that
very different methods of experimentation allow the same speci-
fic cause to come into action makes necessary a differentiation

between the means used by the experimentor and the specific
gausal factors, when judging of each abnormal formation:

The demanas. made herewith in the treatment of developmental-»
mechanioal questions have as yet been only incompletely satis-
fied, Our knowledge off cell-physiology is proved to be insuffi-
client in every way, We oan let our glance wander over a mighty
field of work, whioh begins to be passahle in only a few paths,

We will now pass over to the special discussion of the
aifferent nctive fastors and will briefly explain the special
ferm of their action by a number of examples,

i, Influence of Mechanical Pressure and Strain

The effect of mechanical pressure gnd strain on living
plants and especially on the formation of tissue, may be con-
Sidered from different points of view.

Force effect alone is present, when, for example, through
pressure, the elements of a tissue are changed from their normal
position and are twisted and bent. Tissue characterized by such
twisted cells are discussed on p, 177, Again, force effect is
present when the elements, attacked during growth, are kept
from further enlargement, The inhibition of growth alone natur-
ally does not of itself cause the formation of abnormally con-
structed tissue, If the cell division continues its course in
arrested growth, abnormally small-celled tissue @s produced.

In fact s uch may be produced, when (by means of a plaster ban-
dage) the objects under investigation are subjected to a suffi-
ciently strong pressure (see above p. 29).

Thus we gre concerned with stimulus effect, not only when,
by mechanifal pressure and streink the cells are incited to
or or division or special processes ef differentiation,

ut also when certain formative processes gre in any way in-
eaponces in their direction by the factors mechanically effec-
ive.

Examples ef this directive influence of presswe and strain
will be found in Kny's reports, Under the influence &f mechani-
cal pressure the meristem cells of the medullary rays in
branches of Salix and Aesculus divide in a different direction
than under normal conditions, Double rowed medullary rays are
produced”, It seems to me that a case studied by Klebs belongs

(276) here (fig. 56). If the walls of the cells of Hormidium are —
made incapable of any further surface gro th (by treatment vith
Congo red), abnormal effects of pressure will be exercised on
the growing protoplasts ‘yhich are enclosed by them, It is very
probable that these abnormal pressure egnditions cause the ab-
normal direction of the new cross-walls”. It does not seem

| ee ee ~

1 ueber den Binfluss ven Druck %, ‘Zug, u. 8. W, Pringsheim's
Jahrb, f, wiss, Bot,, 1901, Bd, XXXVIL, p. -8B.

: Compare alse above p, 163,

9 236

impossible that, in the above named "stimulus effect" ana
Similar ones, some are concerned which later may be recognized
as force effects, when the knowledge of the mechanics of pto-
toplasmaz and of the physiology of cells has become more exast,

That cells may be incited by mechanical pressure and
strain to definite processes of growth, division and differen-
tiation, is proved by the phenomena of so-called passive
growth, by cambial cells brought to cross-division by strong
pressure and by the cell division which Kny found in the pith
of Impatiens and others under the influence of pressure, Fur-
ther, attention is again called to the activity of hyperplasia
of mechanical tissue (oompare p, 142),

Thouvenin hes shown (compare p, 48) thet definite pro-
cesses of differentiation can be made impossible under the in-
fluence of mechanicel factors,

_ We mentioned abeve (p. 269) the influenoe, which, ac-
cording to Neigert and others, is exerted upon tissue-for-
mation by the removal of hinderances to growth, ‘The con-
sideration of the action of mechanical factors, is of the
greatest importance here and, in fact, Ribbert™ has re-
cently attempted to explain very different forms of peath-
Ological growth - regeneration, inflamation, formation of
tumors - by the removal of mechanisal hinderance to growth.

P So far as the formation of abnormal plant tissues is
concerned, not one of their many forms have been suffi-
ciently explained as yet by an omission of hinderances to
growth. It may be steted ag very probabie thet in the pro-
duction of callus, wound-v7ood, and others, the removal of
bark pressure and similar hinderances to grosth is not
without influence on the formation of the wound tissue,
However, there is no necessity for the assumption, that the
removal of the pressure exfect causes the formation of
wound tissue. We may find an outgrowth of tissues of very
different kinds even without previous injury vr release
from pressure and also of many excrescences (those pro-
duced endogenously,- such as galls and intumescences).

2. Temperature

All life-processes, and also processes of formation and
differentiation, like many physiological or chemical ones, can
be carried through only within certain temperature limits. The

' formation of tissue on the groving shoots and roots will be

(277)

discontinued if the temperature falls below the requisite min-
imum or if it rises above the admissible maximug, But the same
temperature Jimits do not hold good for all processes of forma-
tion and differentiation taking place in a growing organ or or-
ganism. Certain processes may still take place, although others
have already become impossibles If unfavorable temperature con-
ditions make certain processes of differentiation impossible for
developing tissue, "incomplete" abnormal tissues are produced
(hyperplasias). In many plants, formation of the chlorophyll is
rendered impossible by tooolow a temperature (p. 36). Hans-:
found that the formation of cross-walls in groviing cells ot

Lehrb. d, allg, Pathologie, 1901.

(278)

237

Bacterium Pasteurianum was omitted when the temverature was too
high (p. 1). Thus the living cytoplasm can permanently for-
feit its activity for certain processes, as in our first example,
or its capacity for reaction to certain (external and internal)
stimuli is again made possible so soon as the disturbing. effects
of the unsuitable temperature are removed - ag in our second
example (see above),

No absolutely certain case is known cs yet in which abnormal
temperature conditions oan cause the formetion of abnormal tis-
Sue in any way other than by the arrestment of certajn processes,
In Prillieux's experiments (see ebove p, 89) the arresting ao-~-
tion of a high degree of warmth seems to combine with the action
of air which is free from water vapor. AS pegards the observa-
tion, thet abnormal cé1l-division occurs in mony fungi at high
temperatures, it seems to me thet we ore still insufficiently
oriented as to the disarticulating cction of temperature,

8. Light

The influence of light on the formation of tissue is at any

rate slight, since no specific effects of this form of energy
are known,

; It was demonstrated that illuminatian can cause the forma-
tion of chlorophyll and anthocyanin and that the formation of
pigment is often lacking in the dark, But since it was shown _
that the formation of chlorophyll (in various algae) is possible
even in the dark, when certain nutritive substances are added
and that, in the same way, cells can be incited to a formation
of anthocyanin independent of light or darkness,- we may assume
that the formation of pigment after illumination does not repre-
sent a very specific action of light, but that it is caused by
nutritive conditions, the production of which is mde possible
in the cells by theinfluence of the light.

If the tissues in etiolated plants reach only a moderate
degree of differentiation, while the individuel cells often be-
come larger than under normal conditions, we may not see in this
any specific result of a lack of light, but the effect of ssenty
nutrition, and reduced transpiration, We observe the same tissue
changes in examples which are raised in the light in a damp room
that we find in cultures made in the dark.

The question as to whether continued illumination can
"arrest" certain formative processes, as seems to follow from
Bonnier's experiments (see above p, 57), needs closer investiga-
tion. 5

4, Chemical Substances

So far as any inSight into the factors which are effective
in the formation of tissue is possible in the present state of
our knowledge, we may indeed maintain, that the great majority
ef the processes of growth, formation and fifferentiation are
brought about by stimuli given out by chemical substances,

Without doubt, each process of growth, etc. presupposes the
presence of certain substances, no matter whether they are sup-
plied to the cells from without or are produced in them autoch-
thonously by assimilation, If these substances are lacking, or
are preseng in insufficient amounts, certain processes of grovth
and formation are omitted and "arrestment forms" are produced,

238

if the cells are over-abundantly provided with those substances,
many processes of growth and formation may in one ‘way or another
be continued beyond the normal standard. However, it will
scarcely be possible to decide in a single case as to whether
the nutritive substances act as stimulation causes er whether
the cells are not rather given the Gapacity for reaction by
these substances, in order to react, in the way described, to
any stimulation causes which a8 yet have been discovered,

. In some cases we may now conolude that most probably the
supplying of nutritive substances has only some "preparatory"
action. Roux has show thet the hypertrophy of activity in mon
and animals can not be a reaction to functional hyperaenia
(and the supplying of nutritive substances connected’ with it)
but isyto be understood as a specifio effect of the incregsed
deminad™, The same conditions exist for the activity byperplasies
ef mechanicnl plant tissues described above, The supplying of
nutritive substances, which certainly precedes their formation,
-aopparently only makes the tissues onpable of reqoting in the
above desoribed way to stimuli of a definite kind;~ in the present
ease to mechanidcel strain ond pressure, The cotucl freeing
nomentum does not lie in the supplying of nutritive substances
but 4n the action of mechanical factors;- hence the nesessity of
mentioning activity hyperplcsins under 1. If ve find that def-
inite formétioh# of tissue ocour efter the supplying of nutritive
suhstances, it will be necessary, even whan no other factors my
bs found to be the cause of stimulation, te think of the possi-
bility that the supplying of nutritive substances is effective
only os a preparntion,-+ not os a setting free,- and thet the f
favtors which do set free are Still unknown. I w4ll return ot
once to this point.

The action of oxygen and water is exclusively prepsratory.

Among the oases, which ore of interest to us, not one oan be
found jn which a freeing stinulus proceeds from the supplying of
oxygen”, The numerous cases in which the supplying of water acts
releasingly will be discussed in another sub-division besause ©

(279) in them apparently the water does not act as a nutritive sub-
stance, being effective only beceuse of its physical qualities,
not at all because of its chemical ones,

The conditions are much clearer when tha effective sub-
stances are not nutritive ones, hut are poisons, which inei te
the cells to some activity without themselves furnishing any
puilding material. We may assume that no "preparatory" effect
proceeds from them, but a freeing one.

-_-— -— = a
Cn Pe a ee i ool al ane

1 Roux, Der zuchtende Kampf der Teile in Organisms,
1881. Ges, Abhandl, Bd. 1, p. 315 ff.

a That, under certain conditions, the supply of oxygen
may also bring into existence directly or indirectly, rgleasing
effects is shown by Natzuschita's investigations on ennarenis
bacteria, which ferm spores under the influence of oxygen. Zur
Phys. der Sporenbildung 4. Bacillen etc, Dissertation Halle,
1902, Arch, f. Hyg., 1902, Ba. XLIII, p. 267).

Ae

239

Some cases will be discussed later, in which the ection
of nutritive and poisonous substances and their trophic and tox-
ic effects will be illustrated, As seid above, in many eases it
must remain undecided for the present in trophic action, whether

a freeing or © vreparatory influence of the living cells end
tissues is invalved here,

Trophic effcets, varying from the normel are produced in
various vways,- an insufficient supply of nutritive substanoes
causes hypoplasin, while an over abundant one leads to hyper-
trophy or hyperplasia/

An hypoplastic formation bf cells and tissues always occurs
when insufficient amounts of nutritive substances lie at the
disposal of the organisms or of its spparate parts,~ or the con-
position of the food stuffs offered does not supply the sub-
stances required for a normal devejlopment/ We observed hypo-
plasia in plents which live in the dark or in places free from
cambon dioxid, which therefore by assimilation can not priduce
from themselves the necessary amount of nutritive substances;
furtherk in thods plants, in which transpiration is srrested by
cultivation under water or in moist places as well as by the
exclusion of light, and whose transpiratory current is therefore
too weak to supply the needed amount of nutritive substances
to the different parts of the organism. "Shade-leaves" are also
to be considered in this connection. It must remain doubtful
whether in the production of galls bearing the character of hy-
poplasias, the giving up of nutritive material to the parasite
which produces the gall may play the chief part or not. We can
further observe hypoplasia in plants, which must support their
existence without iron, caleium or other "indispensable" sub-
stances, The conditions in the homoeoplastic excrescences of the
sugar beet already described (p, 139) are more complicated,

Ne@ formations are produced, which apparently use up all the
available amounts of nutritive substances, so that the neighbor-
ing tissues seem to be arrested developmentally, The “struggle
of the parts_of the organism" leads here to a "cbrrelation
hyperplasia",

A continuance of the processes of grovth and differentiation
is produced by trophic influences when the cells are brought, by
some means, to the production of substances without which cer-

(280) tain processes can not take place. The formation of chlorophyll
is clearly dependent on some unknown substances, which in most
plants are produced in the cells themselves only under the influ-
ence of light. Many algae, however, are known to form chlorophyll
in the dark, after having been supplied with organic nutriment
and it seems not at all impossible that future investigations

wate et a as ae Re A ee ee ee ee a er GR ee ne ee ee a OO cee

(p. 140) for Aristolochia-ridges (Observations by Magnus).- If
in Erineum galls, the epidermal cells hypertrophy greatly, but

effect of gall-poison,

(2824

‘ 249

Will make known certain subst
even ag ee plants will be in
in the dark,

ances by the supplying of which
& condition t@ produce chlorophyll

We will venture to explain the metaplastic anthocyanin forn-
ation in Saxifrage leaves (see above p,. 58)_ the pro duction of
correlation-homoeoplasias and heteroplasias! and in part aiso the
formation of many callus tissues not by an abnormal new eodne~
tion of nutritive substances but wy an abnormal aastunid tenn of
substences already present and those prodused aa the norma:
course of life-processes, Local accumulation of nutritive svb-
stances as a result of abnormally increased transpiration might
also be operative in the formation of wound-cork,

; No absolutely certain example has been known as yet in
Which abnormally increased supplying of nutritive substances
from without can promote the formation of tissue beyond the nor-
mal amount ¢ Arrestment phrnomena seem rather to Be caused by
abnormally increased transpiration which gccelerates the trans-
piratory current, as is shown by dwarf examples in dry habitats,
Zs yet, at any rate, no normal formation of tissue has been in-.
cited by an artificial supplying of organic nutrition from with-
cut,- yet it is to be hoped that the experiments recently made
by Haberlandt and Winkler on isolated plant cells will lead in
the future to positive results. ,

Toxic effects, consisting of degeneration changes of the
cell, may be left unconsidered, Those cases are importart for us,
in which an arrestment or a promotion of certain processes is
noticeable after the action of any poison,

Arrestment may be brought ato ut by very different kinds of
substances, Some, taken up by the plants in small doses as food
steff and there worked over, can acti as "poisons" when used in
greater amounts, Mention must be maie here also of the arresting
effect of organic focd in green flagellates, diatoms and others,
Which become “apochiorct:ic' wader tne influence of en abnormiiry
abundant supplying cf nutritive substances, Farmer and Chander
(see above p, 48) have made reports on the arresting infinens?
of air which -ebounds iu carbon dioxid, In order to arrest the

1. The formation of correlation-homoeoplasias and heteropas-
ias belongs among those cases of abnormal tissue production, in
which the abnermai supply of material does not act releasingly
perhaps, but oniy as a preparation or as a qualifying effect,

If any cambium or any parenchyma capable of division, under the
influenca of the supply of food stuff, continues longer the pro-
duction of celis and acts more intensively than under normal con-
ditions, the releasing agent may well be sought in "internal"
factors, Similar but more complicated examples are discussed with
the same point of view by Driesch (Die organischen Regulationen,
Leipzig, 190%, p. 118). I share completely his interpretation

ef this matter, It is difficult to answer the question, as to
what factors in hyperplastic formetion of vascular bundles in
dahiia tubers {V5chting's experiments} act releasingly as a re-
suit of increased demand upon them (Activity-hyperplasia, see
above p, 145), whether, perhaps in this ease, the intensity of

‘the current, i. s. Something mechanical, caused the stimulus

(Oriesc: loc. cit.) or whether here aiso only “internal” factors
were at work and the intensive current of food stuff created only
the necessary nutritive condition, the desired ability to react.

