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SMITHSONIAN
Jj
MISCELLANEOUS COLLECTIONS
VOL. 82
“YERY MAN IS A VALUABLE MEMBER OF SOCIETY WHO, BY HIS OBSERVATIONS, RESEARCHES,
AND EXPERIMENTS, PROCURES KNOWLEDGE FOR MEN’’—SMITHSON .
(PUBLICATION 3132)
GITY OF WASHINGTON
PUBLISHED BY THE SMITHSONIAN INSTITUTION
1931
PALTINORE, MD., ‘U.S. A.
ADVERTISEMENT
The present series, entitled ‘“ Smithsonian Miscellaneous Collec-
tions,” is intended to embrace all the octavo publications of the
Institution, except the Annual Report. Its scope is not limited,
and the volumes thus far issued relate to nearly every branch of
‘cience. Among these various subjects zoology, bibliography, geology,
uineralogy, anthropology, and astrophysics have predominated.
The Institution also publishes a quarto series entitled “ Smith-
sonian Contributions to Knowledge.” It consists of memoirs based
on extended original investigations, which have resulted in important
additions to knowledge.
CG: ABB@A,
Secretary of the Smithsonian Institution.
(ii)
N
10.
ine
14.
CONTENTS
. AppoT, C. G., AND FREEMAN, H. B., Absorption lines of the
infra-red solar spectrum. 17 pp., 5'pls., Aug. 31, 1929. (Publ.
3026. )
Snopcrass, R. E., The thoracic mechanism of a grasshopper and
its antecedents, III pp., 54 text tigs., Dec? 31, 1929. (Publ.
3027.)
Aspot, C. G., The radiation of the planet earth to space. 12 pp.,
2-pisse Noy. 16, 1629: (Publ. 3028.)
MILLER, GERRIT S., JR., The Characters of the Genus Geoca-
promys Chapman. 3 pp., I pl., Dec. 9, 1929. (Publ. 3029.)
MILter, Gerrit, S. Jr., Mammals eaten by Indians, owls, and
Spaniards in the coast region of the Dominican Republic.
Ttowppe2 pls, Dec. 11,1920, (Publ. 3030!)
Berry, Epwarp W., The past climate of the North Polar region.
29 pp., 6 figs., Apr. 9, 1930. (Publ. 3061.)
Crayton, H. Heim, The atmosphere and the sun. 49 pp., 33
text figs., June 9, 1930. (Publ. 3062.)
Netson, E. W., Four new raccoons from the keys of Southern
Florida. 12 pp., 5 pls., July 10, 1920. (Publ. 3066.)
HeErRoN-ALLEN, Epwarp, F. R. S., The further and final re-
searches of Joseph Jackson Lister upon the reproductive proc-
esses of Polystomella crispa (Linné). 11 pp., 7 pls., Nov. 26,
1930. (Publ. 3067.)
SCHEDL, Kart E., Morphology of the bark-beetles of the genus
Gnathotrichus Eichh. 88 pp., 40 figs., Jan. 24, 1931. (Publ.
3068. )
. Haury, Emit W., anp Harcrave, Lynpon L., Recently dated
Pueblo ruins in Arizona. 120 pp., 27 pls., 35 text figs., Aug. 18,
1931. (Publ. 3069.)
BusHNELL, Davin I., Jr., The five Monacan towns in Virginia,
1607. 38 pp., 14 pls., Nov. 18, 1930. (Publ. 3070.)
MILter, Gerrit S., Jr., A note on the skeletons of two Alaskan
porpoises. 2 pp, 1 ipl, Dec. 23, 1930. ( Publ. 3107.)
Miter, Gerrit S., Jr., The supposed occurrence of an Asiatic
goat-antelope in the Pleistocene of Colorado. 2 pp., 2 pls.,
Dee: 22; 1930. (Publ. 3168.)
(v)
v1
15.
16.
7
18.
CONTENTS
MILLER, GERRIT S., Jr., Three small collections of mammals
from Hispaniola. 10 pp., 2 pls., Dec. 24, 1930. (Publ. 3109.)
Reese, A. M., The ductless glands of Alligator mississippiensis.
14 pp., 3) pls.,, March ‘9, To3n. (@eubl are: )
KENNARD, A. S., A. L. S., SaAtispury, A. E., AND WooDWARD,
B. B., F. L. S., The types! of Lamarck’s eenera, of, shellsvas
selected by J. G. Children’im 1823" 40 pp: july 11, log
(Bubl 31125)
McInpoo, N. E., Tropisms and sense organs of Coleoptera.
70 pp, 2 pls:, 19 text figse expr, 15, 19aT, Geublaine))
SMITHSONIAN MISCELLANEOUS COLLECTIONS
VOLUME 82, NUMBER 1 _
ABSORPTION LINES OF THE INFRA-RED
SOLAR SPECTRUM |
(WitTH Five PLarTEs)
BY
CG. G. ABBOT AND H. B. FREEMAN
(PUBLICATION 3026)
CITY OF WASHINGTON
PUBLISHED BY THE SMITHSONIAN INSTITUTION
AUGUST 31, 1929
SMITHSONIAN MISCELLANEOUS COLLECTIONS
VOLUME 82, NUMBER 1
ABSORPTION LINES OF THE INFRA-RED
SOLAR SPECTRUM
(WiTH FIvE PLateEs)
BY
CG. G. ABBOT AND H. B. FREEMAN
<->
PHOS OBE Jy
an Mingcroe
(PUBLICATION 3026)
CITY OF WASHINGTON
PUBLISHED BY THE SMITHSONIAN INSTITUTION
AUGUST 31. 1929
The Lord Battimore (Press
BALTIMORH, ‘MD., uU. 8. ine i
fyi
=
ABSORPTION LINES OF THE INFRA-RED SOLAR
SPECTRUM
By C. G. ABBOT anp H. B. FREEMAN
(WitH 5 PLATES)
In the decade 1890 to 1900, the bolometer was used under Langley’s
direction at the Astrophysical Observatory of the Smithsonian Institu-
tion to feel out the positions of lines and bands in the infra-red solar
spectrum. The results were published in Volume I of the Annals of
the Observatory. In the spectral region A to Q, about 550 lines were
recorded as observed in the spectrum of a 60° prism of ordinary
telescope flint.
At Mount Wilson, in the summer of 1928, Dr. H. D. Babcock
urged that further bolographic studies of the infra-red solar spectrum
should be undertaken with apparatus of higher resolving power. Our
EXEGeele
vacuum bolometer equipment, then on Mount Wilson, presents a senst-
tive strip of approximately 0.1 mm. width, and the combined outfit
of bolometer and galvanometer was certainly not less than five times
as sensitive as the most sensitive outfit employed at Washington 30
years before.
It appeared practicable to undertake a brief bolographic study of
the upper infra-red solar spectrum from A to © in the time available.
Accordingly we set up a spectroscope (fig. 1) comprising a slit 6 cm.
high and (usually) 0.4 mm. wide; a collimating cylindric mirror of
543 cm. focal length; a set of three telescope flint-glass prisms, two
of 60°, the third of 64° angle, and all presenting faces approximately
6 cm. square. From thence a plane silver-on-glass mirror reflected
the spectrum to an image-forming spherical mirror of 230 cm. focal
length. The vacuum bolometer, above mentioned, whose sensitive
strip was 16x 0.1 mm. received the rays at focus. The spectroscope
SMITHSONIAN MISCELLANEOUS COLLECTIONS, VOL. 82, No. 1
2 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82
was fed by a two-mirror coelostat with silver-on-glass mirrors. The
solar rays were not concentrated on the slit. Hence they represented
the integrated rays of the entire solar disk.
The infra-red solar energy spectrum was recorded on moving photo-
graphic plates 8 x 24 in. in surface. The clockwork was arranged
so that 4 cm. of plate corresponds to 5’ of spectrum, and the plate
passed the recording light-spot of the galvanometer at the rate of
2 cm, in I minute.
The three prisms were set according to computations so that the
beam of rays of wave-length 1.054 would pass through each one
of the prisms approximately in minimum deviation. This same setting
was continued unchanged in all the observations. The total deviation
of the rays of this wave-length was roughly 180° and the dispersion
from A to Q was about 5° 25’. Hence we were obliged to use five
61-cm. plates to cover the entire region with overlap sufficient for
identification. A
Generally three curves of each of the five regions were impressed
on a single photographic plate. Care was taken to arrange them
vertically in close superposition, so as to facilitate comparison. Plates
I to 5 give reproductions of some of the most satisfactory observations.
Linear scales are drawn on plates I to 5 parallel to the direction
of motion of the recording photographic plate. They have numbers
closely agreeing with those of the extensive table 3 of linear measures
and wave-lengths, given below. In each group of three curves the
air-mass of observation decreases as between the several curves from
the bottom upward and in each curve (except in pl. 5) from left
towards right. In most plates there is a very considerable increase
of air-mass between the upper and lower curves. This will facilitate
the discrimination, by those interested, of solar and telluric lines. De-
tails of times of observation and air-mass and notes on the conditions
are given in table 2.
A very considerable increase of detail appeared in these energy
curves when compared with those taken 30 years ago with a single
glass prism. In the A line, for instance, not only could the doubles
be recognized, but in many of them the individual components were
resolved separately in the energy curve. Some of the bands near wave-
length 0.82» showed as many as five veridical lines in the new curves
where only one broad band could be distinguished in the older work.
The identification of lines was done entirely by Mr. Freeman, and
in the following manner. A series of several bolographs was super-
posed, either on millimeter cross-section paper or on a comparator
NO. I INFRA-RED SOLAR SPECTRUM
ABBOT AND FREEMAN S
in which a stretched wire was displaceable over a milk-glass back-
ground. Lines were considered provisionally veridical when found
as deflections of similar form and similar setting in three or more
bolographs. After completing this preliminary study, the positions of
all deflections considered possibly veridical were measured on three
bolographs with the excellent Warner and Swasey comparator de-
scribed on page 64 of Volume I of the Annals. Mean values were
computed of positions on three (or in some cases two) of these
bolographs on which the deflections were found. When found on only
two of the three they were questioned, and rejected unless supported
by further evidence.
In assigning intensities, Mr. Freeman used practically the same
system that was used in Volume I of the Annals. Grades a, b, ¢, d,
and d? were employed. All lines falling within great bands like
A, por, $, W, and © are joined in a bracket and designated as a whole
with “a.” Bands hardly reaching this first-class prominence are
similarly bracketed and marked “b.” Individual deflections, or com-
posites of several small deflections which altogether make a depres-
sion of 5 mm. or more in bolographs are marked “c.” Smaller indi-
vidual deflections, whether in the bands or outside of them, are marked
“dq.” When considerable doubt remains as to the veridical character
of such a deflection, it is marked “d?.’’ We do not guarantee that
all the lines included in the table are veridical, but we believe a very
large proportion of them are so. The curves are very free from
accidental deflections as deep as a single half millimeter, and the
repetition on several bolographs of similar configurations of intensity
“qd” is regarded as strong presumptive evidence of reality of corre-
sponding solar or terrestrial absorption lines.
To determine the wave-lengths of the lines observed, the advice of
Dr. Babcock was sought. From his studies of all existing laboratory
determinations of infra-red line spectra, amplified by his own extensive
photographic work in the upper infra-red spectrum as far as A=
1.1018 Angstroms, he sent a list of 112 identifications of wave-length
places, given according to our bolographic work in Volume I of the
Annals, as compared to more recent determinations. A curve of cor-
rection to the wave-lengths given in Volume I of the Annals has been
prepared from this material. In summary it is as indicated in table 1.
The data for corrections beyond 1.18 are so scanty and so conflict-
ing that there seemed no justification for applying any corrections in
that region.
4 SMITHSONIAN MISCELLANEOUS COLLECTIONS VoL. 82
TABLE I.—Corrections to Wave-Lengths of Annals, Volume I
(Corrections are stated in Angstroms, wave-lengihs in microns.)
Wave-lengths...| 0.76 to 0.84 | 0.85 | 0.86 | 0.87 | 0.88 | 0.89 | 0.90 | 0.91
Corrections..... fe) +5 +5 +5 +3 +2 fe) —2
Wave-lengths...| 0.92 | 0.93 | 0.94 | 0.95 | 0.96 | 0.97 | 0.08 | 0.99 | 1.00
Corrections..... Gt Oo Sele 2 Sg ee o.| ===
Wave-lengths...| 1.01 | I1.02to 1.06] 1.07 | 1.08] I1.09| 1.10 I.11|1.12 Tires
Gorpgectionse a —8 —I0 —9 | —7| —6/—5 | —4 | —3 |] —1
Wave-lengths...| 1.14 to end
Cornsections-no-. fe)
In further determination of wave-lengths, Mr. Freeman identified
81 deflections as corresponding each to each in the old and the new
bolometric work. These deflections covered fairly uniformly the range
from 0.76 to 1.80%. Having taken out from the tables of Volume I
of the Annals the corresponding wave-lengths, he then applied to these
values the corrections fixed by table 1. He then plotted on a sufficiently
large scale the observed linear places of these 81 deflections as ordi-
nates, and the corrected wave-lengths as abscissae. The curves thus
defined could easily be read off to a single Angstrom. From them
were read all the wave-lengths given in table 3, which contains over
1200 lines.
TABLE 2.—Circumstances of Observation
Time Air-mass
Date - tS
1928 Curve Start Finish Start Finish Notes
Septet aete I 0: 39 10: 09 ihe Bil Dee
2 LOL, 10: 47 1.21 1.16
3 10: 52 lis 22 Tesh rene
Sept 4am ason I 6: 28 6:58 4.85 3023
2 TiS O 8: 29 1.97 1.69
3 8:51 Or 1.54 1.38
Sept esmemre cone I 6: 34 7:04 4.49 3.05 Slight earthquake
2 Q: II 9:41 1.43 Lest
3 0:50 10: 20 1.28 1.20
Seper ree yah I 6: 29 6:59 4.70 3.15
2 9: 19 9: 49 1.36 e277
3 0:58 10: 28 1.24 Kee le7,
Sepiileoreencce 3 B34 Se Gil 1.82 2.18 Ends off plate
2 2:58 3:28 Te54 Hg 7ZA0)
I Po ae Te A3 Tey 1.23
NO. INFRA-RED SOLAR SPECTRUM—ABBOT AND FREEMAN
TaB_eE 3.—Lines and Bands in the Infra-Red Solar Spectrum
Linear Wave- Linear Wave-
measures Intensity length measures Intensity length
—34.130 d 1 7582 —25.233 d 7727
auogs, - det 4d 7583 122 d? 7728
33.003, da?) 7598 25.019 d 7730
32.858 dy b | 7602 24.831 d } 7733
707 d | 7604 418 d 7740
682 -d | 7600 .322 d 7741
32.575 di 7608 7233) id 7743
31.911 d 7618 153 d A 7744
300. «duct 7628 24.036 d 7746
31.191 d 7630 23.801 d 7750
z0819 0 od | 7636 696 d 7752
TAZ, | ed 7638 573 7754
516 d | 7641 461 d? 7755
451 d 7642 .176 d? 7760
264 d 7045 23.079 d 7762
.190 Gl iy 7640 22.964 di 7704 —
30.119 d? 7647 .690 d 7760
29.805 d 7651 621 d | 7770
827 2d? 7652 i272 d 7776
570 d A 7656 .178 di i 7778
.499 d 7658 22.046 d [{ 7780
.266 d. Fb +a 7661 21.906 d 7782
29.185 d 7662 .807 d 7784
28.921 d | 7665 606 d 7786
.846 al 4 7668 472 al | 7790
581d 7672 343") vid 7792
08 od | 7674 240 «2d 7704
415 d? | 7675 21.005 d? 7796
28.069 d | 7680 20.871 d 7800
27.847 d 7684 687 d 7803
.701 d | 7686 521 d 7
377 .-d 7601 gio) us 7809
281 d 7602 20.114 d 7812
27.173 +d 7695 19.935 d 7816
26.898 d J 76908 826 d 7817
769 d 7701 .756 d 7818
.664 d 7703 650 d 7820
545 d 7705 547. dl 7822
431 d 7707 .226 d 7827
242 d 7710 19.111 d 7820
146 d 771 18.951 d 7832
26.059 d 7712 .837 dc 7834
25.9290 4d 7714 755 _ a 2 J AS “i “Ne ° r va ;
d
VOL. 82, NO. 1, PL. 5
SMITHSONIAN MISCELLANEOUS COLLECTIONS
: Vaias
F ATIC SOLAR SPECTRUM
lengtl ) to 18200 Angstroms
|
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wi
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4
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SMITHSONIAN MISCELLANEOUS COLLECTIONS
VOLUME 82, NUMBER 2
THE THORACIC MECHANISM OF A
GRASSHOPPER, AND ITS
ANTECEDENTS
BY
R. E. SNODGRASS
Bureau of Entomology,
U. S. Department of Agriculture
(PUBLICATION 3027)
CITY OF WASHINGTON
PUBLISHED BY THE SMITHSONIAN, INSTITUTION
DECEMBER 31, 1929
SMITHSONIAN MISCELLANEOUS COLLECTIONS
VOLUME 82, NUMBER 2
THE THORACIC MECHANISM OF A
GRASSHOPPER, AND ITS
ANTECEDENTS
BY
R. E. SNODGRASS
Bureau of Entomology,
U. S. Department of Agriculture
(PUBLICATION 3027)
CITY OF WASHINGTON
PUBLISHED BY THE SMITHSONIAN INSTITUTION
DECEMBER 31, 1929
ae
fo -T:"
- ~
The Lord Waltimore Press
BALTIMORE, MD., U. S. A.
ie THORACIC MECHANISM OF A GRASSHOPPER,
AND ITS ANTECEDENTS
By R. E. SNODGRASS
BuREAU OF ENTOMOLOGY
U. S. Department of Agriculture
CONTENTS
PAGE
| (aye a KGS SCO a Re Gis Oks chats Shee teks S OREO RTE CLOGS ONS Sete SSR ee eA een ee te I
PRR Grerieral mC ISCUSSIONMet saak cece sos lantc acto ee Se Teen Sais GS 3
Mp emnth@ ra Cle atel agar ncyns chiral cco ake che OVE eee os ankct sie 5
Mhea thoracic” pleutalees a svc coere seks Sele ee ere On OO ne eee 10
MihemthOracie sstemmMalnyia weve sichacs. eters eee a ere eter Canes SaaS 21
Wether thonaciceskeletonmonn isco Sterna eames an ieie ag
PlemCernyl calltuse lenitesy er.cucavNerurcs creme een tie ere caterer Meehan nee 33
Milnes TO Ha Ona ee te teeecoat eve oro locsucke area raeuees Poe Meenas See Oa eee ela 34
Mshie AOLCTOEMONAR? (A cche.ce kee sates aton sel horny Saisie hte s od cease sae antes 37
iiieenhesthoraciesamuscles) ob issostewaeanscans soe sae oe eee earls 51
Misclestotathe neck andeprothorasssc erie einen a baer eee 53
Mnrsclesronr thee pterotho cacy. carte co aGeereceyerts settee ke as eh sven soe ean sei 59
Aihewmesounoracic siniSClesmsee arene tela ta ere cassie er eee 60
hem metathonraciclstnlScless cae Mere ane crise cars Meiners oes 66
ie eetae lees and theme musclestss sic. once assess soenleins = cha sete oe oo 72
SEE HEEUEC HO LEON COS «eats eas hae ee Rix! siciarit con ohacrenastets sen Miko elena bes 73
Miss CLES Cheb R Sy cea cya tinea eyes each slonistxiale ne ae belies he esa. 78
Nee toeawities and. teit tMECHANISIe Ss gmt. i225 5,8 84
Girrnrehbtrauloie adaee WINE De ws dons bacco wgvlootnte dae Fos oases aomoe Ee 84
PEA WOM MEE NanIS Meares curs stciein: team ecrttentec ecole Shc Rie scale sll aaiyle) «sees 92
PMMA CES OITA CIES | scase he Hie te NEUS oe LO Nucci aseimy ceake i etalanes ate ala hs Mie faln Midvaco heh lovee o 99
MppLevIAONs Sed Ol Ter MINES e souk chsh aa) w sin Se eteteivers Mespeid Sa) RG «iste = 108
TRXSr ETRE a I ol GBT Ne ee a rica Sintate ao lei bios accents oie sree 109
INTRODUCTION
The principal elements in the motor mechanisms of arthropods are
the muscles and the body wall, though the blood often plays an im-
portant secondary part as a hydraulic medium. All movements, how-
ever, come primarily from muscle contractions. A contracted muscle,
when it relaxes, must be actively extended before it can operate again,
and therefore muscles generally occur in antagonistic sets. But the
muscles of insects are not necessarily opposed by other muscles ; the
counter force may be produced by the elasticity of the part of the
body wall on which a muscle is attached. For this reason it is often
SMITHSONIAN MISCELLANEOUS COLLECTIONS, VOL, 82, No. 2.
SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82
bo
found in studying the anatomy of insects that a muscle has no an-
tagonist. Moreover, while most insect muscles are muscles of motion,
some are tensors inasmuch as they appear merely to maintain rigidity
between parts that are subject to strain from other muscles.
The ectodermal cell layer of the body wall, or epidermis (commonly
known as the “ hypodermis”’), is covered externally by a cuticula of
which the general constituent is probably chitin, but in which other
substances are deposited to form hardened areas called sclerites. The
nature of the sclerotizing substances in insects is not yet known, but
it appears to be definitely established that the sclerotic areas of the
cuticula are not places where the chitin is thicker or denser (Campbell,
1929). Sclerites are secondary formations in the body wall, and it
would be both interesting and important to know the physiological
processes that produce them, for we should then be better able to
evaluate sclerites as morphological units.
The major plates of the body-wall of an insect are very definite
structures that are consistently reproduced by the deposit of sclerotiz-
ing substances throughout the whole series of insect forms, and some
of them appear to be homologous with corresponding plates in other
arthropod groups. On the other hand, all parts of the insect skeleton
called “ sclerites ”’
Many of them are simply areas of larger plates which have become
secondarily demarked by lines of inflection in the cuticula that have
formed internal strengthening ridges. The so-called sclerites in such
cases are in themselves of no significance. The important morpho-
logical features are the endoskeletal structures ; these are the rafters,
the joists, and the upright supports that give strength to the edifice
and enable it to withstand the strain of the muscles pulling on its walls.
It frequently happens, however, that a primary region of sclerotiza-
tion becomes broken up by a discontinuity in the hardening substance
of the cuticula, thus producing true secondary sclerites. The inter-
vening “ membrane ” may take the form of a narrow line of flexibility
(“‘ suture ’’), or it may cover a large part of the original hard surface
and reduce the primary sclerotization to two or more widely separated
plates. Or again, an original sclerotic area may be contracted to a
relatively small sclerite, or it may be obliterated. It then becomes a
question, if the primary plate has been given a name, whether we are
to apply this name to the area originally occupied by the plate, or
restrict it to the sclerotic remnants or remnant. It is the usual prac-
tice to apply the name only to the sclerite, whatever its extent, and,
if the sclerite is obliterated, to say that the part in question is obsolete
in descriptive entomology are not of equal value.
NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—-SNODGRASS 3
or lost. This usage has convenience for descriptive purposes, but it is
likely to confuse our morphological conceptions, since an anatomical
part is the same thing regardless of the nature of its surface covering.
I. GENERAL DISCUSSION
If all that has been written about the thorax of insects were true,
or could be made to fit with our present knowledge of insect struc-
Pe acs _-T. Pe acs
PY i Ginteuleakig = iy id
Ser Ist
Fic. 1.—Diagram of the theoretical structure of a primitive thoracic segment.
The tergum (7) includes the segmental and preceding intersegmental sclero-
tization of the dorsum; the ventral sclerotization consists of a primary seg-
mental sternal plate (Stn) and intersegmental intersternites (/st) ; the pleural
area is occupied by a basal subsegment of the leg, the subcoxa (Scx), divided
dorsally into a eupleuron (Eupl) and a eutrochantin (Eutn).
acs, antecostal suture; c, d, dorsal and ventral subcoxo-coxal articulations ;
Eupl, eupleuron; Eutn, eutrochantin; Jsg, primary intersegmental line; Jst, in-
tersternite; Mb, secondary intersegmental membrane; Pc, precosta; Scx, sub-
coxa; Sin, primary sternite; 7, tergum.
ture, there would be little need of prefacing a special description of
the thoracic skeleton and musculature of the grasshopper with a gen-
eral discussion. Science, however, is not a collection of facts but a
concept in which to hold the facts. As our collections of facts become
larger, our concepts must be altered and enlarged from time to time.
Moreover, we often think that we have nicely fitted a fact into a
mental container, only to discover presently that it does not fit at all,
or that an important part of the fact has been left out. There is noth-
4 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82
ing to do then but to discard the container or to remodel it as best we
can to make it serve its intended purpose. The writer, therefore, finds
it necessary to enlarge some general conceptions previously expressed
concerning the nature of the thoracic mechanisms and their apparent
evolutions from simpler origins, in order to accommodate new obser-
vations that must be admitted.
The primary intersegmental infoldings of the integument of arthro-
pods are the original lines of attachment of the longitudinal muscles,
and in most cases the principle longitudinal muscles are still attached
on them. When the cuticula becomes sclerotized, the intersegmental
inflections are usually converted into apodemal ridges, and a primary
segmental plate is laid down in the dorsum and generally in the venter
of each segment. In some cases the intersegmental sclerotizations take
the form of narrow intersegmental sclerites alternating with the seg-
mental plates. This condition is found more frequently in the ventral
than in the dorsal region, though it exists dorsally in some insect
larvae.
The typical sclerotization of the dorsum of any segment in an adult
insect consists of a plate (fig. 1, 7) which covers most of the dorsal
area of the segment, and which is continuous anteriorly with the inter-
segmental sclerotization bearing the intersegmental fold or ridge
(fig. 2 A, Ac). The definitive tergum, therefore, occupies a primary
segmental region and the preceding intersegmental region; it bears
anteriorly a submarginal, intersegmental ridge, or antecosta (fig. 2 A,
Ac), marked externally by the antecostal suture (figs. 1, 2 A, acs),
and it terminates anterior to this ridge and its suture in a narrow
lip, or precosta (Pc).
The ventral sclerotization of the segment may take the same form
as the dorsal sclerotization, as in the abdomen of most insects, where
the definitive terga and sterna duplicate each other in structure
(fig. 3). The functional intersegmental rings of the body in such
cases are the posterior, non-sclerotized areas of the primary segments,
and the definitive segmentation is clearly a secondary one. The sternal
sclerotization, however, may preserve a more primitive condition, as
in some of the chilopods (figs. 8, 15) and in the thorax of certain
insects, where the primary sternal and intersternal plates remain inde-
pendent (figs. 1, 2 A, Stn, Ist).
In the membranous areas of the lateral, or pleural, walls of the seg-
ment are implanted the bases of the segmental appendages. In most
arthropods the basis of the appendage (coxopodite) is preserved as
an integral limb segment. In the body segments of the chilopods, the
thoracic segments of insects, and the ambulatory segments of decapod
NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 5
crustaceans, however, it appears that the limb basis has become sub-
divided into a coxa and a subcoxa, and that the latter has been incor-
porated into the wall of the body segment (fig. 1, Sca), where it either
forms a “ pleuron” supporting the free part of the limb, or also the
base of the wing, or it becomes degenerate and reduced to small
sclerites having little significance or function.
/ | x
3Ph =DMel RB 2Ph 3Ph
Fic. 2—Diagram showing the relation of the longitudinal muscles to the tergal
and sternal sclerites of the body.
A, three successive segments in which the terga include the primary inter-
segmental regions bearing the intersegmental ridges (Ac, Ac), but in which
the primary sternites (St) and intersternites (/st) are distinct. B, the tergal
region of the thorax in an insect in which the precostae (A, Pc) are enlarged to
form postnotal plates (PN).
Ac, antecosta; ac, antecostal suture; DMcl, dorsal longitudinal muscles; /st,
intersternites ; JT, first abdominal tergum; L, positions of leg bases; Mb, secon-
dary intersegmental membrane; Pc, precosta; 1Ph, 2Ph, 3Ph, the three thoracic
phragmata; PN, postnotal plates; Sin, primary sternite; V Mcl, ventral longi-
tudinal muscles.
THE THORACIC TERGA
The dorsal plates of the insect thorax never retain in all three seg-
ments the simple structure of the definitive abdominal terga, and in
the Pterygota the mesothoracic and metathoracic terga are modified
in various ways correlated with the development of the wings.
The prothoracic tergum (fig. 4, 7) always lacks an antecosta, and
the principal longitudinal muscles (DMcl) that extend forward from
6 SMITHSONIAN MISCELLANEOUS COLLECTIONS voL. 82
the anterior phragma of the mesotergum (zPh) run continuously
through the prothorax and the neck (Cv) to be inserted on the post-
occipital ridge of the head (PoR). This ridge, as the writer has else-
where contended (1928), is evidently the intersegmental fold between
the first and second maxillary segments. The neck, therefore, must be
derived from the posterior part of the second maxillary, or labial,
segment and from the anterior part of the prothorax, there being no
satisfactory evidence of the existence of a separate neck segment.
If so, the first postcephalic intersegmental line, or that between the
labial and prothoracic segments (fig. 4, 1/sg), must be contained in the
membranized cervical region, where the protergal costa is lost. By the
suppression of the primary intersegmental line between the head and
Fic. 3—Diagram of the body segmentation of an insect, and the primitive
relation of the longitudinal muscles to the definitive segmental plates of the body
and to the head; showing the reversed overlapping of the sterna between the
thoracic and abdominal regions.
Cv, cervix; DMcl, dorsal longitudinal muscles; H, head; /S, first abdominal
sternum; JT, first abdominal tergum; Ppt, periproct, or terminal segment;
Si, S2, Ss, thoracic sterna; 71, Tz, Ts, thoracic terga; V Mcl, ventral longitudinal
muscles; XJ, eleventh abdominal segment.
the thorax, giving continuity to the muscle fibers of two segments,
the head acquires a much greater freedom of motion than it could
have if it were attached to the body by an ordinary intersegmental
membranous ring.
The loss of the protergal antecosta deprives the prothorax of the
possibility of being a wing-moving segment, and there is nothing to
suggest that the prothorax ever possessed movable organs of flight.
The reduction of the primitive gnathal region of the body and its con-
densation into the head capsule, accompanying the transfer of the
enathal appendages to the head, shifted the center of gravity pos-
teriorly in the insect’s body, and the paranotal lobes of the second and
third thoracic segments were developed into movable wings, leaving
the prothorax as a free segment between the head and the pterothorax.
The most conspicuous modifications of the thoracic terga occur in
the mesothorax and the metathorax of winged insects, where clearly
NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS I
they are correlated with the part the terga of these segments play in
the mechanism of flight. In the Apterygota the corresponding terga
are simple plates showing none of the special characters of the wing-
bearing plates of pterygote insects.
The first important tergal modifications connected with the develop-
ment of the paranotal lobes into movable organs of flight pertain to
the ridges upon which the dorsal muscles of the mesothorax and
metathorax have their attachments. These ridges, which are the ante-
costa of the mesotergum, the antecosta of the metatergum, and the
antecosta of the first abdominal tergum, bear each a pair of apodemal
plates, varying in size, that project into the body cavity to give in-
creased surfaces of attachment for the greatly enlarged dorsal muscles
(fig. 2 B, DMcl) which have become depressors of the wings. The
antecostal apodemes, primarily intersegmental, are the thoracic phrag-
mata (IPh, 2Ph, 3Ph).
The lengthwise pull of the dorsal muscles on the phragmata de-
mands sclerotic continuity in the dorsum, since the function of these
muscles as depressors of the wings depends on their ability to produce
a dorsal curvature in the terga on the relaxation of the antagonistic
tergo-sternal muscles. To insure action by the dorsal muscles the
intersegmental membranes between the mesotergum and metatergum
and between the latter and the first abdominal tergum must be prac-
tically eliminated, and their suppression has been accomplished either
by a fusion of the succeeding terga, or by a forward extension of the
precostal lips of the terga into the territory of the membranes. In the
second case, the precostae become postnotal plates (fig. 2 B, PNs,
PN;), often of large size, lying behind the true tergal plates of the
mesothorax and metathorax (72, T;), where they appear to be parts
of these segments, to which, in fact, they do belong since they lie
anterior to the antecostal sutures (ac, ac) which are the primary
intersegmental lines.
In those insects in which the fore wings are the principal organs of
flight, the second thoracic phragma becomes partially or wholly de-
tached from the metatergum, and both the phragma and the postnotal
plate establish a: close association with the mesotergum, while the ex-
tremities of the postnotum commonly unite for security with the pos-
terior dorsal angles of the mesothoracic epimera. In those insects in
which the hind wings’ have taken on the chief function of flight, the
middle phragma always remains attached to the metatergum, and the
precosta is not enlarged. The third phragma may preserve its connec-
tion with the first abdominal tergum, as it does in the Orthoptera
(fig. 25, PN;), but in most cases it becomes more or less separated
8 SMITHSONIAN MISCELLANEOUS COLLECTIONS VoL. 82
from the abdomen and, together with the precosta, becomes trans-
ferred to the metathorax, where the precosta forms a distinct post-
notal plate united laterally with the epimera. Thus it is usually found
that the segment which assumes the leading role in the flight mechan-
ism is provided with a phragma at both its anterior and its posterior
end.
Since the tergal plates of the mesothorax and metathorax are the
intermediary elements in the wing mechanism between the dorsal mus-
ie ye / \ Ke !
SA, 5; 15s Db: 2cS
Fic. 4.—Diagram of the typical relation of the head and the prothorax in
pterygote insects.
Cv, cervix; Icv, 2cv, first and second lateral cervicai sclerites; DMcl, dorsal
longitudinal muscles; H, head; r/sg, 2Isg, first and second primary interseg-
mental lines; rPh, first thoracic phragma; Poc, postocciput; PoR, postoccipital
ridge; PT, posterior arm of tentorium; Si, S2, thoracic sterna; SA, sternal
apophyses; Ss, spinisternites; 71, 72, thoracic terga; V Mcl, ventral longitudinal
muscles.
cles of the segments and the bases of the wings themselves, it is clear
that a proper execution of their function depends upon the ability of
each to respond to the muscle tension at its ends with a dorsal curva-
ture reaching its maximum at the transverse line between the wing
bases. For this reason, as Weber (1924, 1925) has pointed out, the
terga of the wing segments are provided with’internal ridges so ar-
ranged that the force of the muscles will not merely deflect the an-
terior and posterior parts of the plates, but will be distributed gradu-
ally toward the middle from each extremity, and thus produce an even
dorsal flexion with its apex between the fulcra of the wings.
NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 9
The posterior gradient of an alar tergum usually has the form of a
V-shaped ridge with the apex directed forward and the arms diverging
toward the posterior lateral angles of the tergum (fig. 5 B, VR). The
anterior gradient is less commonly developed than the posterior one,
but, when present, it generally consists of two ridges, the parapsidal
ridges (fig. 5 B, Pak), converging from the anterior margin of the
tergum toward the middle, where they usually terminate without meet-
ing. In some insects the anterior part of the tergum is strengthened
by a transverse prescutal ridge (PR). In addition to these more gen-
eral endoskeletal structures of the tergum, there may be present also
Pe Pse JE ps acs ee Pse Ph PR Ac
Aw \ a X
we fff] i} IX Hh =A i
AxC Rd A\ B oe
Fic. 5.—Structure of a wing-bearing tergum, not including a postnotum,
diagrammatic.
A, dorsal. B, ventral. Ac, antecosta; acs, antecostal suture; ANP, anterior
notal wing process; AC, axillary cord; Aw, prealar process of tergum; Em,
lateral emargination of tergum; Pak, parapsidal ridge; pas, parapsidal suture;
Pc, precosta; Ph, phragma; PNP, posterior notal wing process; PR, prescutal
ridge; ps, prescutal suture; Psc, prescutum; Fd, posterior fold, or reduplication,
of tergum; Sc/, scutellum; Sct, scutum; VR, V-shaped ridge; vs, suture of the
V-ridge, or scuto-scutellar suture; W, base of wing.
a variety of accessory ridges, or even lines of flexibility in the tergal
cuticula ; but all such features are highly variable in different groups
of insects, and homologies can be traced between them only within
limited groups.
On the outer surface of the tergum the positions of the endoskeletal
ridges are marked by the lines, or “sutures,” of their inflection
(fig. 5 A, ps, pas, vs). The tergal areas defined in this manner by the
more constant of the inner structures can be identified as homologous
in different insects, and some of them have been given distinctive
names used in descriptive works (fig. 5 A, Psc, Sct, Scl). It is quite
impossible, however, to follow the lesser modifications consistently
through the various orders of winged insects, and attempts to do so
have only led to confusion. In any case, it must be recognized that
IO SMITHSONIAN MISCELLANEOUS COLLECTIONS VoL. 82
the external “ divisions”’ of the wing-bearing terga have no signifi-
cance in themselves ; they are merely incidental to the formation of
the internal ridges by cuticular inflections, the ridges being the true
functional structures adapting the tergum to its part in the flight
mechanism.
THE THORACIC PLEURA
The lateral walls of arthropod segments, or the areas along the sides
of the body between the terga and the sterna, when dorsal and ventral
plates are present, may properly be designated the pleural regions.
The pleural areas of the segments are primarily membranous, and
Fic. 6.—Diagram of the theoretical elementary musculature of the segmental
appendages.
a-b, primitive dorsoventral axis of the appendage; J, tergal promotor muscle;
J, tergal remotor; K, sternal promotor; ZL, sternal remotor; 7, tergum;
S, sternum.
within them are implanted the bases of the limbs (fig. 6). In some
arthropods, as in many of the Arachnida, each limb basis occupies
almost the entire space between the tergum and the sternum, and may
be articulated to one or the other of these plates, or to both of them.
In most cases, however, a membranous area partially or entirely sur-
rounds the limb base. In this area there are sometimes developed true
pleural sclerites, as in the chilopod family Geophilidae, where there
is a series of lateral plates of the body wall lying between the terga
and the leg bases (fig. 8 A, pl), or in the larvae of some insects where
similar plates occur on the sides of the abdomen. In many arthropods,
however, there are plates in the definitive lateral walls of certain seg-
ments that appear to have been derived from the bases of the appen-
dages. While such sclerotizations are, therefore, not true pleural prod-
ucts, they are generally termed pleuwrites, and those of each side of each
segment constitute collectively the so-called pleuron of the segment.
NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—-SNODGRASS Il
It is claimed by Becker (1923, 1924) that the pleurites, the coxae,
and the trochanters in the Chilopoda are formed, during the develop-
_ ment of the individual, from numerous schlerotizations in the lateral
-Eppd
SY
y)
(S 4:
Fic. 7.—Maxillipeds and pleuron of a decapod crustacean, Macrobrachium
jamaicensis.
A, first maxilliped, left, posterior surface. B, second maxilliped, right, an-
terior. C, third maxilliped, left, posterior. D, left pleuron, or inner wall of bran-
chial chamber.
Brn, branchia, gill; Cx, coxa; Cxpd, coxopodite; Endp, endopodite; Eppd,
epipodite; Expd, exopodite; Scx, subcoxa; 177Y, first trochanter.
walls of the body segments, which unite to form the definitive leg
bases and the pleural sclerites of the adult. Though the apparent
facts in the development of the chilopods may be as Becker describes
them, it is difficult to see how they can be interpreted literally as repre-
12 SMITHSONIAN MISCELLANEOUS COLLECTIONS VoL. 82
senting the phylogenetic origin of the definitive pleural plates and the
leg bases. It would seem more probable that they are ontogenetic phe-
nomena only, and that Becker’s observations really show simply that
the pleurites and the bases of the legs have a common origin.
In the decapod crustaceans the inner walls of the gill chambers,
which are covered externally by lateral folds of the carapace, are
formed of large cuticular plates bearing the gills (fig. 7 D). Each
plate, or pleuron, shows subdivisions (Sc1.-Sc#s) corresponding with
the body segments of the ambulatory legs, and each subdivision bears
a gill (Bra.-Brng). In the second maxilliped (B) the homologue of
the gill is borne on an epipodite (Eppd) which is distinctly carried by
/ x
PO ex Stem. Act B
Fic. 8—A body segment of Strigamia bothriopus (Chilopoda, Geophilidae).
A, lateral view, with leg removed beyond the coxa. B, ventral view, including
bases of legs. Cx, coxa; /st, intersternite; pl, pleurites between the tergum and
the subcoxa; Sex, subcoxa ; ‘Sp, spiracle ; Sin, primary sternite; 7, tergum; Ty,
trochanter.
the basal segment of the appendage, or coxopodite (Cxpd). In the
third maxilliped (C), however, the gill arises from a subcoxal part of
the limb basis (Scx). In the ambulatory region (D) the gills on the
pleuron are successively more and more removed from the coxae. It
thus becomes evident that the pleural wall of the branchial chamber in
the decapod crustaceans has been formed from dorsal extensions of
the subcoxal parts of the leg bases, and that the coxae have acquired
special articulations with the subcoxae. In the majority of crustaceans
the leg base is an undivided coxopodite.