241

precess of cel). division, Garassimoff used substances which
act as "poisons" in every concentration and under all circun- .
stances, It is possible to produce suecessfully asporogenic
"races" in different kinds of hoeteria, by treatment vith var-
jous aciéa (hydrochloric, rosel and cerbolic acids)~.

The exciting effects of poisons heaomes noticeable there-
fore when it 1s possible to increase the growth intensity of
lover or higher plants by treatment with onaesthetics or metal-
lic compounds, Abnormal tissue formetion as a result of the
exciting action of toxic substances has been repeatedly des-
eribed above. Poisons produced hy necrotic decomposition ‘of
the cells and tissues seem able, under certcin conditions, to
incite the formation of :‘ound-cork ond wound-wood, As Winkler
has shown (see above p, 98) foreign substances, supplied from
without, are able to inoite cell-division, Finally the aotion
of poisons is also the cause of gall formetions,- such ns, for
instance, all proseplasmas,

5, Turgor, Osmotic Pressure end Diffusion-Currents

The significance of water in the processes of cell growth
and tissue formetion liew especially in the fact that all these
processes are peasible only when a definite amount Bf water is
present. The "preparatory" action, proceeding frem a supplying
of water and its absorption, 4s unmistakable, Only with a def-
inite degree of turgor do the cells become cnpable of an activity
which leads to a normal or to an abnormal formetion of tissue.
The question es to whether increase or decrease of turgor oan

set free definite formative processes still remains to be dis-
cussed,

In fact, examples are known for an action of this kind due
to changes in turgor, I include here especially hyperhydric
tissues (compare p, 74). When the amount of water given off by
any cel] whatever is reduced, the turgor of the cell will be in-
creased by & continued absorption of water. By this abnormally
high turgor, the cell is incited to growth -activity, producing
long cylindrical tubes, such as those pictured in figures 19,

23 and others, The abnormal amount of water pokes possible the
stimulus to which the cell reacts with growth”.

We -have named first of all cases in which, by the absorp-
tion of water, (the increase of turgor) the cells have been in-
cited to definite action. ‘The question must still be settled,
as to whether formative stimuli can also proceed from changes
of an oppesite kind.

¥ree~-lying cells, like fungus hyphae, root hairs, unicellu-
lar forms and the like, are easily accessible for experimenta-
tion, Root-hairs are especially useful since they react very
easily and quickly to influences of all kinds. The deformations
described above (p. 120) and easily produced prove that abnormal
processes of growth ané set freeeven in a treatment with material &

— =
-— = oe ee ~— ae ne wee elle el _— ot le

f. Hyg., 1889, Bd. VII.

£ The interpretation of the authors who speak of the growth
as a direct resuit of turgor ("ae a force effect") is erroneous.

° 242

(282): Which withdraw water,- thus reducing the turgor of the cells,

{2983 )

increasing the concentration of their contents and so the os-
motic pressure, The hairs grow chiefly in thickness, instead
of continuing their normal growth in length, Reinhardt ob-
Served the same phenomens (See above) in fungus hyphae. Changes
in concentration and composition of the surrounding medium as
well as fluctuations in tempersture heave eAlled forth the same
deformetions, In both sases we my venture to explein the ab-=-
norme] forms by fluctuations in turgor ond osmotic pressure,

In just this connection in my opinion belong the Vaucherie. gells
of Notommate, the involution forms of bacteria @nd others,

There is a need of 8 closer testing of the question as to
whether sbnorm.] processes of growth in etiolated plants, the
phenomena of "starvation-etiolation” and others, may be ex-
plained in the same way, - end further whether hypertrophies,
produced after poisoning (gall hypertrophies), may in part at
least be underatood to be the result pf phytical chenges in the
cell-miocroosmos, It may indeed by possible that substances are
supplied to the infected plant cells by the parasite, which act
on the cell life to the host plant less through their chemical
qualities than their physical characteriéties and may perhaps
eause an abnormally high osmotic pressure within the infected
celis, This poijt also will have to be considered in a future
analysis of the "gail-stimulus", Let us remember further that
any abnormal absorption of water reduces the concentration with-
in the cell, and therefore its osmotic pressure, but that amal-
ogous changes in osmotic pressure are produced not only by the
absorption, or the giving off of water, but also by fluctuations
in temperature and by chemical transpositions within the cell,
in which substances osmotically effective are converted into
ineffective ones, or osmotically ineffective substancds are
changed to effective ones, As is shown, a varying connection
exists between the osmotic pressure wit hin the cell and the ex-
fernal conditions of life, A wide fiend of work lies open here
for future ihvestigation. Por the present we must limit our-
Selves to the mention of new questions,

)
The diffusion currents in the cell page) are closely
connected with the osmotic pressure wibhin the cell, these

I will mention briefly,

The growth of a crystal in its mother solution undoubt-
edly leads to some changes in the concentration of the
solution immediately stirrounding the crystal, The changes
in concentration for their part result in diffusion-cur-
fents which are definitely directed, Differénces in the
processes of diffusion and therefore in the conditions
necessary for the continuance of growth on the aifferent
parts of the cryatal will apparently be produced so much
the sooner, the greater the amount of the surface of the-
srystal here concerned, The fact that crystals of definite
substances usually continue their "normal" growth only tona
certain size,- and then grow “abnormally",- makes it possi-
ble to conclude without doubt as to unequal conditions of
crystallization on the different parts of the crystal, and
we may conceive of some minute "disturbances" in the co... 362
of the diffusion currents.

These diffusion currents must ve produced in the living
cells just as in the erystal-mother-solution, if a crystel
or a conglomerate of crystals is produced anywhere in the

243

cells, or if any soluble substance is gradually corried
“over into an insoluble compound, Therefore, for example,
in the construction of a starch grain, in the growth of a
membrane ete., we may nov assume thet the course of this
process of growth becomes irreguler when different parts

of the growing form ore placed under dissimilar conditions
of growth, by disturbances in the rerular process of diffu-
Sion, ‘Yithout doubt disturhances of this kind occur so
much the more easily and cam become so much the more con-
spicuous, the larger the grovring forms are.

It is a notevorthy fact thot even in the organic king-
dom there exists some connection between abnormal size end
abnorm:] form, Figure 120 gives at B some abnormel giant
Starch grains from the gorreletion-heteroplasmas discussed
above (p, 152), which Vochting found in the form of "leaf
tubers” in Oxalis crassicaulis., The abnormel grains (B)
appear, beside the Simple normal ones (A) as bizarre as is
possible. "All show peculiar appendages, some short and
knob-like, ethers longer, sometimes lang and straight, or
again bent like hoods", At times irreguler humps ore pro-
duced, which can fill whole cells. We do not know why
star¢eh greins should be come Larger in the above-named

(284) abnormal tissues, then under normal cenditions, Their ab-
normal form is caused, I expect, at least in port, by the
above discussed differences in the conditions of growth’.

In A consideration of entire cells, we also often find
abnormal forms associated ~ith abnormel size. <A vell-known
wxample of this is furnished by the involution forms of
bacteria, among which are found broancted forms, lying next
to vesicular or spindle-like ones. The latter cre evidently
produced by differences in the conditions of growth in dif-
ferent parts of the ce}l membrane, and by the unlike dis-
tribution of substances. The branching vill arise ceteris
paribus on the places "preferréd" ~ those better provided
with building material. The larger the cells, the more
easily are produced the described differences in the in-
tra-cellular distribution of substances through disturbance
Of the diffusion currents.

B. On Reaction to Stimuli

The preceding chapters have contained more detciled reports
on the reaction to stimuli of cells and tissues in so far as
they consist of processes of growth and differentiation. Only
a few general remarks remain to be added to this point,

In the normel course of life of a cell, we find that cell
division regularly follows cell growth in such a way that nu-
Clear division and the formetion of cross walls takes place as
S00n a8 the definite cell size is reached, Fvidently, during
the growth of the cell, some physical conditions or some chemi-~
cal substances are produced, which incite the cell body to di-
vision, In this process we are cdncerned «ith the effects of
stimulation action and indeed of internel stimulation, the ef-
fective factors being produced Py the activity of the cell it-
seif. By means of innumerable examples, pathologieal plent

at work.

(285)

244

anatomy nov proves that cell division and growth co not et all
represent inseparably linked processes and that the total re-
sult of separate processes, which in the nornal course of Ge-
velopment are constantly repeated in the sane way, is capable

of very different modification. ‘Je can cause cells to divide
without previous growth, which under normal conditions, would
have been enlarged and then have divided, and converscly can
cause their growth without any division taking place. The first
experinent is successful, when we take away from the cells the
conditions presupposed by growth. Therefore, with previous’
growth, those factors may also becone effective in the cell,
which incite division. In experinents of the second kind, we
neke the cell incapable of reacting nornadly to these very
factors, or we do not allow any of the coriditions and substances
to appear which incite division. No matter how we ney wish to
interpret the state of affairs here described, it teaches at

any rate that factors leading to division in the cell can also
be produced without any previous growth and that conversely
division should not be understood to be a physically necessary —
result of growth which has already taken place, - tn other words,
that the phenomenon of cell growth and that of cell-division

can Occur independently of one another, according to the con-
ditions, which are already effective on the cell and in the cell.

This sane "independence" oceurs in all other processes of
division, the sum pf which nakes up the developnent of an or-
aa In growing root hairs etc., an inerease in cell volune

eeps pace with the new formation of cell walls. We nay arrest
the growth and still find that the cellular products continue
their course. Cell division and nuclear division are indeed
independént. of one another. Even in plants, which under normal
conditions consist of only unicellular units, multicellular
Blenents are produced under certain circumstances, if for any
reason the conditions tlecessary far the formation of cross-
walls are not filled. On the other hand, nuclear division can
be "arrested", Just az "independent" as the processes of di-
vision just named, are also those which give the cells their
characteristic "inner fom" and signify all differentiations

of cells and tissues. The processes of tissue differentiation,
taking place normally after a certain nunber of cell divisions,
can also occur abnormally early, before the normal nunber of
cells is present, or can be lacking even when the usual nunber
has been reached, or indeed exceeded, and the like.

According to the number of processes of division taking
pert in the formatibn of various abnormal tissues, we can con-
struct a list beginning with the simplest hypertrophies and
ending with the nost complicated hyperblasias. Growth of the
cells alone was observed in the production of many hyperhydric
tissues (katapblastic hypertrophie), growth together with in-
crease of cytoplasm, for instance, in the gall hypertrophies,-
growth, cytoplasmic increase and nuclear division lead to the
formation of nultinuclear giant cells; the same processes to-
gether with cross-wall formation may be found taking place in
almost all hyperplasias. In the preceding chapter in the dis-
cussion of prosoplasnatic gallls, it was shown, how diverse are
the conbinations in which the different kinds of differentiation
processes can be united with other processes, the production of
which is made possible by a hyperplastic tissue outgrowth, with-
out its being connected with them. We find that lignification
takes place in nany abnormal tissues after repeated cell civi~
sion. - The same process is enacted in other cases, however,

(286)

245

even without previous enlargement and divisions of the cells
concerned, Parenchymatic excregscences of Solanum tuberosum

may be produced (according to Vochting's experiments) even
without any deposition in them of the usual starch masses,

On the other hand, there ene many cases, in which 1t is found
that abundant quantities of starch heve been accumulated, with-
out any preceding form.tion of any excrescence whatever eto,

It hes not yet been proved experimentally that o11 pro-
cesses actually oonre cted with one onother in normel develop-~
ment, so far os time and place are concerned, can asst: their
"indepdanence” under suitable conditions and cen ocour indepéne
dent of those other processes with which they seem to he com-
bined narmally, Yet the actunl material ct hend justifies ever.
now the essumption thet 211 processes of division should be
termed “independent” in the mecning here explained, The capa-
city for certcin formative ond differentiating processes id de-
termined, to be sure, by the speeinl qualities of the oytoplesn
of the alfferent plant varieties, The combination in space,
however, end the sequence, in which we find the separate pro-
cesses enacted ina normal course, may be understood os caused
by the influence of all #ffeotive "internal" ond "externel"

factors, the majepity of which ore evidently still withheld from
our knowledge,

Khebst proved for the lower organisms, in the growth of
which teletively few formetive processes of division ere re-
peated, thet the combination of these takes place quite differ-
ently under changing conditions of life and can be modified ex-
perimentelly at pleasure, Thet in higher plants only the incom-
pleteness ef our knovledge and our methods of experimentation
prevent the carrying through of similer experiments is attested

to by the results of pathologionl plant anatomy/

It is now desirable $0 approach in still another way the
point treated here,

If we compare the cells ef abnormal tissues with those of
normal ones, we will find either complete correspondence (hom-
ceoplasias) or more cr less striking differences, The variation
of individual cells from the normpl is only moderate when the
individual cells in one or more ways resemble the undeveloped
elements of normal tissues (hypoplastas and many kataplasmas)%
‘On the other hand, the differences are often very mekked in
metaplasia, in prosoplastic hypertrophy and especially in proso-
plasmetic galls. The diversity of abnormal calls brings up the
question, whether a plant under abnormal conditions can develop
other kinds and forms of cells than those which compose the
normally developed plant boty,~ whether the same normal kinds
ef cells are always repeated in the prosoplasmetic galis, in
new and "abnormal" arrangements and combinations,

This question has always been repeatedly akked in the dis-

‘cussion of galls, the most striking of abnormal] tissues, and
has been answered in different ways/

1668, Bd, Il, especially p. 550; Beding. d. Fortpflanz. bei ein-

‘igen Algen u. Pilzen, Jena 1896, and others.

. 246

Gobel, in Bis "Organographie"*, states in regards to
this, that in galis, neither is anything morphologically
new produced, nor any "new tissue elements otherwise not
existing in phe plants". "New alone are the combinations
of the vlants' possibilities, the characteristics which
furnish the changing pictures of the kaleidospope. Forys
transitional between the organs are produced here very
abundantly", A note supplements "Cell forms vere 2190
found, which do not exist in any undisturbed development,
thet is, thome of the heir formation in "Erineum" galis.

(287) These hoir formations, which are coused by mites, aré of
sérvice to the porasites end varg from the normal pair forms

- the plants ooncerned", Appe1® seems to share Gobek's
view.

Beyerinck® holds a different view, According to hin
"new" oell and tissue forms may indeed be found in galls =
at times the representatives gt the Tinctoria and Kalleri
gall type. Herbst*, Berthold” ond others think the sane,
I have expressed my vier ns being the same as the authors
here named”,

Of the yopresentatives ofthe opposite theory, I will
nome deVries’ According te him, galls even of the highest
differentiation are oomposed only of such anatomical ele-
ments e8 are found also in the plants which bear them.
“Only the elements uf tha peculiar stone sell layer in many
Gynipides gells®, which develops later into a thin-walled
nutritive tissue, form an exoeption as yet got entirery
explained, which may be only an apparent one".

All other abnormal tissue forin tions should be inves-
tigated from the same. points of View as galls.

Berthold (loc, oft.) emphasizes the abnormal structure
3 which may he obsegvable jn regeneration and the healing of
ox wounds, Vochting” hed already obtained similar results,;
= he found new kinds of cells preduced in wound tissue such
as activity-hyperplasias,

-— mn
ft ete te ee — ww es a wr nm Ow ee ee ~~ -

: Organographie, 1698, Ba. 1, pp. 169, 170.
© veher Phrto- und Zoomorphosen. Konigsberg. 1899.

° Beob, ueber dia ersten Entwickelungsphasen einiger
Cynipidengalien. Amsterdam, 1882,

* Ueber die petenting a, Reizphysiologie, 2. Tl., Biolog.
Cb1., 1895, Ba. XV, p, 721.

. 98
Untersuch. zur Phys, der #flanzl. Organization, 1698,

Bd. 1; ‘Einleitung, p, 9. Here also Goebel in Flora, 1899, Bde
LXXXVI, p. 234. Compare also Prillieux, Etude s, ls formation’ et
le developp. de quelqu. galless Ann, Sc, Nat. Bot,, 6 Serie,
1876, 7, Ill, p. 135.

6 Beitr, z. Anat, a, Gallen Flora,1900, Bd.IXXXVII, p.176 ff.
7 Intracellulare Pangenesis, 1689, p. 117,
8 Compare ghove p, 254,

9 ved. Transplantationen am PflanzenkSrper, 1892; 4. Phys.
@er Knollengew. Jahrb, f. wiss, Bot., 1900, Bd. XXXIV, p. 1.

(288)

(269)

: 247

The lack of unanimity of these authors is doubtless ez-

plained by the present lack of clearness in the interrogation
of the phenomena,

It is indeed evident that even unusual hyperplasias like
normal parts of plants are composed of cells, The question is,
how must the cells be constituted if they may be termed "new"
kinds of cells, Evidently the investigators here nered heve
enswepad this question differently and thus have arrived at
different results, in drawing their conclusions, We vill first
of all be obliged to understand clearly the prekiminary ques-
tion, before taking up once more the oft discussed problen,

"New" qualities, that is, ones which vary from the normal,
may be expected to arise in different ways. The conditions of
size may be "new", or the forms, or finally the inner structure
of the cells, We will therefore have to compare abnormal cells
with normal ones, as to size, form and inner structure.

1. Size of the Cells

Aside from the individual unbranched latex tubes, which’
seem to be distinguished (theoretically) by unlimited grovth,
each kind of cell in plants forming tissues possesses a definite

size, which is attained early,- and fluctuates only within
narrow limits in the individual species,

We have seen above thet cells of very different tissue

forms may hypertrophy; nt. 6. may enlarge their volume beyond

a normal amounts The question must still be discussed, as to
whether the largest cells, to be found in a normally developed
plent body, may not perhaps give a maximum cell volume valid
for the species concerned, beyond which no celi of any tissue’
whatever of that species can hypertrophy,- in sich a way that,
so far as cell size is concerned, the plant cen furnish nothing
which could not be attained by it also under normal conditions.

The conditions in primitive organisms are most easily sur-
veyed, which, under normal conditions, develop cells of only
one size, such as, for instance, bacteria, The often gigantic
involution forms of the sohizomycetes prove forthwith thet,
under abnormal conditions, cell-growth can far exceed the normal
standard while no definite limits would be recognizable.

P The conditions in higher plants are just the same. In
them too we find no support for the assumption that a Limiting
volume, determined in the plant body, may be determinative for
cells grown under abnormal conditions, Figure 12], at the left,
illustrates some libriform fibres and pieces of ducts of Quercus
at the right some cells of the oak gall produced by Spathegaster
baccarum, No further explenation is needed to show that abnor-
mal cells can far exceed the volume of normal ones,

Cells of a tissue under abnormal conditions freauently
become appreciably lerger than corresponding normal ones; cher
may more rarely occur appreciably smaller. . However, no fixe
poualrries exist also for this lower limit. I will call at...
tion later to the dwarf Desnidiaceae described on page 27, to the
ducts of hypoplastically developed plants which have abnorme11ly
narrow lumina and to mycelial threads with excessively naprow
lumina, which may be found produced in solutions poor in nutri-
tive substances,

(290)

248
To summarize:- In regard to their size, the cells of a

plont developing pathotogically ard not restricted to that
Which the normal plant may accomplish.

£2. Form of the Cell

The form of membraned cells in plants is olmost elvays
identical with thet of their cellulose covering. The form of
whe jatter is determined by the manner of its production, b7
conditions of space ets., but especially by the processes of
surfece grovth, which have taken phceee in the membrane,

The growing cells of a Spirogyra thread remain cylindrical -
I follow the supporters of the theory of intus-susoeption = so
long 2s the newly superimposed particles ore deposited equelly
on all sides and longitudinally between those already present,
When © copulatory branch is produced, deposits must hive been
made on a definite part of the cylindricel wall, longitudinelly
and tangentially, All chenges in form in © gro‘ving cell mey be
traced back to the fact that either new particles of metter have
been deposited on every part of the membrones, or only in pleces,
sometimes in one direction, sometimes in severel.

If swollen, barrie -like oells are produced on Spirogyra
threads, by the coctidn of ethert we must assume that new parti-
cles have been deposited tangenticlly end more ebundently in the
middle of the cell then at the ends. Therefore, uncer nbnorre]
conditiens differently distributad dJeposits are made on the

cells, whereby other structures srg Formed then under normal
conditions,

A ocnsideration of the deformed root-heirs, fungus hyphae
etc, descrized above (p, 120) is still more instructive. When
the hemispherical form of cell ends is persistently retained,
during continued growth in length, we may assue with Reinhardt
(loc, cit.) that the individual particles of the head are, es @
rule, shoved toward the outside, until they have reached their
ultimate position in the cylindrical mantel and that thereby
the deposits of new perticles must be most abundant near the
long axis, grdaually decreasing towards the edge, in order to
cease entirely in the cylindrical-mantel". V,ry marked vgria-
tions appear under abnormal conditions, club or ball-like forms
are produced sccording to the degree to which the deposits in-
crease tangentially, If.the part lying back of the tip grows
more strongly than the tip itself, bowl-like forms are ppoduced.
If an especially active growth takes place at several different
places, branched forms arise and the like. There are indeed no
forms which could not be produced by abnormal modification of
the surface growth, nor which, under abnormel] conditions, have
not been found actually occurring in the objectscnemed.

The epidermal cells of leaves and shoots es well as ground
tissue cells (fig. 43) can grow cut into similar forms as al-
ready discussed in chapter IV,

The question as to whether the formal repertoire of norret
cells is determinative for deformetions vhich are possible under
abnormal conditions, must be answered absolutely in the negative.

"2. gerassimoff, Bull, Soc, Imp. Nat: Mascou, 1896, Nr. 3.

Nathansohn in Wahrb. f. wiss, Bot., 1900, Bd. XXXV, p,65,

(291)

24¢

I call attention again to the bacteria which developing nor-
mally, only become rod-like cells, the involution forms of
which, however, seem to have been most diwversely swollen,
twisted or’branched, The form of ebnormal cells, es vell as
their size, has free scope for development which may be said to
be unlimited, The noteworthy Erineum heirs (Fig, 40), the two-
armed trichon of the gell of Neuroterus numismeatis (Pig, 102)
and many others prove thet the same holds good for higher plents.
Under normal conditions cells of this form are never produced
on the plants bearing the Erineum nor on the host plcnt of the
numismatis gall,

ve can thus affirm that the intensity, the localization,
the direction of the membrane growth and thereby the form of
the cell, are determined by the sum of all the faetors which
act (internally and externally) on the cell and thet under cbnor-
mal conditions fnew" cell-forms ean actually be produced,

3, Inner Structure of the Cells

Only by considering the inner structure of the cells, will
we become acquainted with the limits which, even under ebnormel
conditions, remain decisive for the development of plant cells.

In the last three chapters, repeated mention vas mode of
the fact that very different kinds of cells, of very different
origin, cen under certain abnormal conditions assume "foreign"
characteristics which often warrant conclusions as to changes
in the physiolobical effectiveness of cells, Cells, which re-
mein colorless under normel conditions, develop chloroplasts.
Thin-walled cells obtain, through thickenings of their membrane§,
an especial wall structure; for example, 2 reticulated one, and
so forth, Closer consideration now proves, thet on abnormal
turning green takes place only in plants which even und er na -
mal conditions somewhere develop chloruplasts, that, further,
abnormal reticulated wall-thickenings occur only in plants, in
which the same formetive process is known already in certain
normal elements, Therefore peculiarities of the cytoplasm’ con-
‘Sidered as pre-requisites for the formation of ghlorophyll,
certain wall-thickenings, etc,, are not produced "anew" under
the influence of certain abnormal conditions, but only becoma
active in those cells and tiseues in which, in a normel develop-
ment the external and internal conditicns necessary for chloro-
phyll formation are not realized, Among others we must consider
the nutritive conditions of the cells; in which, therefore, in
other words, the cytoplasm for some reason does no& "make use
of its capacity for developing chloroplasts etc.

Although the plant, so far es the inner structure of its
cells is concerned, even under abnormal conditions, must manage
to live with. the same capabilities that age also active in nor-
mal development, yet all possible heterogeneous kinds of cells
may be produced in such a way thet the known processes of dif-
ferentiation are enacted in the larger or smaller cells, or in
those formed otherwise than under normal conditions, I call
attention agein to the peculiar callus hypertrophies of the
Orchids (Fig. 26), to the parenchymitic tracheids in callus
tissue (Fig. 67), to branched woody fibres (Fig. 70), to the
tracheids which occur at times in prothallia and meny others.

(292)

: 250

It must still be noted that definite processes, known’ in
normal deveicpment, can take place with abnormal intensity,
more weakly cr mere strongly than under normel conditions, and
further that different parts of the cell can undergo an unequal
formation, when the determinative conditions can not become
effective ‘n the same way in all perts of the cell,

Unce: norme] conditions, plants, possessing the ability
to form sciereids, can produce unusually thin-walled or very
thick-walled selLereids; or, stead of cells distended equally ©
on oll sides, one-sided ones may be produced etc, To be sure,
we know nothing of the causes of the stimulation here offective,
But the galis speak in favor of our hypethesis,- at times the
Cynipides gall of Quercus, in which we found developed very
aifferent kinds of sclereids, The fact has been discussed
above in detail (p. 241) that certain kinds of unequally thick-
ened sclereids as well as many other histological characteristics
furnish attributes oonstant for the separate gall forms,

Only an apparent exception to the rule here developed ~
is made by the irregular, sometines elliptical or sphericel,+
sometimes cone or ocoral-like wall-thickenings, which are
often fermed by the action of external disturbances butare
absolutely lacking in norme1 cells of the plant. speeles com-
cerned. I have already referred (Chapter III) to the fact
that these thickenings have no definite form and no charac-
teristic structure in so far that all pitting is lacking
in them, I would therefore like to assume that this kind
of wall-thickening so far as its ultimate form is concerned,
is not ‘dependent on definite capabilities of the cytoplasm,
Rather, its special qualities seem to have as littie te do
with the form of the thickenings as they have possibly with
the form of the precipitates produced in the cell by the
action of external factors. The formation of membrane accun-
ulations, coralloid oones, etc, does not in my opinion make
necessary the assumption that newly oocurring qualities of
the oytoplasm lie gt the base of their formation.