In the Chilopoda there is a definitely circumscribed subcoxal area
about the base of each leg, which may be continuously sclerotized, as
in Strigamia (fig. 8 A, Scx), or which may contain one or more
sclerites, as in Lithobius (fig. 9), Scolopendra, or Scutigera (fig. 10).
The coxa is usually articulated to a sclerotized part of the subcoxa
dorsally (fig. 10 A, c), or ventrally (figs. 9, 15, d) ; but since the axis
NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 13
Fic. 9.—A body segment and leg of Lithobius (Chilopoda), left side.
c, dorsal articular point of coxa; Cx, coxa; d, ventral articulation of coxa with
subcoxa; Fm, femur; Ptar, pretarsus; S, sternum; Scx, subcoxa; Sp, spiracle;
T, tergum; Jar, tarsus; 7b, tibia; 17r, first trochanter; 277, second trochanter.
pe == i
Y
cpl ~ 4
dk
Fic. 10.—The leg base of Scutigera forceps (Chilopoda).
A, external view of base of a left leg and part of segment. B, internal view
of base of right leg, showing muscles.
c, dorsal subcoxo-coxal articulation; cpl, supra-coxal plate of subcoxa; Cy,
coxa; Fu, furca; J, tergal promotor muscles; J, tergal remotor muscle; K,
sternal promotor; L, sternal remotor; M, subcoxo-coxal muscle; JN, sternal
adductor of coxa; N’, furcal adductor of coxa; Scx, subcoxa; Stn, segmental
sternite; 7, tergum; 177, first trochanter.
14 SMITHSONIAN MISCELLANEOUS COLLECTIONS voL. 82
of movement in the coxa is always between its dorsal and ventral
angles, we may presume that the chilopod coxa has had both a dorsal
and a ventral articulation with the subcoxa (fig. 1, c, d), though one
or the other, or both of the articulations (fig. 8) may lose the struc-
ture of definite articulating surfaces.
In the geophilid Strigamia bothriopus (fig. 8) the subcoxal area of
the pleuron has the form of a complete basal limb segment (A, Scr),
though its ventral margin is expanded and united with the sternum
(B), and the coxa turns upon it by an obliquely vertical axis. In
Scolopendra, Lithobius (fig. 9), and Scutigera (fig. 10) the subcoxal
area is mostly membranous, but it contains one or more well-sclerotized
plates.
The tergal muscles of the leg bases in the Chilopoda are inserted not
on the coxae but on the subcoxae. In Scutigera the tergo-subcoxal
muscles are strongly developed, those of each leg comprising a pair
of anterior (promotor) muscles (fig. 10 B, J) inserted upon the dorsal
plate (coxopleure, cpl) of the subcoxal region, and a single large
posterior (remotor) muscle (J) inserted on the posterior dorsal mar-
gin of the subcoxal region.
The structure and musculature of the subcoxal region in the
Chilopoda can leave little doubt that this area is the true base of the
leg, which has become flattened into the lateral body wall, where, in
most forms, its sclerotization has been more or less broken up and
reduced. The sternal muscles of the leg base in the chilopods have
gone over to the ventral rim of the coxa (fig. 10 B). They include
an anterior (ventral promotor) muscle (K) and a posterior (ventral
remotor) muscle (L). In Scutigera (fig. 10) the first of these mus-
cles arises in the anterior lateral angle of the sternum, but in Scolopen-
dra the corresponding muscle arises mesally on the anterior half of
the sternum. The fibers of the posterior muscle in Scutigera (fig. 10 B,
L) are mostly continuous from one coxa to the other, but a small
anterior group on each side arises on the sternum at the base of the
ligamentous endosternal furca (Fu). In Scutigera the coxa has no
ventral articulation with the subcoxa or the sternum, but in those
chilopods in which a ventral subcoxo-coxal articulation is present, the
anterior and posterior ventral muscles (K, L) must act as promotors
and remotors.
The base of the coxa in the Chilopoda is provided also with median
dorsal and ventral muscle. The dorsal median muscle in Scutigera
(fig. 10 B, M) consists of a flat band of short fibers arising on the
dorsal plate of the subcoxa (cpl), and is inserted on the rim of the
coxa just behind the dorsal articulation with the subcoxa. This muscle
—— *
NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS T5
appears to be a remotor of the coxa in Scutigera, though it may have
an abductor function also. The ventral median muscles of Scutigera
comprise two bundles of fibers, one arising medially on the sternum
(fig. 10 B, NV’), the other (V’) arising on the lateral arm of the en-
dosternal furca. These muscles are coxal adductors since the coxa
has no fixed ventral articulation in Scutigera. The ventral coxal mus-
cles are covered dorsally by large bands of trochanteral muscles that
take their origin on the sternum.
Fic. 11.—Diagram of the basal musculature of an insect leg.
Bs, basisternum; Cx, coxa; J, tergal promotor muscle; /, tergal remotor;
K, sternal promotor (anterior rotator); k, furcal suture; L, sternal remotor
(posterior rotator) ; 17, abductor of the coxa; M’, M”, abductors of the coxa
that become the basalar and subalar muscles in the wing-bearing segments of
adult insects; N, adductor of the coxa; SA, sternal apophysis; Scx, subcoxa;
SI, sternellum; T, tergum; 7, trochantin.
In the insects the sclerotic areas of the subcoxae of the legs evi-
dently become the pleural plates of the thoracic segments. The tergal
promotor muscle of the leg base (fig. 11, 7) retains its connection with
the subcoxa in the more generalized pterygote insects, being inserted
on the, trochantinal sclerite of the subcoxa (7) except when the
trochantin is lost, the muscle then having its insertion on the anterior
angle of the coxal base. The remotor muscle (/), which may be repre-
sented by several fiber bundles, is always inserted on the coxa or on
coxal apodemes. The anterior and posterior sternal muscles (K, L)
arise on the sterna or the sternal apophysis, or on the spinasternum.
16 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82
The median coxal muscles are represented in insects by both dorsal
(M) and ventral (NV) fibers. In the wing-bearing segments of ptery-
gote insects the first comprise three distinct groups of abductor fibers
(M, M', M") arising dorsally on the pleuron, and inserted ventrally
on the coxa both anterior and posterior to the dorsal articulation of
the latter (c). The second and third muscles of this group (M’, M”)
Fic. 12—Thoracic pleural sclerites of Apterygota.
A, lateral view of left side of mesothorax of Acerentomon doderoit (from
Berlese, 1910). B, thorax, base of head, and base of abdomen of Jsotoma sp.
(from Ewing, 1928). C, left mesothoracic leg turned forward, and lateral re-
gion of mesothorax of Acerentulus barberi (from Ewing, 1928).
c, dorsal articulation of coxa; Cx, coxa; d, ventral articulation of coxa; Fm,
femur; H, head; JT, JIT, first and second abdominal terga; Ptar, pretarsus;
S, sternum; Scr, subcoxa; 7:1, T2, T:, thoracic terga; Tar, tarsus; 7b, tibia;
Tr, trochanter.
become wing muscles in the adult by the partial or complete detach-
ment of the epipleural areas on which they arise to form the basalar
and subalar plates of the wing base. The ventral median muscle of the
coxa (JV) is present in insects that lack a ventral coxal articulation ;
it arises on the sternal apophysis and functions as a coxal adductor.
In the Apterygota the subcoxa becomes rudimentary. In most of
the Protura its sclerotization is reduced to two slender plates arched
concentrically over the base of the coxa (fig. 12 A, C, Scx), as shown
by Berlese (1910) and by Ewing (1928), though Prell (1913) has
NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 7
described the pleural sclerotizations of Eosentomon germanicum as
consisting of a number of small sclerites, which, however, fall into
two concentric series. (See Snodgrass, 1927, fig. 8.) In the Collem-
bola, as shown by Ewing (1928), the subcoxal sclerotizations of the
mesothorax and metathorax (fig. 12 B, Sca2, Scx3) consist in each
segment of two slender, supra-coxal arches ; the subcoxal sclerotiza-
tion of the prothorax (Sc) is a single plate with an incomplete sub-
division. In the Thysanura the subcoxal pleurites likewise take the
form of two arches over the coxal base, or they become reduced to a
single sclerite. The coxal and subcoxal musculature of the Aptery-
gota has been but little studied.
In the thoracic segments of the Pterygota the subcoxae evidently
become the sclerotized parts of the lateral segmental walls known as
the pleura (cf. figs. 1 and 13). The ventral rim of each subcoxa, lying
between the coxa and the sternum (fig. 13 A), may be reduced to a
membranous fold, though in rare cases it contains a large plate (fig. 17,
Ls., Ls3), and in others a rudimentary sclerite (fig. 16 A, Ls). In the
majority of insects, as has been shown by Weber (1928, 1928 a), the
ventral arc of the subcoxa has apparently fused with the primary
sternite to form a laterosternite of the definitive sternum (figs. 13 B,
ihe 0 Re Bod
The coxa of insects is universally hinged to the subcoxa by a dorsal
articulation (fig. I, c) ; it may also have either an anterior articulation
with the trochantinal piece of the subcoxa (fig. 13 B, e), or a ventral
articulation (A, d) with the ventral rim of the subcoxa or with the
subcoxal laterosternite. The trochantinal articulation of the coxa is
peculiar to certain insects and is, therefore, probably a secondary one.
The ventral articulation, however, so frequently recurs both in the
Chilopoda (fig. 15, d) and in the more generalized insects (fig. 16 A,
B, d) that there can be little doubt that the primitive axis of the
subcoxo-coxal hinge was vertical or approximately so. The writer,
therefore, would retract the opinion, expressed in a former study of
the thorax (1927, pp. 34-36), that the primitive axis of the coxal
movement was a horizontal one between anterior and posterior articu-
lations with the eutrochantinal arch of the subcoxa. The ventral ar-
ticulation of the coxa is highly variable in insects ; it is always absent
in the more generalized Pterygota that have a well-developed trochan-
tin. In the members of the higher orders lacking a trochantin it is
commonly present, but it is to be suspected in such cases that the
articulation is a secondary one developed between the coxa and the
sternum.
2
18 SMITHSONIAN MISCELLANEOUS COLLECTIONS voL. 82
The usual trochantin of the pterygote pleuron (fig. 13 B, Tn) is
clearly a remnant of a more extensive, primitive, supra-coxal scleroti-
zation (fig. 1, Eutn) carrying the dorsal articulation of the coxa (c),
which Crampton (1914) has named the eutrochantin, and which is
best preserved in the ventral arch of the apterygote pleuron (fig.
12). The eutrochantin is retained as an independent sclerite also
in the prothorax of the Plecoptera, but in all other Pterygota (fig. 13,
Pe acs le Pe acs
ce ~ /
/ / \ , / \ i
yAN Ist Stn Sa Ist B Ps Es) Stn Sssciss)
Fic. 13.—Diagrams suggesting the development of the pterygote pleuron from
the subcoxa of the leg basis. (Compare with Fig. 1.)
A, subcoxal sclerotization (Sc) united ventrally with edge of primary ster-
nite (St), its dorsal extremity prolonged upward as a wing support (B, WP),
posterior part of entrochantin (fig. 1, Eutn) fused with eupleural arch (fig. 1,
Eupl) of subcoxa.
B, a fundamental structural condition of pleuro-sternal region of a wing-
bearing segment: the area of subcoxa differentiated into an episternum (Eps),
an epimeron (Epm), a precoxal bridge (Acx), a postcoxal bridge (Pcwx), a
laterosternite (Ls), and a trochantin (7); the definitive sternum includes the
primary segmental sternite (St), the following intersegmental intersternite, or
spinasternite (Ss), and a subcoxal laterosternite (Ls) on each side; the ventral
coxal articulation (A, d) is lost, and coxa has a secondary anterior articulation
with trochantin (ce).
A, B) its dorsal and posterior parts unite or fuse with the upper arch
of the pleuron (eupleuron), and only its anterior part remains as a
free sclerite (fig. 13 B, Tm) carrying the anterior coxal articula-
tion (@).
The elaborate pterygote pleuron has evidently been developed to
give support to the paranotal lobes, or to the wings evolved from the
latter. It is therefore strengthened by an internal ridge formed from
a linear inflection of its wall, the pleural suture (fig. 13 A, PIS), ex-
tending from the dorsal articulation of the coxa (c) upward to the
wing support (B, IP). The area lying posterior to the pleural suture
is the epimeron (B, Epm), that situated anterior to it and dorsal to
NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS IQ
the trochantin is the episternum (Eps). The sclerotized parts of the
subcoxa lying anterior and posterior to the coxa are the precovral and
postcoxal bridges (Acx, Pcx), or precoxalia and postcoxalia. The
ventral wall, or infra-coxal arc, of the subcoxa, as already noted, prob-
ably unites in many cases with the edge of the primary sternum (Stn)
to form a laterosternal element (Ls) in the definitive sternum, though
it may be reduced to a separate sclerite or form a membranous fold
between the coxa and the sternum.
All parts of the pleuron are subject to innumerable secondary modi-
fications taking the form of sutures that subdivide the primary areas,
of of membranous lines and spaces that break them up into separate
sclerites. Such modifications are not necessarily homologous between
different orders, but within an order or group of orders they may give
valuable evidence of the evolution and interrelationships of the fami-
lies and genera. An example of this is given by Shepard (1930) ina
study of the secondary pleural sutures of Lepidoptera.
In the wing-bearing segments of the Pterygota two large pleuro-
coxal muscles (fig. 11, M/’, WM”) become important muscles of the
wings. These muscles evidently are derived from the abductor system
of the coxa. In nymphal Orthoptera (fig. 27 C) the anterior muscle
(M’) has its origin on the dorsal part of the episternum, the posterior
muscle (/”) on the dorsal edge of the epimeron. In adult insects,
however, the areas upon which these muscles are attached become par-
tially or entirely separated from the pleuron and intimately associated »
with the base of the wing, the first lying before the pleural wing
process, the second behind it. In this way the muscles come to func-
tion as wing muscles, though each retains its ventral attachment on the
coxa.
The epipleurites (“paraptera”’), or sclerites detached from the
pleuron in connection with the coxo-alar muscles, include one or two
episternal sclerites, or basalares, and usually a single epimeral sclerite,
or subalare. The subalare is always completely detached from the
epimeron in adult insects (fig. 14 A, B, Sa). A basalar plate, how-
ever, is not always present as a distinct sclerite ; it frequently occurs as
but an imperfectly separated lobe of the upper end of the episternum
(fig. 14, Ba), and its area is sometimes marked only by the insertion
of the anterior coxo-alar muscle (/’). Even when the basalare is dis-
tinct from the episternum, it is generally hinged to the upper edge of
the latter in such a manner that it is deflected by the contraction of its
muscle. Frequently there is present a second basalar muscle (figs. 27 C,
E) having its origin on the pleuron or on the sternum.
.
20 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82
The theory of the origin of the principal pleural sclerites of the
Chilopoda and Hexapoda from subcoxal segments of the legs has
much in its favor. There is little evidence, however, that a subcoxa
is a primary segment in the general arthropod appendage. The limb
bases of the Arachnida, Xiphosura, and most Crustacea are the primi-
tive coxae (coxopodites), for there can be no doubt of the identity
of the coxo-trochanteral articulation in all arthropods. The writer
Fic. 14.—The mesopleuron and base of the middle leg of a scorpion fly,
Panorpa consuetudims.
A, external view. B, internal view, showing muscles. a, accessory sclerite
of basalar lobe; Ba, basalar lobe of episternum; bcs, basicostal suture of coxa;
Bex, basicoxite; Cx, coxa; Epm, epimeron; Eps, episternum; MM’, basalar
muscle; M”, subalar muscle; Mer, meron; O, levator muscle of trochanter ;
PIS, pleural suture; Sa, subalar sclerite; WP, pleural wing process.
clearly was mistaken in suggesting in a former paper (1927, p. 33)
that the large basal leg segments of the ticks (Ixodoidea) are sub-
coxal ; and he now believes that the segmentation of the arachnid limb
can be given an interpretation different from that proposed by Ewing
(1928), who would make the basal segment in most cases a subcoxa.
In the decapod crustaceans the inner walls of the gill chambers, as has
already been pointed out, are evidently expansions of the subcoxal
regions of the bases of the ambulatory legs, to which the coxae of the
latter have become articulated; but there is no evidence of the pres-
ence of subcoxal segments in the limbs of the more generalized Crus-
tacea. In the myriapods and insects, moreover, as the writer has else-
NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—-SNODGRASS 21
where shown (1928), there are no true subcoxal segments in the
mouth part appendages. From the evidence at hand, therefore, it ap-
pears most in accord with the known facts to conclude that the subcoxa,
wherever it occurs as a basal leg segment, has been produced by a
secondary subdivision in the primitive limb basis, or coxopodite.
THE THORACIC STERNA
Sternal plates are by no means so constant a feature in the scleroti-
zation of arthropod segments as are the tergal plates. They may be
present or absent within the same major group, and, where present,
(Chilopoda).
Cx, coxa; d, ventral subcoxo-coxal articulation; Jst, intersternite; Scx, sub-
coxa; Stn, segmental sternite; rT r, first trochanter; 27r, second trochanter.
they are often highly variable both in form and extent of development
between closely related groups and in the different body regions of
almost any species.
In adult insects the sternal mechanism of the thorax differs in three
important respects from that of the abdomen, and the functional dif-
ferences in the two body regions are reflected as three distinctive struc-
tural features in the sternal parts.
The first distinction to be noted in the sternal structure, as between
the thorax and the abdomen, pertains to the segmental relations of the
intersegmental sternites. In the abdomen of adult insects the inter-
segmental sclerotizations of both the dorsum and the venter are con-
tinuous with the segmental sclerotizations following, and the trans-
verse inflections in the cuticula of the primary intersegmental regions,
22 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82
on which the fibers of the longitudinal muscles are attached, become
the antecostae of the definitive terga and sterna (fig. 3). In the
thorax, on the other hand, the ventral intersegmental sclerotizations
either remain as small, free sclerites (fig. 1, Jst), or they unite with
the posterior parts of the segmental plates preceding. The interseg-
mental sternites, or intersternites, of the thoracic region are the
spinasternites (fig. 18 D, Ss), so-called because each usually bears a
small median apodemal process, the spina (fig. 4). A spinaster-
nite occurs typically between the prothorax and the mesothorax, and
between the mesothorax and the metathorax; there is never a free
spinasternite following the metasternum because the corresponding
intersegmental element goes with the first abdominal sternum to form
the antecosta of the latter, except where it is lost as a result of the
degeneration of the first abdominal sternum. The first spinasternite
is more commonly persistent than the second which is usually fused
into the posterior part of the mesosternum, where it may become
entirely obliterated.
The second structural difference between the thoracic and abdomi-
nal sterna accompanies the difference in the relations of the interseg-
mental sclerites to the segmental plates, but is not necessarily corre-
lated with it. It consists of a reversal in the overlapping of the sterna.
The successive abdominal sterna overlap regularly in a posterior direc-
tion, as do the terga of both the abdomen and the thorax (fig. 3). The
sterna of the thorax, on the other hand, overlap anteriorly. The meta-
thoracic sternum, therefore, stands as a dividing plate between the
anteriorly overlapping sterna of the thorax and the posteriorly over-
lapping sterna of the abdomen (fig. 3, S3).
This reversal in the overlapping of the sternal plates as between the
thorax and the abdomen is probably the oldest structural differentia-
tion between the two regions of the body, for it is well shown in some
of the Apterygota, particularly in Japyx, and is exhibited by all
pterygote insects in which the thoracic sterna remain free from each
other. It was probably, therefore, established when the thorax was
first set apart as the locomotor center of the body, and has nothing
to do with the development of the wings. Just what advantage accrues
to the thoracic mechanism from the reversed relations of its sternal
plates is not clear, but presumably it gives a better device for the
movement of the legs or for the movement of the successive seg-
mental plates on each other.
The third distinction between the thorax and the abdomen occurs
in adult pterygote insects, and pertains to the attachments of the ven-
tral muscles. We have assumed that the primitive attachments of the
NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 23
fibers of the longitudinal muscles are on the intersegmental folds or
on intersegmental sclerotizations (figs. 2, 3). The dorsal muscles
throughout the length of the body, and the ventral muscles of the
abdomen are thus attached, except where the anterior ends of the fibers
may have migrated to the segmental regions of the definitive terga
and sterna. In the thorax of adult pterygote insects, however, most
of the sternal muscles are stretched between paired apodemal processes
of the segmental sternites (fig. 4, SA,, SA2), except that the anterior-
most fibers are inserted anteriorly on the head, while the posteriormost
fibers extend into the abdomen. Only a few slender median muscles
retain a connection with the intersternites (7Ss, 2Ss). The paired
Fic. 16.—Sternal structure of ephemerid and odonate nymphs.
A, ventral surface of mesothorax, metathorax, and first abdominal segment
of an ephemerid nymph, showing ventral articulations of coxae (d) with sub-
coxal, laterosternal sclerites (Ls).
B, ventral surface of neck and prothorax of an aeschnid nymph, showing direct
articulation of coxae (d) with laterosternal parts (Ls) of the definitive sternum.
apophyses of the thoracic sterna are the so-called furcal arms, which
in the higher orders are united upon a common median base and here
constitute a true furca.
The anterior ends of the ventral muscle fibers, as we have noted, are
attached on the back of the head. In orthopteroid insects the attach-
ment is with the posterior arms of the tentorium (fig. 4, PT), but this
condition is clearly a secondary one since the posterior tentorial arms
are tergal apodemes. In many adult insects, and in most holometabo-
lous larvae, the anterior ventral muscles are inserted on the posterior
part of the head wall. Morison (1927) enumerates three pairs of
prothoracic sternal muscles in the honeybee, all of which are attached
anteriorly on the lateral occipital regions of the head. In the caterpil-
lars the corresponding muscles are inserted on apodemes of the ventral
margin of the foramen magnum. In all such cases the insertion points
of the ventral head muscles must have acquired their present positions
24 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82
by a migration from the true sternal region of the last head segment,
which is the membranous floor of the neck behind the base of the
labium.
The ventral muscles of the thorax retain apparently the primitive
condition in the larvae of most holometabolous insects. In the cater-
pillar, for example, the principal longitudinal ventral muscles consist
of two wide bands of fibers lying to each side of the ventral nerve
cord, extending through the entire length of the body, and attached
regularly on the intersegmental folds as are the dorsal longitudinals.
External to the dorsal and ventral intersegmental muscles of the cater-
pillar there is an intricate complex of small muscles disposed in all
directions against the wall of each segment.
In certain larval forms, as in some Coleoptera, the attachment of the
ventral body muscles shows a condition intermediate between the
usual larval condition and that of the adult. In the larva of Dytiscus,
for example, as shown by Speyer (1922), though most of the ventral
thoracic muscles are intersegmental, being attached either to processes
of the intersegmental folds or to transverse ligaments arising from
the folds, some of the fibers extend between segmental furcal apo-
physes, which are present on each primary sternal region of the
thorax. The ventral muscle bands of the thorax are continued into
the abdomen, some of the fibers of the first abdominal segment being
attached anteriorly on the intersegmental fold behind the metathorax,
others on the furcal arms of the metasternum. In the adult of Dytiscus
(Bauer, 1910) all the ventral muscles of the thorax are interfurcal in
their attachments, and none extends from the thorax into the abdomen.
Ventral muscles from the thorax into the abdomen are absent in the
adult stage of many pterygote insects (fig. 35), though they may be
present in the larval or the nymphal stages. In the nymph of Psylla
mali, according to Weber (1929), two bundles of fibers diverge from
the base of the metafurca to the anterior edge of the second abdominal
sternum, but these muscles, Weber says, are lost in the adult.
In some insects, however, the ventral thoracico-abdominal muscles
are present in the adult stage. They are well developed in the cock-
roach (Blatta orientalis), comprising here three pairs, the first arising
on the second spina, the second on a ligamentous bridge between the
bases of the metasternal apophyses, the third on the apophyses, all of
which are inserted posteriorly on the anterior margin of the second
abdominal sternum. The fibers arising on the metapophyses form the
anterior ends of the ventral longitudinal muscle bands of the abdomen.
In Gryllus, Voss (1905) describes a median pair of muscles arising
on the metafurca which branch posteriorly to the third, fourth, and
NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 25
fifth abdominal sterna, and two lateral groups on each side which go
to the parasternal plates of the second abdominal segment. In the
Cicadidae ventral muscles extend from the metathorax to the second
abdominal sternum. In the Tenthredinidae, according to Weber
(1927), a pair of muscles extends from the metafurcal arms to the
second sternum of the abdomen, and in the honeybee Morison (1927)
describes two corresponding pairs of muscles going from the meta-
furca to the anterior margin of the second abdominal segment. Inas-
much as these muscles, which represent the ventral muscles of the first
abdominal segment, have no connection with the first abdominal ster-
num, it is evident, as Morison points out, that their insertions, normally
on the intersegmental anterior edge of the first abdominal sternum,
have been secondarily transferred to the furcal apophyses of the meta-
thoracic sternum. In the Ephemerida, however, Diirken (1907)
records the presence of a pair of muscles attached anteriorly on the
bases of the metasternal apophyses and posteriorly on the anterior
margin of the first abdominal sternum. These muscles would appear
to correspond with the furco-spinal muscles, which are present in the
prothorax of the grasshopper (fig. 35, 61).
Even a brief review of the comparative musculature of larval and
adult holometabolous insects thus shows that there takes place during
metamorphosis a rearrangement in the attachments of the ventral
muscles of the thorax, and, in some cases, of those of the first abdomi-
nal segment, as a result of which most of the persisting fibers lose
their intersegmental connections and acquire segmental attachments on
the furcal apophyses of the thoracic sternal plates.
The larval condition of intersegmental muscle attachments is clearly
a more primitive one than that of the adult. The adults of insects with
incomplete metamorphosis resemble those of holometabolous forms in
having the principal ventral muscles attached on the furcal arms.
Therefore, we must suspect that the latter condition is one secondarily
acquired in all pterygote insects, and that it has come about during
the evolution of the thorax as a specialized locomotor region of the
body. Since the transposition of the ventral muscles takes place in
the prothorax as well as in the other two thoracic segments, we cannot
attribute its inception to the development of the wings. As yet, how-
ever, we may draw only tentative conclusions concerning the evolution
of the ventral musculature of the thorax, since our knowledge of the
nymphal muscles in hemimetabolous insects and of both the larval and
adult muscles in the more generalized holometabolous forms is very
incomplete ; but the facts known point strongly to the transformation
suggested above.
26 SMITHSONIAN MISCELLANEOUS COLLECTIONS voL. 82
An alteration in the attachment of the ventral muscles similar to
that which evidently has taken place in insects may be observed also
in the Chilopoda, here between members of different families. In the
Geophilidae and in Lithobius the ventral longitudinal muscles consist
principally of two flat, widely-separated bands of fibers lying close
against the body wall and inserted on intersegmental sclerotizations.
Fic. 17.—Ventral view of the base of the prothorax, the mesothorax, the
metathorax, and the base of the abdomen of the large South American embiid,
Cylindrachaeta spegazzinii.
d, ventral articulation of coxa with subcoxal laterosternite (Ls); k, furcal
suture; /, secondary suture of mesosternum; Ls, laterosternite; 1S:, anterior
plate of mesosternum; 252, posterior plate of mesosternum (furcasternite) ;
T,, ventral fold of protergum.
In Scolopendra and Scutigera, on the other hand, both the longitudinal
ventral muscles and many other muscles of each segment are attached
on two ligamentous supports that arise from the posterior parts of the
segmental sternites. In Scolopendra each ligament has a separate
origin on the sternum ; in Scutigera the two ligaments in each segment
arise from a common base, forming thus a furca-like structure
(fig. 10 B, Fu) suggesting that of the higher pterygote insects.
It is scarcely possible that there is any genetic relation between the
furcal apophyses of insects and the muscle-supporting structures of
NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 27
Scolopendra and Scutigera, but it is clear that the muscle attachments
have been altered by a transposition which is of a parallel nature in the
two cases.
In the Chilopoda the sternal plates are uniformly developed through-
out the length of the body. In Strigamia, Lithobius, and Scolopendra
there is a series of alternating segmental sternites (figs. 8 B, 15, St)
and intersegmental intersternites (Ist). The intersternites are lacking
in Scutigera; they are highly developed in the geophilid Strigamua
bothriopus, where their lateral ends extend upward on the sides of the
body between the subcoxae (fig. 8 A), but they are small and incon-
spicuous in Lithobius (fig. 15). In both the geophilid and lithobiid
as we have seen, the longitudinal ventral muscle bands have their at-
tachments on the intersternites.
The presence of alternating sternites and intersternites in the chilo-
pods might suggest that this condition was the primitive one in in-
sects, and that the intersternites (spinasternites) have remained free
in the thoracic region or have united with the preceding sterna, while
they have fused with the segmental sternites following in the abdomen.
In the odonate larva shown at B of figure 16 there is a long interseg-
mental sclerite (27st) between the posternum (S;) and the mesoster-
num suggestive of the intersternites of the Chilopoda, and the fold
(zIst) in the ventral side of the neck (Cv), which bears the cervical
sclerites laterally (cv), appears to be likewise an intersternite between
the labial segment and the prothorax. In the Acrididae the spinaster-
nite between the prothorax and mesothorax (fig. 21, Ss) is a well-
formed plate attached to the prosternum (.S)) ; that between the meso-
thorax and metathorax is indistinguishably fused into the posterior
border of the mesosternum, though the spina persists (fig. 31, 25pm).
In many insects the first spinasternite is a free sclerite, and in the Blat-
tidae both the first and the second are distinct plates (fig. 19 A,
TS 29S):
The definitive thoracic sterna of most insects are undoubtedly com-
posite structures. The first and second intersternites are usually con-
tained in the posterior parts of the prosternum and mesosternum,
respectively, or at least are closely associated with them, though the
first frequently retains its independence. The ventral arcs of the sub-
coxae contribute laterosternal elements in many insects. The evident
union of the ventral rim of the subcoxa with the sternum has been
noted in the Hemiptera (Heymons, 1899, Snodgrass, 1927), but
Weber (1928, 1928a) has given ample reasons for believing that this
fusion of subcoxal elements with the primary sternum has taken place
in the majority of insects. The frequent ventral articulation of the
28 SMITHSONIAN MISCELLANEOUS COLLECTIONS voL. 82
coxae with the lateral margins of the sternum in generalized insects
(figs. 12 C, 16 B, d) is further evidence that the sternum in such cases
includes the infracoxal parts of the subcoxae, especially since it is
found that, where distinct subcoxal laterosternal sclerites exist (figs.
16 A, 17, Ls), the coxae articulate with these sclerites (d).
It is difficult to find in the insects a good example of a simple pri-
mary sternal plate, comparable with the sterna of the Chilopoda (fig.
15), that does not contain either the following intersternite or sub-
coxal laterosternal elements, or both. In the mesothorax and meta-
thorax of the ephemerid nymph shown in figure 16 A, the sterna
(Sz, Ss) may contain the intersternites, but the two small sclerites
in each segment (Ls, Ls) that articulate between the sternum and the
coxa on each side appear to be the only remnants of subcoxal lateroster-
nites. In the large embiid Cylindrachaeta (fig. 17) laterosternal plates
(Lsz, Ls3) likewise are distinct, though the intersternites are clearly
united with the primary sternites. In the prothorax of the aeschnid
larva shown in figure 16 B the intersternite (2/st) is independent of
the sternum, but the laterosternites (Ls) are fused into the lateral
sternal margins.
These several forms make it clear that the definitive thoracic ster-
num of insects is typically a compound plate. It consists of a primary
sternite (fig. 18 A, B, Stn), to which may be added the succeeding
intersternite (Ist), which becomes the spinasternum (C, D, Ss), and
a pair of laterosternites (D, Ls, Ls) derived from the ventral arcs of
the adjoining subcoxae (B, C, Scr).
The possession of paired apophyses, or furcal arms, is character-
istic of the thoracic sterna of all pterygote insects. The apophyses
arise from the sternal plates between the bases of the legs, and their
outer ends are usually closely attached, either by fusion or by short
muscle fibers, to the inner ends of the corresponding pleural apophyses.
Weber (1928, 1928a) advances the view that the sternal apophyses
are primarily invaginations formed on the line of union between the
primary sternites and the subcoxal laterosternites. In some insects,
however, in which there are laterosternal plates not united with the
sterna (figs. 16 A, 17), the origins of the sternal apophyses (sa) are
still well within the sternal margins; and in an aeschnid nymph (fig.
16 B) the apodemal invaginations (sa, sa) are removed from the
apparent margins of the laterosternite sections (Ls) of the definitive
sternum. From evidence of this nature the writer would regard the
sternal apophyses as invaginations in the primary sternal plate itself
(fig. 18 B, Stn), though there is much in favor of Weber’s view. The
mesosternum of wingless females of the black aphis, Aphis fabae,
NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 29
Weber (1928a) says, presents a case in which there can be no doubt
that the furca arises at a point between the basisternite, the furcaster-
nite, and the subcoxal laterosternite.
In the higher insects the sternal apophyses approach each other in
each segment and unite upon a common basis produced by a median
Fic. 18.—Diagrams suggesting the theoretical evolution of a thoracic sternum.
A, primitive condition in which the ventral sclerotization consists of alter-
nating segmental sternites (Stn) and intersegmental intersternites (Jst); the
leg basis (LB) is an undivided coxopodite.
B, primary sternite marked by the pits (sa) of a pair of internal apophyses,
intersternite (/st) by the pit (spn) of a median process, or spina; leg basis
(A, LB) subsegmented into subcoxa (Scr) and coxa (Cx), articulated dorsally
and ventrally (d).
C, area of primary sternite (A, B, Stn) divided into basisternum* (Bs) and
sternellum (S/) by a furcal suture (k) forming an internal furcal ridge between
bases of sternal apophyses; the following intersternite has become a spinaster-
num (Ss) by union with segmental sternite; subcoxa (Scr) united ventrally
with sternum.
D, typical definitive sternum, composed of primary sternite (A, B, Stn), a pair
of subcoxal laterosternites (Ls, Ls), and the spinasternite (Ss); area of pri-
mary sternite divided into basisternum (Bs) and sternellum (S/) by the furcal
suture (k), and with a narrow presternum (Ps) set off by a secondary presternal
suture (7).
inflection of the sternal wall. In this way is formed the typical, forked
endosternal structure known as the furca, the evolution of which has
been portrayed by Weber (1928). The part of the sternum bearing
the furca lies between the coxae, and is usually much narrowed by
comparison with the region of the sternum anterior to it.
The definitive sternal plate, whether it includes subcoxal lateroster-
nal elements and the following intersternite, or does not, is commonly
subdivided into an anterior and a posterior region. Fundamentally the
30 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82
dividing line is a transverse inflection, or “ suture,’ passing through
the bases of the sternal apophyses (fig. 18 C, k). The inflection is
usually strongly sclerotized, forming an internal ridge evidently de-
signed to brace the sternum and to support the apophyses (figs. 21 B,
31, k) ; it sometimes remains weak, however, and establishes a line
of flexibility in the sternum. In either case the sternum is demarked
by the furcal ridge and its suture (k) into a prefurcal area (fig. 18 C,
Bs) and into a postfurcal area (ST).
The anterior region of the sternum has been variously named
sternum, in a restricted sense, antesternum, mesosternum, basisternum,
eusternum, and sternannum; the second has been called sternellum,
poststernum, metasternum, and furcasternum. There are objections
to all but one of these terms. ‘“‘Antesternum” and “ poststernum ”
(Amans, 1885) are applicable in some cases, but there is often a pre-
sternal piece before the “‘ antesternum,” and very commonly the inter-
segmental spina-bearing plate forms an actual posternal element of the
definitive sternum behind the “ poststernum.” ‘“ Mesosternum ” and
““metasternum ” (Berlese, 1909) violate the priority of the segmental
prefixes. “ Basisternum ” and “ furcasternum ”’ (Crampton, 1909) are
misleading because the part designated by the first is not basal,.and that
bearing the second name does not always carry the furcal apophyses.
“ Eusternum ” (Snodgrass, 1910) implies that the part so named is
the “true” sternum, which it is not. “ Sternannum” (Mac Gillivray,
1923) has no grammatical standing, so far as the writer can find.
“ Sternellum ” (MacLeay, 1830) alone can be given a clean bill. Of
the terms applied to the prefurcal area, however, “ basisternum ” ap-
pears to be the least objectionable. In the present paper, therefore,
the writer adopts the following terms for the principal divisions of the
definitive sternum (fig. 18 D): presternum (Ps), basisternum (Bs),
sternellum (Sl), and spinasternum (Ss). The first three are secon-
dary subdivisions of the primary segmental sternum; the fourth is the
intersegmental intersternite. To the primary sternal region there may
be added on each side a subcoxal laterosternite (Ls).
The parts of the definitive thoracic sternum as described here fit
exactly with the definitions of the sternal sclerites given by Weber
(1928, pp. 250, 251), with the understanding that the term “ sternel-
lum” is substituted for “ furcasternum,” and that the poststernite is
the intersegmental spinasternite. This idea of the sternal composition
differs from Crampton’s (1909) conception in that the fundamental
transverse dividing line of the sternum is assumed to be the furcal
suture (k) between the bases of the sternal apophyses, and not a divi-
NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 31
sion anterior to the apophyses. A prefurcal division sometimes does
occur (fig. 17, 1), but it is clearly of a secondary nature and is vari-
ously produced.
The furcal suture is subject to much diversity in form, being some-
times produced forward and branched laterally, or curved posteriorly,
thus giving a variety of structure to its apodemal ridge, and often
obscuring the primary line of the sternal division.
The form and size of the sternal plates are frequently altered by a
variation in the extent of the ventral sclerotization in the different
thoracic segments. In the Blattidae it is evident that a partial de-
sclerotization of the sternal cuticula has produced the unusual shapes
and relationships of the sternal sclerites of the thorax (fig. 19). The
prosternum most nearly preserves the typical form (B). It comprises
two median plates (A, Bs,, Sl,) separated by a transverse fold (k)
across the sternal region, from which arise the prosternal apophyses
(SA,). A comparison with the assumed generalized structure of a
thoracic sternum (B) will easily suggest that the transverse fold is the
furcal suture (k), and that the pattern of the prosternal plates (C)
has been produced by suppression of sclerotization in the lateral fields
of the sternal area. In the mesothorax of Blatta (A) the ventral sclero-
tization is reduced to a pair of basisternal plates (Bs.), and a Y-shaped
furca-bearing sclerite (S7,), the two separated by an ample mem-
branous area. In the latter are remnants of the sternal fold (k) from
which arise the sternal apophyses (SA.) at the ends of the sternellar
arms. The diagram D shows more clearly the relation of the mesoster-
nal structure in the roach to the fundamental sternal structure (B),
and again suggests that the peculiar features of the thoracic sterna of
the roach are results merely of a reduction in the extent of the sclero-
tized areas. The metasternum of Blatta (A) is essentially the same as
the mesosternum, but the sternal fold appears to be suppressed and the
apophyses (SA;) arise from the sternellum (S7;).
In some insects a thoracic sternum may be divided into two parts by
a suture that is quite independent of the furcal suture. A clear case
of this is seen in the thorax of the large embiid Cylindrachaeta (fig.
17), where a suture (/) cuts the mesosternum into an anterior plate
(1S,) and a posterior plate (2S.). The second plate is marked by the
usual furcal suture (k) and bears the furcal arms; it is a true furca-
sternite. The metasternum has the usual structure, though the sternel-
lum is reduced to a narrow band behind the furcal suture (#).
Most entomologists have believed that the sternum of a thoracic
segment of an insect is “composed of ” two principal plates, and the
32 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82
pattern of the sternal sclerites in the cockroach (fig. 19) has had much
to do with establishing this idea, for students have not recognized
that the separated plates here are products of sclerotic degeneration,
and that the fundamental structure, as shown best in the prothorax,
is the same as in insects with undivided thoracic sterna. While the
Blattidae undoubtedly retain some relatively generalized structural
sa A
Fic. 19.—The thoracic sterna of a cockroach, Blatta orientalis.
A, general view of the three thoracic sterna and their paired apophyses. B,
diagram of typical structure of a sternum. C, diagram of prosternum of Blatta.
D, diagram of mesosternum of Blatta.