On account of the peculiar thickening of their sell
walls; (compare p. 211) the threads found in the gall of
Ustilago Treubti, which resemble capilliatia, ere very no~
ticeable. ns illustration given out by Solms-Laubach
throvis no exact light on the nature of these thickenings
nor of their production, Doubtless, we will be concerned
in their formation only with processes, of which the normal
cells are also capable,

As long as it is not possible to cause a turning green of
the cells of plents which are free from chlorophyll, of the de-
velopment of tracheids in the tissue of ceil eryptogames 50
long as stone ceils or vwood-fibres are not found in the abnorme 1
tissues of plants which are free from sclereids or stereids, -
we may hold to the assumption that in the formation of cells
under abnormal conditions, only the "normal" capacities of the
cells will come intc question and rew cuelities will never
arise, Should anyone eve¥ be so fortunate as to call forth
new qualities experimentally, he will thereby solve a phylogen-
etic question and produce a new species,

So far as i$ known at present, the varying structures of
abnormal tissues are produced hy combinations of processes. of
growth and formation, other than those made under normal condi-
tions, Just as a "piano by virtue of its construction is

a

251

capable of giving forth harmonies and discords which were not
thought of when it was made, thus an organism, by virtue of its
structure and peculiarities and the capacities conditioned by
these, is able to carry through reactions, which normelly do

not take piece, and which possibly never took place in its. pro-
geniters"’, If we wish to consider the reactions which occur
during the formation of galls etc, as ,abnormel combinations of
normal components, yet we vill not venture to compare among
themselves the individual cells, of which the normal end abnormal
tissues are composed, but must go further in our anilysis and
compare the individual partic] processes by which the cells of
the normal ond abnormel tissues are produced, If we compnre the
cells as a whole sith one another, we arrive at the conclusion
that the orgenism is able to produce something "new", But if

we keep to the individunl partial processes, ve recognize the
fact thet the "ném" quality :wes ita origin to the same pro-
esses and same qunlities of the cytoplasm as do normal elemerts,
The localization, the intensity end the combinetion of these dif-
ferent particl processes oan, however, oocur very differently,
according to the effective conditions ond can produce very d4i-
verse products,

I helfeve that the contradiction in the statements of the
authors above named may he thus explained: We will heve to
express Ourselves 2s for or against the production ef née"
elements, ccording to whether we eompare the complete cells with
one another or fix our glance on the pertin] processes by which
they sre produced,

The individual partial, processes making up the processes of
formation of the different normal cells, can thus be 80 diverse~
ly combined that literelly an unlimited nomber of cell and tis-
sue forms can be produced, I call attention again te galls, es-
pecially prosoplasmas, The examples, described ahove, will heve
given already an idea of the wealth of their tissue ferms, The
diversity in the reactions of the cells and tissues corresponds
to that in the combination of the effective factors, which like-
wise can be varied unlimitedly, ‘Je will not explain the distin-
guishable renctions existing in gall formations ete, by previous-

(293)xly fixed reaction mechanisms of which first ene and then another
is set in action, but by the varied combination af (internal and
external) factors, The manner of action of each individual fac-
ter always remains the same in the same substratum, the diversity
in the tissue products of the plant being explained by the pecul-
jar combination ef the different effective factors,

C. On the Capacity for Reaction

Almest all the processes in the living plant cell which are
of interest to us presuppose primarily a definite nutritive cén-
dition, a definite degres of temperature, accessibility to air
(oxygen) and the pressure of water. The cell becomes capxble of
ea only through the fulfilling of these prescribed céandi-

ions, !

We have already distinguished between a specific and an
accidental inability to react ~ the accidental being conditioned
by the energetic condition of the cells, the specific by the

‘ ,
ey Oa, -— ee ~~ =e = em oe _=- Fm ~ Pel rll rll rl

sit Pfeffer, Pflanzenphysiologie, 2, Aufl,, 1901, Ba, If,
Pe 6 es

(294)

° 252

unchangeable peculic: ities of their living cytoplasms, Acci-
dental inability to react occurs when, at too low or too high
temperatures, definite reactions of the plent are left out; -
specific inability to react 1s shown,by plent tissues when
acted upon by magnetism and the like’,

If we compare ameng themselves cells and tissues which
are able to react we oan easily preve that different kinds of
oolls respond to like stimuli vith unlike reactions, Either
only the intensity of the utimuletory effect is different, or
the reactions also differ from one another qualitatively, If
we compere cells of different plant specie s with one anotzer,
we muy explain this different behavior partly by the specific-
ally unlike conditions of their cytoplasms, If the cells of an
organism or of an organ display differences in their ability to
react, we may assume thet the unlike conditions, to which the
cells in the op¢ganism in correspondence with their course of de-
velopment are 6xposed, miy cause these differences, Dissimiler
conditions not only have intensely influenced the cells in the
course of their whole development, but still act upon them even

at the moment of stimulatisn and during the reaction to the
stimuli,

Bn the following, we will consider briefly the dissimiler

behavior of different plents gnd tissues towards the same kinds
of stimuli, .

When comparing lower and higher plents with one another,
eryptogams cond phanerogams, we find that in all the arresting
faotors exercise about the same kind of effect, They are, how-
ever, unequally capable of reactions consisting of abnormal
growth and abnormal tissue proliferations,

The seanty development of wound tissues in crytogams is
especially striking, Indeed, cases are not lacking in which cal-
lus tissue is produced but no such extensive formations have been
observed in them as are produced in phanerogams in the form of
callus an@ wound-woed, In thallophytes, at times in algae and
thalloid liverworts, when abnormal processes of growth are

rr ee
Ct ed ome me en eS Se SS eS

‘ Our slight knowledge of the "internal" stimuji makes it
very difficult fer us to judge of ability to react and inability
to do so. Wo will be able to trace back in many cases the
omission of a reaction to the ‘omission of some "internal" stim-
ulus, as well as tq explain them by (accidental or spe cific)
inability to do a0. A better insight is possible for us at |
present only in the cases, in which we have recognized definite
reactions aS caused by definite external factors, In many of
the following statements, only future investigations will be able
to decide, whether they ate instructive on the ability of the
cells to react, or rather on the causes of the stimulation, Also
the distinction between accidental and specific inability to re-
act can not be carried through in many cases, Hansen has shown
that many yeasts lose their ability to form spores, when brought
back into "favorable" conditions, may be cultivated further as
"asporogenic races", If continuous, sporeless "races" are &c-
tually involved, it is a case in which “accidental” ability to
react, caused by increase in temperature, becomes "specific
inability to do so, when the unfavorable life conditions are ef-
fective for any length of time,

(295)

253

called forth by injury, we find the production chiefly of normel
tissue - froliferations of various kinds, In vascular cryptogams

callus tissues are also rare, Fungi also seem very slothful to
reaction,

No instance #8 known as yet in which eryptogams have pro-
duced hyperhydric tissues, Tyloses cre rare in vasculer cryptogems

Attention should also be called to the small port played
by galls on the lower plants, Right here, however, we must re-
frain from abstract conclusions as to the cellular capacity for
reaction, since Jike m-ny others, the question hos not yet been
answered, as to how eryptogams react to the poison of gall in-
sects which produce prosoplasmas and inhabit phanerogams if this
poison is introduced ortificially in the plants,

if Goebeit, in his consideration of the formation of organs
in plants, has arrived at the conclusion that lower plants, es-
pecially fungi, are more "plastic" for malformations than are
higher plants, we can affirm in regard to the formation of tissue
that higher plants are capable of greater production. Likewise,
we find in phanerogams and especially dicotyledons the most ex-
tensive formations of tissue as well as the most abundantly and
diversely differentiated ones,

If we compare tissues of different ages with one another,
permanent tissues with young tissues, somatic with embryonic,
we find that young tissue in many cases exceeds already differ-
entiated or completely matured thssve in productive ability, but
that, on the other hand, in many other cases, the cells of the
permanent tissue have also retained their ability to react and
can. be incited to an extraordinarily lively formation of tissue.

The fact that the organisms which produce galls seek out
young parts of the host plant, in order to incite these to pel
formation, has often been treated and was mentioned above [p.<
(fhomas, Sachs ang others), However, the conditions are not at
all so simple as Sachs© essumes;~ that gail form&tions are more
abyndant and more™complicated, the younger the tissue from which
they are produced, In many cases we findthat, just as richly
adfferentiated abnormal excrescences are produced from tissue
already differentiated - and still capable of growbh - as from
the tissue of the vegetative tip, Appel (loc. cit.) has tried
to explain cases of this kind by the statement that in them the
producer of the gall is able "to bring tissue already differen-
tiated back to its original form, to make embryonic tissue from
somatic", so that in the latter instance, embryonic tissue still
produces the gall. I have already (lot. cit.) expressed my views
against this theory and have referred to the fact that the embry-
onic tissue produced from the somatic under the influence of
geall-stimulus represents in itself the young gall. With its pro-
duction is proved the ability of the differentiated tissue to pro-
duce abnormal richly differentiated gall products from itself,

In my opinion it would be absolutely unjustifieble to bring the
differentiation of the gg11 products into interdependence with

Ca ee

Organographie, 1898, Bd. 1, p. Ll,
Physiol, Notizen, VII (Flera, 1893, Bd, LXXVII, p. 240).

254

the occurrence of the absence of a gall-plastein¢, We find at
times with the same kind of cell-division, the products of

which may be called gall plastein, @ produotion of highly dif-
ferentiated galls and at times one of simple, homogeneous tis-

Sue excrescenees, The quality of the stimulus is the decisive
factor,

I again call attention here to the bark gall of Chermas
fagi, described by Hartig, which is likewise produced by obun-~
unt tangential cell-divisions, as 180 the richly differentic-
ted Banisteria gall, illustrated in Figure 93. The.forrer
arises portly from bark tissue which is several yerrs ald ond
thus furnishes proof that even mature tissue is still fit to
produce grills. At any rate the Chermes gall here mentioned con-
Sists of the simplest, undifferentiated tissue, corresponding
histologically to the onllus excrescences produced ofter injury.

It must also be emphasized here, that gall formations are
but little suited for a treatment of the question es to the ~
distinct capacity of young and old tissues for reaction, sincé,
for the present, in a decision ag to the possibilities of the
plant, we are dependent upon material present in nature end
since no experimental treatment of the question has yet been
successful, Sinead the gall'insects always deposit their virus
in the same kind of tissues, we can not find out how other tis-
sues would act under similer treatment, i. e, after infection

(296) with the same poisons, The existence of any difference in prin-
ciple between tissues of different ages, so far as their behev-
for toward chemical substances 18 concerned, is but little
probable, since the cells even of permanent tissue several years
eld, like those of young tissue mterinil,can be incited to aim-

ilar or the same reaction to stimuli, by very different ©
stimali ef some other kind,

Often cells ef the permanent tissue cre inoited to abnormal
growth ana division by injury - instances of which are furnished
by tyloses, and callus excrescences of the bark and pith. I
may also call attention here to gdventitious sprouts produced »
after injurv en mature Begonia leaves, The abijity to "restituée"
tissue which has been lost by mutilation is pessessed particular -
ly by young tissues (compare chapter 1).

Kny has recently proved in Impatiens and others thet the
cells of the permanent tissue can also be incited to division
by mechanical factors.

We find that hyperhydric phenomena of growth, occu# in
young bark cells aS Well as in those which are several years
oja. (Compare Chapter IV, 3).

-—_— we
Li i oe ee? rc a a aon

crumpling of the leaves, ormomyia species, en the contrery,
structures of comparatively high differentiation, oth stimull
however, act in the same period, if not exactly at the same time;
i. @, at the time of leaf distension, The difference censiste

in this, thet the stimulus of the leaf jice encounters in this
case mature tissue, which can not be transfermed into one ‘re-
sembling plastein, the stimulus ef the Hormemyga, however, is
able to degelep embryonic tissue, from which pew tissue struc~
tures oan he differentiated, (loc. git.).

a

teo7)

: EDO
There remains finally a comparative consideration of the
fate of the different tissue forms,- epidermis, ground tissue,
vascular*bundle tissue, In this we vill limit ourselves to
vascular plants. The above-said holds pood so far as the util-
ization of galls in general conclusions is concerned.

1. Epidermis

The epidermis proves itself in general pretty resistant to
arresting influences. In oultiures in the dark, in moist pleces
etc, its composition of histologically different eiements re-
mains approximately normal, Tobe suré pubescence is more oF
less reduced in the cultures mentioned, but the stomata are el-
most always retiined, Gauchery proved in dwarfed plants, that
the size of the epidermal cells remains normal in elmost cll of
the speeles investigated,

The epidermis is easily susceptible to favorable influences.
It ts possible, under very different kinds of cultural conditions
to produce abnormally lerge epidermal cells, In cultures in
moist places, ofter infection by fungi eto,, we find a produc-
tion of abnormilly large epidermel cellsp- even the guard cells
can attain an abnormal size (fig. 16), Gallus hypertrophy of
the epidermal cells, of which the guard cells ere slso capable,
is illustrated in figure 28, Instanaes my also be found among
intumesoenoes in which the epidermol cells have become abnor~
mally enlarged (Pig, 22), Especieljy interesting is the fate
of the epidermel oells, whioh ere incited by gall mites to hy-
pertrophic growth, growing out to extensive, almost always uni-
cellulcr phuches differently formed, (Figs, 38, 40).

When considering abnormel cell-division in the epidermis,
we must distinguish between divisions perpéndicular to the
upper surface of the plant organ concerned, and those parallel
to this surface, ;

In the produstion of many galls, we find that extensive
exoresoences arise by outgrowth of the ground tissues which are
sovered on all sides by epidermis, In this caso, the epidermis
follows the growth ef the gall-structare by repeated division
perpendicular. to the upper surface of the organ, It can not be
stated definitely, whether the cells are incited to the pro-
cesses of division only by passive distention or by the gell
poison, That the epidermal cells are actually acted upon by the
goll poison, hovever, and infituenced by it, 1s proved by the oby
ak hairs which often grow out of its cells et the infected
spots~.

Division parallel to the upper surface is rare, Only ine
few golis do we find a many Jeyered epidermis formed from the
normal one-layered one (Spathegaster baccarum, Nematus ete.).
Compare figures 98 and $9), and in some Invumescences (see above).
But even where cross-division does take place in the epidermal
cells, it. occurs less frequentiy than in the grovnd tissue cells _
belonging to it, ‘The same holds good in the dovelopment of sil

1 in many oases, the epidermis 48 not able to follow the

pene eared the internal tissues by ne uae e call
attention to the gall of Hermonvia piligera (fig, 8 6
Jaoquinia gail (fig,101) Sid Hany Invumoscences (fig, 20).

256

tively to cross division, has not yet been obgervedt,

* It is possible that in the Marchantiaceae also a
Similar difference exists hetween the “epidermis” end the
renaining tigsue, ag in the described higher plants. Ao-
sording to Vochting* the "epddermis" in contrast to other
tissue forms remains inactive in regenerative phenomena,
Ruge” observed Budding from the epidermis,

2 Ground Tissue

‘The ground tissue - the ogsimiletory as well as the moohon-
sen to name its two most important forms - 18 especiolly
9) ostio.

Arvesting influences of very different kinda are sble to

* BUPprossHh more or less completely ell processes of differentia-

(298)

tion, to decrease the normal oe11 number ond to prevent the full
maturing of the indicidual cells (size, development, thickening
of the membrane, formation of ohlorophyll eto,), The oells of
the ground tissue are shown to be in every way extraordinarily
susoeptible,

Favorable influences call forth in it hyperhydris, oallus
or gall hypértrophies in whieh, the cells of the grouad tissue
ean grow out into greet pouches and vesicles, So far as its
eopacityfor cell division 1s concerned, the wound tissue is
greatly superior to, the epidermis, Gails espesially demonstrate
that the cells of the mesophyll, of the bark eta. are aapeble
of extensive division in ell direc tions, the products of which
can undergo most diverse differentiation, The ground tissue
also participates greatly in the formation of callus tissues and
is constantly livelier in its actioncothan is the epidermis,

~
_— mmm hemp mmm make mcm mt em

UVeb. @. Regeneration d. Marchantiaceen, Pringshein's
Jahrb, f. wiss, Bot, 1885, Bd. XVI, p. 367,

Beitr, z, Kenntnis der Vegetationsergane der Lebermoose,
Flora 1893, Ba, IXXVII, p. 279.

, 257
3. Vaseular-bundle Tissue.

; The same plasticity exists in vascular bundle tissue, as
.in ground tissue,

To_arresting influences of very different kinds, the plant
reacts especially by the production of abnormally narrow ducts.
It is known that under the action of continued and powerful dis-
turbance, the normal composition of the xylem is lost, the libri-
form fibres disappear, ultimately the ducts also, resulting in a
severe attack, in a completel homogeneous, parenchymatie tis-

sue (callus tissue ~gall wood). The phloem experiences a simi-
lar hypoplasia.

; Favorable influences call forth abnormally large cells. We
find that the bark grows out to hyperhydric tissues through the
hypertrophy of its different elements, the wood-parenchyma cells
form tyloses ete. or very extensive excrescences in the form of
callus, wound-wood or galls are produced. In all essential
points, the same holds good for this as for ground tissue.

Of the different parts of the cambium layer, that formed
from the embryonic tissue, the cambium itself, if always capable
of accomplishing the most. Yet even the tissue of the phioen,
as shown above, cm grow out into extensive callus rob or fur-
nish large galls, rich in cells. The smallest part in the pro-
duction of abnormal tissues is performed by the xylem, of waich
in fact the elements are mostly dead or lignified. Attention has
already been called to tyloses. All other phenomena, known in
the elements of the woody-part, play only a subordinate role.

If, after these brief discussions, we condider once more
the different cell tissue forms arising during abnormal growth,
(299) it. may be affirmed, that the derivatives of very different kinds
of tissues can assume very diverse forms. In the formation sf
galls true epidermis, bearing trichomes, can be produced from the
mesophyll (compare for example, fig. 87), nighty sclereid con-
plesas can be derived from the delicately walled mesophyll (fig.
90), true epidermis and typical ground tissue with stone cells
can develop from mascular bundle tissue etc. in the fornation of
galls. - In the fornation of callus, we find the production of
derivatives of the pith, the secondary bark etc. and of tracheids
etc. in short, from each tissue all can be formed, the course of
their development is determined by the sum of all the factors
acting on then. We find callus developing from the pith of
wounded sprouts and the production in it of the same tracheal eleé
nents which under normal conditions are net with only in the xyler
If in the interior of the normally developed shoot a cylinder of
ground tissue is developed, instead of vascular bundle tissue —
containing tracheids, it is not due to any inherent peculiarities
of the cells lying centrally, but is the result of all (internal
and external) factors which have been active during the whole
developnental period. Further, not only the cells of the derna-
toeen can develop "typical" epidermis bearing trichones, but also;
as proved by galls,- all other tissue forms. Further, the "nor-
nal" naturing of the ground tissue into assinilatory, palisade
parenchyma, ete. is not a result of its specific constitution,
which would pernit of anly one developmental course, but is con-
ditioned by the factors, to the action of which the self-develop-
ing ground tissue is subjected under normal conditions. The fact
that we always find the sane tissues in the sane order, in nor-
nally developed organs, proves nothing further than that in.
then the decisive agtive factors always come to expression in
the same Way.

(300)

t 256

Although all pessible kinds of tissue can be produced from
each kind, yet according to the presont extent of our knowledge,
2 diffetente still exists betwenn the chief tissue forms in so
re that the epidermis, as already stated, reacts with greater

fficulty than the other forms of tissue and usually furnishes
ao numerous products during processes of @ivision, while its
faye es do not seem capable of so extensive a differentias,
. Ae as do those of ground tissue or of vascular bundle tissue”.

et that the cells of the epidermis are able to produce all tis-
sue forms from themselves, has been proved by the cdventitious
Sprouts of Tegonia leaves - to neme only one example, These ere
known to develop fron epidermal celis,

Therefore in plants, no such"specifioness of the tissue"
exists os is usucl in onimal and human tissnes, Do we find here
a differenoe in prinoiple between animel ond vegetable tissues,
or is the difference explained perheps by the fact thet the
Course of development of the anim.l tissues is determined chief-
ly by "internel” factors and is not so actively influenced by a
chenge of “external” faotors, with which we work in any experi-
ment, 2s is the course of development of vegetable tissue?

The knowledge that similar derivatives can be produced &t°
different places, i, 6, from different parts of the plant body,
that, therefore, the capacities of the different plant tissues
are fundamentally ond everywhere the same forces as to the cdn-
glusion that, under norm1 as under abnormal conditions, the
developmental fate of the cells and tissues in the last in-
Stance (within the possibilities of the plant) are determined
only by the forces acting upon them, by the quality, intensity
and combin-tion etc, of these, From this point, we are led at
once to nev; tasks and new discussions, When, in the formation
of callus from pith and bark, or of galls from the derivatives
of the ground tissue etc, the same vascular bundle elements ere
produced which usually in a normal course of tissue development
Occur in a circle around the medullary cylinder or among the
cell elements furnished from the cambium, the question must be
asked,~ after we have recognized as impossible any specific
cell-constitution,- whether, in the cases of normel end abnorre1
cell production here named, the same farmative processes may ol-
ways ib the last instance be traced to the action of the same
factors, We must ask ourselves the same question, when the de-
rivatives of the ground tissue and of the vascular bundle tissue
grow out to just such epidermal cells ond hairs as the elements
of the dermatogen under normal conditions, The treatment of this
and all similar questions which might lead to a developmental
mechanics of plent tissues, has never been attempted as yet. It
has already, however, become quite evident that no unsurmountable
hinderances stand in the way of carrying out this treatment and

eny valuable results may be expected from it, I mean to dis-
cuss latar in another connection the incentives to a treatment
of developmental mechanical problems (here indicated) which the
pathologival anatomy of plents and especially the anatomy of
galls, can give,

1 T% should be noted here that the galls, to which we must
refer first of all, have been by no means sufficiently investi-
gated frbm histological and developmental points of vidw, Thus,
for instance, developmental reports on the cbundant gall-flora
of North America are practically entirely lacking - the galls of
Southern Europe have been investigated, at least predominantly
as to their habitats and their most striking morphological pécul-
iarities.- Perhaps I will succeed in inciting by these lines),
nev; developmental studies, which, it must be stated, are urgent-
ly desired,

Remarks3

The German floral and animal (faunal) names

are not given in the following index; also,
with a few exceptions, only the generic names
are givens Statements as to normal histologic-
al conditions have not been taken into con-
sideration in the index,

Numerals refer to those in upper left hand cor
ner of page. Marginal numerals in text refer
to pages of German originals

Abies, 75, 96, 159ff, 166, 184, 188,

Abnormal,.Explanation of the term lk.

Acacia, 81, 188.

Acer, 74, 106ff, 147, 164, 192ff.

Acerineae, Rare.formation.of tyloses, 96+

Achyranthes, 96, 162,

Acmena, 166.

Aconitum, 135.

Acraspis, 209ff, Ae macropterae. fige 106.

Activity-Heteroplasia, 137. :

Activity-Hyperplasia of the mechanical and conductive
tissues. 128.

Adventitious Sprouts and Adventitious Roots from the
callus, 154, and without the intermediation of
the callus, 155. In Thallophytes after injury,
252. In liverworts, 256, From epidermal -
cells, 256. After infection by fungi (witches
brooms) 18%. And plant lice (Stag neads} 189%

Aecidium, 30, 17%, As elatinum 188, A. Englerianum 182,
As Rhamni, 182. ‘

Aerenchyma, 73, 80ff.

ASrating Tissue in galls, 219ff.

Aesculus, 17, %75, 96, 160.

Agaricus, 179, 184.

Agave, 8c : ;
Age of Tissue, Influence on abnormal tissue production,
253.6 e

Ageratum, 162.

Agolaospora, 185.

Ailanthus, 166+

Air Chambers, Filled with tyloses, 100.

Albinos, 36.

Algae, Restitution, cf. Siphoneae, Rhodophyceae, Phae~
ophiceae; Chlorophyll formation in the dark,
34, Hypoplasia, 40 ete. Callus, 140, Galle:
producing algae 177, Gall-bearing algae, 116,
177, 178, Involution forms, 116.

Alliaria, 47.

Allium, 90.5

Alnus, 74, 96, 1l06ff., 160, 188.

Aloé, 8s : i

Alpine Climate, Influence on the formation of tissues,
49, Hypoplasia, 20, 45, 49, 56«¢ Formation of.
anthocyanin, 566 : j

Alternanthera, 35+

Amitosis, Through budding, 119ff, In callus, 150+

Ampelopsis, 35, 74, 85, 95, 96«

Amygdalus, 1546

Anabaena, 110. a
Anacardiaceae, Tendency to formation of tyloses, 96.
Anadyomene, 10, 12,

Anatrobic Bacteria, Spore formation, 238s

Anaesthetica, Arresting influence on cell division, 68.

Andricus, 206, 220ff., A. quadrilineatus, figs 100.

Anherstiee, 214, :

Anemone, 27.

Annual Plants, Transformation to perennials througn

copulation, 133,

Annual Ring, Abnormal; Half rings, 2ls After infec-
tion, 22. Restitution from too strong pres-
sure, 22. Abnormal wood, cf. Red wood and
Gall wood, :

Anthers, Hypoplasia, 47.

Anthocerotaceae, 109s

Anthocyanin, Abnormal omission of its formation, 35ff.
Abnormal occurrence of its formation, 56ff. In-
fluence of light, 35, 56, 222. Of nutrition,
56, 56, 57, 58. Of injury 35, Of temperature
562 In galls, 566 In graft hybrids 56+ Pre-
mature ripening 56, In callus 150, In
Synchytrium galls 103. In other gall hyper-
triphies 107ff. In prosoplasmatic galls,222.

Anthurium, 100.

Anthirrhinum, 366

Antithamnion, 67.

Ants,115.

Aphids, Their excretions, 60. Honey dew 60. Lignifica-
tion, due to aphids 62. Kataplasmas 197ff. Sac
galls (prosoplasmas) 192. Cf. Schizoneura,
Tetraneura, Aphis, Pemphigus, Lachmuse

Aphis, Oxyacanthae 181, Fig. 75.

Apical Cell, Abnormaily enlarged 67.

Apical Growth, Vells with 112.

Apterostigma 115,

Aralia 75, 82, 96.6

Araucaria 75.6

Arctic Climate, Influence; Hypoplasia 20, 45, 56. Forma-
tion of anthocyanin 56.6 :

Aristolochia 16, 95ff., 127.

Aristolochiaceae, Abundant formation of tyloses, 95ff.

Armoracia 150.

Arrested Developments 17ff.

Artemisia, 220.

Artocarpareae, Tendency to formation of tyloses 966

Artocarpus 966

Arundo 43, 96s

Asarum 95ff., 966

Ascomycetes, Gall Producing 177s

Ascophyllum 178,

Aspergillus 115.

Aspidiotus 34.

Aspidium 188.

Asplenium 43.

Asporgenous Genera 241, 2526

Assimilatory Tissue. Correlative promotion of its devel-
opment 135. In abnormal Cucurbita root tubers
139. In galls 218 Cf. Mesophyll.

Asterodiaspis 62. :

Atta 115.

Aulacodiscus 28.

Aulax 195ff., 218.

Aurigo 82,

Axillary Sproutse Transformation to swellings, 158, 166.5

Azolla 56, 109. :

A

Bacteria, Arrestment of pigment formation 36, Abnormal
size 69, Involution forms 116ff., Gall pro-

ducing bacteria 177, 185, In mworine algae 140.
Bacterium 68, 117.

Bac teriods 116:
Bactridium 115,
Bambusa. 42,
Banisteria 96, 199ff.
Barbarea 178,
Bark Excrescences 7%.
Bark Formation in Galls 207,

ae Hypoplasia, Reduction of the cell number 20,

“ Hypertrophy of the bark cells ("Bark excres-
cences": 77, (Intumercences)81ff., Par-
ticipation in the callus 142, Callus hypere
trophy 88, Wound wood 163, Abnormal bark in
kataplasmas 185, Cf. also. Wound Bark and
Gall Bark.