Bs, basisternum; JS, first abdominal sternum; k, furcal suture; SA, sternal
apophysis; sa, external pit of sternal apophysis; SJ, sternellum; spn, external
pit of spina; Ss, spinasternum; S, segmental sternum.
characters, they are in many respects highly specialized insects adapted
to a particular kind of habitat, though to one almost universally dis-
tributed. The flattening of the body has been accompanied by a struc-
tural alteration in most of the under parts of the thorax, and there is
every reason to believe that the sterna, covered as they are by the bases
of the legs, have become largely membranized to allow of an inflection
of their posterior parts. We should be on very unsafe ground, there-
fore, if we take the fragmented condition of the sternal sclerotization
NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 33
in the thorax of the roach as representative of the primitive structure
of the thoracic sterna in insects.
A search for a generalized thoracic sternum among all groups of
insects, the writer believes, would reveal nowhere the thing sought for,
because it does not exist. A study of the arthropods as a whole, how-
ever, suggests that the original area or areas of sclerotization in the
ventral region of each segment spread into a continuous plate between
the leg bases. The thoracic sterna of insects have been variously modi-
fied by the development of apodemal braces where rigidity is demanded,
and by secondary divisions or by reductions in the areas of sclerotiza-
tion where flexibility is important. This theory recommends itself by
the fact that it permits all kinds of specific structures and sclerotic
patterns to arise, and does not assume that homologies must exist
where none can be established.
if. THE THORACIC SKELETON OF DISSOSTEIRA
The Carolina locust, Dissosteira carolina, is here used as the subject
for a special study of the thorax and its mechanisms because it is an
insect sufficiently large for work on internal structure and is readily
obtained, and because its muscular system is simple and comparatively
easy to dissect. The thorax of the Acrididae is by no means general-
ized, but for this reason it offers a good test for the application of gen-
eral principles to the solution of specific problems. The structural
features of the thorax in the locust, however, are those common to
all insects, and in the musculature there is almost no addition of special
muscles such as are found in most of the higher insect orders and to
some extent in the other orthopteran families.
The thorax of the jumping Orthoptera is so distinctly divided into a
prothorax and a pterothorax that it is scarcely to be regarded as a unit
in the organization of the body. The box-like structure of the com-
bined mesothorax and metathorax, the oblique slant of the pleurites
of these segments, and the firm connection of the first abdominal seg-
ment with the metathorax are characters evidently correlated with the
development of the hind legs as saltatorial organs.
THE CERVICAL SCLERITES
The grasshopper ordinarily keeps its head retracted against the pro-
thorax, in which position the insect appears to have no neck, for the
ample neck membrane (fig. 20 B, Cv), as well as the back part of the
head, is thus concealed within the projecting anterior rim of the
pronotum.
3
34 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82
The neck skeleton of Dissosteira consists of two pairs of small
cervical sclerites situated ventro-laterally in the membranous walls of
the neck (fig. 20 B, rcv, 2cv). The two sclerites of each pair in the
grasshopper are closely hinged to each other, and form a bridge on
each side between the head and the prothorax. The first sclerite (rcv)
is an irregularly triangular plate articulating with the occipital con-
dyle (fig. 32, g) of the posterior rim of the head, situated just above
the base of the posterior tentorial arm (A, PT). Immediately behind
its articulation this plate bears externally two small lobes that are
conspicuous by their covering of short hairs. The second cervical
sclerite (fig. 20, B, 2cv) is a slender bar articulating posteriorly with
the anterior margin of the prothoracic episternum (Eps) just within
the overlapping edge of the protergum. The two cervical sclerites of
each pair are movably hinged to each other at an angle directed ven-
trally. They are mostly concealed when the head is in the usual re-
tracted position, but they form a small prominence of the neck pro-
jecting just behind the base of the maxilla. The probable function and
mechanism of the cervical sclerites will be described in connection with
the account of the muscles inserted upon them.
The lateral, muscle-bearing cervical sclerites are probably homolo-
gous structures in all insects in which they occur. Dorsal and ventral
neck plates are presnt in some insects, but they are variable in size and
arrangement and are probably secondary sclerotizations of the neck
membrane.
THE PROTHORAX
The prothorax of the grasshopper is a highly individualized segment
of the body, for, though its posterior dorsal and lateral parts widely
overlap the anterior part of the mesothorax, it is separated from the
latter by an ample intersegmental membrane (fig. 20 B, Wb).
The external parts of the prothorax comprise tergal, pleural, and
sternal sclerites. The principal plate is the tergum, a large bonnet-like
piece that covers the back and most of the sides of the segment (fig.
20 A, T). Only a corner of each pleuron shows externally: this is
the small triangular lobe lying anteriorly between the base of the leg
and the lower margin of the tergum (fig. 20 A, Eps). The rest of the
pleuron is deeply invaginated within the lateral wall of the tergum
(B, Eps). The prosternum consists of two sclerites in the ventral wall
of the segment between the bases of the first legs (fig. 21 A, S, Ss),
the anterior one connected by the precoxal bridges (dcx) with the
pleura. The prothoracic legs appear to be inserted between the ster-
num and the lower edges of the tergum, but the lateral connections of
NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 35
the legs are really with the inflected pleura covered by the tergal ex-
’ tensions. The procoxal cavities are “ open” behind, that is, there are
no postcoxal sclerotizations. Lying before the coxa of each leg in the
articular membrane of the leg base is a small trochantinal sclerite
(fie. 20 A, Tn).
The protergum.—tThe tergum of the prothorax, besides covering
the back and sides of its own segment, projects posteriorly over the
dorsum of the mesothorax in a wide, triangular lobe which fits between
the bases of the folded front wings. The top of the tergal bonnet
Frc. 20.—The prothoracic tergum and pleuron of Dissosteira carolina.
A, outer view of left side. B, inner view of right side, showing episternum
invaginated within the tergum.
a, posterior edge of anterior fold of tergum; b, anterior edge of posterior fold
(B, Rd) of tergum; c, d, e, the external vertical grooves or sutures of the ter-
gum (A) forming the internal tergal ridges (B); f, g, h, 1, horizontal sutures
and their ridges connecting the vertical sutures and ridges.
(fig. 20 A, T) is cut by a deep transverse notch somewhat before the
middle, and the part before the notch is compressed into a median
ridge.
Each lateral area of the protergum is marked by a number of grooves
forming a definite pattern, and by two non-impressed lines. The first
non-impressed line (fig. 20 A, a) lies near the anterior border of the
tergum and runs parallel with it; the second (b) extends downward
in a sinuous course just posterior to the dorsal tergal notch. These
two lines mark the limits of the inner folds of the anterior and pos-
terior inflections of the tergal wall (B, a, b). The grooves of the tergal
surface (A, c-i) lie in the space between the two non-impressed lines.
They have no significance in themselves, but it is important to note
36 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82
their positions because they form ridges on the inner surface (B)
which have definite relations to the muscle attachments of the proter-
gum. The first (c) is a short curved line on the upper lateral part of
the tergum ; the second (d) is a longer line extending from the back
almost to the ventral margin of the tergum; the third (e@) begins at
the dorsal notch and reaches ventrally just before the second non-
impressed line (b) to the middle of the side. Connecting the three
vertical grooves are four short longitudinal grooves, one (f) lying be-
tween the first and second vertical grooves (c, d), the other three
(g, h, 1) between the second and third vertical grooves (d, e).
A study of the inner surface of the tergum (fig. 20 B) will show
the endoskeletal ridges (c-i) formed by the external grooves. There
~
Settee
Fic. 21.—The prothoracic sternum and pleura of Dissosteira.
A, ventral view of sternum and lower edges of pleura, showing the spina-
sternum (Ss) united with the segmental sternal plate (S), the latter continuous
with the episterna (Eps) by the antecoxal bridges (Acx). B, dorsal surface of
oa ee bases of sternal apophyses (SA, SA) united by a furcal
ridge (k).
will also be noted the anterior and posterior inflections of the tergal
walls. From the margin of the first inflection (a) the neck membrane
(Cv) is reflected forward, and from the margin (b) of the posterior
fold or reduplication (Rd) the intersegmental membrane (Mb) is
reflected posteriorly to the mesothorax. The first spiracle (Sp2) is
located in this membrane.
The propleura—-We have already noted that each pleuron of the
prothorax appears externally only as a small plate projecting from
beneath the edge of the tergum anterior to the base of the leg (fig. 20 A,
Eps). It is to be seen on the internal surface of either half of the seg-
ment (B), however, that the pleural piece exposed externally is merely
the lower anterior corner of a much larger triangular sclerite (B,
Eps) extended upward within the lateral tergal wall by a deep inflec-
tion of the tergo-pleural membrane. The posterior margin of the
sclerite is turned inward, forming the pleural ridge, which gives off
NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS Bl
the pleural arm (PIA) and ends ventrally in the articular process of
the coxa (CaP). Behind the lower part of the pleural ridge is a small
epimeral piece (Epm) fused with the lower border of the tergum and
concealed just within the edge of the latter. The anterior ventral angle
of the episternum is continuous through the precoxal bridge (Ac-+r)
with the anterior lateral angle of the prosternum (fig. 21 A).
The prosternum.—tThe sternum of the prothorax in the grasshopper
consists of two distinct plates (fig. 21 A, S, Ss) separated by a trans-
verse suture. The anterior plate (S) is the larger and the more
strongly sclerotized. It is continuous laterally with the precoxal bridges
(Acx) from the episterna (Eps). The definitive sternal plate of the
prothorax, then, evidently includes laterosternal elements derived from
the pleura (subcoxae), but the true pleuro-sternal limits are entirely
obliterated. The anterior rim of the sternum is set off as a narrow
presternal strip (Ps) by a submarginal external suture (A, 7) and
a corresponding internal ridge (B, 7). Posteriorly the first sternal
plate is marked by a deep transverse groove which forms a strong
ridge on its inner surface (fig. 21 B, k) between the bases of the
sternal apophyses (B, SA, SA), which latter are indicated externally
by a pair of pits (A, sa, sa). The first prosternal plate in the grass-
hopper, therefore, is divided in the primitive fashion (fig. 18 C) into
a basisternal and a sternellar region by the suture of a ridge connecting
the bases of the apophyses. The prosternal apophyses are simple arms
(fig. 21 B, SA) diverging dorsally and laterally. Their distal ends are
solidly united with the corresponding pleural apophyses.
The second prosternal plate (fig. 21, Ss) is a spinasternite, and is,
therefore, the intersternite between the prothorax and the mesothorax
which has become closely associated with the primary sternite of the
prothorax. It is mostly overlapped by the anterior margin of the
mesosternum. The spinasternite of Dissosteira is triangular in shape,
and is marked by a deep median impression (fig. 21 A) which forms
the spina internally (B, Spi).
THE PTEROTHORAX
The united mesothorax and metathorax of the grasshopper consti-
tute a unit in the body mechanism. The pleural and sternal walls of
the two segments are solidly united, forming a trough-like structure
perforated only by the openings of the coxal cavities. The leaping
force of the hind legs is thus applied to a rigid middle section of the
body, which also bears the wings. The dorsum of this body section is
covered by the mesothoracic and metathoracic terga, but these plates
38 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82
are freely attached to the upper pleural margins of the pterothoracic
trough by the ample membranes of the wing bases, and they are mov-
ably joined to each other. As we shall later see, the wing mechanism
demands at least a limited freedom of movement in the wing-bearing
terga.
In the grasshopper the back plates of the pterothorax (figs. 22, 24)
differ somewhat in shape and in details of form and proportion, but
the two have the same essential structure. They are relatively small,
and when the insect is at rest they are hidden beneath the folded wings.
The pleurites are defined externally by distinct grooves (fig. 26)
forming strong ridges internally (fig. 28), which slant posteriorly and
downward in a manner to suggest that they serve thus to brace the
pleural walls against the projectile force of the hind legs. The sterna
of the wing-bearing segments are wide plates fused laterally with the
pleura before the leg bases (fig. 30).
The mesotergum.—tThe tergum of the mesothorax (fig. 22 A) isa
rectangular plate ending posteriorly in a distinct, transverse fold (Rd),
the extremities of which are continued into the posterior thickened
margins, or axillary cords (Axc), of the wing bases. Close to the
anterior margin of the tergum is a deep groove (acs). This is the
antecostal suture, or primary intersegmental inflection which forms
the antecosta of the internal surface of the definitive tergum (B, Ac).
The antecosta bears laterally two wide, flat apodemal plates (zPh)
projecting into the cavity of the thorax (fig. 25), which are the first
pair of thoracic phragmata.
On the external surface of the mesotergum, two sutures (fig. 22 A,
ps, ps) diverge laterally and posteriorly from the antecostal suture
(acs). They form internally a pair of strong ridges (B, PF) extend-
ing to the bases of the anterior wing processes (ANP). The large, ir-
regular, triangular regions (A, Psc, Psc) forming the anterior lateral
angles of the tergum, set off by the divergent sutures (ps, ps), con-
stitute the prescutal areas of the tergum. In the metathorax the
prescutal sutures do not meet the antecostal suture, and the lateral
prescutal lobes are continuous by a narrow median bridge behind the
antecostal suture (fig. 24). In some other Acrididae, as in Melanoplus,
the continuity of the prescutal area is more pronounced. In other
orthopteran families the prescutum is narrow, but in the Blattidae and
Gryllidae there is a suggestion of its separation from the scutal area.
In any case, however, the prescutum of the Orthoptera must be re-
garded as a secondary differentiation of the anterior part of the tergum.
Its lateral parts become most sharply defined in the mesotergumr of
the Acrididae by the strong development of the prescutal ridges (fig.
NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 39
22 B, PR) that brace the anterior wing processes. Upon the irregular
surfaces of the prescutal lobes are attached the tergo-sternal muscles
which are the principal elevators of the wings.
A prescutum similar to that of the Orthoptera occurs also in certain
other insects, though very likely it may be an independent differen-
tiation formed as an adaptation to similar demands. In many insects
of the higher orders, however, such as the Hemiptera, Diptera, and
Hymenoptera, a prescutal area of quite a different nature is set off in
the anterior median part of the tergum by the development of two
Fic. 22.—The mesothoracic tergum of Dissosteira.
A, dorsal surface. B, ventral surface. Ac, antecosta; acs, antecostal suture;
ANP, anterior notal wing process; Aw, prealar arm of tergum; 1A~x, first
axillary; 4A, fourth axillary; AxC, axillary cord; Em, lateral emargination
of tergum; Mb, secondary intersegmental membranes; n, lobe of prescutum
articulating with base of subcostal wing vein; o, lobe of scutum articulating
with posterior part of first axillary; Pc, precosta; 7Ph, first phragma; ps, pre-
scutal suture; Psc, Psc, lateral prescutal areas; Rd, posterior reduplication of
tergum; Scl, scutellum; Sct, principal part of scutum; sct, sct, posterior lateral
subdivisions of scutum; s, s, secondary ridges of tergum; tg, tegular rudiment;
VR, remnant of V-ridge of tergum.
lateral ridges, the parapsidal gradients (fig. 5 B, Pak), which extend
a varying distance posteriorly from the anterior tergal margin, and
usually converge. These ridges and their sutures apparently lie in the
scutal region of the tergum, for there is sometimes present a narrow
transverse prescutal band anterior to their bases. Parapsidal ridges are
absent in the Orthoptera.
The area of the mesotergum of Dissosteira posterior to the ante-
costal and prescutal sutures is differentiated topographically into a
large anterior scutal region (fig. 22 A, Sct), a median, posterior, tri-
angular scutellar region (Sc/), two small, lateral, posterior scutal re-
gions (sct, sct), and a posteriormost, deflected marginal region (id).
The structure here presented is quite different in appearance from
that of a typical wing-bearing tergum (fig. 5 A) in which the surface
40 SMITHSONIAN MISCELLANEOUS COLLECTIONS voL. 82
is divided into scutal and scutellar areas (Sct, Scl) by the suture (vs)
of an internal V-shaped ridge (B, VR), the arms of which are con-
vergent forward from the posterior lateral angles of the tergum.
In the Acrididae the V-shaped endotergal ridge (fig. 22 B, VR)
is almost obliterated, and the tergum is braced by two secondary ridges,
one on each side (s), that converge posteriorly from the posterior
lateral margins of the scutal area and intercept the arms of the rudi-
mentary V-ridge (VR). The altered structure of the acridid tergum
Rd
Fic. 23.—Diagram of the structure of a wing-bearing tergum of Acrididae.
The prescutal suture (ps) is either continuous, or suppressed medially; the
usual V-ridge and its suture (vs) are partially suppressed and subordinated to a
secondary ridge of similar shape but having its arms (s,s) convergent posteriorly.
may be expressed diagrammatically as in figure 23, where the sup-
pressed suture (vs) of the obsolete V-ridge is crossed by the dominant
suture (s) of a secondary ridge of similar shape but having its arms
convergent posteriorly. Thus the scutum consists of a principal an-
terior scutal area (Sct) and of two small postero-lateral scutal areas
(sct, sct) ; and the scutellum is divided into a median scutellar area
(Scl) and two lateral scutellar areas (scl, scl), including the posterior
fold of the tergum (Rd). The evolution of this condition can be traced
in other Orthoptera from the primary structure which occurs in the
Blattidae. A similar modification has taken place in the mesotergum
of Hemiptera and Coleoptera, producing the triangular elevated shield
of the scutellum that lies between the bases of the folded wings.
NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS = 41
It is clear that the external “ divisions”’ of the wing-bearing ter-
gum are incidental to the development of the internal ridges, which
are adaptations to the part the tergum plays in the mechanism for
moving the wings. The old idea that the tergum is “ composed of ”’
sclerites gave undue emphasis to surface features. Though a study
of the latter may have a value for descriptive purposes, the student
must look to the internal characters for a true understanding of the
skeleton of insects.
There is no postscutellar plate in the mesothorax of the grasshopper.
The posterior deflected margin of the scutellum ends in a narrow inter-
segmental membrane (fig. 25, 21/b) uniting the mesotergum with
the anterior margin of the precosta of the metatergum. The tergum
of the mesothorax of the grasshopper, therefore, is a typical dorsal
plate of a secondary segment, comprising the primary segmental
sclerotization and the preceding primary intersegmental sclerotization
of the back. In the latter the primary intersegmental fold is marked
by the antecosta (fig. 25, dc) and the antecostal suture (acs).
The lateral margins of the mesotergum are very irregular (fig. 22).
The wings are extended from the tergal edges between the middle of
the prescutal borders and the posterior reduplication of the scutellum.
Anterior to the wing bases the anterior angles of the tergum are ex-
tended as short prealar arms (fig. 22 A, Aw) to which are articulated
the dorsal processes of the first basalar plates (fig. 26, Ba). The lat-
eral margin of the prescutal area forms posteriorly a small process
bearing a socket-like surface (7) in which the base of the subcostal
wing vein turns when the wing is flexed or extended. Posterior to this
process the anterior angle of the scutum is produced to form the large
anterior notal wing processes (ANP), which support the neck of the
first axillary sclerite of the wing base (14). The inner edge of the
first axillary bridges the lateral emargination of the tergum (Em)
and articulates with a marginal lobe (0) behind the latter. There is
no posterior notal wing process in the mesotergum of the grasshopper ;
the fourth axillary (4A), which is itself probably a detached piece
of the tergal margin, articulates with the edge of the scutellum.
The metaterguu.—tThe tergal plate of the metathorax (fig. 24) is
somewhat longer than that of the mesothorax, since it must support
the wider bases of the hind wings; but in many respects it is more
weakly developed than the mesotergum, there being extensive non-
sclerotized areas in the posterior part of the scutal region.
The precostal rim of the metatergum (fig. 24, Pc) is narrow, except
medially where it forms a conspicuous lip before the deeply inflected
42 SMITHSONIAN MISCELLANEOUS COLLECTIONS voL. 82
antecostal suture (acs). The prescutal ridges and their sutures (ps,
ps) are much weaker than those of the mesotergum, but they are not
confluent medially with the antecostal ridge and suture, and the lateral
prescutal triangles (Psc, Psc) appear to be continuous across the back
in a narrow, weakly sclerotized area deflected into the antecostal
suture (acs).
/ Z
Rd AxC
Fic. 24.—The metathoracic tergum and postnotal plate of Dissosteira.
acs, antecostal suture; ANP, anterior notal wing process; rd44, first axillary,
4Ax, fourth axillary ; AxC, axillary cord; Em, lateral emargination of tergum;
n, prescutal lobe to which base of subcostal wing vein is attached : o, tergal lobe
to which posterior end of first axillary articulates; p, tergal arm supporting
anal veins of wing (see fig. 47 B); Pc, precosta; 2Ph, second phragma: PNsz,
postnotum; ps, prescutal suture ; Psc, prescutum; Fd, posterior fold of tergum
(see fig. 25, Rd:); s, s, sutures of secondary tergal ridges ; Sel, scutellum; Sct,
principal part of scutum; sct, sct, subdivisions of scutum.
The surface features of the scutal and scutellar regions of the meta-
tergum have even less relation to the generalized structure of a wing-
bearing tergum than do those of the mesotergum, because the tergal
ridges (fig. 23) are here almost completely suppressed, and the exter-
nal characters are the result of secondary inflections which produce a
topographical pattern quite independent of the primary divisions of
the tergum (fig. 5). Most of the scutal region (fig. 24, Sct) and the
NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 43
median triangle of the scutellar region (Sc/) are confluent in a large
shield-shaped area that forms the principal part of the tergal plate.
The depressed posterior lateral parts of the scutum (sct, sct) are cut
transversely by the faintly-marked sutures (s, s) of the posteriorly
convergent ridges, which are obsolete in the metatergum, though
strongly developed on the mesotergum (fig. 22 B, s). The posterior
marginal area of the metatergum (fig. 24, Rd), which is a part of the
true scutellar region, is sharply inflected (fig. 25, Rds) and is continu-
ous with the greatly extended precosta of the first abdominal segment,
which constitutes a postnotal plate of the metathorax (figs. 24, 25,
PN3).
Pe Set,
acs :
|
pele sind Setz
1iMb \
Sel-
aes ip
—
Fic. 25.—Median longitudinal section of mesotergum, metatergum, and meta-
thoracic postnotal plate of Dissosteira, showing the phragmatal lobes of the
right side.
Ac, antecosta; acs, antecostal suture; 7, first abdominal tergum; 7M/b, 2Mb,
secondary intersegmental membranes; z7Ph, 2Ph, 3Ph, first, second, and third
phragmata; PNs:, postnotal plate of metathorax, or greatly enlarged precosta of
first abdominal tergum; Fd, posterior reduplication of tergum; Sct, scutum;
Scl, scutellum.
The lateral margins of the metatergum present the same features as
do those of the mesotergum. The posterior angle of each prescutal
area projects as a small marginal process (fig. 24, 1) which is con-
nected with the head of the subcostal wing vein by a ligament-like
thickening of the basal wing membrane; it does not articulate with the
vein as in the mesothorax. The anterior notal wing process (ANP)
is a flat lobe of the scutum, to which the first axillary (1A) is closely
hinged. Behind the wing process is a deep emargination (Em) of the
scutellum, posterior to which is a second lobe (0) articulating with
the posterior end of the first axillary. The slender fourth axillary
(4Ax) articulates with the extreme posterior angle of the lateral scu-
tellar area (sct). Each extremity of the posterior marginal fold of
the tergum (Rd) gives off into the anal membrane of the wing a long
arm (p) that supports the anal veins (fig. 47 B).
44 SMITHSONIAN MISCELLANEOUS COLLECTIONS VoL. 82
The pterothoracic pleura——tThe pleurites of each side of the meso-
thorax and metathorax are firmly united to form continuous lateral
walls of the pterothoracic region (fig. 26) in which the episterna and
epimera (Eps, Epmz) are distinct plates separated by oblique grooves
sloping from above downward and posteriorly. The first principal
groove is the pleural suture of the mesothorax (PIS2), the second is
the intersegmental line, the third is the pleural suture of the meta-
thorax (P/S;). Each pleural suture terminates above in a large wing
Fic. 26.—The pterothoracic pleura of Dissosteira.
Ba, basalar sclerites; Cx, coxa; Epm, epimeron; Eps, episternum; Fms, base
of hind femur; 7, prepectal suture; P/S, pleural suture; PNs, lateral arm of
metathoracic postnotum; Ppct, prepectus; r. pleuro-sternal suture; S, sternum;
Sa, subalare; Sp:, mesothoracic spiracle; Ss, metathoracic spiracle; Tn, tro-
chantin; Tr, trochanter; WP, pleural wing process.
process (WP2, WP;), and below in the pleural articulation of the
coxa. The episternum of each segment (Eps, Eps) is united ven-
trally before the coxal cavity with the edge of the sternum, the line of
union (7) in the adult insect being obsolete in the mesothorax, but
distinct in the metathorax. In the nymph of Dissosteira and of other
Acrididae (fig. 27 A) the ventral edge of the precoxal part of the
pleuron in both the mesothorax and the metathorax is distinctly sepa-
rated from the sternum; in the nymph of Gryllus (B) a precoxal plate
(Acx) is separated from the pleuron and intervenes between the
episternum and the sternum. The episternum of the mesothorax of
Dissosteira (fig. 26, Eps.) is marked anteriorly by a submarginal
NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 45
suture (j) which is continuous through the anterior part of the meso-
sternum (S;) and sets off from the sternum and the two episterna a
narrow anterior marginal piece, or prepectus (Ppct), which is analo-
gous to the similar sclerite of the Ichneumonidae and some other
Hymenoptera. To the posterior margin of the epimeron of the meta-
thorax (Epms) is attached the large lateral extension of the meta-
thoracic postnotum (PN3;).
The two pairs of spiracles of the thorax are presumably the meso-
thoracic spiracles and the metathoracic spiracles, each pair being dis-
placed anteriorly. The first spiracle on each side (fig. 26, Sp2) is
PIS
/
/
Fic. 27.—Pterothoracic pleura of orthopteran nymphs.
A, pterothoracic pleura of an acridid nymph, showing laterosternal arms of
pleura (Ls) separated from sterna (S2, Ss) by the pleuro-sternal sutures (7, 7).
B, mesopleuron and coxa of young nymph of Gryllus assimilis, showing a dis-
tinct precoxal sclerite (Acx) between episternum (Eps) and sternum (S).
C, inner view of B, showing the basalar and subalar muscles of the nymph
(M’, M”) attached dorsally on edges of episternum and epimeron, respectively.
situated laterally in the intersegmental membrane between the pro-
thorax and the mesothorax, where it is covered by the posterior fold
of the protergum. The second spiracle (fig. 26, Sp3) appears in the
adult to lie in the lower posterior angle of the mesepimeron (Epmz)
just above the base of the middle leg, and anterior to the fold between
the mesothorax and the metathorax (fig. 28), but in the nymph
(fig. 27 A) it occurs in the intersegmental fold.
The structural pattern of the internal surface of the pleural wall of
the pterothorax (fig. 28) is a replica of that of the outer surface,
except that the impressed lines of the latter are represented by ridges.
Each pleural ridge (PIR:, PIR;), however, gives off from its lower
end a large pleural arm, or pleural apophysis (P/A., PIA;), that
projects inward across the coxal cavity, where it is closely associated
with the lateral arm of the corresponding sternal apophysis (fig. 31,
46 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82
PIA, SA), and the two are connected by a dense mass of short muscle
fibers (figs. 34, 35, 86, II5).
Of particular interest in the pterothoracic pleuron are the epipleu-
rites, or the small plates situated in the membranes below the bases of
the wings (figs. 26, 28, 29, Ba, Sa). Upon these plates are inserted
the principal so-called direct muscles of the wing mechanism. In the
grasshopper there are three epipleurites in each segment, two (Ba)
B WP
os /, 5
|
\ 2: ve
/
Fic. 28.—Inner surface of right pterothoracic pleura of Dissosteira, showing the
endoskeletal features.
Lettering as on figure 26, with the following additions: CaP, pleural coxal
process; P/A, pleural arm; P/R, pleural ridge.
situated before the wing process and articulated to the episternum, and
one (Sa) in the membrane behind the wing process and above the
epimeron. The episternal epipleurites are distinguished as the
basalares, or basalar sclerites (Ba), the epimeral epipleurite as the
subalare or subalar sclerite (Sa). In most insects there is but a single
basalare. In Dissosteira the basalar sclerites are freely hinged to the
upper margin of the episternum before the wing process (fig. 29, 1Ba,
2Ba) so that they can be turned inward and downward by the muscle
inserted on their inner faces (fig. 49, E, M’). The function of the
epipleurites in connection with the movement of the wings will be de-
scribed in Section V.
NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 47
There can be little doubt that the epipleurites are derived from the
upper parts of the pleura. In a nymphal orthopteron the muscles that
are inserted on the epipleurites in the adult (fig. 49) are attached
directly to the upper edges of the episternum and epimeron (fig. 27 C,
M’', M”). In many adult insects the basalare remains as an undetached
lobe of the episternum (fig. 14 A, Ba).
In the membranous corium at the base of each leg there is a small
plate (fig. 26, 7) situated before the coxa and loosely attached by its
lower end to the rim of the coxa. These scierites are evidently rem-
nants of the trochantins (fig. 13 A, B, Tm) since they exactly cor-
Ta \ =
PIR Epmg
Fic. 29.—Upper edge of the metathoracic pleuron and epipleurites of Dissosteira,
inner view.
1Ba, first basalare; 2Ba, second basalare; Epm, epimeron; Eps, episternum ;
Sa, subalare; WP, pleural wing process.
respond with the small trochantin of the prothorax (fig. 20 A, Tn),
which is identified as such by the attachment of the promotor leg
muscle upon it (fig. 33 A, 62).
The pterothoracic sterna.—The sternal plates of the mesothorax and
metathorax are united in a broad plastron covering the ventral surface
of the pterothorax, and continuous laterally, in the adult, with the
pleura by a fusion with the precoxal parts of the latter (fig. 30 A).
In the nymph of Dissosteira and of other Acrididae, as already noted,
the pleural plates of the mesothorax and metathorax (fig. 27 A, Plo,
Pl;) are distinctly separate from the sterna (S2, S;), and the pre-
coxal part of each pleuron is extended ventrally and posteriorly as a
slender arm (Ls, Ls) between the sternum and the coxal corium.
These arms are clearly remnants of the infra-coxal arcs of the sub-
4
48 SMITHSONIAN MISCELLANEOUS COLLECTIONS VoL. 82
coxae (fig. 18 B). In the adult grasshopper they form the ventral rims
of the coxal cavities, that of the mesothorax becoming a weakly
sclerotized plate, that of the mesothorax a membranous fold. The
definitive sterna of the pterothorax in the Acrididae, therefore, do not
appear to contain subcoxal laterosternal elements as integral parts of
their areas. In the adult of Dissosteira the pleuro-sternal suture
(fig. 30 A, r) is obsolete in the mesothorax anterior to the coxa, but
remains distinct in the metathorax.
Fic. 30.—Pterothoracic sterna and the base of the abdomen of Dissosteira.
A, general view of pterothoracic sterna and first two abdominal sterna.
B, diagram of probable structure of mesosternum. C, diagram of probable struc-
ture of metasternum. D, diagram of structure of first abdominal sternum.
acs, antecostal suture of first abdominal sternum; Bs, basisternum; Cr, coxa;
CxC, coxal cavity; IS, JIS, first and second abdominal sterna; 7, prepectal
suture; k, furcal suture; Pc, precosta; Ppct, prepectus; r, r, pleuro-sternal
sutures; sa, sa, roots of sternal apophyses; S/, sternellum; ¢, t, infra-coxal lobes
of metasternum.
The mesosternum of Dissosteira is a broad plate (fig. 30 A, Bs2, Sl2)
bounded laterally by the obsolete lines of the pleuro-sternal sutures
(rv) and the rims of the coxal cavities. Its anterior edge is slightly
convex ; its posterior border is deeply emarginated to receive a median
rectangular extension of the mesosternum (Bs;) which is dove-tailed
into the mesosternal notch. A prominent transverse suture (k), which
forms internally a ridge through the bases of the sternal apophyses
and extends laterally toward the coxal cavities (fig. 31, k, k) is coin-
cident with the posterior edge of the median part of the sternum and
NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 49
contains the external impressions of the sternal apophyses (fig. 30 A,
sa, sa). The suture, therefore, is the furcal suture of the mesoster-
num, and the two postero-lateral, quadrate mesosternal lobes (Sl2,
Sl,) lying laterad of the median projection of the metasternum must
belong to the sternellar region of the mesosternum. A median pit
(spn) opening just behind the furcal suture (%) marks the site of the
internal spina (fig. 31, 2Spn), which normally is intersegmental be-
tween the mesosternum and the metasternum, but which is here fused
with the mesosternal furcal ridge (k). There can be no doubt, there-
fore, that a part of the mesosternum normally intervening between
the furcal ridge and the spinasternum, which is the median area of the
mesosternellum (fig. 30 B, S7), has been obliterated in Dissosteira, and
that the spinasternum itself has been reduced to little more than the
base of the spina.
The mesosternum of Dissosteira is thus to be analyzed into the same
structural elements that are preserved in a less modified form in the
-prosternum. The sternellar region of the sternum (fig. 30 B, S/, S7)
has been cut into a pair of lateral lobes (A, S/2, Sl.) by the suppres-
sion of its median area, and the following spinasternum (B, Ss) has
been reduced to the base of the spina (fig. 31, 2Spm), which is united
with the furcal ridge (Ff). ;
The endoskeletal features of the mesosternum consist principally of
the strong furcal ridge (fig. 31, k, k) and the two sternal apophyses
(SA, SA). The latter are broad, tapering plates arising from thick
bases and extending laterally beneath the pleural apophyses, to which
they are attached by short muscle fibers (figs. 34, 35, 86). Each has
a triangular basal lobe directed forward. Anteriorly the mesosternum
is marked by the sternal part of the prepectal ridge (fig. 31, 7) which ©
cuts off a marginal presternal strip continuous laterally with the pre-
episternal areas of the prepectus (figs 26, 30, Ppct).
The metasternum of Dissosteira (fig. 30 A, Bs3) is wider than the
mesosternum and is separated laterally by distinct sutures (7) from
the precoxal parts of the metapleura. Its anterior margin, as just ob-
served, is extended in a large, median, quadrate lobe which is dove-
tailed between the scutellar lobes of the mesosternum. Its posterior
edge is broadly emarginate to receive a corresponding extension of
the first abdominal sternum (Pc). The median scutellar region of the
metasternum, shown diagrammatically at C of figure 30, is suppressed
in the same manner as is that of the mesosternum, and the suture of the
transverse sternal ridge (fk) is here also coincident with the transverse
margin of the sternal notch; but the suture does not extend laterad of
the apophyses (sa, sa), and the lateral sternellar lobes are, therefore,
4
50 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82
not set off by sutures as in the mesosternum. The small triangular
plates (t, t) bordering the coxal cavities appear to be subdivisions of
the sternellar lobes rather than subcoxal laterosternal pieces, since the
ventral arms of the pleurites in the nymph (fig. 27 A, Ls) form only
the membranous folds beneath the coxal cavities in the metathorax.
There is no spina associated with the metasternum. Crampton
(1918) says the spinal pit has disappeared from the metasternum, but
he gives no evidence of its former existence. As we have seen, the
intersternal sclerotization between the metasternum and the first ab-
dominal sternum remains as an integral part of the latter, or disappears
Fic. 31.—Inner surface of ventral pleuro-sternal region of mesothorax.
Bs, basisternum; C4#C:, coxal cavity; Epm, epimeron; Eps, episternum;
Isg, intersegmental groove; 7, ridge of prepectal suture; k, furcal ridge; PIA,
pleural arm; P/R, pleural ridge; P/S, pleural suture; Ppct, prepectus; S:, an-
terior part of metasternum; SA, sternal apophysis; S/, sternellum; 2S pn, second
spina, united with furcal ridge of mesosternum.
when the first abdominal sternum becomes rudimentary. In Dissosteira
the ventral muscles of the first abdominal segment (fig. 35, JS) are
attached anteriorly on a weakly developed ridge (Ac) which crosses
the first abdominal sternum between the angles of the sternellar lobes
of the metasternum. The line of this ridge appears externally as a
faint transverse suture (fig. 30 A, D, acs). The ridge (fig. 35, Ac),
therefore, is the antecosta of the first abdominal sternum, and the
representative of the spinae of the prothoracic and metathoracic sterna.
The median plate dovetailed into the metasternum (figs. 30 A, D, 35,
Pc) is the enlarged precosta of the first abdominal sternum. It cor-
responds exactly with the postnotal plate of the metathorax (fig. 25,
PN;), which is an extension of the precosta of the first abdominal
tergum.
NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 5!
III. THE THORACIC MUSCLES OF DISSOSTEIRA
The evolution of insect structure has been largely an evolution of
mechanisms made up of the cuticula and the muscles. Though the
study of the insect skeleton will remain the most important branch of
insect anatomy for purposes of taxonomic description, it is becoming
evident that the morphology of the skeleton is not to be understood
without a knowledge of the relations that exist between the cuticular
modifications and the muscles. Systematists and anatomists have con-
sumed much time and have occupied much printed space with discus-
sions of homologies between sclerites, which, in many cases, are of
little value because the fundamental structure of the parts in question
has not been studied and because mechanical relationships have been
entirely ignored. The time is at hand when we must understand in-
sects as living creatures rather than as museum specimens. Morphol-
ogy must become a basis for the study of function, including both
the physiological processes by which the insect is maintained as a liv-
ing thing, and the mechanisms by which it directs its bodily activities.
A grasshopper furnishes a particularly good subject for the study
of insect musculature. Not only are the individual muscles easily dis-
tinguished in dissections, but the muscles present are principally those
that are common to all generalized insects. Fresh specimens do not
serve well for the purpose of muscle study, but after twenty-four
hours’ immersion in 80 per cent alcohol the fiber bundles become more
compact and are more readily seen as separate muscles. Since most
of the insect’s muscles are arranged laterally, a median sagittal section
of the body will give the best approach to the muscles for an initial
examination ; but eventually it will be necessary to cut specimens into
numerous pieces, for each muscle must be followed from one attach-
ment to the other. Never accept a supposed observation for a fact
until it is seen alike in at least two preparations—not that specimens
differ, but that observations frequently do.
It is customary in describing muscles to follow them from their
origins (fixed ends) to their insertions (movable ends), but the mus-
cles of insects are in general more easily studied by finding the inser-
tion points first and then tracing the bundles of fibers out to their
basal attachments. The origins of muscles are likely to vary more in
different segments and in different species than are the insertions, and
branched muscles are often confusing until their common parts or
apodemes of insertion are determined.
The student will find that the principal thoracic muscles of Dis-
sosteira more nearly correspond with the description of the muscles
of the field cricket, Liogryllus (Acheta) campestris, given by Carpen-
52 SMITHSONIAN MISCELLANEOUS COLLECTIONS VoL. 82
tier (1923) than with the description of the muscles of Gryllus domes-
ticus given by Voss (1905). The musculature of the cricket is in some
respects more elaborate than that of the locust; but the extra fibers
constitute small and apparently secondary muscles that are not defi-
nitely repeated in insects generally. The account of the musculature of
Gryllus pennsylvanicus given by DuPorte (1920) contains inaccura-
cies, especially with regard to the muscles of the legs ; the leg muscles
of Gryllus are in no essential way different from those of Dissostetra.
No attempt will be made in this paper to homologize the muscles of
Dissosteira with those of other insects, or to correlate them with the
muscles described by other writers, since this would add too much to
the size of the paper. The student, however, should consult the recent
descriptions of the thoracic musculature of insects contained in the
works of Bauer (1910, 1924, adult Dytiscus), Speyer (1922, 1924,
larval Dytiscus), Carpentier (1923, Acheta campestris and Tachy-
cinus asynamorus), Weber (1927, Tenthredinidae; 1924, 1928, Lepi-
doptera ; 1928a, Aphis fabae ; 1929, Psylla mali), and Morison (1927,
Apis mellifera). Berlese’s (1909) review of the musculature of in-
sects will need some revision in the light of more extensive compara-
tive studies of insect muscles; but a general myology of insects can
not yet be undertaken since we need more extensive information con-
cerning such groups as Apterygota, Plecoptera, and Neuroptera.
The terminology of insect musculature offers some difficulty for the
reasons that in different species the number of muscles in a functional
group is variable, the attachments may shift from one point to another,
and the functions of muscles undoubtedly homologous are often
changed as a consequence of altered relations in the skeletal parts. In
the following description of the thoracic musculature of the grass-
' hopper individual muscles are designated numerically for convenience
of reference only, and the series of numbers (46 to 139) follows the
enumeration of the head muscles of Dissosteira given in a former
paper by the writer (1928).
Dissection of the thoracic muscles is simplified when the general
plan of the segmental musculature is understood. The thoracic mus-
cles of insects fall into a few major groups which, in a general way, are
as follows: (1) dorsal body muscles; (2) ventral body muscles; (3)
tergo-sternal muscles; (4) special wing muscles; (5) pleuro-sternal
muscles ; (6) coxal wing muscles; (7) body leg muscles ; (8) muscles
of the leg segments; (9) muscles of the spiracles. In addition there
are the muscles of the neck plates, and often oblique, lateral interseg-
mental muscles.
NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 53
MUSCLES OF THE NECK AND PROTHORAX
The prothoracic and neck muscles of the grasshopper are best studied
from the mesal plane of the body. They may be exposed by cutting
into lateral halves a specimen that includes the back of the head, the
prothorax, and the mesothorax. Before removing the alimentary
canal, a branched muscle should be observed going from the side of
the protergum to the crop and the gastric caeca, which is,
Pe cA bs sf GS B
Fic. 32.—Muscles of the neck of Dissostcira, right side, internal view.
A, muscles extending between head and prothorax, omitting 52, 53, and 54,
shown in B, inserted on first cervical sclerite. B, muscles of cervical sclerites.
Bs, basisternum of prothorax; c, first ridge of protergum; Cv, neck; icv,
first cervical sclerite ; 2cv, second cervical sclerite; d, second ridge of protergum;
e, third ridge of protergum; Eps, prothoracic episternum; Eps, mesothoracic
episternum; g, process of head articulating with first cervical sclerite; H, head;
Ph, first phragma; Pok, postoccipital ridge of head; PT, base of posterior ten-
torial arm; fd, posterior fold of protergum; SA, prosternal apophysis; 1Spn,
first spina; Ss, spinasternum; 71, protergum.
40. Posterior protractor of the crop and gastric caeca (fig. 33 A).—
A slender, branched muscle arising on lateral surface of protergum
from lower end of first tergal ridge (c) just before base of tergal pro-
motor of coxa (62) ; branching posteriorly to lateral wall of crop and
tips of gastric caeca.
The alimentary canal and fat tissue should now be removed in order
to expose the muscles in the side of the neck and prothorax, some of
which extend from the mesothorax to the head. Functionally there are
three groups of these muscles, namely, those that move the head, those
that move the prothorax, and those that move the fore leg.
54 SMITHSONIAN MISCELLANEOUS COLLECTIONS VoL. 82
It is impossible to determine, from an anatomical study alone, the
individual action of the muscles attached on the back of the head and
on the cervical sclerites (fig. 32 A, B), since their functions may vary
according to whether opposed sets of them act together or as antagon-
ists. It is evident that the dorsal muscles (fig. 32 A, 47, 48, 49) and
the ventral muscles (55) may tilt the head up or down respectively by
pulling on opposite sides of the fulcrum of the cervical sclerites (q),
or also that they may turn the head laterally if both sets on either side
act as antagonists to those of the other side, while, finally, if they all
act together they would become retractors of the head. The dorsal
muscles of the cervical sclerites (A, B, 50, 51, 52, 53) must be the pro-
tractors of the head, since their combined pull would straighten the
angles between the two sclerites of each pair and thus push the head
forward. The oblique ventral muscles of the cervical sclerites (fig. 35,
54) would appear to be accessory to the lateral movement of the
head.
47. First protergal muscle of the head (fig. 32 A).—A slender
muscle arising dorsally on protergum ; inserted dorso-laterally on post-
occipital ridge of head (Pok).
48. Second protergal muscle of the head (fig. 32 A).—A larger
muscle arising dorsally on third ridge (e¢) of protergum; inserted with
47 on postoccipital ridge of head.
49. Longitudinal dorsal muscle of the neck and prothorax (fig.
32 A).—A broad muscle from first thoracic phragma (zP/) to post-
occipital ridge of head just below 48.
50, 51. Cephalic muscles of the cervical sclerites (fig. 32 A, B).—
Origins on postoccipital ridge below 49; both extend ventrally and
posteriorly, the first (50) inserted on first cervical plate, the second
(51) on second cervical plate.
2, 53. Protergal muscles of the cervical sclerites (fig. 32 B).—
Origins dorso-laterally on protergum at lower end of first tergal ridge
(c) ; both extend ventrally and anteriorly, crossing internal to 50 and
51, to insertions on first cervical sclerite, the first muscle with a branch
(52a) to articular process (g) of head.
54. Prosternal muscle of the first cervical sclerite (figs. 32 A, B,
33 C, 35).—A horizontal, diagonal muscle arising on prosternal apo-
physis (figs. 32, 35); inserted anteriorly on first cervical sclerite of
opposite side (figs. 32 B, 35), the right and left muscles crossing each
other medially (fig. 35).
55. First ventral longitudinal muscle (figs. 32 A, 33 A, 35)—A
broad, flat muscle from base of posterior arm of tentorium to apophy-
sis of prosternum (figs. 32 A, 35, SA).
NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 55
56. Dorsal lateral neck muscle (fig. 32 A)—A band of slender
fibers from first phragma (7zPh) inserted on base of neck mem-
brane (Cv).
57. Ventral lateral neck muscle (fig. 32 A, B).—A short, flat mus-
cle from anterior edge of prothoracic episternum (E/s,), inserted on
base of neck membrane (Cv).
The prothorax is movable on the mesothorax by two oblique, lateral
intersegmental muscles on each side (fig. 32 A, 58, 59), and by three
pairs of ventral intersegmental muscles (figs. 32 A, 35, 60, 87, 88).
58. Tergo-pleural intersegmental muscle (fig. 32 A).—A broad
muscle of several sections, attached anteriorly on protergum behind
upper end of ridge d; extends posteriorly and ventrally to interseg-
mental membrane just before upper end of mesepisternum (Eps2).
59. Sterno-pleural intersegmental muscle (figs. 32 A, 33 A, 35).—
Attached anteriorly on upper end of prosternal apophysis (figs. 32 A,
33 A, SA) ; extends posteriorly and dorsally to dorsal end of anterior
margin of mesepisternum (Eps,). In some insects this muscle 1s at-
tached posteriorly on the anterior angle of the mesotergum.
60. Second ventral longitudinal muscle (figs. 32 A, 33 A, 35).—
Extends between prosternal and mesosternal apophyses. Attached
anteriorly by broad base on prosternal apophysis ; tapers posteriorly to
attachment on anterior margin of mesosternal apophysis (fig. 35).
The other two sternal muscles that move the prothorax are the third
and fourth ventral longitudinals (figs. 32 A, 35, 87, 88) attached an-
teriorly on the first spina (71S pn), but they will be described with the
mesothoracic muscles.
61. Sterno-spinal muscle (figs. 33 C, 35).—A very small muscle
arising on base of prosternal apophysis (S.A) ; the two from opposite
sides converging posteriorly to insertions on anterior end of first spina
(1Spn). Since the spinasternum (Ss) is but little movable on the
prosternum (S,) in the grasshopper, this pair of muscles can act only
as tensors or levators of the spinasternum.
The muscles that move the prothoracic leg of Dissosteira represent
the tergal promotor (fig. 11, I), the tergal remotor (J), and the
sternal remotor (L) of the primitive limb base, and the abductors (M)
and the adductors (N) of the coxa. A representative of the sternal
promotor (K) is absent in the prothorax of Dissosteira. The sternal
remotors function as posterior rotators of the coxa by reason of the
single articulation of the latter with the pleuron only; in Dissosteira
one branch of the sternal remotor arises on the spina.
56 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82
62. Tergal promotor of the coxa (fig. 33 A).—The largest muscle
of the prothorax. Origin on upper lateral wall of protergum, posterior
to lower end of first ridge (c) ; insertion ventrally on the small tro-
ehantin® (fies 330 A548. Didi).
63. First tergal remotor of the coxa (fig. 33 A).—Origin on lateral
wall of protergum mesad of upper end of 62 below ridge f; extends
ventrally and posteriorly external to 50 and 60 to insertion on posterior
angle of base of coxa (fig. 33 B, C, D).
64. Second tergal remotor of the coxa (fig. 33 A, B, C, D).—A
short muscle arising on lateral wall of protergum (D) beneath ridge 7;
insertion on posterior angle of coxa (C, D).
65. Third tergal remotor of the coxa (fig. 33 A, B, C, D).—A
slender muscle arising on protergum (D) in angle between ridges e
and h; insertion ventrally on posterior angle of coxa.
66. First posterior rotator of the coxa (figs. 33 C, D, 35).—Origin
on base of sternal apophysis (figs. 33 C, 35, SA); insertion on pos-
terior angle of coxa.
67. Second posterior rotator of the coxa (figs. 33 C, D, 35).—
Origin on side of spina (figs. 33 C, 35, 1Spm) ; insertion on posterior
angle of coxa. .
68. Abductor of the coxa (fig. 33, B, D).—A flat, two-branched
muscle arising on inner face of episternum (Eps), the larger branch
(68b) dorsally, the smaller branch (68a) in anterior ventral angle ;
both inserted by a common stalk on outer rim of coxa (D) just before
pleural coxal articulation (C#P). .
69. Adductor of the coxa (fig. 33 C).—Origin on outer end of
sternal apophysis (SA), or at union of the latter with pleural apo-
physis (PIA) ; insertion on inner rim of base of coxa (Cx).
The following nine muscles (70 to 78) pertain to the segments of
the telopodite of the prothoracic leg. Three branches of the depressor
of the trochanter (71) have their origins within the body.
zo. Levator of the trochanter (fig. 36 A).—Origin dorsally in an-
terior part of coxa; fibers converge to insertion on tendon arising from
dorsal lip of base of trochanter. This is the lifting muscle of the
telopodite.
71. Depressor of the trochanter (figs. 33 A, B, C, 36 A).—A five-
branched muscle, two groups of fibers arising in the coxa and three in
the prothorax, all converging upon a strong apodeme arising from
ventral lip of base of trochanter (fig. 36 A, 714p). The coxal branches
arise anteriorly (77a) and posteriorly in ventral part of coxa; of the
three body branches the first (71b) arises dorsally on anterior margin
ae =
io
NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 57
Fic. 33—Musculature of the base of the fore leg of Dissosteira.
A, inner view of base of right leg, showing coxal and trochanteral muscles
arising on lateral walls of protergum; tergal ridges lettered as on figure 20 B.
B, same as A but with inner muscles removed, showing coxal and trochanteral
muscles arising on episternum, and posterior group on tergum.
C, posterior view of prosternum, right pleuron, and right coxa, showing leg
muscles arising on sternum and pleural arm.
D, articular region of base of right coxa, and associated muscles, inner view.
58 SMITHSONIAN MISCELLANEOUS COLLECTIONS VoL. 82
of episternum (fig. 33 B, Eps), the second (71c) on ventral edge of
pleural arm (fig. 33 C, PIA), the third (71d) on lateral wall of pro-
tergum (fig. 33 A, B) just below ridge h. These groups of fibers con-
stitute the most powerful muscle of the leg and function as the de-
pressor of the telopodite as a whole.
72. Reductor of the femur (fig. 36 A).—A short, broad muscle
in posterior part of trochanter (77) arising on ventral wall of the seg-
ment ; fibers extending dorsally and posteriorly to posterior rim of
base of femur, giving the latter a slight posterior flexion.
73. Anterior levator of the tibia (fig. 36 A).—An extremely slen-
der muscle arising anteriorly in base of femur; inserted by long,
thread-like apodeme on a process from anterior side of base of tibia
(as in middle leg, fig. 36 B, 1054p).
74. Posterior levator of the tibia (fig. 36 A).—Origin dorsally in
proximal part of femur; insertion by a strong tendon on posterior
dorsal angle of base of tibia (as in middle leg, fig. 36 E, 706).
75. Depressor of the tibia (fig. 36 A).—Origin anteriorly (75a)
and posteriorly on ventral wall of femur, with branch (75c) from
base of trochanter (Tr) ; inserted by a strong tendinous apodeme aris-
ing from small ventral plate in membrane of femoro-tibial joint.
76. Levator of the tarsus—Origin on distal third of dorsal wall
of tibia; insertion on dorsal lip of base of tarsus.
77. Depressor of tarsus——Origin on ventral wall of tibia; inser-
tion on ventral lip of base of tarsus.
78. Depressor of the pretarsus: retractor of the claws (fig. 36 A) .—
This muscle comprises three branches, the principal one arising pos-
teriorly in base of femur (fig. 36 A, 78), the other two in upper part
of tibia; all inserted on a long tendon extending from femur through
tibia and tarsus to unguitractor plate at base of claws.
The following two muscles are those of the first spiracle, but since
the first spiracle is situated within the region of the prothorax, its
muscles are to be classed as prothoracic. The mechanism of the spira-
cles will be discussed in Section VI.
79. Closing muscle of the first spiracle (fig. 51 B).—Origin on
ventral process of peritreme (/) ; insertion on lever of posterior lip
of spiracle (7).
80. Opening muscle of the first spiracle (fig. 51 B).—Origin on
ventral process of peritreme; insertion on base of posterior lip of
spiracle.
NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 59
MUSCLES OF THE PTEROTHORAX
The musculature of the wing-bearing segments differs in many
respects from that of the prothorax, particularly in the great develop-
ment of the dorsal longitudinal muscles (fig. 34, 87, 112), in the pres-
ence of large tergo-sternal muscles (83, 84, 113) and special wing
muscles which are lacking in the prothorax, and in te presence of two
pleuro-coxal muscles that become wing muscles in the adult.
The dorsal longitudinals and the tergo-sternals constitute a group
known as the indirect wing muscles because they effect movements of
Me 17
Bp bospnSen MENAUIBAy. 12
Fic. 34.—General view of the musculature in the right half of the pterothorax of
Dissosteira. Median section, seen from the left.
the wings by alternate changes in the curvature of the tergum. There
is but one special wing muscle in Dissosteira connected with each wing:
this is the wing flexor (figs. 37 A, 85; 49, D), a short muscle hav-
ing its origin on the pleuron and its insertion on the third axillary
sclerite of the wing base. In many insects there are several small
muscles from the upper parts of the pleuron to the edge of the tergum
or to the base of the wing, but representatives of these muscles are
absent in the grasshopper. The two pleuro-coxal muscles that become
important wing muscles in the adult are apparently abductors of the
coxa in the nymph (fig. 27 C, M’, M”). The first is the pronator-
60 SMITHSONIAN MISCELLANEOUS COLLECTIONS voL. 82
extensor of the wing (fig. 49, M’), having its dorsal insertion on the
basalar plates of the adult ; the second is the depressor-extensor (M”)
with its insertions on the subalar plate. Associated with the first is a
large muscle (£) arising ventrally on the sternum. These three
epipleural muscles (EF, M’, M”) together with the wing flexor (D)
constitute the so-called direct wing muscles, though only the flexor is
a true wing muscle.
The ventral muscles of the pterothorax are small ; those of the meso-
thorax (figs. 34, 35, 60, 87, 88) serve to move the prothorax ; those of
the metathorax (116, 117) can have but little motor function, since
the mesothorax and metathorax are immovable on each other, and
they are reduced mostly to tendinous strands. The muscles of the mid-
dle and hind legs are essentially the same as those of the prothoracic
leg, but the muscles of the hind tibia are particularly large and not
of the same relative size as those of the fore and middle legs.
A first dissection of the pterothoracic musculature should be made
from the median plane of the body in a specimen cut into lateral halves
(fig. 34) from which the alimentary canal and other visceral tissues
have been removed.
THE MESOTHORACIC MUSCLES
81. Longitudinal dorsal muscles (fig. 34).—A large mass of fibers
in each side of upper median part of mesothorax, attached anteriorly
on lobes of first phragma (rPh) and posteriorly on middle phragma.
82. Oblique dorsal muscles (not shown in figures).—A small mus-
cle laterad of longitudinal dorsals ; arising on lateral part of scutum,
extending posteriorly and ventrally to insertion on outer part of mid-
dle phragma.
8&3. First tergo-sternal muscle (fig. 34).—Attached dorsally on pos-
terior part of lateral prescutal lobe ; attached ventrally on anterior part
of mesosternum.
84. Second tergo-sternal muscle (fig. 34.).—A very large muscle im-
mediately posterior to 83; attached dorsally by inner branch on middle
of lateral scutal area, and by outer branch on marginal lobe of scutum
behind posterior articulation of first axillary; attached ventrally on
mesosternum before inner margin of coxal cavity.
85. Pleuro-alar muscle: flexor of the wing (fig. 37 A).—This mus-
cle lies laterad of the series of dorsoventral muscles in the side of the
segment and may be noted after the latter are removed. It arises by
a broad base on upper part of pleural ridge (P/F), and goes dorsally
and posteriorly between 98 and 99 into wing base where it is inserted
on the third axillary (fig. 49, 347).
NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 61
HA
Fic. 35.—General view of the ventral musculature of Dissosteira from the head
to the second abdominal segment.
62 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82
86. Pleuro-sternal muscle (figs. 34, 35).—A dense mass of very
short fibers connecting the approximated ends of the pleural apophysis
and the sternal apophysis.
87. Third ventral longitudinal muscle (figs. 34, 35)—Attached
laterally on first spina (1Spm) ; extends posteriorly and laterally over
posterior end of 60 to anterior edge of apophysis of mesosternum
(SA2).
88. Fourth ventral longitudinal muscle (figs. 34, 35).—A slender
muscle attached anteriorly on first spina (Spm) and posteriorly on
second spina (2Spn).
The following thirteen muscles (89-101) include the muscles of
the base of the leg and the principal direct muscles of the wing.
89. Tergal promotor of the coxa (fig. 34). —Lies close behind &4
in the innermost series of lateral muscles. Origin on scutum ; inser-
tion on stalked dise (fig. 37 A, B, C, 89) arising from articular mem-
brane at anterior angle of coxa close to lower end of trochantin
(B, C, Tn). The representative of this muscle in the prothorax
(fig. 33 A, 62) is inserted on the trochantin, as it is in most insects
in which the trochantin is well developed.
go. First tergal remotor of the coxa (fig. 34).—Origin on scutum ;
goes ventrally posterior to pleural arm to insertion on stalked disc
arising from inner posterior angle of coxa (fig. 37 A, B, 90).
gi. Second tergal remotor of the coxa (fig. 37 A).—A slender
muscle arising on scutum from outer end of ridge s (fig. 22 B) ; goes
obliquely ventrally and posteriorly to slender apodeme arising from
extreme posterior angle of coxa (fig. 37 A, B, 91). This muscle is
the last of the tergal muscles of the mesothorax; it lies just external
to posterior border of go and is partially visible from median plane
(fig. 34.) between go and 173.
The group of mesothoracic muscles attached dorsally on the tergum
includes two segmental branches of the depressor of the trochanter
(103) which will be described later. When the tergal muscles have
been removed there is exposed a second or outer set of lateral muscles
having their origin on the pleuron (fig. 37 A). These muscles include
the abductors of the coxa, and the direct muscles of the wing. The
wing flexor (85) of the latter group has already been described as a
pleuro-alar muscle; the others are pleuro-coxal, with one pleuro-
sternal muscle. Ventrally there will be seen also the sterno-coxal mus-
cles, or rotators of the coxa, a description of which will logically fol-
low that of the tergo-coxal muscles.
NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 63
Fic. 36—Leg musculature of Dissosteira.
A, posterior view of muscles in proximal part of right fore leg, including coxa
(Cx), trochanter (7r), and base of femur (Fim).
B, anterior and ventral muscles of tibia arising in femur and trochanter of left
middle leg.
C, cross-section near middle of second left tibia, proximal surface of distal half,
showing positions of tibial muscles.
D, dorsal view of trochanter (77) of left hind leg, showing anterior and pos-
terior coxo-trochanteral articulations (f, g), and levator muscles of trochanter
arising in coxa. ‘
E, dorsal view of femoro-tibial joint of left middle leg, showing anterior and
posterior articulations (/, m), and bases of levator muscles of tibia.
F, corresponding view of femoro-tibial joint of left hind leg.
64 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82
92. Anterior rotator of the coxa (figs. 34, 35, 37).—Origin on
sternellar lobe of mesosternum (figs. 34, 35) ; extends anteriorly and
outward to anterior angle of coxa (figs. 35, 37 A, B, C).
93. Posterior rotator of the coxa (figs. 34, 35, 37)-—Origin on
second spina (figs. 34, 35) ; extends outward, above 92, to posterior
inner angle of coxa (figs. 35, 37 A, B).
94,95. First and second abductors of the coxa (fig. 37 A).—Origin
on anterior ventral area of episternum (Eps) ; fibers of each converge
to a pair of long, flat apodemes arising anteriorly on outer margin of
coxa (fig. 37 B, C, 94, 95).
96. Third abductor of the coxa (fig. 37 A).—A wide, flat, fan-
shaped muscle arising on episternal area posterior and dorsal to 95;
fibers converging to insertion on a slender apodeme arising in articu-
lar membrane laterad of base of coxa just anterior to pleural articu-
lation (fig. 37 B, 96).
07. First pronator-extensor of the forewing (fig. 37 A).—A large
muscle inserted dorsally on first basalar plate (7Ba) ; extending ven-
trally to attachment on lateral part of sternum before base of mid-
dle leg.
98. Second pronator-extensor of the forewing (fig. 37 A).—
Insertion dorsally close to 97 on first basalar plate (rBa) ; attached
ventrally on bases of apodemes of first and second abductors of coxa
(fig: 37,B.C,.06
99. Depressor-extensor of the forewing (fig. 37 A).—Inserted dor-
sally on subalar plate of wing base (Sa) ; attached ventrally on flat
extension of basicoxal ridge (fig. 37 B, 90) in meral region of coxa
(Mer) posterior to pleural articulation (c).
100. First adductor of the coxa (fig. 37 A).—A broad flat muscle
arising on posterior margin of mesosternal apophysis; insertion on
inner rim of coxa (A, B, 100).
ror. Second adductor of the coxa (fig. 37 A).—A smaller muscle
arising on mesosternal apophysis ; inserted on posterior angle of coxa
(A, B, ror) between attachments of 90 and 91.
The telopodite of the middle leg, or that part of the limb beyond
the coxa, has the same musculature as the telopodite of the first leg;
its muscles are the following :
102. Levator of the trochanter—Origin dorsally in base of coxa;
insertion on dorsal lip of base of trochanter.
103. Depressor of the trochanter—-A five-branched muscle with all
branches instrted on a tongue-like apodeme arising from ventral lip
of base of trochanter. Two branches arise ventrally in the coxa, one
NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 65
anteriorly, the other posteriorly; the others take their origin in the
mesothorax. The first and second body branches arise on scutum, one
medially the other on lateral margin, both pass into coxa anterior to
pleural arm ; the third body branch arises on ventral margin of meso-
sternal apophysis. The trochantinal muscles effect the movement of
the telopodite as a whole.
Fic. 37—Coxal musculature of the middle leg of Dissosteira.
A, general view of pleural muscles, right side, inner view, and bases of sternal
coxal muscles.
B, base of coxa, inner view, showing muscle attachments.
C, anterior rim of coxa (Cx), trochantin (Tn), and attachments of associated
muscles, inner view.
to4. Reductor of the femur——A sheet of very delicate fibers in
posterior part of trochanter, arising in base of latter, inserted on pos-
terior rim of base of femur. This muscle is much weaker than the
corresponding muscle of the prothoracic leg (fig. 36 A, 72), the femur
of the middle leg being scarcely movable on the trochanter.
105. Anterior levator of the tibia (fig. 36 B, C)—A delicate, at-
tenuate muscle arising anteriorly in base of femur; inserted by a long
tendon-like apodeme arising from dorsal end of a slender process
from anterior margin of base of tibia (fig. 36 E, ro5Ap).
5
66 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82
106. Posterior levator of the tibia (fig. 37 C, E).—A long, pinnate
muscle with fibers arising on almost entire length of dorso-posterior
wall of femur ; inserted by strap-like tendon on dorsal angle of base of
tibia (E, 100).
107. Depressor of the tibia (fig. 36 B, C)—The largest muscle in
the middle femur, comprising three groups of fibers, all inserted on a
long apodeme arising from small plate in ventral membrane of knee
joint. Principal group of fibers (B, ro7a) forms a long pinnate mus-
cle arising ventrally in proximal part of femur; second group a small
bundle of fibers (107b) arising in base of trochanter and joining with
those of first group; fibers of third group (r07c) arise anteriorly and
dorsally in distal two-thirds of femur and converge ventrally to inser-
tion on base of depressor apodeme.
108. Levator of the tarsus (fig. 42 A).—Origin dorsally in distal
third of tibia; insertion on dorsal lip of base of tarsus.
109. Depressor of the tarsus (fig. 42 A).—Origin ventrally in dis-
tal three-fourths of tibia ; insertion on ventral lip of base of tarsus.
110. Depressor of the pretarsus: retractor of the claws (figs. 36 C,
42 A, C).—Fibers arising in femur and tibia ; inserted on long, thread-
like apodeme arising from unguitractor plate at base of claws (fig.
42 C, 110Ap) and extending through tarsus (A) and tibia, and into
femur. Principal group of fibers a long, tapering bundle (fig. 36 C,
TIO) arising proximally on posterior wall of femur and inserted on
end of tendon; two smaller groups of fibers in upper end of tibia, one
arising anteriorly in base of tibia, the other dorsally, both inserted on
tendon just above middle of tibia.
Since the second thoracic spiracle lies within the region of the meso-
thorax, its muscle belongs to the same segment.
r1r. Closing muscle of the second spiracle (fig. 52 B).—Origin on
small lobe (0) of posterior dorsal margin of mesocoxal cavity ; inser-
tion on ventral lobe of spiracular lips (7).
THE METATHORACIC MUSCLES
The musculature of the metathorax almost duplicates that of the
mesothorax, with the principal difference that there are no oblique
dorsal muscles and that there is only one pair of tergo-sternals in the
metathorax.
112. Longitudinal dorsal muscles (fig. 34).—Most of the fibers
extend between middle phragma and third phragma (3P/), though a
few dorsal ones are attached posteriorly on the postnotal plate (PN3).
NO. 2. THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 67
113. Tergo-sternal muscle (fig. 34.).—A large muscle, the first of
the inner lateral series in metathorax, attached dorsally on lateral
prescutal lobe, and below by a wide base on lateral part of sternum
before coxal cavity. This muscle corresponds with 83 of the meso-
thorax, a scuto-sternal muscle (84) being absent in the metathorax.
114. Pleuro-alar muscle: flexor of the hind wing (fig. 38, 114) .—
This muscle consists of two bundles of fibers in metathorax, one ex-
ternal, the other internal, both arising from upper end of pleural ridge,
and inserted on ventral surface of third axillary sclerite of wing base.
The outer muscle is not visible from mesal plane until the first is
removed.
115. Pleuro-sternal muscle (figs. 34, 35).—A dense mass of very
short fibers connecting pleural apophysis with apophysis of meta-
sternum.
116. Fifth ventral longitudinal muscle (figs. 34, 35).—A strong
fiber, apparently a sclerotized muscle, extending from posterior edge
of mesosternal apophysis (SA,) to median anterior angle of meta-
sternal apophysis (SA3;).
117. Sixth ventral longitudinal muscle (figs. 34, 35).—A slender
muscle arising on second spina (2Spn), becoming tendinous pos-
teriorly ; extends posteriorly and laterally to inner extremity of pleural
apophysis of metathorax.
The ventral longitudinal muscles of the metathorax have evidently
lost their contractile nature because of the fusion of the mesosternum
and metasternum, and are converted mostly into sclerotic strands to
brace the pull of the mesothoracic ventral muscles (60, 87, 88) on the
sternal plates of the prothorax.
The following thirteen muscles (118 to 130) are muscles of the
metacoxa and the hind wing.
118. Tergal promotor of the coxa (figs. 34, 38 A).—Lies immedi-
ately behind the tergo-sternal (fig. 34, 773). Arises dorsally on lateral
area of scutum (fig. 38 A) ; inserted ventrally on apodemal disc of
anterior angle of coxa (fig. 38 D, F, 778).
119. First tergal remotor of the coxa (figs. 34, 38 A).—A large
muscle arising from posterior scutal margin; goes downward and
posteriorly, behind pleural arm, to apodemal disc on posterior inner
angle of coxa (fig. 38 D, F, rzo).
120. Second tergal remotor of the coxa (figs. 34, 38 A).—A slender
muscie lying close behind r79, tapering ventrally to slender apodeme
arising from extreme posterior angle of coxa (fig. 38 B, D, F, 120).
68 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82
122 123
\ \
\
Fic. 38—Muscles of the hind coxa and trochanter of Dissosteira.
A, tergal muscles of leg base, and the tergo-sternal muscle (173), right side,
inner view.
B, sternal and coxal muscles of basalar and subalar sclerites (7Ba, 2Ba, Sa).
C, abductor muscles of coxa.
D, general view of muscle attachments on base of right coxa, inner view.
E, sternal muscles of leg base, dorsal view.
F, coxal muscle attachments, dorsal view.
NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 69
The innermost series of lateral muscles includes two body branches
of the trochanteral depressor (fig. 38 A, 733c) which will be described
later. By removing the muscles attached on the tergum, there is ex-
posed the outer series of pleural lateral muscles pertaining to the leg
and wing, and the sternal muscles of the coxa.
121. Anterior rotator of the coxa (figs. 34, 35, 38 E).—A large
muscle with fibers arising in two groups, one from lateral part of ster-
num before base of sternal apophysis, the other from sternellar lobe
behind the apophysis ; all fibers converge to insertions on anterior angle
of coxa just mesad of stalked apodeme of 178 (fig. 38 D, F, 127).
122, 123, 124. First, second, and third posterior rotators of the
coxa (figs. 34, 35, 38 E).—Origins on posterior margin of lateral arm
of metasternal apophysis ; insertions posteriorly on base of coxa, the
first (fig. 38 D, E, F, 122) on process of meral region, the second
(123) just within posterior angle of coxa, the third (724) on posterior
part of meral rim of coxa.
The innermost pleural muscles are the large basalar and subalar
wing muscles (fig. 38 B, 127, 128, 129) ; external to them are the
abductors of the coxa.
125. First abductor (accessory promotor) of the coxa (fig. 38 C).—
A small muscle arising from anterior edge of metepisternum just
behind and below second spiracle (2S/p) ; insertion anteriorly on ex-
ternal margin of coxa (fig. 38 C, D). Anatomically this muscle evi-
dently belongs to the abductor system of the coxa, but apparently it
functions as an accessory of the tergal promotor (D, 178).
126. Second abductor of the coxa (fig. 38 C).—A large flat muscle
arising on inner face of episternum and on anterior surface of pleural
ridge ; fibers converging to insertion on slender apodeme (fig. 38 D, F,
120) arising in articular membrane at base of coxa just before pleural
articulation.
127. First pronator-extensor of the hind wing (fig. 38 B) —A large
muscle attached dorsally on first basalar plate (7Ba), and ventrally on
lateral part of sternum before coxa and laterad of base of the tergo-
sternal muscle (figs. 34, 38 A, 173).
128. Second pronator-extensor of the hind wing (fig. 38 B).—Lies
close behind 127; attached dorsally on second basalar plate (2Ba),
ventrally on lateral rim of coxa (fig. 38, D, F, 728) anterior to pleural
articulation (c).
129. Depressor-extensor of the hind wing (fig. 38 B).—A powerful
muscle, attached dorsally on inner disc of subalar plate (Sa), and
ventrally on wide basicostal surface of meral region of coxa (fig. 38 D,
My 129).
7O SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82
130. Adductor of the coxa (fig. 38 C, D, E, F).—Origin on pos-
terior surface of lateral arm of sternal apophysis (E) beneath base
of first posterior rotator (122) ; goes posteriorly and downward be-
low 123 and 124 to posterior part of inner margin of coxa (C, D,
Ey, 730):
The following muscles belong to the telopodite of the hind leg. The
total number is the same as in the fore and middle leg, but there are
two distinct levators of the trochanter, and a reductor of the femur
is lacking.
131. Anterior levator of the trochanter (figs. 36 D, 39).—Origin
on dorsal part of anterior wall of coxa; insertion on anterior lobe of
dorsal rim of trochanter (fig. 36 D).
132. Posterior levator of the trochanter (figs. 36 D, 39).—A two-
branched muscle arising dorsally in base of coxa; both branches (132a,
132b) inserted on levator apodeme and supporting plate in dorsal
articular membrane close to rim of trochanter (fig. 36 D).
133. Depressor of the trochanter (figs. 38 A, E, 39).—This muscle,
as in the other legs, consists of five branches, two of which arise in
the coxa, and three in the metathorax; all are inserted on ventral rim
of trochanter and together constitute a strong depressor of the telopo-
dite. The coxal branches arise one anteriorly (fig. 39, 133a), the other
posteriorly in ventral part of coxa. Two of the body branches arise
on scutum of metatergum, one from lateral margin, the other (fig.
38 A, 133c) from center of lateral field. These two branches converge
downward and unite before-the pleural arm in a broad, tough band of
fibers that curves posteriorly beneath the pleural arm (P/A) to enter
the coxa. The third body branch arises from under surface of lateral
arm of sternal apophysis (fig. 38 A, E, 133d).
134. Anterior levator of the tibia (figs. 36 F, 39).—This muscle
appears to be represented in the hind leg of Dissosteira by only a very
delicate tendinous strand arising from the anterior angle of the tibial
base (134Ap), and extending proximally for a short distance against
the anterior wall of the distal part of the femur. The writer was un-
able to discover muscle fibers attached to this tendon.
135. Posterior levator of the tibia (figs. 36 F, 39).—This great
muscle occupies most of the cavity of the femur (fig. 39 A, B). The
fibers arise in short, overlapping bundles from anterior and posterior
walls of femur where they are attached on the spaces between the
“ fish-bone ” ridges, with dorsal fibers of posterior set (135b) arising
in dorsal crest of femur. Anterior and posterior fibers converge to
sides of a large, thin, flat apodeme that tapers distally to a thick stalk
NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS Ws
(fig. 39 A, 135Ap) arising from dorsal margin of base of tibia. On
the base of this apodeme are inserted two short, strap-like branches
(fig. 36 F, 135c, 135d) arising dorsally in distal part of femur.
130. Depressor of the tibia (fig. 39).—A relatively small muscle
with long, slender fibers (736a) arising in ventral part of femur and
converging to sides of long, tapering apodeme arising in ventral mem-
brane of knee joint. The terminal, strap-like part of this apodeme
slides over a strong, internal process (@) of ventral wall of femur.
185¢ 155Ap
Sn
Fic. 39—Musculature of the hind leg of Dissosteira.
A, left leg, anterior (outer) view. B, cross-section through basal half of left
femur, proximal end of distal piece, showing positions of levator and depressor
muscles of tibia and of principal tracheae.
Two small, anterior and posterior bands of fibers, arising on dorsal
wall of femur, are inserted on apodeme near its base, the anterior one
(136b) shown in the figure.
137. Levator of the tarsus (fig. 39).—A very small dorsal muscle
in distal end of tibia, inserted on dorsal rim of base of tarsus.
138. Depressor of the tarsus (fig. 39). —A small muscle, but longer
than the levator, arising ventrally in distal part of tibia, inserted on
ventral lip of base of tarsus.
139. Depressor of the pretarsus: retractor of the claws (fig. 39).—
Comprises three small groups of fibers, one arising posteriorly in ven-
tral part of femur among fibers of tibial depressor, the second (139b)
72 SMITHSONIAN MISCELLANEOUS COLLECTIONS voL. 82
in proximal end of tibia, the third (739c) on ventral wall of basal half
of tibia; all inserted on fine, tendon-like apodeme (139 AP) arising
from unguitractor plate at base of claws.
LV. THE LEGS AND THER MUSCLES
The legs of the grasshopper are all of typical form and segmenta-
tion, but the hind legs, being specially developed as organs of leaping,
are not only of greater size than the others but differ from them in
certain details of structure and in the relative proportions of some
of the muscles. When the grasshopper sits in an ordinary resting posi-
tion it supports itself principally on the first and second pairs of legs,
the tibiae of the hind legs being flexed against the under surfaces of
NS he
/ ‘ xe
Tien Cx Tr tin,
Fic. 40.—Middle leg of Dissosteira, anterior surface.
Ar, arolium; Cx, coxa; Fm, femur; Tar, tarsus; Tb, tibia; Tn, trochantin;
Tr, trochanter; Un, claw.
the femora, with the knees usually held low and the tarsi barely touch-
ing the ground. (The grasshopper of illustrations commonly rests on
all three pairs of legs, with the hind knees elevated and the tibiae ex-
tended.) In its natural resting attitude, the insect is always ready for
a leap, the spring being caused by a forcible extension of the hind
tibiae, probably accompanied by a strong depression of the trochantero-
femoral parts of the legs. The chief function of the first and second
legs is the support of the body and the directing of the few movements
of walking or of changing the resting position; the first legs are ac-
tively used also during feeding for grasping and manipulating the
edge of the leaf. When the grasshopper walks the hind legs are used
with the others in the usual fashion.
In describing the legs it is customary to use terms of orientation
as they would apply if the appendage were extended laterally at right
angles to the body. Preaxial and postaxial surfaces are called anterior
and posterior, and upper and lower surfaces are dorsal and ventral.
NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 7S,
STRUCTURE OF THE LEGS
The general form of a grasshoppper’s leg is shown in the illustra-
tion of the middle leg of Dissosteira (fig. 40). The appendage con-
sists of a coxa (Cx), a trochanter (Tr), a femur (Fm), a tibia (Tb),
a three-segmented tarsus (Tar), and a pretarsus comprising a pair of
lateral claws (Un) and a median arolium (Ar). In the articular mem-
brane before the base of each coxa there is a small trochantinal sclerite
(Tn), best developed in the prothorax.
Each leg is set into a membranous area, or coal corium (fig. 26),
occupying an oval interruption in the sclerotic wall of the body between
the pleuron and the sternum, known as the coval cavity, the rim of
which is reinforced by a submarginal inflection. The coxa is hinged
to the body wall by only a single articulation, which is with the pleuron.
The rudimentary trochantin (fig. 40, Tm) does not restrict the move-
ment of the coxa. The anterior and middle coxae are free to move in
any direction, but the hind coxae, which are directed posteriorly, have
a more limited range of motion. The number of muscles inserted upon
the hind coxae, however, suggests that what little movement these
coxae possess is of much importance in the function of the hind legs.
It should be noted that the articulating surfaces of the pleuro-coxal
hinge are formed by inflections of the body and coxal walls, and there-
fore lie on the inner surfaces of the latter (fig. 41 D). In this respect
the basal joint of the leg differs from the basal articulations of the
head appendages with the head wall, for the latter are external sur-
faces of contact lying outside the articular membranes. The peculiar
character of the pleuro-coxal (subcoxo-coxal) articulations attests,
therefore, that these articulations are not homologous with the basal
articulations of the gnathal appendages on the edge of the epicranium.
The coxo-trochanteral joint and the articulations between the seg-
ments of the telopodite, except the trochantero-femoral joint, which is
but little movable, are all of the dicondylic hinge type with anterior
and posterior articulating points on a horizontal axis transverse to the
length of the leg segments. Movement at these joints is approximately
in the same vertical plane. The trochanters are closely attached to the
femora, but the hinge lines lie in a vertical plane, and the presence of a
posterior femoral muscle in the trochanter of the first and the second
leg (fig. 36 A, 72) shows that the primitive motions at the trochantero-
femoral joint were movements of production and reduction. The seg-
ments of the tarsus are movable on each other, but since they have no
musculature, they can be moved only as they are influenced by the
tendon of the ungual retractor which passes through them (fig. 44, +’).
74 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82
The coxae.—The three coxae of the grasshopper differ somewhat in
their positions on the body. The first is the most freely movable; it
projects downward and its base is almost horizontal. The second coxa
is directed outward, downward, and posteriorly; its base lies in an
oblique plane between the pleuron and the sternum. The hind coxa is
directed posteriorly ; its basal aperture is on the inner face and lies in
an approximately vertical, longitudinal plane.
Fic. 41.—Structure of the coxae of Dissosteira.
A, first coxa and base of telopodite, left, anterior surface. B, base of middle
leg, left, anterior surface. C, hind coxa and trochanter, left, anterior (outer)
surface. D, articulation of middle coxa to pleural process, right, inner view.
95Ap, apodeme of second abductor of middle coxa; Bc, basicosta of coxa;
bcs, basicostal suture; c, pleural articulation of coxa; Cs, hind coxa; cxs, coxal
suture; Epm, epimeron; Eps, episternum; f, anterior coxo-trochanteral articu-
lation; Mer, meron; PIS, pleural suture; Tn, trochantin; Tr, trochanter.