Bark Tubers of the Beech 166.

Basidiobolus 121, 125.

Basidiomycetes, Spore formation 94, Gall producing 177.

Bassorah galls 221,

Bastard, of a (Desmidiacea?) 23, Che graft hybrids.

Bead Glands of the Ampelidaceae "85.

Beech Tree Louse, Cf. Lachnus exsiccatore

Beech Wool Louse, Cf. Charmes fagis

Begonia 56, 96, 100, 155, 200.

Berberis 177, 188. : é

Beta 119, 129, 160, 169.

Betula 96, LOSE E.,. 148, 188.

Bidens 13.

Bigonia 96.

Biorrhiza 196, Be, aptera, Figs 89.

Bladder (Vésicle) Calls, -on Viburnum Lantana 111, 197.

Blasia 109.

Blastomeres, Mul ti-nuclear 69»

Blechnum 9.

Blood Louse 120, 179, 183ff.

Boehmeria 96.

Bois rouge (Red Wood) 1306.

Bordeaux Mixture, Influence on the formation of Chlot-
ophyll 56.

Borragineae, Hairs poor in calcium 38.

Botrydium 10,

Brachycome 36.6

Brassica 32, 127, 130, 138, 147, 176, 187.

Broussone tia 74, 13960

Bryonia 10, 13, ’ e

Srycenyiee. Cell restitution 9, Hypoplasia 40, Gail
pearing 179, -

Bryopsis 6, 10, 11, 156.

Bryun 400 .

Burrows, Filled with callus 147.

Buxus 75+

Cabbage Weevil 187.

Cacoma 177, 188.

Cale} cats Necessity of Calcium 44.

atte foten a

Calluna BG»

Callus (seatr, 139, External form 141, Origin
42, Lee " histpey 1453, Histology ae “Ore
itjons of formation 150, Rlarjty fr«

gan faymation jn callus 154; dalaus sh

eryptogams 440, In herbaceous plant 142,

"Knarial in cally 161, Woynd cork in callus
ieee, lus in “gadis 168.

2 r

on

Callus formation, In general 5, Of. Gallus (sistr.),
7 Wound wood and Wound Cork,
Callus Heteroplasia 137, Cf, Callus, Wound Wood,
Wound Cork;
Callus Homeoplasia, 135.
Calyptospora 177,
Cambium, Producing callus 143ff., Galla 1Sl, 20L,
Cell division, Ct. Callus and Wound Wood,
Cessation of its activity 20, Cf. also
Secondary Tissues,
Camellia 82, 96, 150.
Canker, Production of wound wood 162eff., Of gall wood
LS2tF «
Canna 19, 93, 96.
Capillitium in the gall of Ustilage Treubii 191, 250.
Caragana 157,
Carbon dioxid, Influence of air free from carbon
ioe and of air containing carbon dioxid.
a)
Carbon dioxid fissures, In galls 220,
Cardamine 45, 50, 128,
Carica 964 . :
Carnosity 85, 87,
Carotin, ("Eiiolin") in etiolated plants 33.
Carya 96;
Cassia 8l.
Castanea 75, 96, 120.
Catalpa 74ff. ; 96-<
Cattleya 82, 89, 90.
Caulerpa 10, : r
Cecidia, Cf. Galls.
Cecidomyia 17, 152, 192ff..
C. Cerris, Figs i04, 108.
C, tiliacea, Fig. 96, 108, 112.
Cedrus 75,
Cell Division, Abnormal processes in cell division 31,
68, Abnormal direction 125, Cf. Hyperplasia.
Cell Fusion, Arrestment of 30+
Cell Size, Under normal and abnormal conditions 24ff.,
Relation to cell number 136, Cf. Hypertrophy.
Cell Wall, New formation after plasmolysis and cell
injury 7ff., Arrestment of growth in thickness
28, Fauity development of the etching 28,
Incomplete cell wall formation in cell divi-
sion 29, 30, Abnormal thickenings 59, 88,
112, 249, 250, Abnormal surface growth 248,
Abnormal chemical composition 62, 226.6
Celtis 96+
Cephalotus 100.
Cerasterias 117.
Cerasus 75.6
Ceratopteris Ge
Ceutorrhynchus 187.
Chaetophora Ve
Chemical Action 258ff.
Chermes fogi, 1i87ff., 200, Figs 79.
Chichi, of the Kinkgo 167.
Chilaspis 217.
Chiliantus 96+

eS

Ts
®

.

Chlorophy11, Arrested Form ;ion Siff., Dersndence on tem-~-
# perature 51, Nutrition 32, Light and iron 32,
Independence on light 33, Plants lacking chloro-
phyll (apochlorotic) 33, Abrormal formation
in roots, rhyzomes, ete. 55, 139, In -uninter-
rupted illwiination 55, In gall hypertrophies
LO7ff., In callus 148, In prosoplasmas 205,
Regression with over-nutrition oo, Under the 2n-
fluence of oxydizing cuzymes 53, In metaplasia
59, In hypertrophy 79ff., In isolated plant cells
90, In galls 107, 180, Cf, Chloroplests.
Chloroplasts (Chlorophyll grains) Capacity for regenera-
tion 13, Influence of pois’ons on their increase
55, Correlayu’ve increase 134, Abnormally small
Chloroplasts 34, 91, 148, Behavior after in-
fection 34, With autumnal coloration 34, Cf.
Chlorophyll,
Chlorops 111.
Chlorosis, Especially that of the grape vine 33.
Chlorothecium 117. j
Chromatophores, Hypoplasia in the Flagellates and Diatoms
53, Cf, Chlorophyll and Chloroplasts.
Chromogeriic Bacteria, Becoming colorless 36,
Chrysanthemum 19.
Chytridium 67.
Cicatrigation, Cf. Wound Healing.
Cicattization Membrane, .Cf. Restitution Membrane, :
Cioatrization Tissue, Cf, Callus Tissue, Wourd Wood, Wound
Cork and Restitution of the Tissues.
Circaea 119,
Cissus 85.
Citrus 34,
Cladophora 9.
Ciadostephus 67.
Cladrastis 96.
Cleistogamic blossoms, Hypoplasia 48.
Clematis 182.
Closing Tissue in Galls 213.
Clos’ terium 9.
Club Root of Cabbage (Kohlhernie) (Kropf-, Warzelkropf-,
disease) 176.
Club Root Galls, 120, 176.
Cobalt, Action on isolated cells 92.
Coccoloba 96,
Coccomyxa 113.
Coccus 62, 179.
Codium 10, 27.
Coleoptera, Producing kataplasmas 179, prosoplasmas 190.
Coleus 35, 96, 119, 162. _ . .
Collenchyma, Participation in callus by Hypertrophy 89.
Conferva 9.
Conifers, Activity Hyperplasia, Redwood 150, Waved grain
. wood 160, Leaf excrescences 180, Abnormal resin
canals, Cf, Resin canals.
Conocephalys 83,
Contagium vivum fluidum 33,
Convolvulus 96,
Copepods, Gall producing 179.
Copper Salts 83.
Coprinus 15.
Coriaria 74,

=6-
Cork Excrescences 170.

Cork Sickness in Ribes 169.

Cork, Weak development on the shady side of branches 21,
Abnormally large cells V7, In galls 265, Crs
also Wound Cork.

Cornus 964,

Corylus 74, 129, 150, 154, 178,

Corypha 96,

Cosmarium 9,

Cotyledons, Callus 147ff., Wound Wood 163,

Crassula fetta, 10

Crassulaceae, Anthocyan in content 56.

Crataegus 30, 44, 74, 109, 179f?,

Crown Gall 120.

Crucifera, Galls of Phasmodiophora 176, Pineapple galls
178, Ceutorrhynchus galls 187.

Crystals, Hypoplasia 37, In etiotated plants 37, In
callus 150, In gall hypertrophies 111, In
prosoplasmatic galls 221, In gall bearing or-
gans o7, Dole

Cucumis 96, 119.

Cucurbita 6, 10, 13, Oo, 94iTs, 130, 139, 250.

Cucurbitaceae, Tendency to tylose formation 96.

Cupressus 75, 166.

Cuspidaria 95ff,

Cuticula, Regeneration 8, Abnormally thick 62, Ab-
normally thin 28, After injury 62, Cuticula of
the galls 205.

Cuticular Epithelium 206.

Cyanophyceae, Symbiosis with higher plants 1ooff.

Cyathea 97,

Cycadeae, Symbiosis with Anabaena 110.

Cydonia, 74, 160ff.

Cylindrical Gnarl of the Ginkgo, 167.

Cymbidium 59, 8&2.

Cynipides 125ff., 190ff,

Cynips polycera 124, Fig, 55, C. aries 124, Fig. 55, C.
Fernimatis 195, Fig. 84, C. Magri, Fig. 109,
C. tinctoria, Fig. 116, C. strobil ana., Fig. 116,
C,. Kollori, Fig. 118. ,

Cyphomyrmex 115.

Cypripedium 82, .

Cystoliths, Hypoplasia 37, Without calcium 38, Cysto-
lith-like thickenings, Cf. Lignin bodies.

Cystisus, 88.

Cystopus 30,

Cystoseir 177.

Cytological 4, 27, 31, 119, 150, 223,

Cytoplasm, Regeneration of the mutilated cytoplasmatic
body 146

Dahlia 96, 133,

Daphne 44, 74.

Basyscypha 177.

Daucus 119
Defoliation, Influence on blossom coloration 26, On the

formation of the assimilatory tissue in the
trunk 135-6

Defoliation, Tylose Formation 100, Wound cork afterrde-
foliation 170, Zone of separation 170, Pre-
mature defoliation 170.

Degeneration, Slimy, gunny, vacuolated, fatty, cellulose
peor tL ¢ '

ie

Delesseria 140.
Dematium 126,
Dendrophagus 120,
Derbesia 10.
Nesmidiaceae, No cell restitution after plasmolysis 9,
Dwarfs, "Bastard" 23,
Desmidium 9.
Developmental Mechanics 5, 231.
Dianthus 8lff, a
Diastrophus 209, D. Potentillae, Fig. 105,
Diatoms. No cell restitution after plasmolysis 3,
Hypoplasia 28, 29, Colorless diatoms 33, Form-
ing Colonies 39, Involution forms 11%, .
Dicotyledons, Capacity-for cell restitution 9, Abundant
development of cell and other hyperplastic tis-
sues 252.
Dictyostelium 3%,
Diervilla 74,
Differentiation, Hypoplastic 26, Of the celle 26, Of
the tissues 38, Differentiation of hypoplastic
tissue products 257, For Differentiztion of
gall tissues, Cf. Kataplasmas and Prosoplasmase
Diffusion Currents, Abriormal 241.
Digitalis 36, ‘
Diospyros 96
Diplonasty 130. ‘
Diplosis 197ff,., De botulatia, Fige 91, 108, 1210. De
Slobuli, Fig. 108» é : Ps
Diptera, Burrows 147, Kataplasmas 178, Prosoplasmas 190,
192ff
Draba 102.
Drepanophyllum 7.
Dropsy, Cf. Chlorosise ;
Dropsy. , Dropsi¢al organs, Cf. Hyperhydric TissueGe
Drought,-Arresting influence of 21.
Drymo glossum 9s
Dryophanta 211ff., D. Taschenbergi, Figs 85+ ;
Duc ts » Reducation in sige 25, occurrences in galis
205, Uniignified 30, Cf. Tracheids.
Ducts Tyloses 93. ‘
Dwarf Specimens of Fvastrum 23, Of Protozoa 55, Cf.
Nanisms :
Ebenaceae, Rare Forrs.tion of tyloses 96s
Echeveria. 3,
Echinoderm Eggs 69.
Ectocarpus 177.6
Hichhornia 91.
Elaeagnus 97.
Elodea 9, 12.
Enation 127ffe«
Endophyllum 71.
Enlargement of the Cell 247, Hypoplasia 23ff., Cle
Hypertrophy» "
Epidendron 59. ue
Epidermis, Regeneration 15, 16, Hypoplasia: Reduc tion
of the cell number 20, of the cell size 24, in
dwarf specimens 24, Arrestment in tissue differ-
entiation 41ff., Abnormally large cells on
etiolated plants 69, In kataplasmas 181, Pare .
ticipation in abnormal tissue formation 255, On
intumescences 82ff., on the formation of wopnd
cork 167, Callus hypertrophy 90, Hypertrophies
resembling tyloses 100, Gall hypertrophies 101,
Participation in callus 146, In prosoplasmatic _
galls 202, In kataplasmatic galls 181, Bpidermiv'
of galls 205. d

r
o- ,

Epilobium 80, 82.

Epinasty 31,

Erineum Formation 103, 78 ,. 1974

Eriophyes 194, E, similis. Fig. 85.

Eriopus 7. ;

Erysipheae, Haustorium 94.

Etiolated Plants, Hypoplasia 17, 33, 36, 43, Abnorval-

ly large cells 69.

Euastrum 9, 23.

Eucalyptus. S1ff., 151, 139, 166.

Buglena 34.

Eupatorium 73,

Euphorbia 72, 97.

Evonymus, 162ff.

Exanthceme 'Unger} 104.

Exoascus 177.

Exobasidium 30, 177ff.

Fagus 17, 18ff., eo, OF, 106iTs, 131, Te4ifs

Fasciated Branches 164.

Fasciation 164,

Ficus 23, 24, 38, 74, 81, 95ff., 100.

Flagellates, "Colorless 34,

Floating Leaves 42.

Florideae Starch 141.

Foreign Bodies, Cellulose sheath about 60.

Formation of new Cell Walls after Plasmolysis 8&8.

Formative Stimuli 229,

For sythia 154.6

Fragaria 193,

Fraxinus 74, 97, 129, 178ff., 197.

Frost, Sensitiveness to Frost 157, 163, Frost canker ,
Frost wedges , Frost cracks 163.

Fruit Spikes on fruit.trees, Faulty lignification 60,
Abnormally abundant parenchyma contents 164.

Fuchsia 150.

Fucus 140.

Fungal Gardens of the Ants 115.

Fungal Hyphae, Encased by cellulose. 60.

Funaria 9, lle ©

Fungi, Producing galls, Cf. Galls, Gall bearing 179.

Furcellaria 141.

Galium 1936

Gall Bark 210.

Gall-bearing plants 175, 179,

Galis, Gall formation 5, 170ff., Definition 171, Hist-
ory 174, Morphology 172, 191, Symmetrical pro-
portions 197, Development 191ff, Histology 172ff.,
Aetiology 173, Gall poison 173ff., 251, “Ar-'
tificial" galls 174, Classification of galls;
172, Kataplasmas 176, 212, Prosoplasmas 189,
Free and enclosed galis 194, 195, Inner and
outer galls 195, Protective tissue of galls
205ff., Nutritive tissue 214ff., Assimilatory
tissue 217, Conductive tissue 218, Atrating
tissue 218ff., Secretion reservoirs
etce22u2 Galls compared with tumors 202,
Cytology 225ff.

Gall Heteroplasia 107.

Gall Hypertrophy 101, 197.

“9
Gall Plastem 193ff., 254,
Gall Broducers, Phytocecidiae (Mycocecideae) 176ff., 179ff.,

1254 185, 188, 189, Zoocecidiae 178ff., 181,.184,
187, 190. :

Gall Wood. LSSft a, 212.
Gasteria 176,
Geranium 199.
Geum. 10S,
Giant cells, Multi-nuclear 118,
Gigantic growth 126,
Ginkeo 17, 5, 978, 26%,
Glechoma 17, i738, 192.
Gleditschia.74, 97.
Gnarls, Tuberlike 1656
Gnarl Structure 159ff.
Gnarl Tubers (Gnarl balla) 139, 165ff, Produced by Cynip-
ides 212, Z
Gomphonema 29,
Graft Hybrids 33, 47, 58.
Grain Growth in Wood. 159ff.
Gramineae, Mite falls 105ff.
Ground Tissue , .Hypoplaséa 41ff, Callus hypertrophy 89ff,
Intumescences soft , Tyloses: in secretion reservoire
and breathing holes gofr, Gall hypertrophy 110,
Participation in abnormal tissue formation 256, -In
Callus 145, In galls 180, 201, In correlation
he teroplasmas 138, Of, Mesophyll, Bark, Pitis
Growth, Abnormal 63, “Dimensional 66, Growth in masses 66,
Correlative growth 128, 207, Infiltration and
infection growth 203, .Abnormal growth of the epider-
mis in thickness and. surface, Cf, Cell Wall: further,
Hypertrophy.
Grumaria 104,
Guard Cells, Abnormally large ws Callus hypertropky 90,
On galls 219.
Gumming 225, Cf. Wound Gum.
Gymnograms 9.
Gymnosporangium 177, 183ff. E56 ‘ er ere
eration9g.; Hypoplasia: Reducation o er
ae tee Be ecace of eo makes of hairs 43; Hairs of
galls 207; Abnorma} hairs 190, Cf, Erineum Formation;
Hair Formation on peduncles of unfertilized bios-
soms 136.
Halichondsia 28.
Halimeda 9.
Hamamelis 94,
Heart Wood, Tyloses 98.
Hedera 74,.82, 97, 133,
Hadychium. 97,.
Helianthus 7, 129, 138ff.
Heliconia a7 :
ry. Fr]
errno Producing kataplasmas ee sie Prosoplagms pie
Cf. Aphida.
Heterodera 119, 177.
He teromorphosis 64
Heteroplasia 124, 156.
Hibiscus 82, 150, 1694
Homoeoplasia 124fL.
Hormidium 126. 2
Hormomyia 131, 194ff, He fagi phy Figs 58, 86, 105, He pile
igera, Fig. 82a = -

-

°

Humulus 97.

Hydathodes in Conocephalus 34,

Hymenomycetes, Hypoplasia 40,

Hymenoptera, Producing prosoplasmas 178, Cf. Nematus and
Cynipides.

Hyperhydric Tissue 72, Lenticels 73, Bark 7, Inta-
mescences 60, Abnormal Succyulence 86, Abnormal
wood of dropsical branches 164, Hyperhydric
tissue in succulents, 176.

Hypericum 99, é

Hyperplasia 122, Cf. Homoeoplasia, Heteroplasia, Korre-
lation, Heteroplasmas, Callus, Wound Wood,
Wound Cork and Galls»

Hyperplasia due to work, Cf. Activity hyperplasia.

Hypertrophy 3, 63ff., Kataplastic 65, Prosoplastic 65,
Cf. Callus Hypertrophy and Gall Hypertrophye.

Hypoderm, Arrestment of tissue differentiation 41, 188.

Hyponasty 131.

Hypoplasia 17, 188, Reduction of cell number 18, of
cell size 22, Arrestment of cell and. tissue
differentiation 26, Cfe Korrelation hyperpla-
Slae .

Icterus, Cf. Chlorosis.e

Iles 170.

Impatiens 135.

Inactivity hypoplasia 52.

Inanition Phenomena 225-6

Inner Gall 210. ;

Intumescences 80, Formation of Wood cork 169.

Inula 97.

Involution Forms, In bacteria 116, 243, 247, In algae,

fungus spores, et¢ce, 117. -

Ipombea 43, 82,

Iresine 58,

Iris 48,

Iron, Influence on cHlorophyil formation 35.

Isolated cells, Behavior in nutrient solutions, etc., 90,

92.4 ‘ :

Jacquinia 206.

Jasminum 74+

Jatropha 97.

Juglandaceae, Tendency to form tyloses 965

Juglarge 74, 97, 120, 202.

Junipe.us 177,.183ff,.

Juvenile Forms in Regeneration 6+

Karyogamy 69. ~

Kataplasia 65-6

Kataplasmas 125ff., 136ff., 176ffe

Kataplastic Hypertrophy 88, 118.

Kerria 336 P ;

Knarls, In wound wood 159ff., In gall wood 186, 213-6

Koelreuteria 97%.

Kohlrabi mounds 115.

Lachnus juglandis G2, L. exsiccator 179, 18sff. |

Lactuca 48. aa

Laelia 59.

Laminaria 16, 140,.

Lamium 90, 135, 142.

Larix 75, 99, 184.

Lasioptera 196.

Latania 9%. Ste

Latex Tubes, New Formation of cell walls after injury ll,

In callus 150.6 -

-ll-

Laurageae, Tendency to the formation of tyvloses 95
Laurus 94ff.

Lavatera 81.
Leaf Curling (Galls) 179,.191..
Leaf Fleas, Cf, Psyllodese
Leaf Lice, Cf. Aphids.
Leguminoseae, Cotyledons 147ff, 15l, Tubercles 116
Lemna Qe- .
Lenticels, Excrescences 72, In Galls 219.
Lepidium 86
Lepidoptera, Producing Kataplasmas 178, Prosoplasmas 19%.
Leucobryum 40.
Libriform Fibres,.Abnormal formation 134, Absence in
prosoplasmatic galls 208,
Lichen Gonidia 118..
Life Period,.Prolongation of the. 126ff., 133ff~e
Light , Influence on cell wail restitution 14, On Chloro-
phyll formation 35, On anthocyanin formation
56, On abnormal tissue formation 23%..
Lignification, Suppression after infection by fungi 30,
Occurrence after infection with aphids 62.
Ligninfoodies 217.
Ligustrum 74, 9%
Liquefaction Diseases 225..
Lohden 155, Lohdén Wedges 155, 144.
Long Filaments , Long rods of Bacterium Pasteurianum 68>
Lonicera 16-6
Loranthaceae 183, Producing galis (wood roses) Cfe also
Phoradendron.
Loranthus 97.
Loxopterygium 95.
Luffa 151s
Lunularia 15».
Lycopodium 996
Lycopus 80«
Lysimachia 16»
Lythrum 806+
Macleya 8.
Maclura 95ff.
Macronucleus 266
Malignity 2026
Malope 81s
Mansoa 9%.
Maranta 97s
Marchantiaceae, New formation of rhigcids 14, Arrestment
of tissue differentiation 394 40, Regeneration
of the thallus 256e o :
Marchentia 14.
Marsdenia 74.6
Marsilia 42,
Maxillaria 596
Mechanical Pressure and Strain, Effect of oe 126; 129,
1355, 145, 162ff., 235.
Mechanical Ring, Splitting of the 154.6
Mechanical Tissue, Hypoplasia 46, Activity hypoplasia
leoff., Reduction in ‘kataplasmas 182, Develop-
ment in prosoplasmas (mechanical mantel) 20eff.
Medicago 153.
Medullary Rays, Participation in the productién of callus
144, In wound wood 162, Abnormal breadth 163,
255, The same in gall wood 183. z
Medullary Spots 147,

Melaleuca 166

Melosira 9.6

Mentha 43, 109.

Me sembryanthemum 42, 706

Mesocarpus 9, ll.

Mesophyll, Impoverishment in dwarf specimens 18, In shade
leaves 20, 24, Arrestment of tissue differentia-
tion 41ff,, Participation in kataplasmatic galls
180, In prosoplasmatic galls 20l. ;

Mespilodaphne 94ff,

Metaplasia 3, 54,

Micania 9”,

Microcossus 36.

Micronucleus 26.

Micro-chemical construction 2266

Mite Galls 103, Cf. also Phy toptocecidia,.

Mimoseae, Scanty formation of tylosés 95.

Mining burrows, filled with callus 147.

Molle, so called, of the Mushroom 179.

Monophyllaea 7,

Monstera 74.

Moonrings 147,

Moraceae, Tendency to tylose formation 96, Hypoplasia of

the cystoliths 38,

Morphogenic Stimuli 229,

Mosaic Disease 33,

Morus 11, 74, 95ff,

Musci, Cf. Bryophytes, Mucor 118; Mucus Cavities of

Anthoceros 109; Passages filled with tyloses
99; Tendrils 149, 182,

Multi-nuclear Cells 67ff., 118ff, 120,

Musa 93.

Mycocecidia, Cf. Gallse

Mycogonée 179.4

Myosotis 102.

Myrica 74.

Myrtaceae, Gnarl tubers 166.

Myrtus 166,

Myxomycetes, Hypoplasia 39, Developing galls 121, 176,

Nanism 18ff., Reduction of the cell number 18, Of the.

secondary tissues 22, Of cell size 24, Of
the tissue differentiation 41].

Nasturtium 178.

‘Navicula 29,

Nectria 183, 186.

Mematodes as Gall Producers 178.

Nematus 74, 168, 197ff. N. gallarum, Fig. 98, 100,

N, gallisnerii, Fig. 102,

Neottia 60.

Nerium 131.

Neuroterus 196ff., Ne numismatis, Fig. 102,

Nicotiana 33.

Nostoc 109.

Notommata 115ff.

Nuclear Division, Abnormal 26, 119, 120.

Nuclear fusions 69. .

Nucleus, Absence of, in Cells 686 :

Nucleus, Restitution of mutilated nuclei 12, 13, Sigs

nificance of the nucleus in cytoplasm.and .
cell wall restitution 12, 15, Distant ef-
fect and after affect of the nucleus 13, In-
fluence of the nucleus on the chromatophores
55, on cell wall growth 94, Degeneration of

.

-13-

the nucleus 59, Cf. also Multi-Buclear

Cells and Nuclear Division,

Nutritive Epidermis 215.

Nutritive Hairs 215.

Nutritive Parenchyma 215ff,

Nutritive Tissue in Galls 214ff,

Nymphaea 149.4

Ochroma 95ff.

Octomeria 59,

Oedema 77,

Oedogonium 9, 13, 31, 126.

Olea 97, 117, 186,

Oil in Erineum hairs 107.

Oogonia, Vegetative development in Vaucheria 28.

Opening Mechanisms in Galls 213.

Opuntia 55,

Orchids, Formation of netted cells after injury 60, 90.

Orchis 35,

Orificial Wall of the Sac Galls 194.

Osmatic Pressure 112ff., Influence on tissue formation

24le

Ostrya 97, 151.

Overgrowth 151.

Ovula, Hypoplasia 48,

Oxalis 132, 243,

Oxydases, Formation in variegated leaves after injury,
_ After infection by parasites, etc. 33ff., In-
“fluence on the chlorophyll 33ff,.

Oxygen, Influence on the spore formation of the an-

: Herobic bacteria 238.

Oxytrichides 26.6

Padina 67, 88.

Pale-green Varieties (Chrysanthemum, ets.), Hypoplasia

19ffe

Panax 82.

Pandanus 34, 75, 82.

Papilionaceae, Scanty tylose formation 96s

Parenchyma, Formation characteristic of all galls 205.

Parinarium 196ff.

Passiflora 95ffe

Pathological, Explanation of the term le

Paulownia 97.

‘Pediaspis Aceris, Fig. 115.

Pelargonium 74.6

Pelvetia 16.

Pemphigus 192ff, FP. Marsupialis, Fig. 92, bursarius,

Fige 95s

Penium 9.

Peperomia 154,

Periderm 16e .

Peridermium 177, 185.

Peridineae, Hypoplasia 28.

Perilla 58, 97.

Pestalozzia 1384,

Petunia 36.6

Peziza 115s

Phaeophyceae, Regeneration of the bark tissue 15,

Galls of , Cf. Algae,

Phalaris 33.

Pharbitis 97.

Phaseolus 61, 78, 85, 155.6

Phelloderm, Hypertrophy of the 5s

*

Phjlodendron 97.

Phoma i84,
Phoradendron 178,
Phycocecidia Cf. Algae.

Phycomycetes, New formation of cell wall after injury
i}, Developing ae Cf, Cynchytriun.

Phyllanthus ©7,

Pay lleri-im 1e4,

Phylloxera 179;

Physiologica]. Wound: 97%, 154, 170.

Phyteuma it,

Phytoscoidia. UP. Galiss

Phytoptccesisia, Arrested Developments 18, Multi-

nuclear 129m Witches brooms 187, Proso-
plasmas 1897f, Kataplasmas 176, Sac galls
avo, Of, alse. Mite Gallas,

Phytoptus 105, Cf. also Mite Galls. Phe Macrorrhyn-

chus, Fig. 117.