Each coxa presents a well-marked basal rim, or basicoxite, set off
by a submarginal basicostal suture (fig. 41 A, B, bcs) which forms
internally a strong basicosta (D, Bc). Laterally the costa of the mid-
dle coxa (fig. 37 B) and of the hind coxa (fig. 38 D, F) are enlarged
into wide, shelf-like plates for the accommodation of muscle attach-
ments. The basicoxite is very narrow or obsolete on the mesal surface
of the coxa, but on the lateral surface it forms a distinct prearticular
and a postarticular lobe, the latter being known as the meron (fig. 41 B,
Mer). The basicoxal lobes are well developed on the hind coxa (C)
NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 75
but they are inconspicuous externally because each is bent outward and
flattened upon the dorsal wall of the coxa. The articular surface (c)
by which the coxa is hinged to the internal coxal process of the pleuron
(D) is strongly inflected mesally in such a manner as to bring the
point of suspension near the central axis of the coxa, thus giving the
coxal muscles a leverage on all sides of it (fig. 43). Each coxa has a
dicondylic hinge with the trochanter (fig. 36 D, f, g), the axis of which
is horizontal and transverse to the length of the leg. The dorsal sur-
tace of the coxa is deeply emarginate between the hinge points, and
the ample articular membrane that occupies the notch allows a free
upward movement of the telopodite. When the latter is deflexed, the
ventral lip of the trochanter passes inside the lower edge of the coxa.
The anterior wall of the prothoracic coxa is marked by a coxal
suture (fig. 41 A, cvs) which extends from the anterior trochanteral
articulation (f) to the basicostal suture at the articulation of the tro-
chantin (77). The middle coxa (B) has a similar suture (cvs) ending
at the trochanteral articulation (f), but it begins basally at the pleural
articulation (c) and thus falls in line with the pleural suture (PIS)
of the mesopleuron. The suture is absent in the hind coxa (C). The
coxal suture, when present, forms a ridge on the inner surface of the
coxal wall (fig. 36 A), the purpose of which is evidently to strengthen
the latter.
A coxal structure such as that of the middle leg of the grasshopper
(fig. 41 B), in which the anterior wall is divided by a groove (crs)
continuous with the pleural suture, is likely to be confused with the
quite different structure illustrated by the coxa of Panorpa (fig. 14 A),
in which the postarticular part of the basicostal suture (bcs) bends
distally in the coxal wall and also falls in line with the pleural suture
(PIS). The fundamental differences in the two cases, however, are
quite apparent: in the grasshopper (fig. 4t B) the outer wall of the
coxa itself is divided; in Panorpa (fig. 14 A) the meron (Mer) is
greatly enlarged and is extended into the posterior coxal wall.
The internal ridge of the coxal suture in the prothoracic and meso-
thoracic legs of Dissosteira is continued through the anterior coxo-
trochanteral articulation (fig. 36 A, f), giving a firm but flexible union
between the two articulating segments. The posterior articulation be-
tween the coxa and trochanter of the first and second legs consists of
a condyle on the trochanter opposed by a concave surface on the coxa,
but the two are united by membrane. In the hind leg both coxo-
trochanteral articulations consist of opposing processes united by
ligament-like thickenings of the articular membrane (fig. 36 D, f, g).
76 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8&2
The trochanters.—The trochanteral segments of the prothoracic and
mesothoracic legs have the usual form of the trochanter in insects, each
being a short segment articulating as just noted with the coxa, and
united distally with the femur. The trochantero-femoral union has an
obliquely vertical hinge line and is perhaps slightly movable, since a
femoral reductor muscle is present in each of the first and second legs
(fig. 36 A, 72). The trochanter of the hind leg is a short ring-like
segment (fig. 36 D, Tr) expanded on the posterior (mesal) surface,
but so narrow externally as to be scarcely perceptible here (fig. 39,
Tr) between the coxa and the base of the femur. It is immovably con-
nected with the femur but not fused with it, and there is no trochantero-
femoral muscle in the hind leg (fig. 39 A). The apodemes of the leva-
tor and depressor muscles of the trochanter arise from small sclerites
at the base of the trochanter in the dorsal and ventral articular mem-
branes (fig. 36 D).
The femora.—tn the first and the middle leg the femur is a simple
elongate segment (fig. 40, Fim) somewhat flattened in its antero-
posterior diameter (fig. 36 C). At the distal end of the femur the
anterior wall is expanded into a broad lobe that conceals the anterior
femoro-tibial articulation (fig. 36 E, 1); the ventral wall is deeply
emarginate and occupied by an ample articular membrane (fig. 36 B)
which allows a free flexion of the tibia beneath the femur.
The femur of the hind leg (fig. 39, Fm) contains the principal leap-
ing muscles, which are the extensors of the tibiae (735); the hind
femur is consequently greatly enlarged and is provided with special
structural features. Its length is more than twice that of the middle
femur, and its greatest vertical diameter is equal to the length of the
prothoracic femur. The flat anterior and posterior surfaces (fig. 39 B)
are ridged longitudinally above and below, and the space between is
marked by the “‘fish-bone” pattern of a double series of oblique
ridges. The latter separate the lines of attachment of the fiber bundles
of the extensor muscles of the tibia on the inner walls of the femur
(fig. 39, 135a). The distal end of the hind femur (fig. 36 F)
is structurally similar to that of the first and second femora (FE),
but its anterior and posterior walls are strengthened by strongly
sclerotized plates.
The tibiae —The tibiae are of similar form and structure in all the
legs, each being a slender shaft used as a lever rather than as a con-
tainer for muscles, and so constructed that it can be folded beneath the
femur. The femoro-tibial articulation is a strong dicondylic hinge
(fig. 36 E, F, 1, m), and the dorsal lip of the tibial base projects well
within the end of the femur to give an efficient leverage to the extensor
|
NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS WG
muscles (fig. 44). The ventral, flexor muscles are inserted upon an
apodeme that arises from a small sclerite in the ventral membrane of
the knee joint. The knee mechanism is most strongly developed in the
hind leg (figs. 36 F, 39). The base of the tibia here forms a well dif-
ferentiated articular head bent toward the femur almost at right angles
Fic. 42—Tarsus and pretarsus of Dissosteira.
A, tarsus of middle leg disjointed, showing levator and depressor muscles
(108, 109) inserted on basal subsegment, and tendon-like apodeme (1104p)
of retractor of claws (Un) arising on unguitractor plate (Utr) and extending
through tarsus.
B, dorsal view of distal end of tarsus (Tar), arolium (Ar), and claws (Un),
the latter articulated to unguifer (Uf) of tarsus.
C, ventral view of pretarsus and end of tarsus, showing planta (Pin) and
unguitractor plate (Utr) in base of pretarsus.
to the length of the segment (fig.-39), and the dorsal lip of the tibial
base is produced far into the end of the femur by an inflection of the
articular membrane. The first and second tibiae are each provided
with two rows of large, flexible, hollow spines on the distal half of
the under surface, while the hind tibia has two rows of similar spines
on its dorsal surface, but none on the ventral surface except at the end.
The tarsi—The tarsi are each composed of three segment-like pieces
(fig. 40, Tar) ; but the tarsal subdivisions, or articles, are clearly not
78 SMITHSONIAN MISCELLANEOUS COLLECTIONS voL. 82
segments equivalent to the other parts of the leg, for they are inter-
connected only by infolded membranes in which there are no sclerotic
points of articulation, and none, except the basal one, is ever provided
with muscles (fig. 42 A). The large basal subsegment of the grass-
hopper’s tarsus bears three pairs of cushion-like pads on its under sur-
face ; the middle subsegment has a single pair ; the longer terminal one
has no pads. The presence of three pads on the basal subsegment is
suggestive that this piece is a composite of three primary tarsal articles.
The tarsal pads have been termed euplantulae by Crampton (1923).
The pretarsi—The terminal segment in each leg of the grasshopper
bears a pair of large lateral claws (fig. 42 A, Un), but it is itself
reduced to a simple median lobe, the arolium (B, C, Ar), and has two
sclerites in its ventral wall (C, Pin, Utr). The proximal sclerite is the
unguitractor plate (Utr) ; its base is invaginated into the end of the
tarsus and gives attachment to the tendon-like apodeme (110Ap) of
the depressor muscle of the pretarsus, known as the retractor of the
claws. A levator of the pretarsus is lacking in all insects. The distal
ventral sclerite, possibly a subdivision of the unguitractor, is distin-
guished as the planta (Pin). The claws arise from the dorso-lateral
parts of the base of the pretarsus and are articulated dorsally to the
unguifer area on the end of the tarsus (fig. 42 B, Uf).
MUSCLES OF THE LEGS
The muscles of an insect’s leg are comprised in three groups: (1)
muscles that move the limb as a whole; (2) muscles that move the
telopodite ; (3) muscles that move the segments of the telopodite upon
each other. The muscles of the first group have their origins entirely
within the body ; they are inserted on the base of the coxa, on the tro-
chantin, or on apodemes arising in the coxal corium. The muscles of
the telopodite arise in the coxa and within the body ; they are inserted
on the trochanter or on apodemes arising close to the base of the tro-
chanter in the articular membrane of the coxo-trochanteral joint. The
muscles of the individual segments of the telopodite beyond the tro-
chanter arise in the segments proximal to their insertions; they are
inserted either on the bases of the segments they move or on apodemes
arising in the articular membranes.
Muscles of the leg base -—The muscles associated with the coxa that
move the leg as a whole fall into three groups according to their points
of origin ; namely, muscles that arise on the tergum, muscles that arise
on the sternum, and muscles that arise on the pleuron.
NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 79
The basal leg muscles arising on the tergum comprise anterior and
posterior groups of fibers, or tergal promotors (fig. 43 A, J) and
tergal remotors (J). The tergal promotors are usually contained in a
single muscle, which is inserted on the trochantin (B, 7”) when this
sclerite is present and well developed, otherwise in the articular mem-
brane or on the base of the coxa. The tergal remotors often form a
digs pc
Fic. 43.—Diagrams of the cardinal axes of motion in a coxa articulated to the
body by a pleural articulation only, and the coxal musculature in a wing-bearing
segment.
A, mechanism of the coxal movements on the pleural articulation (c), inner
view. The cardinal movements are: (1) promotion and remotion on a trans-
verse axis (c c) by tergal promotor and remotor muscles (J, J); (2) rotation
on a vertical axis (d d) by anterior and posterior sternal rotator muscles
(K, L); and abduction and adduction on a longitudinal axis (b b) by a pleural
abductor muscle (J/), and a sternal adductor muscle (N) arising on sternal
apophysis.
B, diagram of typical musculature of a coxa in a wing-bearing segment freely
movable on the pleural articulation. 7, promotor of coxa, tergum to trochantin;
J, remotor, tergum to coxa; K, anterior rotator, sternum to coxa; L, posterior
rotator, sternum or spinasternum to coxa; M, abductor, episternum to coxa;
M’', basalar muscle, basalare to coxa; M”, subalar muscle, subalare to coxa
(M' and M” are pleural abductors of coxa in the nymph, fig. 27 C) ; N, adductor,
sternal apophysis to coxa.
group of muscles. In Dissosteira the tergal promotor is a single muscle
for each leg: that of the prothorax (fig. 33 A, 62) is inserted on the
trochantin (77) ; that of the middle leg is inserted by an apodeme
(fig. 37 A, B, C, 89) arising between the trochanter and the coxa;
whereas that of the hind leg (fig. 38 A, 178) is attached directly on the
anterior angle of the coxa (A, D, F, 178). The tergal remotors of the
first leg comprise a group of three muscles (fig. 33 A, B, C, D, 63,
64, 65) inserted on the posterior angle of the coxa; those of the
middle leg include two muscles inserted by apodemes on the posterior
angle of the coxa (fig. 37 A, B, 90, 91) ; and those of the hind leg em-
80 SMITHSONIAN MISCELLANEOUS COLLECTIONS voL. 82
brace two muscles (fig. 38 A, 179, 120) similarly inserted (D, F).
The two sets of tergal muscles, promotors and remotors, are clearly
antagonists pulling on opposite extremities of the longitudinal basal
axis of the coxa (fig. 43 A, b-b), the fulcrum of which is at the pleural
articulation (c).
The sternal musculature of the coxa, when complete, includes three
groups of fibers, one inserted on the anterior angle of the coxal base,
one on the posterior angle, and one on the mesal rim. The first two are
the anterior and posterior rotators (fig. 43 B, K, L) serving to turn
the coxa in the plane of its base (A) on the pleural articulation (c).
In the foreleg of Dissosteira an anterior rotator is lacking, but there
are two posterior rotators (fig. 33 C, 66, 67), the first arising on the
base of the sternal apophysis (S.4), the other on the spina (1Spm) ;
both are inserted on the posterior angle of the coxa (C, D). The
middle leg has a single anterior rotator (fig. 37 A, B, 92) and a single
posterior rotator (93), the first arising on the sternellar lobe of the
mesosternum (fig. 35, 92), the second (93) on the spina (2Spn). In
the hind leg there is a single, large two-branched anterior rotator of
the coxa arising on the metasternum laterad of the base of the sternal
apophysis (fig. 35. 127), and inserted on the anterior angle of the coxa
(fig. 38 D, 121) ; and there are three posterior rotators (figs. 35, 38 E,
122, 123, 124) all arising from the arm of the sternal apophysis.
The mesal sternal muscle of the coxa (fig. 43 B, NV) is the adductor.
It pulls upward (A, V) on the inner end of the transverse axis (c-c)
of the coxal base passing through the pleural articulation (c). In each
segment of Dissosteira the coxal adductor arises on the under surface
of the arm of the sternal apophysis (figs. 33 C, 69; 37 A, 100, I0I;
281C,1Ds Sno):
The pleural muscles of the coxa include the functional abductor
fibers (fig. 43 B, M@) which directly oppose the adductor (NV), and, in
the wing-bearing segments, two other muscles (B, J’, M@”) that ap-
pear to be derived from the primitive abductor system.
In the foreleg of Dissosteira the abductor of the coxa is a two-
branched muscle (fig. 33 D, 68a, 68b) arising on the inner surface of
the invaginated episternum (Eps). In the middle leg the abductor
group comprises three distinct muscles (fig. 37 A, 94, 95, 96) all
arising on the episternum. The first two are inserted by flat apodemes
anteriorly on the outer rim of the coxa (B, C, 94, 95) and perhaps
function here as accessory promotors. The large third muscle (A,
96), however, is inserted close before and distinctly laterad of the
pleural articulation (B, c) by a slender apodeme (96) arising in the
coxal corium, and it must be the functional abductor of the coxa. In
NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 81
the hind leg there are two muscles in the abductor group (fig. 38 C,
125, 126), one being a small anterior muscle (125), apparently acces-
sory to the promotor (A, 7178), the other a large posterior muscle
(C, 126) which unquestionably functions as an abductor.
The pleural muscles associated with the functional abductor mus-
cles of the coxa in the wing-bearing segments are attached on the outer
rim of the coxa (fig. 43 B, WM’, MW”) and, in adult insects, arise typi-
cally on the epipleural basalar and subalar sclerites (figs. 37 A, 98, 99;
38 B, 128, 129), and function as wing muscles. In some adult insects,
as in Panorpa (fig. 14 B), the first of these muscles (/’) arises on a
dorsal lobe of the episternum (Ba), which is clearly the homologue of
the basalar plate or plates in other insects, such as are present in the
adult of Dissosteira (fig. 26, Ba). The posterior epipleural muscle
(M”) is always attached to the subalar sclerite in adult insects (figs.
14 B, 37 A, 38 B, Sa). Both muscles, however, in the nymph of
Dissosteira (fig. 27 C, M’, M") and in other nymphal Orthoptera,
arise directly from the upper edge of the pleuron, one on the epis-
ternum, the other on the epimeron, and, if they act together, they
must be abductors of the coxa. The epipleural muscles, therefore,
appear to be groups of coxal abductor fibers that have become specially
developed as secondary wing muscles in the adult. The first is a
pronator-extensor of the wing; the second is the depressor-extensor
of the wing (fig. 49, M’, M”).
The foregoing analysis of the basal leg musculature of Dissosteira
shows that the coxa is provided with six sets of muscles, including
an anterior and a posterior group of fibers arising on the tergum
(fig. 43 B, J, J), an anterior and a posterior group arising on the
sternum (K, L), a lateral group arising on the pleuron (1, and also
M’ and M” in the wing-bearing segments), and a mesal group arising
on the sternum (NV). The anterior and posterior dorsal and ventral
muscles may be supposed to represent the theoretical primary tergal
and sternal promotors and remotors of a primitive limb basis (fig. 6,
I, J, K, L), which have become transferred to the coxal region (fig.
11) after the subdivision of the basis into subcoxa and coxa. The
lateral and mesal muscles, therefore, are subcoxo-coxal muscles, the
fibers of the first (17) retaining their origins on the subcoxal pleuron,
those of the second (N) having been transferred to the sternum,
perhaps by the incorporation of the ventral rim of the subcoxa into
the definitive sternal plate.
Muscles that move the telopodite—The muscles that operate the
telopodite, or that part of the leg beyond the coxo-trochanteral hinge,
6
82 SMITHSONIAN MISCELLANEOUS COLLECTIONS VoL. 82
comprise the muscles normal to the trochanter, which are a levator
and a depressor arising in the coxa (fig. 44, O, Q), and also special
depressor muscles (P) that have their origin in various parts of the
body segment carrying the leg. The basal lip of the trochanter usually
projects into the coxa well beyond the line of the coxo-trochanteral
hinge, thereby giving a strong leverage to the depressor muscles in-
serted upon it.
The branches of the trochanteral depressor arising within the body
segment vary much in different insects and in different segments of
Fic. 44.—Diagram of the mechanism of the hind leg of a grasshopper.
O, levator muscle of trochanter, or extensor of telopodite, origin in coxa;
P, body branch of depressor of trochanter, or flexor of telopodite, origin on
tergum; Q, coxal branch of depressor of trochanter; S, levator of tibia; T, de-
pressor of tibia; U, levator of tarsus; V, depressor of tarsus; X, X, tibial
branches of retractor of claws; x, tendinous apodeme of retractor of claws aris-
ing on base of unguitractor plate.
the same insect. In the prothorax of Dissosteira there are three body
branches of the trochanteral depressor, one arising on the episternum
(fig. 33 B, 7rb), the second on the pleural arm (C, 71c), and the
third on the tergum (B, 71d). In the mesothorax there are two
body branches of the muscle, both arising on the tergum. In the
metathorax a long outer branch and an inner branch (fig. 38 A, 133c)
arise on the tergum, and a short branch takes its origin on the under
surface of the lateral arm of the metasternal apophysis (fig. 38 A, E,
133d). These muscles ordinarily serve to lift the body on the legs,
but those of the hind legs of the grasshopper are probably accessory
to the extensor muscles of the tibiae in the act of leaping (fig. 44, P).
Muscles of the telopodite segments.—Since the trochantero-femoral
joint usually has but little movement in insects, the muscles of the
NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 83
femur arising in the trochanter are small or absent. In Dissosteira
a posterior, or reductor, muscle only is present in the trochanter of
the first leg (fig. 36 A, 72) and in that of the second leg. In the hind
leg there is no movement at the trochantero-femoral joint and femoral
muscles are lacking. The usual flexion between the trochanter and
the femur of insects is anterior and posterior (production and re-
duction), and generally only a reductor muscle is present, called the
“rotator”? of the femur by some writers (Morison, 1927; Weber,
1929).
The femur is occupied mostly by the tibial muscles (fig. 44, S, T),
but it contains also the most proximal branch of the flexor of the
claws (X). The tibial musculature comprises levator muscles (S)
and depressor muscles (7). In Dutssosteira there are two levator
muscles in each leg, a larger posterior one (fig. 36 E, 106, F, 135),
and a very small anterior one (E, 105, F, 134). In the fore and middle
legs the depressor of the tibia (fig. 36 B, C, 107) is larger than the
levator, and it has a basal branch arising in the trochanter (B). In
the hind leg the relative proportions of the two muscles are reversed,
the posterior levator, or extensor, of the tibia consisting of the great
masses of fibers arising on the ridged anterior and posterior walls of
the femur (fig. 39, 735a, 135b), and including smaller branches
(135c) arising on the dorsal wall in the distal part of the femur. The
anterior levator of the tibia in each leg consists of a very slender
bundle of fibers arising anteriorly in the base of the femur (fig. 36 A,
73) and inserted by a long, thread-like apodeme on the head of the
_ tibia (E, ro5Ap, F, 134Ap).
The tibiae contain the levator and depressor muscles of the tarsus,
and the tibial branches of the flexor of the claws. The tarsal muscles
are relatively largest in the fore and middle legs of Dissosteira; in the
hind leg they occupy only the distal part of the tibia (fig. 39, 137, 138).
The tarsus contains no muscles, the tarsal segments, as before
noted, being flexible upon one another but not independently movable.
This condition pertains to all insects. The tarsus is traversed by the
“tendon,” or thread-like apodeme, of the flexor of the claws (figs.
39, 139AP, 44, x).
The claws of insects are provided with only a flexor, or rectractor,
muscle, which is the depressor of the pretarsus (fig. 44 X), or the
homologue of the depressor of the dactylopodite in arthropods gen-
erally. The fibers of the claw muscle arise in several groups in the
tibia and femur, and are inserted on a long tendon-like apodeme that
arises from the base of the unguitractor plate (fig. 42 C, Utr) and
84 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82
extends through the tarsus and tibia into the femur. In Dissostetra
two small groups of fibers of the claw muscle arise in the upper part
of the tibia (fig. 39, 139b, 139c), and one arises posteriorly in the
base of the femur (fig. 36 A, 78). The pull of the muscles on the
tendon retracts the unguitractor plate and flexes the claws ventrally.
The extension of the claws probably results from the elasticity of
their basal connections and the pressure on the supporting surface.
Typically, the muscles of the pretarsus should arise in the tarsus.
It is probable, therefore, that the extension of the fibers into the tibia
and femur in insects (and also in chilopods and diplopods) is a sec-
ondary condition produced by a proximal migration of the primitive
muscle. In Crustacea and Arachnida the pretarsus, or dactylopodite,
is provided with levator and depressor muscles, both of which have
their origin in the tarsus, or propodite. In some Arachnida there are
two pretarsal claws, as in most insects, but the pretarsus has lateral
articulations with the end of the tarsus, and is provided with dorsal
and ventral muscles.
V. THE WINGS AND THEIR MECHANISM
The wing mechanism of the grasshopper is equally developed in
each segment of the pterothorax. The hind wings, though much more
extensive than the forewings, or tegmina, and probably the chief
organs of flight, have no advantage over the latter except in the
stronger development of the flexor apparatus. The forewings, on the
other hand, have a more powerful levator equipment than the hind
wings because of the presence in the mesothorax of the second pair
of tergo-sternal muscles attached dorsally on the scutum (fig. 34, 84).
In structure, the hind wings (fig. 45 B) differ from the forewings
(A) only in the reduction of the costal area and in the great ex-
pansion of the anal area.
STRUCTURE OF THE WINGS
In general structure, articulation, and mechanism the acridid wings
differ little from the wings of other Orthoptera. The tegmina when
at rest are flexed over the body in a manner to form a high roof with
steeply sloping sides (fig. 50 A, W.) covering the back of the abdomen
and inclosing the folded hind wings (W,;) in the space above the
latter. The anal areas of the tegmina overlap dorsally in a median
horizontal plane, the left tegmen being usually on top; the pre-anal
areas form the lateral inclines of the tegminal roof. The bend be-
EE
NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 85
tween the two wing areas takes place along the anal fold (figs. 45 A,
50 A, AF), and is produced mechanically during the flexion of the
wing. The broad hind wings are folded in a complicated manner, to
enSecrer Ml Pra
ea teett sie |
| Z|
\
Tx B
Fic. 45.—The wings and wing veins of Dissosteira.
A, fore wing, or tegmen. B, hind wing. A, anal veins, anal area of wing;
1A, first primary anal vein; 7A, seventh primary anal; C, costa; 1Cu, first
cubitus; 2Cu, second cubitus; /, intercalary vein; 7, 7, secondary anal veins of
first anal plait; k, first concave anal vein; Ju, jugal area of wing; /, second con-
cave anal vein; M/, media; Pra, preanal area of wing; q, basal support of anal
veins; FR, radius; Ax, first branch of radius; Rs, radial sector; r, first anal plait
of wing; R-+ M, united shafts of radius and media; Sc, subcosta; ’D, vena
dividens.
be described later, and when fully flexed are concealed beneath the
overlying tegmina (fig. 50 A).
The area of an insect’s wing presents usually three well-defined
regions, namely, a preanal region, an anal region, and a small, pos-
86 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82
terior, basal region, generally membranous, which Martynov (1925)
terms the jugal region. The three wing regions are shown in typical
form in the forewing of the grasshopper (fig. 45 A). The preanal
region (Pra) is that lying anterior to the anal fold; the anal region
is the region of the anal veins (4), the jugal region (Ju) is the
membranous basal fold of the wing. In many insects the jugal region
contains one or two definite veins unconnected basally, or an irregular
network of small veins.
The hind wing of the grasshopper (fig. 45 B), and of other insects
with similar fan-shaped wings, is usually regarded as differing from
the forewing in the great expansion of the anal region. According to
Martynov (1925), however, the true anal region of the hind wing
in Acridium is that part (fig. 45 B, 7) between the anal fold, or vena
dividens (VD), and the first vein springing directly from the basal
support (q) of the anal fan (designated 7A in fig. 45 B). Three
veins (1, j, k), branching from a common base, lie in this region in
the wing of Dissosteira. The following part of the wing, or that
containing the veins attached directly to the basal support (q) of the
anal fan, Martynov claims is a development of the jugal region of the
more primitive type of wing. A jugal area thus developed into a
functional wing region he calls the “ neala.”
Martynov deduces his interpretations of the morphology of the
acridid wing from a general study of the wings in other orders of.
insects. In Dissosteira, however, the vein designated 7A in the hind
wing (fig. 45 B) is so clearly the homologue of 1A in the forewing
(A), considering the basal relations and the connection with the third
axillary sclerite (fig. 47 A, B, 34x), that Martynov’s interpretation
is not convincing. The area (7) of the hind wing (fig. 45 B), lying
between VD and 1A, forms the first fold of the anal region (fig. 50 B)
in which the vein k occupies the position of a “ concave ”’ vein at the
bottom of the fold, while the two preceding veins (2, 7) strengthen
the anterior wall of the fold. The three veins of this region (fig.
45 B, 1, 7, k) are branches of the first primary anal vein (14). Mar-
tynov’s general study of the wing regions, however, throws much
light on the wing mechanism and morphology.
Venation of the wings——While the venation of the grasshopper’s
wings is comparatively simple, it is difficult to make a satisfactory
interpretation of the homologies of the veins in the posterior parts
of the preanal regions. If the relation of the vein bases to the axillary
sclerites is taken as a guide to the identities of the veins themselves,
the veins of the adult may be named consistently in the two wings, but
their relation to the nymphal wing tracheae is not clear in all cases.
ee a a
NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 87
The forewing (fig. 45 A) has a broad anterior, or costal, area in
which there is no vein represented by a costal trachea in the nymph
(fig. 46 A), though the anterior margin is strengthened by a vein-like
thickening. The first vein (fig. 45 A, C) is evidently the costa branch-
ing from the subcosta (Sc), though the common basal stalk has the
usual relation of the subcosta to the first axillary sclerite (fig. 47 A,
1Ax). The next vein (F) is unquestionably the radius, as shown by
its distal branches and by its basal connection with the second axillary
(fig. 47 A, 2Ax). The media (M) is united proximally with the
radius and with one of the median sclerites of the wing base (m’).
The first long vein following the media is a two-branched cubitus
(1Cu), between which and the basal part of the media is the inter-
calary vein (J). Then comes an unbranched vein, here designated
2Cu, lying close before the anal fold (AF), and finally a group of
three veins (4) connected basally with the third axillary, or flexor
sclerite of the wing base (fig. 47 A, 34x).
If we identify the “anal veins” as those veins lying posterior to
the anal fold and connected basally with the third axillary, there are
then but three anal veins in the forewing of Dissosteira (fig. 45 A,
A, fig. 47 A, 1A, 2A, 3A). An incomplete vein (fig. 47 A, s) lying
just behind the anal fold (AF) is apparently a secondary vein. The
vein immediately before the anal fold (2Cw) is the “ first anal ” of the
Comstock-Needham system, but probably it is the vein regarded as a
part of the cubitus by Tillyard (1919) and others, designated Ci, by
Tillyard and cubital sector by Karny. In Dissosteira the vein in ques-
tion has no basal connections and is here termed the second cubitus
(2Cu). It clearly belongs to the cubital area of the wing. In the nym-
phal wing of an acridid, as illustrated by Comstock and Needham (fig.
46 A), tracheal precursors of the cubitals are not evident, since the
final group of three tracheae springing from a common basal stem
would appear to represent the group of three anals in the adult wing
(fig. 45 A, A). According to Comstock (1918), however, the first vein
of this group is the “cubitus” (fig. 46 A, Cu), and the second the
“first anal” (14). The identity between the nymphal tracheae and
the adult veins in the forewing is certainly not clear, and no solution
of the problem can be offered here.
The vein tentatively called “second cubitus ” in this paper (figs.
45 A, 47 A, 2Cu) is, by nomenclatural priority, the true anal vein,
and the name “ anal,’ though a poor designation, should be retained
for it, while a new term should be devised for the veins lying posterior
to the anal plica associated with the third axillary sclerite. The fan-
’
88 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82
like wing region between the anal and jugal plicae might appropriately
be called the vannus (Latin, fan), and its veins termed the vannal
veins. This region plays a passive part in flight. The pre-vannal part
of the wing is the true remigium (Latin, oar) of the flight mech-
anism, being the region of the wing directly productive of motion. We
might then say that the area of the wing distal to the basal axillary
region is divided into a remigial, a vannal, and a jugal region. The
separating folds, when present, would then become the vannal and
the jugal plicae. The jugal region expanded is the neala of Martynov.
Fic. 46.—Wings of an acridid nymph. (From Comstock, after Comstock
and Needham. )
A, fore wing. B, hind wing. The tracheal identifications as given by Com-
stock and Needham: 14, first anal; Cu, cubitus; M, media; R, radius; Sc,
subcosta.
In the hind wing (fig. 45 B) the costa (C) forms the anterior
margin of the wing and is united basally with the subcosta (Sc).
The base of the subcosta (fig. 47 B, Sc) does not reach the first
axillary sclerite (142), evidently by reason of the reduction of the
anterior process of the latter, neither does it articulate with the pre-
scutal lobe of the tergum (fig. 22 A, 7), but it is connected with the
latter by a ligament-like thickening of the wing membrane (fig. 47 B,
d). The radius (2) is well developed, branched distally, and con-
nected basally with the second axillary (fig. 47 B, 24%). The ap-
parent media is united proximally with the radius; its free part con-
NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 89
sists of a single branch (7) given off from the radial sector (Rs).
Between the basal radio-medial shaft (R + M) and the first anal
fold, there are two veins in the cubital area (1Cu, 2Cu) ; the first
(fig. 47 B, Cw) is united proximally with the radio-media, the second
(2Cu) has no basal connections. In the hind wing, therefore, as in
the forewing, there are two distinct cubitals, here named the first
cubitus (rCw) and the second cubitus (2Cu). Each of these veins
-1is represented by a trachea in the hind wing of the nymph (fig. 46 B) ;
the first is the “cubitus”’ (Cw) of Comstock, and the second: the
“first anal”? (14). Since both of these veins lie anterior to the anal
fold in the adult wing (figs. 45 B, 47 B), however, the writer would
agree with Tillyard (1919) that the second is a cubital rather than
an anal vein. The orthopteran wing suggests that the second cubitus
has the status of an independent vein rather than that of a basal
branch of the first cubitus.
The anal fold of the hind wing is double (fig. 50 B), consisting of
two plicae, or lines of flection in the wing membrane, between which
lies the vena dividens (figs. 45 B, 47 B, 50 B, VD). According to Till-
yard the vena dividens is the “ first anal,” but since it has no basal con-
nection with the other anals (fig. 47 B), the writer would regard it
as a secondary, interpolated vein. The incomplete vein of the fore-
wing lying just behind the anal fold (fig. 47 A, s) may represent the
vena dividens of the hind wing, but it appears rather to correspond
with the vein z of the hind wing (figs. 45 B, 47 B).
The anal veins of the hind wing form a distinct group lying pos-
terior to the anal fold. All the primary anals spring from a basal sup-
port (fig. 47B, q) which is attached anteriorly to the distal arm of
the third axillary (34%), and which, in the grasshopper, is braced
posteriorly by an arm from the tergum (figs. 24, 47 B, p). There
are ten primary anal veins. A fork from the first (1A) divides into
three branches (7, j, k) lying in the first lap of the wing that folds
beneath the preanal region when the wing is flexed (fig. 50 B). Al-
ternating with the primary, or “ convex,” anal veins are nine secon-
dary “concave” veins lying in the troughs of the folds between the
primary anals, while the vein (k) branching from the first anal is the
concave vein of the fold between the vena dividens and the first anal
(fig. 50 B, k).
Articulation of the wings——In the membrane of each wing base
are four axillary sclerites. The first and the fourth (fig. 47 A, B, rAx,
4Ax) are hinge plates articulating with the edge of the tergum; the
second (2A) is the pivotal sclerite of the wing base; the third (3A)
go SMITHSONIAN MISCELLANEOUS COLLECTIONS VoL. 82
A
Fic. 47.—The wing bases of Dissosteira.
A, base of tegmen. B, base of hind wing. 1A, 2A, 3A, 7A, first, second, third,
and seventh primary anal veins; AF, anal fold; 1Ax, 2Ax, 3Ax, 4Ax, first,
second, third, and fourth axillary sclerites; C, costa; 1Cu, first cubitus; 2Cu,
second cubitus; d, attachment of base of subcosta to prescutal lobe of tergum;
I, intercalary vein; i, secondary vein of first anal plait; k, first concave anal
vein; /, second concave anal vein; M, media; m, m’, median plates of wing base;
p, posterior arm of tergum supporting the anal veins; q, basal support of anal
veins ; Fe, radius; R + M, united basal shafts of radius and media; 5, secondary
vein of fore wing behind anal fold; Sc, subcosta; tg, tegular rudiment; VD,
vena dividens.
NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS gI
is the flexor sclerite. In addition to the axillaries there are two plates
in the median area of the forewing (A, m, m’), and a single median
plate in the hind wing (B, m).
The first axillary intermediates between the edge of the tergum
and the second axillary, with each of which it is movably connected,
and usually, by an anterior process, it articulates with the base of the
subcostal vein. The first axillary is confined to the dorsal membrane
of the wing base. In the forewing of Dvssosteira the first axillary
(fig. 47 A, 1A) is a flat plate with a narrow anterior process curved
outward to meet the base of the subcosta. The sclerite bridges the
lateral emargination of the tergum (fig. 22 A, Em) ; its anterior end
is supported on the anterior notal wing process (ANP), and its pos-
terior part is hinged to the lobe of the scutum (0) behind the emargi-
nation ; its oblique outer margin articulates with the second axillary
(fig. 47 A). The first axillary of the hind wing of Dissosteira (B,
1Ax) is exceptional in the reduction of its anterior process which
does not meet the base of the sub¢osta (Sc).
The second axillary presents an exposed surface in both the dorsal
and the ventral membranes of the wing base. Its dorsal part forms
a triangular plate (fig. 47 A, B, 24x) lying lateral of the first axillary,
and closely hinged to the oblique outer margin of the latter; its pos-
terior outer margin articulates with the proximal median sclerite (m) ;
to its anterior end is attached the base of the radius (R). The ventral
part of the second axillary forms a strong, concave plate (fig. 48,
2Ax) resting by its lower edge on the pleural wing process (WP).
The second axillary differs somewhat in shape in the two wings of
Dissosteira, as shown in the figures, but its structure and associations
are the same in both.
The third axillary is developed principally in the dorsal wing mem-
brane (fig. 47 A, B, 3Ax), but it includes also a small sclerotization
in the ventral membrane (fig. 48, 34x). The dorsal part of the third
axillary (fig. 47) has the form of a strong bar extending outward, in
the fully-expanded wing, from the small fourth axillary (44x) to
the anal veins, which latter it supports by an arm bent forward from
its distal end. The mesal part of the sclerite bears a strong, elevated
process on its anterior margin upon which is inserted the flexor muscle
of the wing. Distal to the muscle process, the proximal median plate
(m) is firmly attached to the third axillary and is functionally a part
of it. In the forewing (fig. 47 A) the distal median plate (m’) is
hinged to the outer margin of the proximal plate.
g2 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82
The fourth axillary (fig. 47 A, B, 44%) is a plate of the dorsal
wing membrane only. It is small in each wing and serves merely as a
connective between the edge of the tergum and the third axillary.
It is probably a detached lobe of the tergum, since it is usually absent
in insects that have a posterior notal wing process.
Beneath the base of each wing are the epipleurites, or small scler-
ites derived from the pleuron, which are intimately associated with
the wing mechanism in the adult insect. In Dissosteira there are in
each segment two episternal epipleurites, or basalares, (fig. 48, 1B@s,
2Baz, 1Baz;, 2Ba3), and a single epimeral epipleurite, or subalare
(Sa). The basalares are hinged to the upper edge of the episternum
(Eps), and are connected with the subcostal region of the wing base
by a ligamentous thickening (a) of the ventral wing membrane. The
subalare (Sa) lies free in the subalar membrane behind the wing
process, but it is connected with the ventral plate of the second ax-
illary (2A) by a thickening (b) of the intervening membrane.
4
THE WING MECHANISM
Flying insects are unquestionably descended from wingless an-
cestors. When paranotal lobes were first evolved on the thoracic seg-
ments, the insect was already organized for terrestial locomotion—
there was no provision for future organs of flight. When movable
wings were evolved from the paranotal lobes, they had available for
their purposes only a motor mechanism developed for other pur-
poses. It needed but an area of flexibility at the base of each paranotal
extension to convert the lobe into a movable flap. The dorsal ends of
the pleura, previously supporting the bases of the paranotal lobes,
easily became fulcra on which the wing flaps could rock up and down.
A contraction of the longitudinal muscles of the dorsum could now
give a down-stroke to the wing flaps by producing an upward curva-
ture in the tergal plates of the wing-bearing segments, and probably
at first the elasticity of the terga sufficed to produce the up-stroke.
Thus, apparently, by the simple device of becoming flexible at their
bases, the paranotal lobes became wings, that could be weakly flapped
up and down by the simple motor equipment already at hand.
Modern insects, however, have added much to the primitive wing
mechanism. In each of the wing-bearing segments there are powerful
tergal-depressor muscles, which, since they do not occur in the pro-
thorax or in the segments of the abdomen, are probably specially
developed wing muscles, though they may be supposed to have been
evolved from small, lateral tergo-sternal muscles such as are usually
—-
NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 93
present in the abdomen. Being attached ventrally on the sternum,
these muscles indirectly impart a strong up-stroke to the wings by
flattening the dorsal curvature of the tergum. The down-stroke of
the wings produced by the contraction of the longitudinal dorsal
muscles has been strengthened in two principal ways: first, by the
obliteration of the secondary intersegmental membranes between the
terga, thus eliminating lost motion; and second, by the great enlarge-
ment of the dorsal muscles themselves in the wing-bearing segments.
Sele
a_
WPS 23 a5 Wak
y
~ _—1Baz
-—-2Baz
1Ba,\s es
2Bay Epsy \ Epmy\ Epsz \Epm3
=/
Fic. 48.—Ventral surface of the base of the left tegmen, and upper part the
pleuron of Dissostetra.
a, thickening of membrane uniting basalar sclerites with humeral angle of
wing ; 24x, ventral plate of second axillary; 34x, ventral plate of third axillary ;
b, connection between subalar sclerite and ventral plate of third axillary; 1Ba,
first basalare; 2Ba, second basalare; Sc, base of subcostal vein; Sa, subalare;
WP, pleural wing process.
The suppression of the intertergal membranes has been accomplished
by a fusion between the successive tergal plates, or by a forward
extension of the precostal lip of the tergum until it meets the pos-
terior edge of the preceding tergum. Thus are produced the post-
notal plates between the mesothoracic and metathoracic terga, and
between the metathoracic and first abdominal terga. The enlargement
of the dorsal muscles has been accompanied by the development of
supporting plates (phragmata) from the ridges of the muscle attach-
ments on the primary intersegmental folds. Furthermore, each tergal
plate has been strengthened and better adapted to its function in the
flight mechanism by the development of internal ridges, the principal
94 SMITHSONIAN MISCELLANEOUS COLLECTIONS VoL. 82
ones of which are so arranged as to bring the peak of the curvature
in the tergum on a transverse line between the wing bases.
The Odonata are commonly said to have a wing mechanism quite
different from that of other insects. On the basis of von Lendenfeld’s
(1881) description of the odonate wing muscles, the dragonflies have
been supposed to be equipped with a special set of muscles inserted
directly on the wing bases. A study of the thoracic musculature in
either the Anisoptera or the Zygoptera, however, will show that there
are ony two small muscles that can be regarded as special wing
muscles; one of these is accessory to the pronator of the wing, the
other to the depressor. The large pronator and depressor muscles,
though they arise ventrally on the lower edge of the pleuron and are
inserted directly on the two basal plates of the wing, are evidently the
homologues of the basalar and subalar muscles of other insects. Two
smaller muscles lying mesad of the pronator are clearly leg muscles
since they have their origins on the coxa and their insertions on the
extreme lateral edge of the tergum. Von Lendenfeld ascribed these
muscles to the wings ; he describes them as arising on the pleuron and
as inserted on the wings. Each wing has a homologue of the flexor
muscle in other insects, though it does not function as such because
of the lack of a flexor mechanism in the base of the odonate wing.
The tergo-sternal muscles are highly developed, their ventral attach-
ments are on the sternum and their dorsal attachments on the antero-
lateral lobes of the tergum. The dorsal longitudinal muscles are re-
duced to a pair of small, divergent fiber bundles attached anteriorly
on the median apodemal spine of the tergum, and posteriorly on the
anterior margin of the following tergum. The wing mechanism of
the dragonflies is thus merely an extreme modification of that common
to all insects.
A wing, in order to be an efficient organ of progressive flight, must
be capable not only of an up-and-down movement, but also of anterior
and posterior movements accompanied by a partial rotation on its
long axis. The anterior margin of the wing must be brought forward
and deflected during the down-stroke, and lifted with a posterior
movement during the up-stroke. The rotary movement of the insect’s
wing is caused partly by the structure of the wing itself and its re-
sponse to air pressure, and partly by the nature of the wing articula-
tion on the body, but it is greatly augmented by muscles that pull
downward on the base of the wing, one before the pleural fulcrum,
the other behind it. These muscles are inserted on the basalar and
subalar sclerites beneath the wing base (fig. 48, Ba, Sa). Two of them
NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 95
are evidently muscles of the leg that have been taken over into the
service of the wing, for they are attached ventrally on the coxa (fig.
49, M’', M”) ; the other (£) arises on the sternum, or in some insects
on the pleuron, and is perhaps a specially developed wing muscle. The
two muscles of the basalar sclerites (E, M’) are called pronators be-
cause they deflect the costal wing margin. The muscle of the subalar
sclerite (M”) not only deflects the posterior part of the wing, but it
acts as a powerful depressor of the entire wing by reason of its con-
nection (b) with the ventral plate (c) of the second axillary (24%).
These muscles probably also enable the insect to alter its course during
flight, and, by changing the plane of the wing movements, to hover in
the air, or to fly sidewise or backward.
Finally, most insects have found it advantageous to fold the wings
posteriorly over the body. The folding of the wings has involved
the development of a mechanism for their flexion and extension. The
ability of the wing to be flexed depends upon the mechanism of its
axillary region, but the flexing is caused by one or more flexor muscles
arising on the pleuron and inserted on the third axillary sclerite (fig.
49, D). The extension of the wing is produced by the basalar and
subalar muscles (E, M’, M”). Considering the other functions of
these muscles, the first, therefore, is a pronator-extensor of the wing,
the second a depressor-extensor.
The special features in the mesothorax and the metathorax of the
grasshopper that contribute to the mechanism of the wings have been
described in Section II of this paper. It was there shown that the
fusion of the pleurites and sterna of the mesothorax and metathorax
converts these segments into a strong trough-like structure covered
dorsally by the two wing-bearing terga. The union of the pleural and
sternal elements in the pterothorax is probably a direct adaptation to
the leaping function of the hind legs, but the resulting structure also
gives a strong framework for the support of the wings and the wing
muscles. The tergal plates are separated from the edges of the pleuro-
sternal trough by the ample membranes of the wing bases, and they are
thus free to respond to the downward pull of the tergo-sternal muscles.
The close union of the terga (fig. 25) and the great size of the dorsal
muscles (fig. 34) give efficiency to the latter as elevators of the wings.
When the wings are spread they are pivoted on the pleural wing proc-
esses by the second axillary sclerites of their bases, and, being
closely hinged to the terga by the first and fourth axillaries, they are
sharply thrown upward when the tergal plates are depressed, and
are turned downward when the terga are elevated.
96 SMITHSONIAN MISCELLANEOUS COLLECTIONS VoL. 82
The mechanism for extending and flexing the wing is highly com-
plex. The muscles that produce the movements of extension and
flexion depend for their effect on the details of shape and inter-rela-
tionships in the axillary sclerites, on the articulation of the sclerites
with the tergum and pleuron, on their connections with the bases of
the wing veins, and on the structure of the wings themselves.
Fic. 49.—The pleural elements of the wing mechanism in the mesothorax
of Dissosteira.
a, thickening of cuticular membrane uniting basalar sclerites with humeral
angle of wing (see fig. 48) ; 24, second axillary; 3A, third axillary (first and
fourth axillaries removed) ; b, thickening of cuticular membrane uniting subalar
sclerite (Sa) with ventral plate (c) of second axillary; Ba, first basalare; c,
ventral plate of second axillary resting on pleural wing process (see fig. 48) ;
D, flexor muscle of wing, inserted on third axillary; E, pleuro-sternal muscle,
or first pronator-extensor of the wing, inserted on basalar sclerite; 1’, episternal
pleuro-coxal muscle, or second pronator-extensor of the wing, inserted on
basalar sclerite; M/”, epimeral pleuro-coxal muscle, or depressor-extensor of the
wing, inserted on subalar sclerite; PIR, pleural ridge; Sa, subalare; tg, tegular
rudiment; //’2, base of tegmen, showing dorsal surface.
During extension and flexion the wings do not simply turn forward
and backward on the pleural wing processes, since each wing is at-
tached to the tergum by its entire basal width. The horizontal move-
ments of the wings are made possible mainly by the flexible lines in
the wing bases and by the articulations of the axillary sclerites on one
another. The working of the parts involved may be easily observed in
a freshly killed specimen if the extended wing is slowly flexed.
ee
NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 97
In the fully exended wing of Dissosteira the axillary sclerites lie
approximately flat and in the same plane as the general wing surface
(fig. 47 A, B). When the wing is turned posteriorly, however, the
axillaries take different positions. In the living grasshopper it is
probable that the first movement of flexion is produced by the elas-
ticity of the wing base when the extensor muscles are relaxed, for the
wing of a dead specimen automatically assumes a partly flexed position.
The fully flexed and folded condition, however, undoubtedly depends
on the pull of the flexor muscle (fig. 49, D) on the third axillary.
On the relaxation of the wing, the initial flexing causes the outer
end of the third axillary to turn upward, and the pull of the flexor
muscle brings this sclerite to a vertical position. The movement of
the third axillary turns the attached median plate (m7) likewise to a
vertical position on its hinge with the second axillary (244%). In the
forewing (A), the revolution of the first median plate (m) draws the
second median plate (m’) inward. The second median plate, however,
is firmly attached to the united bases of the median, radial, and sub-
costal veins, and the head of the radius (2X) is flexibly attached to the
anterior end of the second axillary. As a consequence, the movement
of the first median plate turns the entire anterior part of the wing
posteriorly on the hinge between the radius and the second axillary.
But, since the basal connection of this part of the wing forms an
oblique line from the head of the first axillary to the articulation
between the two median plates, the entire preanal area of the wing
is deflected as it turns posteriorly. At the same time, the anal area is
lifted but maintains its horizontal plane as the third axillary assumes
a vertical position. When the wing finally comes to a longitudinal
position over the back, therefore, the anal area is uppermost and the
preanal area slants downward on the side (fig. 50 A). During the
final revolution of the wing the first axillary turns upward on its
hinge with the tergum, the second axillary rotates slightly on the
pleural wing process, and the third axillary revolves posteriorly in its
vertical position on the fourth axillary.
In the hind wing the mechanism of flexion is in general the same
as that of the forewing, but, in addition to the posterior turning of
the wing, the great anal area is folded fan-like into many plaits. The
third axillary of the hind wing (fig. 47 B, 34%) is relatively much
larger than that of the forewing (A), its muscle process stands out
prominently from the shaft, and the flexor muscle inserted on it con-
sists of two bundles of fibers. A distal median plate is lacking in
the hind wing, but the single plate (A, m) attached to the third ax-
7
98 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82
illary affects the anterior group of veins in the same manner as does
the corresponding plate of the forewing.
When the distal part of the third axillary is lifted by the pull
of the flexor muscle, the median plate turns the preanal area of the
wing posteriorly and toward the body, and at the same time deflects
it to an almost vertical position, with the costal margin downward.
The wing surface makes a double fold along the vena dividens (figs.
45 B, 50 B, VD), and the area between the vena dividens and the
AE
2Cu =
Fic. 50.—Positions of the flexed wings of Dissosteira.
A, vertical cross-section through fourth abdominal segment, with wings folded
over body, seen from behind. B, section of right hind wing more enlarged.
IA, 2A, 3A, 7A, first, second, third, and seventh primary anal veins; AF,
anal fold; C, costa; rCu, first cubitus ; 2Cu, second cubitus; J, intercalary vein;
Re secondary veins of first anal plait; k, first concave anal vein; 7, second con-
cave anal vein; M, media; R, radius; R + M, combined basal shaits of radius
and media; S, sternum; is tergum ; VD, vena dividens.
first principal anal vein (1A) is folded outward beneath the preanal
area, with the secondary vein k in the ventral angle of the fold (fig.
50 B). While these maneuvers are taking place in the anterior and
middle parts of the wing, the anal fan is bent downward as it comes
against the side of the abdomen, and its ventral surface is turned
outward beneath the deflected preanal area. The membrane of the
fan is plaited between each two of the first seven principal anal veins
(fig. 50 B, 1A-7A), with the secondary veins occupying the ventral
lines of the folds. The posterior part of the fan spreads out against
the upper part of the side of the abdomen (A).
a
NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 99
A careful study of the forms of the folded wings of the grass-
hopper, as seen in transverse section (fig. 50), will suggest that many
details of structure, both in the tegmina and in the hind wings, are
adaptations to the passive state of flexion rather than to the active
phases of flight.
The extension of the wings is effected probably by the action of
both the basalar and the subalar muscles (fig. 49 E, M’ and M”).
The basalar sclerites (fig. 48, rBa, 2Ba) are connected by a tough
membranous fold (@) with the base of the wing anterior to the wing
process. A depression of these sclerites on their episternal articula-
tions, caused by the contraction of their muscles (fig. 49, E, M’), must
therefore release the flexed wing from its position over the body and
turn it outward. The principal extensor of the wing, however, ap-
pears to be the muscle of the basalar sclerite (fig. 49, M@”). In the
flexed wing, the second axillary sclerite is elevated between the first
axillary on the one hand, which now stands in a vertical plane on its
tergal hinge, and the median plate (7m) on the other, which rises ver-
tically from its hinge on the second axillery. The ventral plate of the
second axillary is connected with the subalar sclerite by a thickening
of the intervening membrane (figs. 48, 49, 0). The downward pull of
the basalar muscle (fig. 49, M’’) is therefore exerted on the second
axillary. It is easy to demonstrate that a downward pressure on the
second axillary flattens the entire wing base by restoring the first
axillary, the median plate, and the third axillary to the horizontal
plane, and thereby extends the wing.
When the wings are extended, the mechanism of flight becomes
operative. This includes the direct and indirect muscles, which ac-
complish the movements of levation, depression, and rotation, and
which have already been described.
VIO THE SPIRACLES
The generalized ancestors of modern insects possibly had a pair
of tracheal invaginations on each of the 17 body segments between
the primitive head, or procephalon, and the periproct. Evidence of
the existence of such invaginations has been found, however, on only
14 segments, namely, the second maxillary segment, the three tho-
racic segments, and the first ten abdominal segments.
Tracheal invaginations of the second maxillary segment have been
reported by Nelson (1915) to be present in the embryo of the honey-
bee. They arise, Nelson says, on the lateral surfaces of the anterior
half of the segment above the bases of the rudiments of the second
I0O SMITHSONIAN MISCELLANEOUS COLLECTIONS VoL. 82
maxillae, shortly behind the boundary between the first and second
maxillary segments. The second maxillary spiracles have thus the
same relative position on their segment as have all the body spiracles
in the embryo, or the abdominal spiracles in adult insects. The em-
bryonic invaginations of the labial segment, according to Nelson,
give rise to a part of the tracheal system of the head, but are later
closed and leave no external trace of their existence in the adult insect.
Prothoracic spiracles are known to exist as functional organs of
the adult only in some of the Sminthuridae (Collembola). They are
situated laterally in the neck membrane close to the posterior margin
of the head, but Davies (1927) claims that the region bearing the
spiracles belongs to the prothorax. These cervical or prothoracic
spiracles are the only spiracles present in the Sminthuridae, and no
other collembolan is known to possess either spiracles or tracheae
in any part of the body. Temporary prothoracic spiracles, followed
by the usual series of spiracular invaginations, have been described
in the embryo of Blattella by Cholodkowsky (1891), and in the em-
bryo of Leptinotarsa by Wheeler (1889).
The usual first pair of thoracic spiracles of adult, nymphal,and larval
insects is always situated either in the posterior part of the prothorax
or in the intersegmental membrane between the prothorax and the
mesothorax. In the embryos of most insects, however, these spiracles
are said to lie anteriorly in the mesothorax; they would appear,
therefore, to be the true mesothoracic spiracles which have become
prothoracic in position by a secondary forward migration. The usual
second pair of adult thoracic spiracles are the embryonic meta-
thoracic spiracles, and they sometimes occur on the anterior part
of the metathorax in the adult, though more commonly they lie in
the membrane between the mesothorax and the metathorax, or in
the posterior part of the mesothorax. The segmental relations of the
thoracic spiracles is somewhat complicated by the fact that the muscles
of their closing apparatus have their origins in the segments on which
the spiracles are situated in the adult. Since, however, the musculature
of the thoracic spiracles is not alike in different groups of insects and
is often different in the two spiracles of the same insect, it.is probably
of secondary development in all cases.
Contrary to the embryological evidence of the segmental relations
of the spiracles, there are many points in the anatomy of the tracheal
system, and in the innervation of the spiracular muscles, that suggest,
as now claimed by several writers, that the spiracles are primarily
intersegmental invaginations, and that their definitive positions are
NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS _ IOI
the result of migrations either forward or rearward into the segmental
regions of the body.
The abdominal spiracles are situated, with few exceptions, on the
anterior lateral parts of the abdominal segments, where they lie
in the tergal plates, between the terga and the sterna, or in the edges
of the sterna. There are usually eight pairs of abdominal spiracles
in adult and larval insects, though the number may be variously
reduced. There is evidence, however, of more than eight spiracles
having been present on the abdomen of primitive insects. Cholod-
kowsky (1891) reports the existence of a pair of tracheal invaginations
on the first nine abdominal segments of Blattella,and Heymons (1897)
says there are apparent rudiments of spiracles on the tenth abdominal
segment of Lepisma. In certain insects the spiracles of the first
abdominal pair are situated very close to the base of the metathorax,
and long discussions recur as to whether these spiracles belong to
the thorax or to the abdomen. In all cases, however, it will be found
that the spiracles in question lie posterior to the third phragma, which
marks the intersegmental line between the metathorax and the first
abdominal segment, or behind the lateral extensions of the postnotal
plate in the metathorax. The spiracles are therefore abdominal, as
is shown also by the destination of their tracheae.
The external aperture of a spiracle may be a simple opening leading
directly from the exterior into the trachea. In most cases, however,
there is a pre-tracheal chamber, or atrium (fig. 53 A, B, Atr), formed
by an inflection of the body wall, from the inner end of which arises
the trachea (Tra). The atrium of the spiracle, therefore, appears
to be a secondary invagination of the body wall, which has carried
the mouth of the original tracheal invagination to a more protected
position beneath the surface. In some cases the edges of the atrial
orifice are elevated to form a pair of protruding lips guarding the
entrance (fig. 53 A, c, d), in others the opening is fringed with
opposing brushes of hairs, usually thickly branched, or it is itself
reduced to a very small diameter.
Spiracles are usually provided with a closing apparatus. In the
Apterygota the spiracles are said to lack an occlusor mechanism
(Du Buisson, 1926; Davies, 1927), and the thoracic spiracles of
Plecoptera are simple apertures giving open passages into the tracheae.
In general, however, the spiracles have either a device for closing
the outer lips of the atrial chamber, or an apparatus for blocking the
passage from the atrium into the tracheae. The occlusor mechanism
of the abdominal spiracles is of the second type; that of the thoracic
102 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82
spiracles may be of similar structure (caterpillars and other larvae),
but usually the closing apparatus of the thoracic spiracles in adult
insects effects a movement of one or both of the outer lips of the
atrial chamber.
The Acrididae possess the two usual pairs of thoracic spiracles and
eight pairs of abdominal spiracles. The first thoracic spiracle on
each side is situated laterally in the ample intersegmental membrane
between the prothorax and the mesothorax (fig. 20 B, 26, Sp.) where
it is covered externally by the lateral part of the large posterior fold
of the protergum (fig. 20 B, Rd). The second spiracle lies in the
posterior ventral angle of the mesothoracic epimeron just above the
base of the middle leg and immediately before the intersegmental
groove between the mesopleuron and the metapleuron (fig. 26, Sps).
The abdominal spiracles are carried by the first eight abdominal terga,
each being placed in the lower anterior angle of the corresponding
tergal plate. The first of the series, therefore, lies in the tympanal
cavity of the first segment, where it is situated on the small triangular
area before the tympanal membrane and just in front of the support
of the chordotonal organ. All the spiracles are well developed, and
each is provided with an efficient closing apparatus, the mechanism of
which presents the usual two types of structure, the first pertaining
to the thoracic spiracles, the second to the abdominal spiracles. The
details of structure, however, are quite different between the two
thoracic spiracles.
The first thoracic spiracle——The first spiracle of the thorax of Dis-
sosteira carolina is contained in a small, irregular plate, or peritreme
(fig. 51 A, Ptr), lying laterally in the intersegmental membrane
between the prothorax and mesothorax (fig. 20 B, Sz), covered
externally by the overlapping fold of the protergum. The lower end
of the peritreme is produced posteriorly and upward in a small, free
process (fig. 51 A, a), bearing on its base a flat-topped, pale-colored
tubercle (b) projecting outward. The tubercle is a little higher than
the lips of the spiracle and evidently serves as a stop to prevent the
covering flap of the protergum from resting too closely against the
spiracle. The spiracular opening is an obliquely vertical slit with a
slight italic curve and strongly protruding anterior and posterior
lips (c, d). The length of the slit is about 0.60 mm. in the male
grasshopper, and about 0.75 mm. in the female. The anterior lip (c)
is a rigid elevation of the wall of the peritreme; its inner face is
soft and deeply grooved parallel with the outer edge. The posterior
lip (d) is a weaker and freely-movable flap, but it has a sharp,
NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 103
strongly-sclerotized marginal band (e) which, when the spiracle is
closed, fits into the groove of the anterior lip.
The cleft of the first spiracle opens into a shallow atrium from
which are given off two tracheae, a larger dorsal one (fig. 51 B, f)
and a smaller ventral one (g). From without, therefore, the first
spiracle appears to have a double opening (A, f, g,). In some of the
Orthoptera that have tympanal organs on the front legs, the trachea
of the ventral (or posterior) opening of the spiracle appears to have
become specialized as an “ acoustic ” trachea since it goes only to the
Fic. 51.—First thoracic spiracle of Dissosteira.
A, outer view of left spiracle. B, inner view of right spiracle. a, ventral lobe
of peritreme; b, process of peritreme protecting spiracle from covering flap of
pronotum; c, anterior lip of spiracle; d, posterior lip of spiracle; e, hard edge
of posterior lip; f, dorsal trachea; g, ventral trachea; h, internal lever of pos-
terior lip forming a septum between the tracheae; 71, head of lever on which
closing muscle (79) is inserted; /, ventral internal process of peritreme on
which spiracular muscles arise; m, external pit forming internal process ]; Ptr,
peritreme; 79, opening muscle; 80, closing muscle.
front leg, where it branches into the two tracheae of the tympanal
organ. This fact led Graber to the conclusion that the double structure
of the first spiracle in Orthoptera originated from the separation of
an “acoustic” trachea from the general respiratory tracheae of the
prothorax. Carpentier (1924, 1925), however, has shown that the
double first spiracle is a character of Orthoptera in general, whether
tympanal organs are present in the front legs or not, and that in most
forms the tympanal trachea is not isolated from the rest of the
respiratory system. The specialization, he says, is carried to its highest
degree in the tettigoniid Phasgoneura viridissima, where the spirac-
ular orifice of the leg trachea is enormously enlarged. Here, ap-
104 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82
parently, is a case of an advantage derived by a specific organ from
a general structure first developed for some other reason.
In the septum between the two spiracular openings in Dissosteira
(fig. 51 A, i) is a strong internal bar (B, h) projecting anteriorly
and ventrally from the posterior lip of the spiracle, and terminating
in a free process (7) that extends anterior to the spiracular opening.
Upon this process is inserted a short muscle (79) which has its origin
ventrally on an inner process (/) of the lower angle of the peritreme,
the site of which is marked externally by a pit (A, m). A second
muscle (B, So) arises from the base of the same process (/) and
extends dorsally and posteriorly to its insertion on the base of the
posterior lip of the spiracle behind the ventral trachea. The first
muscle (79) is the occlusor of the spiracle; the second (SO) is evi-
dently its antagonist. A downward pull on the head of the septal arm
(7), where the anterior muscle is inserted, closes the spiracle by
rotating the movable posterior lip forward on its dorsoventral axis
and bringing thus its sharp free edge into the groove of the anterior
lip. Conversely, a downward pressure on the base of the posterior
lip, at the point where the posterior muscle (SO) is inserted, rotates
the lip in the reverse direction and opens the spiracle. The differential
action of the two muscles results from the opposition of their two
points of insertion on either side of the long axis of the posterior
lip, and is accentuated by the difference in their points of origin
on the ventral process (/) of the peritreme. Vinal (1919), Lee
(1925), and other writers have regarded both muscles of the first
spiracle in Acrididae as occlusors.
The second thoracic spiracle—The second thoracic, or metatho-
racic, spiracle of Dissosteira is located in the lower, posterior angle
of the mesothoracic epimeron of the adult (fig. 26, Sp;), where it
is surrounded by a narrow membranous area (fig. 52 A, mb).
Externally this spiracle presents two thick, elongate oval, valve-like
lips, (fig. 52 A, c, d) separated by a sinuous vertical cleft having a
length of about 0.50 mm. in the male insect. Both lips of the second
spiracle are movable, though they are united ventrally in a broad lobe
(n). The spiracular lips stand out prominently from the body wall
(fig. 53, A, c, d), and between them is a shallow atrium (4ér) from
which arises a single large trachea (Tra) that soon divides into a
dorsal and a ventral branch. The closing mechanism of the second
spiracle includes but a single short occlusor muscle (fig. 52 B, 177).
The muscle arises ventrally from a small process (0) on the posterior
dorsal margin of the mesocoxal cavity, and is inserted on the ventral
NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 105
lobe (7) of the spiracle. There is no special device for opening this
spiracle ; the lips diverge by their own elasticity, as is shown by the
fact that the spiracle is always open in a dead insect. The occlusor
muscle brings the edges of both lips together.
The abdominal spiracles —tThe eight spiracles of the abdomen in
Dissosteira are quite different from either of the thoracic spiracles.
They are not provided with projecting external lips (fig. 53 B),
the body wall being directly inflected in each spiracle to form an open
atrial chamber (Atr). The atrium leads by a narrowed aperture at
Fic. 52.—Second thoracic spiracle of Dissosteira.
A, outer view of left spiracle. B, inner view of right spiracle. c, anterior lip
of spiracle; d, posterior lip of spiracle; Epm, epimeron of mesothorax ; Epss,
episternum of metathorax; /sg, intersegmental fold; mb, membrane surrounding
spiracle; n, ventral lobe ‘of spiracle uniting the lips and giving insertion to
spiracular muscle (1Ir); 0, internal lobe on rim of coxal cavity on which
spiracular muscle arises: r, internal intersegmental fold; Tra, trachea; 111,
closing muscle of spiracle.
its inner end into the spiracular trachea (Tra), and the occlusor
mechanism regulates this opening.
The longer axis of the first abdominal spiracle is obliquely hori-
zontal (fig. 54 A) with the anterior end a little higher than the
posterior. The other spiracles (C, D) are placed more nearly vertical,
so that the dorsal end of each corresponds with the anterior end of
the first spiracle. In each spiracle one wall of the atrium is rigid
(fig. 53 B, ¢), and the other (s) is movable. The rigid wall is dorsal
in the first spiracle (fig. 54 A, t) and posterior in the other spiracles
(C, D). It is strengthened by a thickening in the external body wall
(figs. 53 B, 54 A, #) from which it is inflected. The movable wall
of the atrium (s), which is ventral in the first spiracle (fig. 54 A)
106 SMITHSONIAN MISCELLANEOUS COLLECTIONS VoL. 82
and anterior in the others (C, D), is flexible because the body wall
immediately external to it is weak, and because the two end walls
of the atrial chamber are membranous. The posterior or ventral end
of the movable wall is produced into a long, free manubrium (fig.
54 B, D, q) that projects into the body cavity and gives attachment
to two muscles, one dorsally, the other ventrally. These muscles,
acting antagonistically, either close or open the passage from the
atrium into the trachea (fig. 53 B) by means of their attachments
on the movable wall of the atrium.
The short dorsal muscle of the first abdominal spiracle (fig. 54 B,
CMcl) arises on the rim of the tympanum (/) above the spiracle;
Fic. 53.—Sections of spiracles of Dissosteira.
A, longitudinal section through second thoracic spiracle, showing anterior and
posterior lips (c, d) as projecting folds of body wall (BW) inclosing an atrium
(Atr), or entrance to trachea (Tra).
B, vertical section through first abdominal spiracle, showing direct inflection
of body wall to form atrial chamber (A?r), of which anterior wall (s) is mov-
able, and posterior wall (t) immovable.
Atr, atrium; BW, body wall; c, anterior lip of spiracle; d, posterior lip of
spiracle; mb, membrane surrounding lips of spiracle; g, manubrium or muscle
process of ventral wall of atrium; 1, intersegmental fold; s, ventral wall of
atrium; ¢, dorsal wall of atrium; Tra, trachea; u, plate in tergal wall support-
ing dorsal wall of atrium.
the long, slender ventral muscle (OMcl) arises ventrally on an in-
flection of the integument mesad of the hind coxa and posterior to the
triangular coxal plate of the metasternum (fig. 30 A, ¢). It is easy
to demonstrate that the dorsal muscle (fig. 54 B, CMcl) is the closer
of the spiracle and the ventral one (Omcl) the opener. A dorsal pull
upon the manubrium (q) of the movable ventral wall of the atrium
(s) brings the inner edge of the latter against the inner edge of the
fixed dorsal wall (tf) and thus closes the passage from the atrium
into the spiracular trachea. By a counter movement the passage
is opened.
The mechanism of the other abdominal spiracles is the same as that
of the first. The short, fan-shaped occlusor muscle (fig. 54 C, D,
NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS 107
CMcl) arises on the wall of the tergum immediately behind the
spiracle, and is inserted on the manubrium of the movable wall of
the atrium (q), which projects ventrally and posteriorly. The long
opening muscle (OMc/) arises on the lateral edge of the correspond-
ing sternum and extends posteriorly and dorsally to its insertion on
the manubrium.
VIS D
Fic. 54.—Abdominal spiracles of Dissosteira.
A, first abdominal spiracle, left, outer view. B, inner view of the same spiracle,
showing muscles. C, second abdominal spiracle, right, inner view, with tergo-
sternal muscles of second abdominal segment. D, eighth abdominal spiracle,
right, inner view.
CMcl, closing muscle of spiracle; /Sp, first abdominal spiracle; J/S, second
abdominal sternum; J//Sp, second abdominal spiracle; OMcL, opening muscle
of spiracle; p, anterior margin of tympanal cavity; qg, manubrium of ventral or
anterior wall of atrial chamber; s, movable ventral or anterior wall of atrial
chamber ; ¢, fixed dorsal or posterior wall of atrial chamber; u, thickening of
tergal wall supporting dorsal or anterior wall of atrial chamber; v, anterior
apodemal arm of abdominal sternum; ’///S, eighth abdominal sternum; VIII Sp,
eighth abdominal spiracle; w, posterior angle of tympanal cavity.
The grasshoppers are abdominal breathers. A discussion of the
mechanism of respiration would, therefore, lead too far beyond
the anatomical limits of the present paper. Recent studies on the
breathing of Orthoptera give such varied and conflicting results that
we must conclude either that the subject still needs a critical investi-
gation or that the insects have no fixed methods of respiration.
The weight of evidence is rather in favor of inconsistancy on the
part of the insects.
108
SMITHSONIAN MISCELLANEOUS COLLECTIONS
VOL. 82
ABBREVIATIONS USED ON THE FIGURES
A, Anal veins. 1A, 2A, etc., first anal,
second anal, etc.
Ac, antecosta.
acs, antecostal suture.
Acx, precoxal bridge.
AF, anal fold.
ANP, anterior notal wing process.
Ap, apodeme.
Ar, arolium.
Atr, atrium.
Aw, prealar arm of tergum.
Ax, axillary sclerite. 1Ax, 2Ax, 3Ax,
4Ax, first, second, third, and
fourth axillaries.
AxC, axillary cord.
Ba, basalare.
Bc, basicosta, basal ridge of coxa.
bcs, basicostal suture of coxa.
Bcx, basicoxite.
Brn, branchia, gill.
Bs, basisternum.
BW, body wall.
CMcl, closing muscle of spiracle.
cpl, supra-coxal plate of subcoxa.
Cu, cubitus. 1Cu, 2Cu, first and second
cubitus.
Cv, cervix, neck.
Icv, 2cv, first and second lateral cer-
vical sclerites.
Cx, coxa.
CxC, coxal cavity.
CxP, pleural coxal process.
Cxpd, coxopodite.
cvs, coxal suture.
D, flexor muscle of wing.
DMcl, dorsal longitudinal muscles.
E, basalar-sternal muscle.
Em, lateral emargination of tergum.
Endp, endopodite.
Epm, epimeron.
Eppd, epipodite.
Eps, episternum.
Eupl, eupleuron.
Eutn, entrochantin.
Expd, exopodite.
Fm, femur.
Fu, furca.
H, head.
/, intercalary vein.
tergal promotor muscle of coxa.
I-XI, abdominal segments.
[S-XIS, abdominal sterna.
Isg, intersegmental fold.
[Sp, I1Sp, first and second abdominal
spiracles.
Ist, intersternite.
IT-XIT, abdominal terga.
J, tergal remotor muscle of coxa.
Ju, jugal area of wing.
K, sternal promotor, anterior rotator
of coxa.
L, leg.
sternal remotor, posterior rotator
of coxa.
LB, leg basis.
Ls, laterosternite.
M, media.
abductor muscle of coxa.
m, m’, distal median plates.
M’, basalar-coxal muscle.
M", subalar-coxal muscle.
Mb, secondary intersegmental mem-
brane.
mb, membrane
Mer, meron.
N, N’, adductor muscle of coxa.
O, levator muscle of trochanter.
OMcl, opening muscle of spiracle.
P, body branch of depressor muscle of
trochanter.
Pak, parapsidal ridge.
pas, parapsidal suture.
Pc, precosta.
NO. 2 THORACIC MECHANISM OF A GRASSHOPPER—SNODGRASS
Pcx, precoxal bridge.
Ph, phragma. rPh, 2Ph, 3Ph, first,
second, and third phragmata.
PI, pleuron.
pl, pleural sclerites between tergum
and subcoxa.
PIA, pleural apophysis.
Pin, planta.
PIR, pleural ridge.
PIS, pleural suture.
PN, postnotum.
PNP, posterior notal wing process.
Poc, postocciput.
PoR, postoccipital ridge.
Ppct, prepectus.
Ppt, periproct.
PR, prescutal ridge.
Pra, preanal area of wing.
Ps, presternum.
ps, prescutal suture.
Psc, prescutum.
PT, posterior arm of tentorium.
Ptar, pretarsus.
Ptr, peritreme.
Pw, postalar arm of postnotum.
QO, coxal branch of depressor muscle
of trochanter.
R, radius.
Rd, posterior fold, reduplication, of
tergum.
S, levator muscle of tibia
sternum.
SA, sternal apophysis.
Sa, subalare.
sa, external pit of sternal apophysis.
Sc, subcosta.
Scl, scutellum.
scl, subdivision of scutellum.
109
Sct, scutum.
sct, subdivision of scutum.
Sca#, subcoxa.
S17, sternellum.
Sp, spiracle. Sp., Sps, first and second
thoracic spiracles.
Spn, spina.
spn, external pit of spina.
Ss, spinasternum.
Stn, primary segmental sternite.
T, depressor muscle of tibia.
tergum.
Tar, tarsus.
Tb, tibia.
tg, tegular rudiment.
TmMcl, tympanal muscle.
Tn, trochantin.
Tr, trochanter. r2r, 277, first and
second trochanters.
Tra, trachea.
U, levator muscle of tarsus.
Uf, unguifer of tarsus.
Un, unguis, claw.
Utr, unguitractor plate.
V’, depressor muscle of tarsus.
VD, vena dividens.
VIIISp, eighth abdominal spiracle.
VMcl, ventral longitudinal muscle.
VR, ridge between scutum and scu-
tellum.
vs, scuto-scutellar suture.
W, wing.
IVP, pleural wing process.
X, depressor muscle of pretarsus, re-
tractor of claws.
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\
SMITHSONIAN MISCELLANEOUS COLLECTIONS
VOLUME 82, NUMBER 3
HHodgkins Fund
_ THE RADIATION OF THE PLANET
EFARTH. TO SPACE
(With Two PtatTEs)
BY $
G. G. ABBOT
(PUBLICATION 3028)
CITY OF WASHINGTON
PUBLISHED BY THE SMITHSONIAN INSTITUTION
NOVEMBER 16, 1929
SMITHSONIAN MISCELLANEOUS COLLECTIONS
VOLUME 82, NUMBER 3
Hodgkins Fund
THE RADIATION OF THE PLANET
PAI IO SEAGe
(WitTH Two PLATEs)
BY
GC. G. ABBOT
(PUBLICATION 3028)
CITY OF WASHINGTON
PUBLISHED BY THE SMITHSONIAN INSTITUTION
NOVEMBER 16, 1929
AY ge Vie WA Vis }
; A
AF i,
- i
TS
\
i “a |
The Lord Waltimore Press
BALTIMORE, MD., U. S. A.
a) an -
Hodgkins Fund
THE RADIATION OF THE PLANET EARTH TO SPACE
By C. G. ABBOT
(WitH Two Ptates)
In an illuminating series of papers, G. C. Simpson recently has
approached the subject of terrestrial and atmospheric radiation to
outer space. The first of these papers is entitled “ Some Studies in
Here Simpson makes the unsatisfactory
1
Terrestrial Radiation.”
assumption that the atmospheric water vapor behaves like a “ grey
body ” in absorbing radiation. That is, he assumes that general coeffi-
cients of absorption and of transmission may be employed, without
regard to the wave length of the radiation considered. Arriving in
this way at unexpected and questionable results, Simpson then modi-
fied his procedure in a second paper entitled ‘‘ Further Studies in Ter-
restrial Radiation.’ * Here he makes the following important assump-
tions: (a) The stratosphere contains 0.3 mm. of precipitable water.
(b) The absorptive properties of atmospheric water vapor may be
regarded as so similar to those of steam that Hettner’s * observations
of the absorption of a layer of steam may be taken as representing the
coefficients of absorption of atmospheric water vapor between wave
lengths 4 and 34n.' (c) ‘‘ The stratosphere absorbs all radiation
between wave lengths 53 and 7p, and from wave length 14 to the
end of the spectrum.”
As the Smithsonian Institution has hitherto published considerable
evidence relating to these three subjects, it has occurred to me to see
whether the use of our independently derived data would check well the
* Mem. Roy. Meteorol. Soc., Vol. 2, No. 16, 1928.
“Tbid., Vol. 3, No. 21, 1928.
* Hettner, G., Ann. Physik. Leipzig, 4th Folge., Band 55, p. 476, 1918.
*Simpson nevertheless calls attention to the incomplete similarity between
the absorption of concentrated and unconcentrated vapors, and therefore cor-
rects Hettner’s curve between 84 and Itw from other data derived from atmos-
pheric experiments.
SMITHSONIAN MISCELLANEOUS COLLECTIONS, VOL. 82, No. 3.
2 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82
results of Simpson in this important field. Fowle’ carried on for
several years, 1908 to 1917, experiments on the absorption of radiation
of long wave lengths by the atmosphere contained in tubes of large
diameter and up to 800 ft. in length. These tubes were laden with
water vapor ranging from 0.2 up to 2.5 mm. of precipitable water,
and of carbon dioxide content ranging from 7 grams up to 160 grams
per meter cross-section at normal temperature and pressure.
In his early experiments, Fowle had established means for deter-
mining the quantity of precipitable water in atmospheric air by means
of measurements on the bands por, ¢, and yw of the upper infra-red
solar spectrum. These experiments are fortunately very definite as
to the determination of water vapor equivalent to 0.3 mm. of pre-
cipitable water.
In the summer of the years 1909 and 1910, Abbot. observed the
infra-red solar spectrum from Mount Whitney, California, altitude
4,420 m. Bolographs of the spectrum were obtained, having very
satisfactory quality as far as the delineation of the bands por, ¢, and y
is concerned.” From these, Fowle determined the quantity of total.
precipitable water in a vertical path of atmosphere above Mount
Whitney. On August 14, 1910, he observed 0.6 mm. Considering the
moderate altitude and the summer season, this small observed water-
vapor content hardly prepares one to accept Simpson’s assumption
that the stratosphere, which begins at 12,000 m., and is at a tempera-
ture about 50° C. lower than that which prevailed at the summit of
Mount Whitney on that occasion, can contain half of the precipitable
water above that station. We have other evidence leading to the same
view.
At Mount Montezuma, Chile, altitude 2,710 m., we have observed
spectroscopically the total precipitable water in a vertical column
above the station almost daily for about 10 years at all seasons. The
following table gives average values for the 12 months, and also
extreme values for each of these months, together with associated
surface temperatures.
In illustration of the great alterations in the appearance of the solar
energy spectrum depending on the quantity of atmospheric humidity,
we give reproductions of two days’ observations at Montezuma,
plates I and 2. Note the bands por, ¢, y and Q.
*Fowle, F. E., Ann. Astrophys. Observ., Vol. 4, pp. 274-286. Astrophys.
Journ., Vol. 38, p. 393, 1913; Vol. 42, p. 304, 1915. Smithsonian Misc. Coll.,
Vol. 68, No. 8, 1917.
? See Annals, Vol. 4, fig. 50.
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A SMITHSONIAN MISCELLANEOUS COLLECTIONS voL. 82
From the tabular data, it is clear that values of total precipitable
water are frequently observed at Montezuma closely approaching the
value assumed by Simpson for the stratosphere. These values are
found in winter, with a surface air temperature of +9° C., on the
edge of the tropics at 2,710 m. altitude.
In view of these observations at Montezuma, and considering the
rapid decrease of humidity with temperature (the vapor pressure at
—50° and o° C. being respectively 0.03 and 4.58 mm.) and also the
fact that three-fourths of the superincumbent atmosphere lies between
Montezuma station and the bottom of the stratosphere, one is forced
to conclude that the value of the precipitable water contained by the
stratosphere is vanishingly small, rather than 0.3 mm. as assumed by
Simpson. This materially affects his argument, especially that part
which relates to cloudy skies.
As an independent approach, instead of Simpson’s two other basic
assumptions, which we have designated as (b) and (c), we have em-
ployed Fowle’s two summaries of the results obtained in his long-tube
experiments.. To make these results of Fowle’s applicable to the
problem of atmospheric radiation and absorption, as set by Simpson,
we have prepared a large scale plot, reproduced in reduced size in
figure 1. From this plot we take table 2. In choosing the quantities
of precipitable water to be used, we have doubled the values given by
Simpson for successive layers in the table he designates as “ Fig. I,”
page 72, of his paper “ Some Studies in Terrestrial Radiation.’ This
doubling we do because of the following consideration.
We are proposing to ascertain the radiation which certain layers of
the free atmosphere, containing natural loads of water vapor and car-
bon dioxide, will send upwards in all directions within a solid angle
filling a complete hemisphere. We assume, as does Simpson, that for
monochromatic rays the emission of such a layer bears the same pro-
portion to the emission of the perfect radiator that the absorption of
the layer in question bears to unity. While some rays are emitted ver-
tically, most rays are emitted obliquely, so that the average emission
and absorption of a layer exceeds that which corresponds to the pre-
cipitable water vapor and carbon dioxide found in a vertical path. It
is readily proved by performing the integration over a complete
hemisphere that the average upward path is double the vertical one.
Hence we have doubled Simpson’s figures for the precipitable water
contained in the layers he has chosen. These data appear in table 2.