Picea 97, 158, 184,

Pised 160;

Pineapple Galls 178,

Pinus av, 41, 75, 97ffs, 277, 184; 166.

Piratinera O4EE »

Pirus 0&,. 74. V6, 309, 120, 142, 1642i«s, L78fis, LBSfis,

Pistacia. O71, pte

Pisum 6.

Pith, Producing callus 143, Wound wood 162, Kataplasmas

182 ¢
Pits, In tyloses 94, In Erineum hairs 106, Abnormal
distribution a Gall sclereids 209.

Plantago 97. ,

Plasmodiophora 176.

Plasmolysis, Restitution and drowth after 8a

Platanus 74, 97, 146.6

Plec togyne 35

Pleurotaenium 9»

Pneumatodes of Galls 219,

Poisons, Action of 249, In gall formation 107ff.

Polarity, In the formation of callus 152ff., In the
formation of adventitious shoots 155,
Polarity of the cell 126. 1608.

Pollen sacs,ior tubes), New formation of cell wall
after plasmolysis, etee, Off.-, Not turn-
ing green in the light 55, Abnormal thick-
enings of the cell wall 61, Deformations
116.

Polygonum 35, 37, 44, 58, 178, 190.

Polyides 140.

Polypodiaceae, Regeneration of the prothallium and of
the leafl 7.

Pomaceae, Gnarl tubers 1656

Populus 72ff., 97, 120, 131, 142ff., 161, 178, 192ff.

Portulacca 97.

Potamogeton 62.

Potato Scab 170,

Potato Scurvy 170.

Potentilla 309, 191.

Poterium 109.

Premature ripening after parasite infection 57.

Progressive changes 54e

Prosoplasmas 125, 134, 156.

Prosoplastic Hypertrophy 8éeff.

Protective Palisade Cells, Hypoplasia 27, 28.

Protective tissue of galls, 205ffe

“

ap ote ans Abnormal accuihulation 58.
rotein layer in galls 216,
Prothallia, Regeneration 7, 9, Plasmolyzed celis 9,
Tracheids in 250,. ,
Protomvces 177.
Protonema, Dcformed cells 117,
Protozoa, mee eteeOe of the cells l2ff., Hypoplasia
Dag
Prunus 35ff, 74, 97, 100, LOGI Ls, 220, L95fTs
Pseudo-bulbiis in Selaginella 179,
Pseudoenuclecio 121,
Psyjioda, Proiucing galls 179,
Pteridian i 7c, 3
Pteridophytes, Galls of the 179, Witches brooms on
the 187, Cf. also Prothallim
Pterocarya 97. |
Puceinia. Tl,
Pteris 18%,
Pus tule Galls 178ff,
Quercus 74, 97, 1o7ff., 109, 179, 196ff, (Cynides
galls) ry :
Ranunculus 59, 121...
Raphanus 30, 18%.
Receptive Stimuli 229.
Redwood 130,
Regeneration Ge

Regressive Changes 54, Qf. also Degeneration.
Resin Ducts, Filled with tyloses 99, In wound wood
158, In gall wood 184, 188.

Restitution 47, Of the cell 7, Of the tissues 14, 90.

Restitution, of the cell walls in injured and plas-
molyzed cells, 9ff., Construction, Structure,
Capacity for growth 11, 60, Influence of the
nucleus lL. :

Retinospora 1".

Rhamus 30, 177ff-.

Rhinocola 198,

Rhizoids, Regeneration of the rhizoids in liverworts
15, Abnormal wall thickenings 61.

Rhodophyceae, Regeneration of the bark tissue 15.

Rhodymenia 179,

Rhus 4, 97ff.

Ribes 74, 77ff., 165, 169,

Ricanus 5, 89, Sl, 9%, 150+

Robinia 74, 95ff,

Roestelia 30,

Root Hairs, New formation of cell walls after plas-=-
molysis, etce, 9, Hypoplasia 44, Abnormal
thickenings 61, .-Abnormal forms lleff.

Roots, Resemblange to strings of beads 116, Abnormal
structure in Cardamine and Roripa 128, Len-
ticel excrescences 74ff,, Excrescences
resembling intumescences 78, Tyloses 96,
Callus 147ff, 155ff, Wwund wood 161, Dahlia
tubors 135, Gnarl tubers 166, Root primordia
developed into tuberous swellings 138, Root
galls, etcs, 120, 178, 187, etc. Cf..also
Club Root Gallse :

Roripa 128,

Rosa 17, 78, 97, 155, 141ff., 164. ‘

Rosanoff's Crystals 60+

Rosiflora, Scanty formation of tyloses 96, Erineum

109,

e

-16~-

Rogella 115,
Rozites 115.
Rubia 97.
Rubiaceae, Bacterial knots 186,
Rubigo 104,

Rubus 8, 109

Rudimentary Leaves of Spahagnum 40.

Rumex 97.6

Ruppia 1766

Ruscus 170.4

Saccharomycetes, Cf, Yeasts

Saccharus 119.

Sac galls 192,

Sagittaria 17, 41.

Salvia 109,

Salicineae, Tendency to the formation of tyloses 96.

Salix 16, 17, 44, 56, 72, 74, 75, 97, 109, 141ff., 164,

189, 195ff. (Nematus galls). ;

Sambucus 16, 74, 89, 97,

Santalum 97,

Sap Streams Descending, Influence on the formation of

Gu peeyentn 57, On tissue production (Callus)
a

Sargassum 141,

Sarothamnus 75.

Saxifraga 57.

Saxifragaceae 57,

Scale on Lemons 34, Producing kataplasmas 178, Cf. also

Coccus. :

Sceletonema 29,

Scenedesmus 28, 38, 117,

Sclerids in Callus 151, Physiological significance 129ff.,

In galls 208,

Sclerotia, Regeneration of the bark tissue 15.

Schinus 9%.

Schizoneura lanuginosa 123, 192ff., Fig. 134, S. lan-

igera 178ff., Figs 76, 78. ;

Scitamineae, Tendency to the formation of tyloses 966

Scutellaria 109.

Secretions in and on Galls 220+.

Secretion Reservoirs, Filled with tyloses 99, In galls
2206 at

Secondary Tissues, Hypoplasia: Reduction of the cell

number 19ff., Of Tissue differentiation 47.

Sedum 8, 56, 147.

Seed Receptacles, Hypoplasia 47.

Selaginella 141,

Sempervivum 71.

Senility Phenomena: Formation of tyloses, 100ff.

Separation, Tissue of, In autumnal leaf fall 170.

Shade Leaves, Impoverishment of the mesophyll ,
Reduction of the cell number, cell size
and tissue differentiation 19ff, Bio-
logical significance 48. ;

Short Rods of Bacterium Pasteurianum 68, 69.

Sieve Tubes, New formation of cell walls after
plasmolysis 10.

Siphoneae, Regeneratien 7ff., Hypoplasia: Sim-
plifieation of the cell form 27iis, in
symbiosis with sponges 28, Abnormal
cell wall thickenings 61, Abnormal forms
115, Gall on Siphoneae 115,

+

oe

; -17-

Siphonotladiaceae, Regeneration 8ff., 12. :

So@ium Chlorid, Necessity for Halophytes 46, Influences
on chlorophyll formation 56, On cell size 86s

Solanum 32, 42, 44, 58, 70, 74, 75, 78ff., 82, 97,
doet +4 188, 170. . :

Sorbus 109, 1.29, 148, 178.

Soresphacrs te. -

Sparmannia 95ff,

Spathegaster baccarum 134, l96ff,

Specifity of the Tissue 203, 2576

Sphacelaria 67».

Sphagnum 40.

Spiraea 14 4

Spirogyra 9, 11, 13, 55, 684

‘Spongocladia 28, P

Stagheads 187ff.

Starch in Tylosés $5f, In callus 150, In Erineum hairs
107, Abnornel accumulations warn " Abriormal starch.
grains 243, Formation of starch in plasmolyzed cells
13, Disappearance in hypertrophy 19, Starch layer
in. prosoplasms lene: 2164

Star Parenchyma in Galls 219.

Starvation Etiolation 71,

Stauroneis 29,

Stefaniella 210,

Stigeoclonium 9,

Stigmatophyllum 97.

Stimuli, gnu eaon of, In General 22%.

Std n81d05 roduc tion 126, In abnormally small quantities

or completely lacking 42, Abnormal size 70, Relation
to intumescences 85, To bead glands BS, cf; also
Guard Cells.

Stone Cells, Cfe Schleréidse

Stone Tyloses 94.

Stratiotes 42,4

Streblonemopsis 177%.

Strelitizia 97, %*

Streptocarpus 7.

Struggle of the Parts of the Organism 258ff.

Sturvea, 28,

Suberization, Abnormal, In contact with water, etce 620

Succulence, Abnormal 866

Succulents 42, 57.

Sugar, Inf Luence on the formation of Anthocyanin 564

Sunleaves 19, Cf, also Bhade leaves,

Symphoricorpus 9a

Synchytrium 102, 177, 190.

Synedra 29.4 :

Synophrus 212.4

Sypringa 36, 74, 89, 135, 468s; 188ff.

Tannin in Galls. "222, "Tannin balls" in galls 222, Tannin

vacuoles in gallus 142.

Taphria 104.

Tahprina 188,

Taraxacum 6, 56, 97, 147ff., 161,

Tarsonemus 106s,

Temperature, influence on tissue formation 236.

Tetmemorus 99 ©

Tetramyza 176.4

Tetraneurs 192, Te compressa, Fig. 113, T. Ulmi, Figs 97.

Thujopsis 177, "188.

Thunbergia o7%

r

r

~18=

Thunder Bushes 187.
Disie (eA, L06tr ag 17S, 29STr,
Tissue Covering (Epidermal), Of Callus 146, Of galls

205ff«

Top-shoot Galis, Indication of arrested development
1786

Topping, Influence of topping on tissue formation
L38ff»

Tracheids in Callus 148ff., Abnormally formed 134, 160,
Instead of ducts 30, é

Tradescantia 15, 44, 59, 90, 91, 100, 142, 150.

Transpiration, Influence on. cell number 19, Differentia~
tion of cells and tissue 29ff., agft, 259%

Trentepohlia 15.

Trichomes of Galls 207%

Trigonaspis 218,

Tristania 166. ,

Triticum 71, 106, 111.

Tropaeolum 100. .

Tyloses 89, 92, In ducts 93, In resin canals, etce 99,
In. the.air chambers of stomata 100. Z

Tumors 202.6

Turgor, Changes in turgor and influence on tissue forma~

. tion 241,

Turning Green 55,

Tylenchus 178,

Tylogonus 176.6

Udotea 10, 27.

Ulmaceae,.Tendency to formation of tyloses 966

Ulmus 44, 74, 95ff,

Undulated outlines of epidermal cells 70, Im root hairs,

Siphonae, etc. l..cif. 3 -

Uredineae, Producing galls 177.

Urocystis 177.

Uromyces 71.

Urtica 10, 97, 176, 202.4

Urticaceae, Stimulus to the formation of tyloses 96,
Hypoplasia of the cystoliths 38.

Ustilagineae, Producing galls me On the Myrtaceae 166.6

Ustilago 177,190.

Vaccinium 30, 17%7ff.

Vallisneria Ds

Valonia 10.

Variegated Plants, Hypoplasia: Reduction of the cell size,
24, Reduction of the chromatophores Slff., z
Variegation dependent upon nutrition 31, upon
temperature 31, Crystal content 3@ff.,.Tissue

differentiation 42ff.

Vascular Bundles, Regeneration 16, Hypoplasia 45ff., Ad-
normal formation 158, 219, Activity hyperplasia
2elsff, In Galls 4

Vascular Tissue, Participation in abnormal production
257, In the formation of calls 142ff., In the
formation of galls 182ff., 201ff. Cf.-Ducts,
Tracheids, Duct Tyloses, Wood and Bark.

Vaucheria 9ff., 28, 115.

Veining in Wood 159ff.

Vergriinung 55 (See Turing Green).

Veroinca 176.

Verticillium 179.

er

\

-19-

Viburnum 109, 111, 197.

Vicia 85, 92, 128, 149ff,, 163.

Vicia 17, L7%

Viscum 168,

Vitaceae, Tendency to the formation of tyloses 9656

Vitis 36, 74, 85, 94ff., 147, 178ff,

Water Plants.49. |

Waved Growth 159ff.,

Waved Wood 159ff.

Wax Coating, Regeneration of the 8,

Weakening, due to Cultivation 164,

Weeping Trees 52, 129,

Weigelia 74,

Wind, Influence, Hypoplasia 20, Hyperplasia 150.

Window Galls on the Maple, 111ff.

Witches Brooms 182, 187. .

Wood, Hypoplasia: Reduction of the cell number 20,
Reduction of the cell size 24, Arrestment of
wood formation 21, Abnormal wood 156, In kata-

plasmas 182, 188, 190, Cf. Wound Wood.

Wood Parenchyma, In wound wood .159ff., In gall wood 182ff.,
Partifipation in callus formation 146, Cf.
Tyloses.

Wood Roses 177.

Wooly Streaks in Apples 142, 149.

Woronina 115,

Wound Bark 161.

Wound Cork 167ff.,. In Galls 168, 206.

Wound Gums , In tyloses 95, In callus 149ff.

Wound healing, Cf. Callus Tissue, Wound Wood, Wound Cork,
also Restitution, Wound Healing by a cytoplas-
matic stc,per in Valonia, Bryopsis and the latex
tubes 10, 11, Cf, "Physiological" Wounds.

Wound Stimulus, Analysis of the 231.

Wound Wood 156, Histology 157, Primary, Secondary 158,

Wound Wood Zone, Short Celled.158, Long Celled 1586

Xanthozylon 97.5 -

Xylaria 141.

Yeast, Involution forms 11%.

Yellow Spotting 80, 82.

Zamia 99, 170+. Ug)

Zea 16, 33, 56-

Zoocéecidia, Cf. gallse

Zygnema Off.