*See Annals, Vol. 4, Table 102, p. 286; also Smithsonian Physical Tables,
7th Rev. Ed., 4th reprint, p. 308.
RADIATION OF EARTH TO SPACE—ABBOT
‘A A Yi
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6 SMITHSONIAN MISCELLANEOUS COLLECTIONS VoL. 82
As a second step, we consider the spectral distribution and intensity
of emission of the perfect radiator at different temperatures.’ By
interpolation on large scale plots we have prepared table 3. This gives
the approximate * intensity of emission of the perfect radiator at tem-
peratures corresponding to the mean temperatures of Simpson’s lay-
ers, and to those of his selected latitudes of the earth’s surface.
Multiplying the values in table 2 by corresponding ones in table 3,
we obtain the emission of radiation outwards from each Simpson at-
mospheric layer towards a complete hemisphere. The values are given
in table 4.
Again interpolating in the plots (fig. 3) we next obtained the trans-
mission coefficients for each superincumbent atmospheric mass lying
above the respective Simpson layers. Allowance is made for the ozone
absorption between Qu and IItm. These values are given in table 5.
Multiplying these values by corresponding ones in tables 3 and 4,
we obtained the contributions of the Simpson atmospheric layers and
also of the earth’s surface * at the latitudes g0°, 70°, 60°, 50°, 40°,
and o° to the intensity of emission of the earth as a planet towards
outer space.’ These results are given in table 6.
All of these results apply to cloudless skies. We now assume, with
Simpson, that the earth is 50 per cent cloudy; that the clouds totally
absorb all radiation arising from beneath them ; that they radiate quite
as efficiently as the perfect radiator; and that their upper surfaces
maintain the same average temperature as the earth at 70° latitude.
Weare not able to compute their radiation in Simpson’s manner, since
we have shown reasons to believe that the stratosphere is almost desti-
tute of water vapor, instead of containing 0.3 mm. of precipitable
water as he supposes. We simply assume that the combined emission
of clouds and atmosphere during one-half the time at all latitudes is
the same as that of the earth’s surface and the superincumbent atmos-
phere at latitude 70°. That is: For the atmosphere 0.151 cal. per
cm. per min.; for the cloud surface 0.100 cal., giving a total for com-
pletely overcast sky of 0.251 cal. During the other half of the time,
*See Smithsonian Physical Tables, p. 248.
* We do not guarantee these values to within 2 per cent.
’ We assume, with Simpson, that the earth’s surface may be regarded as a
perfect radiator.
* Notwithstanding our previous evidence that the water-vapor content of the
stratosphere is vanishingly small, we have thought best to estimate 30 per
cent of black-body efficiency as applicable to the stratospheric radiation in the
wave-length region I3u to 504, where water vapor is so very active. We have
allowed 16 per cent of black body efficiency to the ozone band, ou to Ith.
ABBOT
RADIATION OF EARTH TO SPACE
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SMITHSONIAN MISCELLANEOUS COLLECTIONS
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12 SMITHSONIAN MISCELLANEOUS COLLECTIONS VoL. 82
the values at different latitudes are as given in table 6 for clear skies.
For half-cloudy skies we take the mean of the two conditions.
We are now prepared to assembie our results and compare them
with those of Simpson (table 7).
It is clear that our employment to a considerable extent of inde-
pendent data and methods has made no very great difference in the
totals from those of Simpson. The range of our totals for half-
cloudy sky is indeed considerably greater than his as between the
equator and the poles. Our method has enabled us to segregate the
contributions of the atmosphere and of the earth’s surface, which
in Simpson’s second paper are not computed separately. We find the
earth’s surface almost equally contributing at all latitudes, but the
TABLE 7.—Radiation of Earth and Atmosphere to Space
Calories per cm.” per min.
Smithsonian results Simpson results
Tatitude Clear sky Half-cloudy sky Atmosphere plus surface
Atmos-} Sur- Atmos- | Surface Over- | Half-
phere face Total phere jor cloud Total Clear cast. | cloudy
Opens cee || O8220)|10:205)| KOs 251 70st SOn|hOsTO25|.0:2660| (0:3 1on| Oza nk ROzor
CNOA cated egg wees an 0.192 | 0.107 | 0.299 | 0.171 | 0.103 | 0.274 | 0.307 | 0.243 | 0.275
BOs sae 2 2) OnL82 10.105) 20:287" 70.166 4) OnlO2)|0:268 |10:201 | (0:24 0)|80.270
60°.........| 0.162 | 0.104 | 0.266 | 0.156 | 0.102 | 0.258 | 0.274 | 0.252 | 0.265
GRO pubes ave ect 0.151 | 0.100 | 0.251 | 0.151 | 0.100 | 0.251 | 0.253 | 0.253 | 0.253
COs ee ae 011/29) (01096) "0.2255, | 004.0) | OL098) 01238 a esate
atmosphere, which contributes much more than half the total (even
more than two-thirds the total on cloudless days at the equator) emits
very much lesser proportions as we approach the poles. The two
sources are very different as regards wave lengths of principal contri-
bution ; the atmosphere emitting mostly in the region exceeding 16m
in wave length, the surface emitting principally in the region Qu to 13m.
If we sum up the results in the seventh and tenth columns, which
represent our own and Simpson’s totals for half-cloudy sky, and as-
sign weights to them proportional to the areas of earth which they
respectively. represent, we find that the earth as a planet radiates aver-
ages of 0.277 or 0.265 cal. per square centimeter per minute according
as our results or Simpson’s are taken. If we compute the same quan-
tity from the solar constant, 1.94 cal., and Aldrich’s albedo, 43 per
{AU Oe ; :
cent, the result ae x 0.57=0.276 cal. The discrepancies are very
small and far within the probable error of the determinations.
VOE282 SNOws Ree
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SMITHSONIAN MISCELLANEOUS COLLECTIONS
VOLUME 82, NUMBER 4
THE CHARACTERS OF THE GENUS
GEOCAPROMYS CHAPMAN
(WiTH ONE PLATE)
BY
GERRIT S. MILLER, JR.
Curator, Division of Mammals, U. S. National Museum
(PUBLICATION 3029)
CITY OF WASHINGTON
PUBLISHED BY THE SMITHSONIAN INSTITUTION
DECEMBER 9, 1929
SMITHSONIAN MISCELLANEOUS COLLECTIONS
VOLUME 82, NUMBER 4
THE CHARACTERS OF THE GENUS
GEOCAPROMYS CHAPMAN
(WiTH ONE PLATE)
BY
GERRIT S. MILLER, JR
Curator, Division of Mammals, U.S. National Museum
NS
(PUBLICATION 3029)
CITY OF WASHINGTON
PUBLISHED BY THE SMITHSONIAN INSTITUTION
DECEMBER 9, 1929
7 tt
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BALTIMORE, MD., U. 8. A.
THE CHARACTERS OF THE GENUS GEOCAPROMYS
CHAPMAN
By GERRIT S. MILLER, JR.
CURATOR, DIVISION OF MAMMALS, U. S. NATIONAL MUSEUM
(Wir ONE PLATE)
In his “‘ Revision of the Genus Capromys”’ (Bull. Amer. Mus. Nat.
Hist., Vol. 14, pp. 313-323, Nov. 12, 1901) Mr. Frank M. Chapman
established a sub-genus Geocapromys (p. 314) to include Capromys
brownii J. B. Fischer, C. thoracatus True and C. ingrahami J. A. Allen,
animals that were supposed to have skulls and teeth essentially like
those of the species of true Capromys, but to have unusually short
tails and poorly developed thumbs. Sixteen years later Dr. Glover M.
Allen raised Geocapromys to generic rank and added to its characters
the presence of a small supplemental reentrant angle near the front
of the lingual side of the first mandibular molariform tooth (Bull.
Mus’ Comp. Zool. Vol. 61, p. 9, Jan, 1917). In 1919 Mr. H. E.
Anthony noticed that the course of the upper incisor of Geocapromys
is clearly shown on the face of the maxillary as a prominent swelling
on the wall of the antorbital foramen, while in Capromys no such
swelling is present (Bull. Amer. Mus. Nat. Hist., Vol. 41, p. 631,
Dec. 30, 1919). In his 1917 paper Dr. Allen, misled by Chapman’s
imperfect specimens of Geocapromys columbianus, made his own
better material of the Cuban animal the basis of the new name G.
cubanus (p. 9), and proposed (p. 5) the generic name Synodontomys
for the original C. columbianus. These errors he later recognized and
corrected (Bull. Mus. Comp. Zool., Vol. 62, p. 145, May, 1918).
When preparing the copy for my “ List of North American Recent
Mammals 1923” I concluded that the dental features pointed out
by Allen and Anthony did not warrant the generic separation of the
group from Capromys. Not knowing of any other characters I
relegated Geocapromys to subgeneric rank again. More recently, while
examining broken skulls from caves in Cuba, I found that there are
important and constantly present features of both skull structure and
tooth arrangement that fully justify the generic separation of the
two groups. The diagnostic characters may be tabulated as follows:
SMITHSONIAN MISCELLANEOUS COLLECTIONS, VOL. 82, No.4
2 SMITHSONIAN MISCELLANEOUS COLLECTIONS voL. 82
Preorbital bar of maxillary sloping obviously forward; root capsule
of upper incisor terminating in contact with outer half of an-
terior border of alveolus of pm*; bases of alveoli of right and
left pm* separate, not encroaching on floor of narial passage;
pm. with only two reentrant angles on lingual side.............. Capromys
Preorbital bar of maxillary vertical or sloping slightly backward;
root capsule of upper incisor terminating above and ectad to
anterior half of outer border of alveolus of pm*; bases of alveoli
of right and left pm* in contact, encroaching on floor of narial
passage; pm, with a small third reentrant angle on lingual
(0 (or pee ee Mn A UR eho d tate eid un tart NR ete WG he Geocapromys
REMARKS ON GEOCAPROMYS
Skull_—The ascending branch of the maxillary dividing the orbit
from the antorbital foramen is vertical (G. ingraham) or backward-
sloping (G. brownii and G. thoracatus) in relation to alveolar line
instead of conspicuously forward-sloping as in Capromys (pl. I, figs. I
and 2). By this character alone any one of the three living species
can be distinguished from any of the four living Capromys. (I have
not seen a specimen of the extinct G. columbianus in which the as-
cending branch is preserved). The backward slope in Geocapromys
is never so strong as the forward slope in Capromys, but the difference
is obvious when the general direction of the ascending branch is com-
pared with the line of the alveolar margin.
TeethRoot of upper incisor encapsuled in the lower half of the
maxillary wall of the antorbital foramen (see pl. 1, fig 1), the dis-
tance between the outer surfaces of the very obvious incisor capsules
of opposite sides greater than that between the outer sides of the
basal capsules of the opposite first molars. In Capromys the root of
the incisor terminates opposite the antero-inner edge of the lower
lip of the antorbital foramen (pl. 1, fig. 2), and the transverse diam-
eter of the rostrum through the scarcely evident capsules is less
than that through the bases of the first molars. The base of pm*,
which is hidden by the incisor capsule in Geocapromys, often forms
an obvious external swelling in Capromys (as in pl. 1, fig. 2).
These characters indicate that the members of the two genera have
been developing along consistently different lines. In Capromys the
incisor root has pushed back to a position where more advance is
prevented by contact with the base of pm*; in Geocapromys its posi-
tion is such that it could be extended much farther back in a capsule
lying along the outer surface of the molar shafts as in Spalacopus.
The Capromys condition is nearly paralleled in Octodontomys. In
correlation with the position of the incisor roots the molar roots are
NO. 4 THE GENUS GEOCAPROMYS CHAPMAN—MILLER 3
farther apart in Capromys than in Geocapromys. This character is
not visible in complete skulls, but is evident in the broken-away palates
so often found in caves. The upper surface of such a fragment of
the maxillary (lower floor of nares) in the region between the anterior
zygomatic roots is traversed by a deep median sulcus in Capromys
occupying the space between the rather widely separated bases of the
opposite premolars ; in Geocapromys there is no median sulcus between
the premolars, but the maxillary rises as a broad flat plate to the
level of the connate bases of these teeth. Immediately behind this
level the groove begins, passing backward to the posterior nares
between the progressively more separated roots of the molars.
The genus Geocapromys contains four species—the living G. brownii
(Fischer) of Jamaica, G. thoracatus (True) of Little Swan Island,
Gulf of Honduras, G. ingrahani (Allen) of Plana Keys, Bahamas,
and the extinct though geologically Recent G. columbianus (Chap-
man) of Cuba (with its synonym G. cubanus G. M. Allen).
EXPLANATION OF PLATE
All figures natural size
Fic. 1. Geocapromys brownti (Fischer). Adult female. No. 143851, U. S. Nat.
Mus. Jamaica. i= base of incisor capsule.
Fic. 1a. Geocapromys browntt (Fischer). Adult male. No. 141908, U. S. Nat.
Mus. Jamaica. Palate cut away from skull and viewed from above.
pm = base of premolar, i= base of incisor capsule.
Fic. 2. Capromys pilorides Desmarest. Small individual, No. 103884, U. S. Nat.
Mus. Cuba. pm=capsule at base of premolar, i= base of incisor capsule.
Fic. 2a. Capromys pilorides Desmarest. Large individual. No. 253232, U. S.
Nat. Mus. Palate cut away from skull-and viewed from above. pm = base
of premolar, i= base of incisor capsule.
Fic. 2b. Capromys sp. No. 254679, U. S. Nat. Mus. Cuba (cave deposit). Palate
cut away from skull and viewed from above. pm = base of premolar, i = base
of incisor capsule.
SMITHSONIAN MISCELLANEOUS COLLECTIONS VOLE S25 INOW 4 PE. 1
%
1. Geocapromys.
2. Capromys.
(All figures natural size)
SMITHSONIAN MISCELLANEOUS COLLECTIONS
VOLUME 82, NUMBER 5
MAMMALS EATEN BY INDIANS, OWLS, AND
SPANIARDS IN THE COAST REGION OF
THE DOMINICAN REPUBLIC
(WitrH Two PLATEs)
BY
GERRIT S. MILLER, JR.
Curator, Division of Mammals, U.S. National Museum
on s (PUBLICATION 3030)
Bp | CITY OF WASHINGTON
m- PUBLISHED BY THE SMITHSONIAN INSTITUTION
& DEGEMBER 11, 1929
SMITHSONIAN MISCELLANEOUS COLLECTIONS
VOLUME 82, NUMBER 5
MAMMALS EATEN BY INDIANS, OWLS, AND
SPANIARDS IN THE COAST REGION OF
THE DOMINICAN REPUBLIC
(WITH Two PLATES)
BY
GERRIT S. MILLER, JR.
Curator, Division of Mammals, U.S. National Museum
(PUBLICATION 3030)
CITY OF WASHINGTON
PUBLISHED BY THE SMITHSONIAN INSTITUTION
DEGEMBER 11, 1929
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— The Lord Baltimore Press
BALTIMORE, MD., U. 8. A.
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7 i) ay a
MAMMALS EATEN BY INDIANS, OWLS, AND
SPANIARDS: IN THE COAST REGION OF
THE DOMINICAN REPUBLIC
" By GERRIT S. MILLER, JR.
CURATOR, DIVISION OF MAMMALS, U. S. NATIONAL MUSEUM
(WitTH Two Ptates)
In February and March, 1928, I visited the Samana Bay region,
northeastern Dominican Republic with the special object of obtaining
remains of mammals in the Indian deposits that had been previously
examined by Gabb in 1869-1871 and Abbott in 1916-1923. I was
accompanied by Mr. H. W. Krieger, who had charge of the strictly
ethnological side of the work. Together or separately we obtained
material from six localities: four on the south shore of Samana Bay;
one, Anadel, near Samana town, on the north shore of the bay; and
one, a large Indian site at the mouth of the Rio San Juan, on the
Atlantic coast, across the peninsula from Samana.’ Mr. Krieger re-
turned alone the following winter and revisited the places that we had
previously worked. He also made excavations in two village sites
not far from Monte Cristi at the northeastern extremity of the
Republic.
At all of these localities we obtained many bones of mammals from
the heaps of Indian refuse. Only once, however, in a lateral recess
about half way up the sloping floor of the cave that occupies most
of the islet of San Gabriel, off the south shore of the bay, did we
find an owl-made deposit of extinct mammals. Here, as at St. Michel,
Haiti, the small living barn owl had plentifully bestrewn the surface
with dejecta containing bones of bats, small birds, and the introduced
European rats and mice. Immediately beneath its surface the cave
floor material was intermingled with the bones of the larger native
rodents that had been devoured by the great extinct owl. This deposit
was not more than two feet deep, and, unlike the kitchenmidden
lying in the lower level of the cave, it was considerably hardened
*A general account of this work was published in Expl. and Field-Work
Smithsonian Inst., 1928, Smithsonian Publ. No. 3011, pp. 43-54, March 22, 1929.
SMITHSONIAN MISCELLANEOUS COLLECTIONS, VOL. 82, No.5
2 SMITHSONIAN MISCELLANEOUS COLLECTIONS voL. 82
by infiltrated lime drip. Other owl deposits of the same kind may have
once existed in the neighboring caves, but if so, they all appear to
have been removed years ago by guano diggers. The specimens
that we obtained in these caves and village sites form the subject
matter of the present paper.
While no hitherto unknown species are represented in our col-
lections the material proves to be of much interest. It throws ad-
ditional light on the characters and distribution of the two species of
Plagiodontia that I recognized in 1927 as occurring in the Dominican
Republic (Proc. U. S. Nat. Mus., Vol. 72, Art. 16, pp. 1-8, Sept. 30,
1927) ; it furnishes the means to identify all four of the native mam-
mals, the hutia, the quemi, the mohuy and the cori, that Oviedo said
were habitually eaten by both natives and Spaniards during the early
years of the sixteenth century; and finally it shows beyond the possi-
bility of reasonable doubt that this recently extinct fauna included a
ground sloth.
The identity of only two of the mammals that Oviedo ascribed to
the island of Hispaniola remains to be determined—the “ dumb dog ”
and the indigenous rat. The few dog bones collected appear to differ
in no way from the corresponding parts of European dogs, and there
is nothing to prove that they represent the native breed. Hence the
status of the famous “ perro mudo,” the dog that was unable to bark,
is still as much of a mystery as ever. Equally obscure is the question
as to whether or not there were rats on the island at the time of its
discovery. Oviedo relates that on inquiring into this matter he found
those who told him that “mures 6 ratones”’ did in fact then exist;
a circumstance that appeared to him quite believable because these
animals were so well known to be generated, like flies, mosquitoes,
wasps, and grubs, anywhere, out of any kind of putrifying matter,
a not unnatural belief at the time when he wrote, more than 125
years before Francisco Redi had published his “ Esperienze Intorno
Alla Generazione Deg!’ Insetti.”” Nevertheless our search has failed to
reveal a trace of rats or mice other than the European species that
could have easily been brought by the Spaniards on their ships. After
enumerating the specimens that we obtained I shall return to the sub-
ject of Oviedo’s mammals in greater detail.
DESCRIPTION OF COLLECTING STATIONS
1. Railroad cave—A large cave situated about 15 minutes walk
inland along the abandoned railroad on the south shore of San Lorenzo
Bay. There is an extensive kitchenmidden at the entrance. I was
not able to find any trace of a bone deposit made by the extinct owl,
NO. 5 MAMMALS FROM DOMINICAN REPUBLIC—MILLER 3
though pellets of the living bird were abundant in one of the chambers.
This may be the “Cueva del Templo” of Rodriguez (Geografia
fisica, politica e historica de la Isla de Santo Domingo o Haiti, p. 367,
Santo Domingo City, 1915).
2. Boca del Infierno—Two large caves, one in each of the pro-
jecting points at the locality marked Pta. de Boca del Infierno on the
Hydrographic Office chart of Samana Bay.
The larger cave is in the smaller, inner point. It has been extensively
worked for guano, but some of the original floor material remains.
Near the outer entrance there is a small kitchenmidden. A few leg
bones of extinct rodents were found in this cave, but no skulls or jaws.
At the inner entrance to the other cave we found the remnant of
a kitchenmidden left intact by the guano diggers. From this deposit
we unearthed bones of both the “quemi” and the ground sloth,
mammals whose remains have not been found elsewhere among the
Indian refuse.
These caves appear to be, respectively, the “ Boca del Infierno”’
and the “ Cueva del Infierno” of Rodriguez. It is probable that in
one or the other of them Gabb collected the bones of Plagiodontia
that I recorded in 1916.
3. San Gabriel—An islet about two miles west of Boca del Infierno.
Most of its interior is occupied by a large cave, the floor of which
slopes rather steeply upward from an opening on the south side facing
the shore to another on the north side overlooking Samana Bay.
There is a large kitchenmidden near the lower entrance, and a deposit
made by the extinct owl on the left side of the passage leading up
to the north aperture.
4. Rio Naranjo Abajo.—A kitchenmidden was found on a nearly
level rock ledge, perhaps one-fourth acre in extent, on a key lying
about half a mile east of the stream mouth.
These four localities are all on the south shore of Samana Bay in
the region known as the Playa Honda coast. Rodriguez describes
the caves under the general title: “ Cuevas de los Haitis.”’
5. Anadel—aA large village site at a stream mouth on the north
shore of Samana Bay about 14 miles east of Santa Barbara de Samana.
6. Rio San Juan—Another large village site on the Samana Penin-
sula. It lies at the point where the Rio San Juan flows into the
Atlantic Ocean, almost directly north of Santa Barbara de Samana.
7 and 8. Kilometer 2 site and Kilometer 4 site-—Two very extensive
village sites in the foothills of the mountains southeast of Monte
Cristi. Both of these localities differ from those in the Samana Bay
region in being situated in the semiarid portion of the island.
4 SMITHSONIAN MISCELLANEOUS COLLECTIONS VoL. 82
LIST OF MAMMALS COLLECTED
NESOPHONTES PARAMICRUS Miller
Railroad cave-——Humerus, I.
San Gabriel (owl deposit )—Mandibles, 3; humeri, 4; femora, 6;
innominate, I.
It is impossible to determine whether or not the presence of the
humerus in the Railroad cave kitchenmidden indicates that Neso-
phontes was eaten by the Indians. In this cave such a bone might
as well have been dropped by an owl as by a man.
NESOPHONTES HYPOMICRUS Miller
San Gabriel (owl deposit).—Mandibles, 4; humerus, 1; femur, 1;
innominate, I. .
The remains of both species of Nesophontes agree perfectly in size
and other characters with topotypes from St. Michel, Haiti.
SOLENODON PARADOXUS Brandt
Railroad cave.—Perfect right humerus, 1.
Naranjo Abajo.—Mandible, 1; distal half of left feces, ip
Rio San Juan.—Mandible, I.
Kilometer 2 site-—Distal half of humerus, 1.
These specimens do not differ in any way from the corresponding
parts of the living animal. Their presence in three widely separated
kitchenmiddens is sufficient indication that Solenodon was customarily,
eaten by the Indians.
EPTESICUS HISPANIOLAE Miller
MACROTUS WATERHOUSII WATERHOUSII Gray
ARTIBEUS JAMAICENSIS JAMAICENSIS Leach -
A few remains of these common Dominican bats were found in
the owl deposit in San Gabriel cave.
CANIS FAMILIARIS Linnaeus
Kilometer 2 site-—Right mandible, immature, 1; both mandibles
of a very young individual, 1 pair; separate milk pm*, 1; adult m?,
2 (not from same individual); adult canine, 1; adult incisor, I;
auditory bulla, 1; vertebrae, 8; ribs, 2; fragments of pelvis, 4 (repre-
senting at least 2 individuals) ; tibia, proximal end, 1; tibia, distal end
(probably of another individual), 1; calcanea, 2 (opposites) ; astraga-
NO. 5 MAMMALS FROM DOMINICAN REPUBLIC—MILLER 5
lus, I (apparently belongs with the calcanea) ; metapodials, 9; 1m-
perfect scapula, 1; ulna, 1; radius (perfect) 1; radius (proximal end
only), I.
The remains pertain to at least two adult dogs and two puppies.
Taking the radius (total length 127.6 mm.) scapula, and teeth as
guides, the animal must have been about the size of a Scotch terrier
whose skeleton is now in the National Museum, No. 21997 (total
length of radius 120.2 mm.).
I am unable to find characters in any of these specimens that sug-
gest specific or racial peculiarities as compared with domestic dogs
of European origin or with pre-Columbian dogs from either North
or South America. Furthermore, as the middens near Monte Cristi
yielded bones of both pig and cow, there is no reason to suppose that
the dog had any other than European origin. The apparent absence
of dog bones from all the other deposits of Indian’ refuse is a clear
indication that the natives did not habitually use these animals as food.
CERCOPITHECUS ? sp. ?
Plate 2, fig. 4
Naranjo Abajo.—Distal end of tibia, 1.
The well preserved distal end (42 mm.) of a monkey’s tibia was
found among the miscellaneous long bones dug from the kitchen-
midden on the Naranjo Abajo key. The exact level at which it lay
was not determined. In state of preservation the bone is essentially
like the rodent leg bones from the same deposit.
I cannot identify this fragment with the corresponding part of
any American primate, chiefly because the shaft of the bone, im-
mediately above the articular enlargement is too robust. By this
character the fragment (pl. 2, fig. 4) can at once be distinguished
from specimens of Cebus (pl. 2, fig. 6) Ateles, and Alouatta, the only
common genera containing species large enough to approach it in size.
When compared with Cercopithecus (pl. 2, fig. 5), however, the dis-
crepancy is less obvious, though I have not been able to find an African
tibia that I should regard as certainly pertaining to the same species.
As members of this genus were early introduced into the Lesser
Antilles I am inclined to believe that the monkey of the Naranjo
Abajo key had been brought over alive before the Indians abandoned
the coast of Samana Bay.
BROTOMYS VORATUS Miller
Plate 1, fig. 3
Railroad cave.—Skull, lacking braincase and all teeth except pm’,
1; fragments from interorbital region, 2; mandibles, a
6 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82
Boca del Inflerno— Humerus, I.
San Gabriel (owl deposit ).—Lower incisor, I ; humeri, 3.
San Gabriel (culture deposit).—Mandible, I.
Naranjo Abajo.—Right side of palate with pm* and m? in place, 1;
mandibles, 3.
Anadel.—Mandibles, 14.
Rio San Juan.—Right side of palate with all four teeth in place, 1;
fragment of premaxilla with incisor in place, 2; mandibles, 43.
Kilometer 2 site-—Right premaxilla and anterior portion of palate
with pm‘ in place, 1; palate with all the alveoli and pm* left and pm*
and m!? right in place, 1. Left side of palate with alveoli of all four
teeth, I; mandibles, 61.
Kilometer 4 site-——Mandibles, 16.
The frequency with which the bones of this animal occur in the
Indian deposits indicates that Brotomys must have been abundant
and generally distributed in pre-Columbian days. It was probably
much like the living South American spiny-rats in size and general
form, but with heavier, less elongated head. I have little doubt that
this animal was the mohuy described by Oviedo as the most eagerly
sought for of the native edible quadrupeds (see p. 13).
This material agrees in all essential features with the original
specimens from San Pedro de Macoris and with those that have been
collected in the Haitian cave deposits. Except for individual pecu-
liarities that appear to be due to age the jaws are very constant in all
their characters. I can detect no differences between those collected
in the humid Samana Bay region and those from the semiarid country
near Monte Cristi.
In one jaw from Kilometer 2 site, the premolar is in a stage of wear
to show that the small enamel “lake ”’ usually present in the anterior
lobe of the crown is the remnant of a reentrant fold penetrating from
the outer side of the tooth.’ In two others from Rio San Juan, the lake
has been joined to the tip of the anterior inner reentrant fold, while
in one specimen from the same locality, the crown, though not exces-
sively worn, shows no trace of the anterior “lake,” its pattern thus
resembling that of the molars.
ISOLOBODON PORTORICENSIS Allen
Plate 1, fig. 6
Railroad cave-—Imperfect skulls, 4; left half of rostrum, 1; right
premaxillary with incisor, 1. Left half of palate, without teeth, 1;
right half of palate, m* in place, 1; mandibles, 20.
* An even better specimen in the same stage was collected by Arthur J. Poole
in the small cave near St. Michel, Haiti.
NO. 5 MAMMALS FROM DOMINICAN REPUBLIC—MILLER If
Boca del Infierno—Imperfect palate with left m* in place, 1;
mandibles, 7.
San Gabriel (culture deposit).—Palate, 1; fragment of left pre-
maxilla with incisor, I ; mandibles, 3.
Naranjo Abajo.—Palate with right m? in place, 1; upper molar of
a larger individual, 1; mandibles, 3.
Anadel.—Palate with all teeth, 1; fragments of rostrum with in-
cisor, 5; occipitals, 1; mandibles, 41. Numerous odd teeth.
Rio San Juan.—Broken skull, 1; complete palate with all teeth, 1;
palate lacking left m*, 1; fragments of palate, 9; fragments of rostrum
with incisor, 10; mandibles, 184.
Kilometer 2 site—Imperfect skull, 1; fragments of palate, 3;
mandibles, 10.
ISOLOBODON LEVIR (Miller)
Plate 1, fig. 5
San Gabriel (owl deposit )—Imperfect skulls, 2; palate with right
molars in place, 1; separate maxillary teeth, 2; mandibles, 13.
Kilometer 2 site—Palates and fragments, 21; mandibles, 281.
These specimens agree with the original series from caves near St.
Michel, Haiti, and differ obviously from the remains of Jsolobodon
portoricensis recovered from the kitchenmiddens in the Samana region.
Among I5 jaws selected for large size, the length of mandible from
articular process ranges from 44.6 to 48 mm., height of ascending
ramus through articular process from 20.6 to 23 mm., and alveolar
length of toothrow from 16 to 17.6 mm. In 11 jaws of J. portoricensis
from the San Juan River, also selected for large size, the extremes .
of the same measurements are respectively 50 to 52.6 mm., 24 to
26.6 mm. and 19 to 20.8 mm.
After examining the entire series of Santo Domingan Jsolobodon
remains I am still as unable to distinguish the large form from the
Porto Rican J. portoricensis as I was in 1918 on the basis of the very
few specimens then collected. It seems improbable that such a
distribution could exist without human intervention. No other species
of rodent has been found to be common to the two islands and
no species could be expected to remain constant in two areas that
have been separated as long as these two land masses. Finally,
Porto Rico and the eastern part of the Dominican Republic, together
with the Virgin Islands, where the same large /solobodon also occurred,
are in a region known to have been freely traded over by pre-
Columbian man in his sea-going canoes. It must be admitted, however,
that the hypothesis of human transportation meets with a difficulty
S SMITHSONIAN MISCELLANEOUS COLLECTIONS VoL. 82
not easy to dispose of, namely, the fact that no Plagiodontia or
Brotomys seems to have been carried in ue opposite direction to
Porto Rico or the Virgin Islands.
At only two localities have the large and small forms of Jsolobodon
thus far been found together, in the kitchenmidden at the Kilometer 2
site near Monte Cristi and in San Gabriel cave. In the kitchenmidden
the remains of the two were mingled together—ten jaws of the large
animal among a total of 290. In the cave they occurred separately—
the large animal in the culture deposit at the main (south) opening,
the small one in the owl deposit near the middle of the long, ascending
passage that leads up to the aperture facing north. All the bones in
the owl deposit have the appearance of much greater age than those
in the midden. The material in which they were found is heavily
and uniformly impregnated with lime, while that in the midden, like
that in the human deposits in all the neighboring caves, shows no
such infiltration except at spots where actual drip from the ceiling
is now taking place. The presence of Aphetreus montanus among
the owl refuse may also be an indication of greater age, as this rodent
has not yet been found in any midden, though it is the second most
common species in the owl-made cave deposits near St. Michel, Haiti.
On the assumption that [solobodon portoricensis was introduced
by man in the Samana Bay region, these facts would be explained by
supposing that the San Gabriel owl deposits were formed before the
importation of this larger species and the subsequent extermination
of the smaller indigenous form. The process of replacement of the
smaller animal by the larger would have afterward become so com-
_ plete throughout the Samana region that no remains of the native
species have been found in the deposits left by the Indians. Extending
its range westward, Jsolobodon portoricensis would have just begun
to establish itself near Monte Cristi when both it and the Indians
became extinct.
APHATREUS MONTANUS Miiler
San Gabriel (owl deposit )—Mandibles, 3.
These specimens show no peculiarities as compared with jaws from
the type locality, near St. Michel, Haiti.
No bones of Aphetreus have yet been found in any culture deposit.
PLAGIODONTIA ADIUM F. Cuvier
Plate 1, fig. 2
Anadel—tImperfect skulls, 2; fragments of palate, 2; mandibles,
20; odd teeth, 9.
NO. 5 MAMMALS FROM DOMINICAN REPUBLIC—MILLER 9
Rio San Juan.—Rostrum with incisors and first two cheekteeth, 1 ;
fragments of premaxilla with incisor, I ; mandibles, 30; odd teeth, 25.
Kilometer 2 site—Fragments of palate, 2; complete mandible, 1;
fragments of mandibles, 2; odd teeth, 3.
Kilometer 4 site —Fragment of palate, I; mandibles, 6; odd teeth, 5.
PLAGIODONTIA HYLZUM Miller
Plate 1, fig. I
Railroad cave—Imperfect skulls, 2; right side of rostrum with
incisor, 1; palate lacking m* of both sides, 1; mandibles, 4.
San Gabriel (owl deposit )—Mandible, 1 young; left lower incisor,
adult, I. d
The specimens now at hand enable me to confirm the original
diagnosis of Plagiodontia hyleum and also to add two important
characters.
That the living animal is decidedly smaller than Plagiodontia edium
is abundantly shown by comparison of the skulls and jaws from
Guarabo and the south shore of Samana Bay with the remains of the
larger animal collected on the Samana peninsula and near Monte
Cristi. The 12 jaws of P. hyleum whose measurements are given in
the original description range from 51 to 55.2 mm. in length. An
additional specimen from the Railroad cave is slightly imperfect but
its length must have been about 51 mm. One mandible of P. edium
from San Pedro de Macoris was recorded as slightly more than 62 mm.
long. Unfortunately most of the jaws from the Samana Peninsula are
injured at one end or the other, so that their length cannot be de-
termined, but two from Anadel give measurements of approximately
61 and 62mm. A measurement that is more useful, because mandibles
are seldom so badly broken that it cannot be taken, is the depth from
the alveolar margin to the protuberance made by the root of pmy,.
In 10 jaws of Plagiodontia ediuwm this depth averages 16.3 mm. with
extremes of 15.4 and 17.4 mm. In an equal number of jaws of the
smaller animal the average depth is 13.2 mm., the extremes 12.2 and
14.0 mm. Similarly obvious and constant is the difference between
the alveolar length of mandibular toothrow in the two species. Ten
specimens of each give the following averages and extremes: P.
hyleum, 19.8 mm. (18.6 to 20.6 mm.) ; P. edium, 24.2 mm. (23.2 to
25.4 mm.).
The most important character brought to light by the new material
is, however, the difference in relative length of the first and second
maxillary cheekteeth. In Plagiodontia hyleum the crown length in-
10 SMITHSONIAN MISCELLANEOUS COLLECTIONS voL. 82
creases gradually and rather uniformly from the fourth tooth to the
first; in P. edium there is the same gradual increase from fourth to
second, and then an obviously and abruptly greater increase from
second to first (see pl. 1, figs. 1 and 2). The relative lengths of the
first and second teeth, measured along the median line of the grinding
surface is as follows in seven specimens of each species: P. hyleum,
pm*, average 6.1; m’, average 5.1; ratio of premolar to molar 119.8;
P. edium, pm‘, average 7.6; m’, average 5.6; ratio of premolar to
molar 135.7.
CAPROMYS PILORIDES Desmarest
Plate 1, fig. 4
San Gabriel (culture deposit)—Complete nasals and turbinates,
1; right mandibles (all toothless), 5; upper incisors, 2.
These specimens were found near together in the San Gabriel
kitchenmidden at a depth of about three feet. They do not differ
from the corresponding parts of Cuban skulls of Capromys pilorides
in any way that I can discover. Consequently I have no doubt that
the animals to which they pertained were brought to the cave as food,
either by the Indians or by early European sailors.
QUEMISIA GRAVIS Miller
Plate 2, fig. 3
Boca del Infierno—Distal half of right femur, 1; proximal ex-
tremity of left ulna, I.
Both fragments (pl. 2, fig. 3) were found at a depth of about four
feet in the kitchenmidden near the south entrance to the outermost
of the two caves.
As compared with the corresponding part in the Porto Rican
Elasmodontomys the distal extremity of the femur has a reduced
antero-posterior diameter (ratio to lateral diameter about 78 instead
of 92.5 and 93.6 in two Elasmodontomys) ; the shaft is more flattened
on its anterior aspect and less flattened on its posterior aspect; and
the antero-posterior diameter at middle of shaft is less in proportion
to the transverse diameter.
As compared with the femurs of Jsolobodon and Plagiodontia from
the Samana region this fragment is at once distinguishable by its
strikingly greater size. It appears to correspond perfectly with the
opposite end of the femur of Quemusia that I found in one of the
caves near the Atalaye Plantation, St. Michel, Haiti; and its presence
No. 5 MAMMALS FROM DOMINICAN REPUBLIC—MILLER Via
in a kitchenmidden confirms my belief that this large rodent is
Oviedo’s “ quemi.”’
CAVIA sp.
Anadel_—Mandibles, 2 (opposites but not from one individual).
I cannot distinguish these jaws from specimens of Cavia porcellus.
They present every appearance of having been buried as long as the
remains of Brotomys voratus and Plagiodontia edium with which they
were associated.
ACRATOCNUS COMES Miller ?
Plate 2, fig. 2
Boca del Infierno—Penultimate phalangeal bone, probably of sec-
ond or fourth pedal digit, 1.
This bone was found in the kitchenmidden at the south entrance
to the outermost of the two caves. It was unearthed at a depth of
not more than four feet, near the femur of Quemuisia, with which it
agrees in its perfect and seemingly unmodified condition of preserva-
tion. Both bones, in fact, seem to be, so far as it is possible to de-
termine from superficial inspection, in essentially the same state as
bones of the living species of Plagiodontia with which they were
associated. There appears to be no longer the slightest reason to
doubt that a ground sloth was a member of the recently man-exter-
minated fauna of Hispaniola.’
This bone (pl. 2, fig. 2) is similar in general form to the second
right pedal phalanx of the Patagonian Hapalops elongatus as figured
by Scott (Rep. Princeton Univ. Exped. Patagonia, Vol. 5, Palaeont, 2,
pl. 41, fig. 2), but it is about 2 mm. longer and its proximal extremity
appears to be deeper. It also resembles in a general way an isolated
phalangeal bone of Acratocnus from Porto Rico figured by Anthony
(Mem. Amer. Mus. Nat. Hist., n. s. Vol. 2, Pt. 2, fig. 53 f, p. 425,
1918). From an imperfect specimen that may represent the cor-
responding bone in Acratocnus comes it differs rather noticeably in the
less diameter of the distal articular region (compare pl. 2, figs, 1 and
2) and the more abrupt deepening toward the proximal end.
TRICHECHUS MANATUS Linnaeus
Rio San Juan—Fragments of palate, 2 (large and small); im-
perfect ribs, 2.
*T have already discussed the evidence to this effect furnished by the conditions
existing in the caves near St. Michel, Haiti (Smithsonian Misc. Coll., Vol. 81,
No. 9, pp. 25-26, March 30, 1929).
12 SMITHSONIAN MISCELLANEOUS COLLECTIONS voL. 82
Kilometer 2 site —Palate, 1; odd teeth, 8; vertebrae, 2.
Kilometer 4 site—Fragments of occipital region, 2; fragments of
mandible, 2; broken ribs, 13; humerus, 1; distal end of humerus, 1;
fragment of scapula, 1; fragment of femur, I.
These specimens do not differ appreciably from Florida material,
except that the alveoli in the palate found at the Kilometer 2 village
site appear to be exceptionally large.
THE MAMMALS DESCRIBED BY OVIEDO
Gonzalo Fernandez de Oviedo y Valdés (1478-1557), the first
European chronicler of things West Indian, was alcalde of Santo
Domingo City from January, 1536, to August, 1546. In his H1sTorta
GENERAL Y NATURAL DE LAS INnp1AS, Book 12, Chapters I to 6 (pp.
389-392 of the edition issued by the Royal Academy of History,
Madrid, 1851) he described the following mammals as known or
believed by him to inhabit the island of Hispaniola: the hutia, the
quemi, the mohuy, the cori, the dumb dog (“perro mudo”’) and
the mice (“mures 0 ratones’’).
Hitherto there has been much doubt as to the exact identification
of these animals, for the reason that Plagiodontia edium and Soleno-
don paradoxus were, up to a few years ago, the only indigenous
mammals known, other than bats and sea-cows. It now seems possible,
however, to allocate all of Oviedo’s names, with the exception of
the “dumb dog.” I shall take them up in order.
THE HULDA
Oviedo writes that there occur in this island of Hispaniola, and
in others lying in the seas near it, animals called hutia, four-footed,
and resembling a rabbit, but smaller sized, smaller eared and rat-tailed.
The natives, he says, kill them with small dogs that they have in
domestication, dumb and not knowing how to bark; and the Christians
do this much better with the dogs they brought from Spain. “ These
animals are grizzled gray (pardo gris) in color according to the
evidence of many who have seen and eaten them and who praise
them as food; and there are now many persons in this city of Santo
Domingo and in this island who say so. But at present these animals
are no longer found except very rarely.”
This account would apply so well to the species of Plagiodontia,
and presumably also to the Jsolobodons, that there seems to be no
reason to doubt that these were the animals that Oviedo had in mind.
By the present day Dominicans the name seems to have been trans-
NO. 5 MAMMALS FROM DOMINICAN REPUBLIC—MILLER 13
ferred to Solenodon; at least, such persons whom I met as knew of
an animal called hutia expatiated on the great length and pointedness
of the creature’s snout. The very few who were acquainted with
Plagiodontia hyleum happened to be English speaking descendants
of negroes from the United States. They always spoke of the animal
as the “ muskrat,’ and they told me that many of these creatures
had been killed by the workmen who cleared the narrow San Lorenzo
Peninsula for cocoanut planting 20 or more years ago.
THE QUEMI
The quemi resembled the hutia in color and general appearance,
but was much larger, its size equaling that of a medium-sized hound.
Oviedo did not see it himself, and he believed it to be extinct. How-
ever, he assures his readers that: “‘ There are many persons in this
island and in this city who have seen and eaten these animals and
who declare that they were good food; but in truth, according to
what has been said and known about the hardships and deprivations
that the first colonists endured in this island it can be presumed that
everything that could be eaten must have then appeared to them
very good and delicious, even when it was not.”
The qualifications of an animal resembling the hutia, good to eat,
and as big as an ordinary hound seemed to me to be fulfilled by the
large rodent whose remains I found in the caves near St. Michel,
Haiti, in 1925. Consequently I proposed for it the generic name
Quemisia. The presence of the same creature in the Boca del Infierno
kitchenmidden appears to confirm my guess.
THE MOHUY
“The mohuy is an animal somewhat smaller than the hutia: its
color is paler and likewise gray. This was the food most valued and
esteemed by the caciques and chiefs of this island; and the character
of the animal was much like the hutia except that the hair was denser
and coarser (or more stiff), and very pointed and standing erect or
straight above. I have not seen this animal, but there are many who
declared it to be as aforesaid ; and in this island there are many persons
who have seen it and eaten it, and who praise this meat as better
than all the others we have spoken about.”
There can be little,if any doubt that the animal Oviedo thus de-
scribed was Brotomys voratus. This rodent was smaller than either
Plagiodontia hyleum or Isolobodon levir, and its remains have been
found in every kitchenmidden that has been examined in the Domini-
Ia! SMITHSONIAN MISCELLANEOUS COLLECTIONS voL. 82
can Republic (the type specimen came from San Pedro de Macoris),
a fact that shows how universally it was liked as food. Finally the
account of stiff, pointed, erect-standing hairs of the back seems
especially applicable to a relative of the South American spiny-rats.
THE CORI
Oviedo had first-hand knowledge of the cori. Consequently his
description of it is more detailed and accurate than in the case of
the three preceding animals. He writes: “ The cori is a small quad-
ruped, the size of a half grown young rabbit. These coris appear to be
a species of the rabbit kind although they have a muzzle like a rat but
not so pointed. They have very small ears which they hold so close
that it appears as if they lacked them or did not have any. They
have no tail whatever ; they are very slender as to feet and hands from
the joints or hams downward; they have three fingers and another
smaller, and very slender. They are wholly white, and others every-
where black, and the most of them spotted with both colors. Also
some are wholly reddish and some spotted with reddish and white.”
Continuing his account he says that the coris are kept in the house
and fed on grass, with some cassava to fatten them. He has eaten
them and found them to taste like young rabbit. When he wrote
they were plentiful in Santo Domingo City. They were also to be
found on other islands and on the mainland.
It is not difficult to recognize the guineapig in this account of the
cori; but if any doubts might have existed, in the absence of more
tangible evidence, they are disposed of by Mr. Krieger’s discovery
of the two Cavia jaws in the kitchenmidden at Anadel. It remains
an open question whether the guineapig was introduced by the Span-
lards or by native trade with South America. I incline to the first
alternative, chiefly because remains of the animal have been found
in only one midden. Bones of cow, horse, and pig, as well as artifacts
of European origin occasionally occur in the Indian deposits, showing
that the native village sites continued to be used for some time after
the Spanish conquest began, and that material brought in by the
newcomers found its way to the aboriginal refuse heaps. Such might
easily have been the history of the guineapig jaws at Anadel.
THE DUMB DOG
In his account of the hutia we found Oviedo alluding to a native
dog that could not bark, but which was, nevertheless, very useful
as a game getter. On pages 390-391 of the 1851 edition of his book
NO. 5 MAMMALS FROM DOMINICAN REPUBLIC—MILLER I5
he gives an extended account of the dogs formerly and at the time
of his residence (1536-1546) occurring on the island of Hispaniola.
Parts of this account I translate as follows: ‘Domestic cur dogs
were found in this island of Hispaniola and in all the other islands
of these seas (inhabited by Christians). They were bred by the Indians
in their houses. At present there are none; but when they had them
the Indians used them to capture all the other animals [that is, the
hutia, the quemi, the mohuy and the cori] that have been spoken of
in the preceding sections. These dogs were of all the colors that dogs
have in Spain; some of a single color and others spotted with white and
blackish or reddish or ruddy or any color that the coat is accustomed
to have in Castile. Some woolly, others silky, others short-haired ;
but the most of them between silky and short-haired, and the hair
of all of them more harsh than our dogs have, and the ears lively
and alert like those of wolves. All of these dogs, here in this island
and the other islands, were mute, and even though they might be
beaten and killed they did not know how to bark: some of them yelped
or whined when they were hurt.”
Continuing, he tells us that he has seen dogs of the same kind on
the mainland in the province of Santa Marta as well as in Nicaragua,
and that in the latter country the natives regularly used them as food.
He makes no mention of the eating of dogs by the natives of
Hispaniola, and the complete absence of bones of this animal from
the collections made by us in the Samana region and by Theodoor
de Booy at San Pedro de Macoris makes it seem probably that this
habit did not exist, or at least that it was not very general. If the
dumb dog was anything else than a special breed of Canis famuliaris
we have as yet no evidence of the fact.
The five animals thus described are, Oviedo insists (p. 391), the
only furred terrestrial quadrupeds, other than rats or mice, native to
Hispaniola. It therefore seems evident that he knew nothing about
Solenodon or the ground sloth.
With regard to the mice, which he believed to be indigenous, there
is no reason to suppose that they were not brought over by the
Spaniards themselves. No native mammal the size of a mouse, except
Nesophontes, has been found in any owl deposit or kitchenmidden on
the island, and it seems improbable to the highest degree that this
small insectivore could have been the animal known to Oviedo and
supposed by him to have been spontaneously generated from some
kind of corruption in this remote part of the world.
1G SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82
EXPLANATION OF PLATES
PLATE I
All figures natural size
Fic. 1. Plagiodontia hyleum Miller. Adult male. No. 239891, U. S. Nat. Mus.
The largest specimen of the living animal collected by Dr. W. L. Abbott.
Guarabo, Dominican Republic, Nov. 24, 1923.
Fic. 1a. Plagiodontia hyleum Miller. Adult female. No. 239888, U. S. Nat.
Mus. Guarabo, Nov. 23, 1923.
Fic. 2. Plagiodontia edium Desmarest. Adult. No. 254376, U. S. Nat. Mus.
Anadel, Dominican Republic.
Fics. 3 and 3a. Brotomys voratus Miller. Nos. 254683 and 254684, U. S. Nat.
Mus. Railroad cave, San Lorenzo Bay, Dominican Republic.
Fic. 4. Capromys pilorides Desmarest. Adult. No. 2544490, U. S. Nat. Mus.
San Gabriel cave, Samana Bay, Dominican Republic. (Observe spacing of
ridges in alveoli as compared with that of the ridges in alveoli of Jsolobodon,
fig. 6.)
Fic. 5. Isolobodon levir (Miller). Adult. No. 254686, U. S. Nat. Mus. Near
Monte Cristi, Dominican Republic.
Fic. 6. Isolobodon portoricensis Allen. Adult. Railroad cave, San Lorenzo Bay,
Dominican Republic.
PLATE 2
All figures natural size
Fic. 1. Acratocnus comes Miller. Phalangeal bone from cave near St. Michel,
Haiti. No. 253210, U. S. Nat. Mus.
Fic. 2. Acratocnus comes Miller ? Phalangeal bone from kitchenmidden in Boca
del Infierno cave, Samana Bay, Dominican Republic. No. 254680, U. S. Nat.
Mus.
Fic. 3. Quemisia gravis Miller. Parts of femur and ulna from kitchenmidden in
Boca del Infierno cave, Samana Bay, Dominican Republic. No. 254681, U. S.
Nat. Mus.
Fic. 4. Monkey. Lower end of tibia from kitchenmidden on Naranjo Abajo Key,
Samana Bay, Dominican Republic. No. 254682, U. S. Nat. Mus.
Fic. 5. Cercopithecus pygerythrus. Lower end of tibia. Changamwe, British
East Africa. No. 163327, U. S. Nat. Mus.
Fic. 6. Cebus capucinus. Lower end of tibia. North Ecuador. No. 113418, U. S.
Nat. Mus.
SMITHSONIAN MISCELLANEOUS COLLECTIONS WAGES t35 INOS ie Teta 7
1. Plagiodontia hyleeum. 4. Capromys pilorides.
2. Plagiodontia zedium. 5. Isolobodon levir.
3. Brotomys voratus. 6. Isolobodon portoricensis.
(All figures natural size.)
SMITHSONIAN MISCELLANEOUS COLLECTIONS VOES 82s NOs onn plans
Sa
Monkey (not identified ).
. Cercopithecus pygerythrus.
. Cebus capucinus.
1. Acratocnus comes.
2. Acratocnus comes °
3. Quemisia gravis.
ans
(.\ll figures natural size.)
SMITHSONIAN MISCELLANEOUS COLLECTIONS
VOLUME 82, NUMBER 6
THE PAST CLIMATE OF THE NORTH
POLAR REGION
BY
EDWARD W. BERRY
The Johns Hopkins University
(PUBLICATION 3061)
GITY OF WASHINGTON
PUBLISHED BY THE SMITHSONIAN INSTITUTION
APRIL 9, 1930
toss
SMITHSONIAN MISCELLANEOUS COLLECTIONS
VOLUME 82, NUMBER 6
THE PAST CLIMATE OF THE NORTH
POLAR REGION
BY
EDWARD W. BERRY
The Johns Hopkins University
(PUBLICATION 3061)
CITY OF WASHINGTON
PUBLISHED BY THE SMITHSONIAN INSTITUTION
APRIL 9, 1930
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fae PAS! CLIMATE OF THE NORTH POLAR REGION”
By EDWARD W. BERRY
THE JOHNS HOPKINS UNIVERSITY
The plants, coal beds, hairy mammoth and woolly rhinoceros; the
corals, ammonites and the host of other marine organisms, chiefly
invertebrate but including ichthyosaurs and other saurians, that have
been discovered beneath the snow and ice of boreal lands have always
made a most powerful appeal to the imagination of explorers and
geologists. We forget entirely the modern whales, reindeer, musk ox,
polar bear, and abundant Arctic marine life, and remember only the
seemingly great contrast between the present and this subjective past.
Nowhere on the earth is there such an apparent contrast between the
present and geologic climates as in the polar regions and the mental
pictures which have been aroused and the theories by means of which
it has been sought to explain the fancied conditions of the past are
all, at least in large part, highly imaginary.
Occasionally a student like Nathorst (1911) has refused to be
carried away by his imagination and has called to mind the mar-
velously rich life of the present day Arctic seas, but for the most
part those who have speculated on former climates have entirely
ignored the results of Arctic oceanography. Recently, Kirk ~ has mar-
shalled some of the evidence of the abundance of the present marine
life in the Arctic, and he concludes from this survey that marine
organisms are not dependable as indicators of geologic climates. |
think this conclusion is impregnable, and therefore if we are ever to
get any information regarding past climates, the evidence will be fur-
nished by fossil plants, and not too precisely either. Here again
prudence is the watchword; imagination must be entirely suppressed,
and the distribution of recent plants must be understood and used.
A correct solution of the problem is not only of prime interest to
geologists and paleontologists but it offers assurance to geophysicists
confronted with the now fashionable belief in wandering poles, and
* Given in summary before the Paleontological Society at the December, 1928,
meeting.
* Kirk, Edwin, Fossil marine faunas as indicators of climatic conditions. Ann.
Rep. Smithsonian Inst. for 1927, pp. 2090-307, 1928.
SMITHSONIAN MISCELLANEOUS COLLECTIONS, VOL. 82, No. 6
2 SMITHSONIAN MISCELLANEOUS COLLECTIONS voL. 82
likewise comfort to meteorologists confronted with the traditional
view of a lack of climatic zones during most of the eons of earth
history. I propose to pass in review what we know of the past dis-
tribution of plants in the Arctic, after which I will endeavor to evaluate
what they mean in terms of climate.
Aside from some very scrappy plant fragments from the Silurian
of Norway, the oldest traces of land plants in the north occur in rocks
of Devonian age. Devonian plants have been discovered within the
Arctic Circle at the three localities shown on the accompanying map
(fig. 1). These range from a few scraps, such as those found in
Ellesmere Land and Spitzbergen, to the extensive flora found on
Bear Island which embraces 31 named forms. These three floras
are of upper Devonian age but not necessarily synchronous, since an
earlier and a later horizon is represented on Bear Island and probably
on Spitzbergen.
I have shown on the map (fig. 1) the occurrence of some other
Devonian floras outside the Arctic Circle and some in lower latitudes
in order to give an idea of the known geographical range of Devonian
plants in the present North Temperate Zone. The oldest of these is
the Lower Devonian flora of Roragen, Norway, embracing eight
very interesting forms. Of particular interest are the Middle Devonian
plants found in silicified peats at Rhynie in northern Scotland and
the flora described recently from Germany, since these give us our
first considerable insight into the structure of these ancient plants.
In looking over the list of identifications from Bear Island, all
except Pseudobornia are seen to belong to widely distributed types,
several are identical with species from the south of Ireland, and similar
forms occur rather generally in lower latitudes. There are several
seams of coal at both the older and younger horizons, to which
Bothrodendron contributed a large amount of material. Beneath the
coal seams are underclays with roots in place and the plant remains
show no sorting—that is, delicate material is mixed with stems and
branches of all sizes—both facts indicating conclusively that the bulk
of the material was not transported but grew in the immediate vicinity.
The same statement is true of the Devonian of Ellesmere Land.
The plants of the Devonian are so remote from living forms that
I do not feel that any conclusions regarding the climate are warranted
beyond the statement that they show that there were no climatic
barriers to prevent most of the types found in Latitude 45° to 50°
extending northward to Latitude 75°. There are, however, certain
types which have not yet been found in the north, such as Eosper-
No. 6 PAST CLIMATE OF NORTH POLAR REGION—BERRY
-
~~
SCALE FOR AREA w
100,000 SQUARE MILES LAMBERTS AZIMUTHAL, EQUAL AREA PROJECTION,
For class use in Geography, History, Civics, Economics, etc. Prepared by J. Paul Goode. Published by The University of Chicago Press, Chicago, IIL
Copyright 1920, by the University of Chicago
Fic. 1—Location of Devonian and Lower Carboniferous northern floras.
. Melville Island. Devonian
. Ellesmere Land. Devonian
New Brunswick, Maine, etc. Devonian
Northeast Greenland. Lower Carboniferous
Spitzbergen: Devonian and Lower Carboniferous
Bear Island. Devonian and Lower Carboniferous
. West Norway. Devonian
Rhynie, etc. Scotland. Devonian
. Nova Zembla. Lower Carboniferous
. Northern Urals. Lower Carboniferous
. Siberia. Devonian.
2 HIANUARY Dm
a
HH ©
4 SMITHSONIAN MISCELLANEOUS COLLECTIONS VoL. 82
matopteris from New York and Cladoxylon and Aneurophyton from
Germany, that may possibly indicate more genial climates in those
places than obtained farther north, and Pseudobornia seems to be a
northern type, but until Devonian floras become much better known
no adequate conclusions can be reached.
There are one or two points that deserve emphasis in this connection.
These northern Devonian floras all consist of plants belonging to the
Pteridophyte, Arthrophyte, Psilophyte, Lepidophyte and Pteridosperm
phyla, and such existing representatives of these phyla as have sur-
vived to the present, though few and not directly filiated, such as
Equisetum and Lycopodium, are singularly unaffected by temperature.
For example, there are now two species of Equisetum and one
of Lycopodium found within 10 degrees of the pole in northwestern
Greenland (Ostenfeld, 1925). To be sure these modern Greenland
forms do not reach the size of their Devonian relatives, but this is
true of all existing members of these genera irrespective of latitude.
Moreover, all of these northern Devonian plants appear to have
been bog types. This conclusion is indicated by their forming coal in
place and by the structures disclosed in the silicified peats of Rhynie.
Therefore, we conclude that the chief climatic factor was moisture
rather than temperature. The fact that many of the Devonian plants
were palustrine also gives force to an observation which I have
elaborated in another place * that these Devonian plants while ancient
and simple were not primitive and ancestral, but were the reduced
descendants of more highly organized ancestors. Since speculation
was to have no part in this discussion I refrain from elaborating my
own belief regarding the more precise character of Devonian climate.
LOWER CARBONIFEROUS
(DINANTIAN oR CULM)
Fossil plants have been found in the Lower Carboniferous, or
Mississippian as Americans prefer to call it, at five or six localities
within or near the Arctic Circle. These floras range in extent from
a few doubtful specimens at some localities to the 59 nominal species
described by Nathorst from Spitzbergen. The latter extend to 79°
North Latitude, and a considerable flora of similar species to the
number of ten at least is found between 80° and 81° North Latitude
in northeast Greenland.
* Berry, Edward W., Devonian Floras. Amer. Journ. Sci., Vol. 14, pp. 109-120,
1927.
No. 6 PAST CLIMATE OF NORTH POLAR REGION—BERRY
own
The Spitzbergen flora comprises 12 fernlike plants, 5 pteridosperms,
1 arthrophyte, 25 lepidophytes, 1 cordaites (wood), and 15 of un-
certain botanical affinities. Stigmarias and various roots occur in
place beneath the coal seams, showing that the vegetation was pre-
served essentially in place; and Lepidodendron stems have been col-
lected up to 16 inches in diameter. There are no peculiar Arctic types
in this most extensive known Culm flora nor are there any genera
that are not common to floras of the same age from lower latitudes.
The single wood, Dadoxylon spetsbergense Gothan, fails to disclose
any seasonal growth changes, which might be expected to result from
the Arctic night. No other traces of the Cordaitales other than this
wood have been discovered here, which leads Nathorst to suggest
that the wood may have been carried by currents from some more
southern clime, where also the woods fail to show growth rings.
This may be true, but on the other hand there is great specific varia-
tion in the degree to which growth rings develop in existing conifers,
as Antevs has pointed out, and they tend to be absent under fairly
uniform conditions of humidity. That this is an individual trait of
this particular species and is probably without climatic significance is
shown by the presence or absence of rings in Devonian and Mississip-
pian Dadoxylon woods from lower latitudes. For example, Dadoxylon
beinertianum Endlicher from Silesia, Dadoxylon Tchichatche ffianium
Fndhicher from Russia, and Dadowxylon vogesiacum Unger from the
Vosges, all of the same age as the Spitzbergen species, show distinct
seasonal rings, but other contemporaneous European species fail to
show them.
I cannot see any very conclusive indications of climate in these
Lower Carboniferous floras, other than the fact that they extended
in places to within 10 degrees of the pole. Palustrine types pre-
dominate as in the case of the Devonian, and more than half the
known forms are Lepidophytes which we have reason to believe show
little response to temperature. Sphenophyllums are entirely wanting
in Spitzbergen, but are found farther north in Greenland and occur
on Bear Island, so that their absence in Spitzbergen is merely an
accident of preservation or discovery. In general Arthrophytes are
much rarer in the far north than in middle latitudes at this time and
the same seems to be true of a number of genera of large fronded
fern-like plants, which is taken to indicate differences due to latitude.
TRLASSIC
Triassic plants except in the latest or Rhaetic stage are scarcely,
if at all known in the north polar region. There is a species of
6 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82
Schizoneura recorded from the New Siberian Islands which may be
Rhaetic and there are scattered Rhaetic plants in Greenland and
Spitzbergen; and somewhat farther south in northwestern Norway
(Ando) and southern Sweden.
The most extensive northern Rhaetic flora is that from Scoresby
Sound, East Greenland, between 70° and 71° North Latitude. This
comprises 51 named forms and several additional ones which are not
named. Cycads and ferns predominate, and so far as we can judge
at this lapse of time all belong to cosmopolitan Rhaetic types. Harris,
who has given an excellent account of these plants concludes that
they indicate a temperate climate, largely on the ground of the pre-
dominance of certain forms indicative of relatively pure stands and
the absence of mixtures such as occur in recent tropical assemblages.
He concludes also, from a study of the cuticles of many of the species,
that moisture was plentiful. The wood of Dadoxylon in the Rhaetic
of Spitzbergen has very feebly marked seasonal rings.
JURASSIC
Supposed Jurassic floras completely surround the pole and are
extensively developed throughout Siberia, in Alaska, Greenland, Spitz-
bergen, Franz Josef Land, New Siberian Islands, and elsewhere.
Formerly, many of these, as those in Siberia, were considered Middle
Jurassic, but Nathorst is the authority for the statement that all of
the more northern ones are post Oxfordian, and several, such as that
of Spitzbergen, are on the border between the Jurassic and the Lower
Cretaceous.
The Spitzbergen flora is the most extensive and, according to
Nathorst, includes 2 horizons, one Portlandian and the other possibly
as young as Neocomian. A combined list of these comprises 57
species, including 11 fern-like plants, 1 lepidophyte (Lycopodites),
1 arthrophyte (Equisetites), 4 cycadophytes, 4 Ginkgoales, 23 conifers
and 13 of uncertain affinities. Nine different types of coniferous
woods have been described and all show pronounced seasonal growth
rings. Most of the generic types have a very great geographical range,
but several, such as Phoenicopsis, Torellia and Drepanolepis, appear
to be distinctly northern, and the predominance of conifers suggests
a cool temperate climate. They are found in sandstones associated
with coal seams and freshwater mollusks (Lioplax, Unio) and evi-
dently grew in the vicinity of their burial place.
No. 6
SCALE FOR AREA
100.000 SQUARE MILES
PAST CLIMATE OF NORTH
POLAR REGION—BERRY 7
LAMBEAT'S AZIMUTMAL EQUAL AREA PROJECTION
For clase use in Geography, History, Givics, Economics, etc. ° Prepared by J: Paul Goode. Published by The University of Chicago Press, Chicago, Ill
Copyright 1920. by the University of Chicago
Fic. 2.—Location of Triassic and Jurassic northern floras.
t. Manchuria. Triassic and Jurassic
2. Ussuri. Jurassic
3. Amur. Jurassic
4. Trans Baikal. Jurassic
5. Irkutsk, etc. Jurassic
6-10. Alaska. Jurassic (?)
tr. Bathursy Island. Jurassic
12. New Siberian Islands. Triassic (?)
and Jurassic
13. Mouth of Lena. Jurassic
14.
15.
. King Charles Land. Jurassic
. Spitzbergen. Triassic and Jurassic
. Northeast Greenland. Jurassic
. East Greenland. Jurassic
. Scoresby Sound. Triassic
21. Ando, Norway.
. Scania. Triassic and Jurassic
. Scotland. Triassic and Jurassic.
Solitude Island. Jurassic
Franz Josef Land. Jurassic
Triassic
8 SMITHSONIAN MISCELLANEOUS COLLECTIONS VoL. 82
LOWER CRETACEOUS
Lower Cretaceous floras are found along the east coast of Asia,
in Alaska, Greenland, and King Charles Land. From the last a
number of coniferous woods have been described by Gothan. These
show pronounced growth rings, said to be more prominent than in
woods of the same age from central Europe. Nathorst records an
incomplete trunk 32 inches in diameter and showing 210 seasonal
rings. The most extensive Arctic flora of Lower Cretaceous age is
that described by Heer from the Kome beds of western Greenland,
but this, although generally considered to be of Barremian age, is
subject to doubt as to age and content because collectors appear to
have mixed several Cretaceous horizons. As it stands in the literature
it comprises over 100 species, including 46 ferns (no less than 15
are referred to Gleichenia, and although these surely represent that
genus they are artificially multiplied), 1 marsilea, 1 lycopod, 3 equise-
tums, 13 cycads, 20 conifers, 2 ginkgos, 5 monocotyledons, 3 or
4 dicotyledons, and 6 of uncertain identity. The abundance of ferns
indicates a humid climate as does the presence of coal. This flora
differs very little from those of corresponding age in lower latitudes
(e. g., the Kootenai of western Canada and Montana).
UPPER CRETACEOUS
Strictly Arctic Upper Cretaceous floras are limited to Alaska and
Greenland but others of this age are found in northern Europe and
eastern Asia. The most extensive is that from the two horizons in
West Greenland known as the Atane and Patoot beds. These have
in large part been described by Heer and there is a great and un-
warranted multiplication of species. That from the Atane beds has
184 recorded species. It includes 31 ferns, 1 equisetum, I selaginella,
I marsilea, 12 cycads, 2 ginkgos, 25 conifers, 4 monocotyledons, 94
dicotyledons and 14 of uncertain affinities.
The seemingly most incompatible plant is the authentically deter-
mined Artocarpus and this raises a question which cannot be decided
without prejudice. If a genus which is tropical at the present time
is found fossil associated with a preponderatingly temperate flora,
which is to be given the most weight? The one or the many, bearing
in mind the latitude where they occur? My own feeling is that the
majority are less likely to have altered their environmental require-
ments than the minority, but this falls short of actual proof.
The Patoot flora includes 1g ferns, I equisetum, 19 conifers, 2
monocotyledons, 80 dicotyledons, and 2 uncertain.
No. 6 PAST CLIMATE OF NORTH POLAR REGION——BERRY 9
[| SCALE FoR AREA
100.000 SQUARE MILES
LAMBERT'S AZIMUTHAL, EQUAL AREA PROJECTION.
For das us in Geography, History, Civics, Economics, etc. Prepared by J. Paul Goode. Published by The University of Chicago Press, Chicago, Ill.
Copyright 1920, by the University of Chicago
Fic. 3—Location of Cretaceous northern floras.
1. Japan tr. Vancouver Island
2. Sakhalin Island 12. Kootenai
3-4. Siberia 13. Mattagami, Ontario
5. Klin 14. West Greenland (Kome, Atane,
6-8. Alaska Patoot)
9. Spitzbergen 15. Scania
10. Queen Charlotte Islands 16. Wealden.
10 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82
TERTIARY
Tertiary plants from the Arctic have been encountered at very
many localities, usually associated with coal. This, and plants with
their roots in place as in the case of Equisetum in Spitzbergen; the
association with fresh water mollusks, as in Greenland; or aquatic
beetles, as in Spitzbergen and Iceland; as also the presence of fresh
water diatoms in the matrix and the mixtures of branches and delicate
foliage, prove conclusively that these Arctic floras and the associated
coals cannot represent drift material from lower latitudes as some
have supposed.’
The similarity in facies and their mode of occurrence, as well
as the similar petrographic character of the intimately associated
basalts suggest that all of these Tertiary Arctic floras are essentially
similar in age, although it is clear that in Spitzbergen, Alaska and
probably elsewhere, more than a single horizon is represented. Heer,
the pioneer in this field, called them Miocene, just as Lesquereux
called the Fort Union and Wilcox floras Miocene, but the Arctic Ter-
tiary floras are certainly older than Miocene and younger than Ft.
Union. This is indicated by the determination of the so-called Kenai
flora of Alaska as of upper Eocene age, and if any one of them is
proved to be upper Eocene none of the others can be older than
middle Eocene or younger than Oligocene. Collateral evidence of their
age is furnished by the age of the greatest extension of subtropical
floras into the Temperate Zone, which is in upper Eocene (Jackson)
to middle Oligocene (Vicksburg) time.
Plants or coal of Tertiary age are found at the numerous widely
distributed localities shown on the accompanying sketch map (fig. 4).
These completely encircle the pole and reach to within 8$° of it
(Grinnell Land). These will be treated at greater length than the
older floras because in some cases they are more extensive and also
because they consist very largely of species belonging to existing
genera, and hence can be discussed more intelligently than the older
floras.
It may be well at the start to dispose of an oft quoted assertion,
as for instance “most of Heer’s determinations were based upon
leaves, which give no data for generic identification’ (Gregory, op.
cit., p. 413). I would readily admit that much of Heer’s material was
fragmentary, that he was over sanguine in some of his determinations,
* Gregory makes much of this idea, which as we have seen is easily disproved.
Gregory, J. W., Congres Géol. Intern. Compte rendu X¢me Session Mexico,
1906, p. 413, 1907.
NO. 6 PAST CLIMATE OF NORTH POLAR REGION
BERRY L(t
SCALE FOR AREA
100.000 SQUARE MILES LAMBEATS AZIMUTHAL EQUAL AREA PROJECTION,
For clase use in Geography, History, Civics, Economics, etc. Prepared by J. Paul Goode. Published by The University of Chicago Press, Chicago, Il
Copyright 1920, by the University of Chicago
Fic.4.—Location of Tertiary northern floras.
1. Commander Islands 21. Prince Patrick Island
2. Japan 22. Melville Island
3. Sakhalin Island 23. Bathurst Island
4-8. Eastern Siberia 24. North Devon
9-11. Northern Siberia 25-26. Ellesmere Land
12. Central Siberia 27-28. West Greenland
13. Vancouver Island 29. New Siberian Islands
14. British Columbia 30. Nova Zembla
15-18. Kenai 31. Spitzbergen
19. Mouth of the Mackenzie 32. Iceland
20. Banks Land 33. North Ireland and Mull.
12 SMITHSONIAN MISCELLANEOUS COLLECTIONS VoL. 82
and described a great many more species than he should have done.
Some genera do not have a characteristic leaf form, but to make such
a statement of genera such as Liquidambar, Betula, Corylus, Ulmus,
Platanus, Sassafras, Liriodendron, Acer, Potamogeton, Cornus, and
Nymphea, to mention but a few of those recorded from the Arctic
Tertiary, is the height of misunderstanding. Moreover, as I pointed
out in 1922 (op. cit., p. 4): “ Plant fossils have this merit aside from
any question of botanical identification, and this feature seems to have
been lost sight of by numerous critics of paleobotanical practise:
that the size and form of leaves, their texture, the arrangement and
character of their stomata, and the seasonal changes in wood, afford
criteria that are quite as valuable climatically even though the species
or genus to which they belong remains undetermined.” Furthermore,
a great many of the generic determinations are corroborated by fruits
and seeds, as for example, the genera Vitis, Acer, Nyssa, Hicoria,
Juglans, Liriodendron, Fraxinus, etc.
As recorded in the literature the number of species varies from
the single Pinus recorded from Bathurst Island, 5 species from Elles-
mere Land, 6 species from Banks Land to 55 species from Iceland,
168 species from Spitzbergen, and 283 species from Greenland, the
last being greatly overelaborated. I have shown * that Heer’s 30 species
of fossil plants from Grinnell Land (Lat. 81° 42’) represent not more
than half that number; and that Viburnum, Alnus, Ulmus and Tilia
represent Populus and Corylus. As thus revised the Grinnell Flora
contains nothing extraordinary unless it be the supposed Nymphea
rootstock and this may really belong to one of the plants represented
by fragments of grasses or sedges.
I will consider only the four most extensive of these floras in any
detail. These are Iceland, Spitzbergen, Greenland and Alaska.
The Icelandic flora is preserved in tuffs, along with fresh-water
diatoms, Unios, Potamogeton; and the wood and branches appear
to have been broken off and buried by showers of ashes. The woods
show sharply marked seasonal rings; and conifers, willows, alders,
birch, and hazel are prominent. The only plants certainly determined
that might not justly be considered cool temperate are the following:
Platanus, Liriodendron, Acer, Juglans, Ginkgo, Fraxinus, Hicoria.
Representatives of all of these except Ginkgo, which is not a native,
and Liriodendron, which reaches its northern limit in southern New
England, are hardy in northern New England (Platanus) or eastern
Canada (Acer, Juglans, Hicoria, Fraxinus) at the present time.
*Berry, Edward W., Proc. Amer. Phil. Soc., Vol. 61, pp. 8-9, 1922.
No. 6 PAST CLIMATE OF NORTH POLAR REGION——BERRY I
-
o*)
The Spitzbergen flora comes from two horizons and the two total
168 species and are not essentially different in facies. They are as-
sociated with coal seams and are clearly continental palustrine associa-
tions. There are 4 ferns, a Ginkgo, 27 conifers, 27 monocotyledons
and 80 dicotyledons. Three woods described by Gothan show marked
seasonal rings. The warmer elements are Taxodium, Platanus, Jug-
lans, Nympheza, Magnolia and Nyssa. Here also oaks, hazels, willows,
poplars and conifers predominate. There is not a single tropical or
subtropical type and not one justly considered warm temperate.
The Greenland Tertiary flora comprises 283 nominal species and
includes 8 fungi, I moss, 1 lycopod, 1 equisetum, 19 ferns (all tem-
perate types), I Ginkgo, 28 conifers, 21 monocotyledons and 202
dicotyledons. The petrified coniferous woods show well marked
seasonal rings and the only genus that is seemingly out of place in
the far north is Taxodium, whose abundance in all Arctic floras and
in proved temperate floras of other regions and other horizons shows
that it was not out of place here. The monocotyledons include mostly
miscellaneous leaf fragments, not generically determinable, as well
as two supposed palms (Flabellaria). It has frequently been pointed
out by others as well as by myself that the nature of the last cannot
be considered as proving the presence of palms. The dicotyledons
are very much overelaborated. Probably 100 species is nearer the
correct figure than the 202 which Heer differentiated.
In Greenland as in all known Tertiary Arctic floras the leaves of
willows, poplars, birches, and hazels predominate, but there are many
other genera whose identification cannot be disputed, such as Liquid-
ambar, Alnus, Fagus, Quercus, Ulmus, Platanus, Sassafras, Fraxinus,
Cornus, Liriodendron, Acer, etc. Vitis is represented by both leaves
and seeds, and other genera also show fruits. The genera that appear
to me to be highly questionable are the following: Castanea, Juglans,
Pterocarya, Benzoin, Laurus, Myrsine, Apeiobopsis, Pterospermites,
Zizyphus, Colutea, Dalbergia, Diospyros, Sapindus, and several others.
I base this conclusion on the fossils and not on the probabilities of
their presence. Some, such as Zizyphus and Ficus clearly do not
represent those genera, in fact Heer’s discussion shows his lack of
conviction of the latter and he queried his determination.
Heer devoted considerable space to a discussion of the climatic
significance of this as well as other Arctic floras and concluded that
the Greenland plants indicated a mean annual temperature of 53.6° F.,
or a considerably lower figure than he estimated by the same methods
for the supposed contemporaneous flora of Switzerland, thus clearly
recognizing a climatic zonation.
14 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82
The so-called Kenai flora of Alaska was originally described by
Heer and additions to it have been published by Lesquereux and
Knowlton. Hollick has been engaged in a revision of this and related
floras from Alaska for a number of years, but his results are not
yet published. That from the type locality as listed by Hollick in
1915 comprised but 40 named species and contains not a single
tropical or subtropical type. Associated with the plants are thick
coal seams and fresh water mollusca (Unio, Anadon, Amicola, Mel-
ania), as well as beetle elytra.
He states in a recent letter that localities in the southeastern coastal
region of Alaska (Alexander Archipelago) have yielded a Tertiary
flora that is distinctly indicative of warmer climatic conditions than
those from farther north, including cycads, palms, and such dicoty-
ledonous genera as Anona, Dillenia, etc., but he has not yet determined
whether they are the same or different in age. In either case they sup-
port the conclusion that climatic zoning is indicated.
As listed by Knowlton* in 1919 the Kenai flora (so called)
comprised about 120 species. The most abundant forms are willows,
oaks, poplars, walnuts, beeches, birches, hazels, and alders—dis-
tinctly temperate, and cool rather than warm temperate types. Per-
haps the most abundant plants individually, certainly the widest rang-
ing geographically in northern latitudes (Holarctica), are the leaves
of hazel bushes (Corylus). Of the 54 genera of Knowlton’s list, the
following nine are not present in the existing flora of North America:
Ginkgo, Glyptostrobus, Taxites, Hedera, Paliurus, Elacodendron,
Pterospermites, Trapa, and Zizyphus.
It may seem that I am juggling the evidence in omitting these nine
genera from further consideration, but let me point out that the three
of these about which there seems to be no doubt regarding their iden-
tity, namely, Ginkgo, Trapa, and Glyptostrobus, are all temperate
types in the existing flora. The remaining six genera are under more
or less suspicion of quite a different order from any differences of
opinion among paleobotanists regarding the identification of the hazels,
birches, alders, etc., with which they are associated. Opinion might
differ as to whether a particular species of the latter was a Betula or
Alnus, an Ulmus or a Carpinus, or a Planera; or whether one or
several species of Corylus should be recognized as distinct species ; but
opinion is unanimous that the choice is thus narrowed, whereas in the
case of such things as Tavites—all any one knows is that it represents
* Hollick, A., U. S. Geol. Surv. Bull. 587, pp. 88-80, 1915.
* Knowlton, F. H., U. S. Geol. Surv. Bull. 6096, pp. 786-780, 1910.
No. 6 PAST CLIMATE OF NORTH POLAR REGION——BERRY 15
some Conifer. Why waste time trying to explain the climatic signifi-
cance of Paliurus, a mostly extinct genus, when the particular fossil
is probably not a Paliurus; or why concern oneself with an Arctic
species of Zizyphus when the form in question is probably a Ceano-
thus? I ask, can any one prove that the form-genus Pterospermuites
is genetically related to the existing genus Pterospermum? or that
Elaeodendron is a sound botanical identification? I think not!
On the other hand, the great mass of not only the Kenai but of all
the Arctic Tertiary floras are the readily recognizable, normal units of
a natural assemblage, which individually leave but slight room for dif-
ferences of opinion regarding their identity. If fruits chance to be
found in association with the leaves, they are such things as birch or
alder cones, never the fruits of the “ suspects’ above mentioned.
Of the remaining genera listed in the Kenai flora, all but the follow-
ing six are represented in the existing flora of Canada: Asculus,
Diospyros, Ficus, Liquidambar, Sequoia, and Taxodium. It may be
said of these that the 4sculus may not be an Z¢sculus, but a Hicoria;
that the two species that have been referred to Ficus do not belong
in that genus; and that Sequoia is on the verge of extinction at the
present time and its modern range bears little relation to its former
range. The case of Sequoia is of especial interest in its bearing on my
thesis. Formerly a Holarctic type, it survives today in a most re-
stricted area particularly favored by humidity.
The remaining genera of the Kenai flora appear to be determined
with reasonable certainty. Not only are 39 of these represented in
the existing flora of Canada, but the following are still represented in
the existing flora of Alaska, or adjacent areas in northwestern
Canada, or as far north as Labrador and Hudson Bay in eastern
Canada: Abies, Acer, Alnus, Alnites, Andromeda, Betula, Carex,
Corylus, Equisetum, Fraxinus, Myrica, Osmunda, Phragmites
(grass), Picea, Pinus, Populus, Prunus, Pteris, Quercus, Sagittaria,
Salix, Spiraea, Thuites, and Vaccinium.
Seventeen of the Kenai species are conifers, and the only types that
would seemingly be out of place in a cool temperate climate with
well-distributed moisture are Liquidambar, Paliurus, Taxodium, and
Zizyphus. I have already given reasons for discrediting the deter-
minations of some of these, and all of them have frequently been
found fossil in temperate assemblages.
The significant feature about these Eocene Arctic floras is that
they show a comparable northward swing of not alone their northern
limits, but also of their southern limits, which in turn is comparable
to the northward advance of the Jackson flora that I have considered
16 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82
to be of the same age. The Jackson flora reaches Latitude 37° North.
The most similar existing flora to that of the Jackson does not extend
above Latitude 26° North, and then only under especially favorable
conditions of situation with respect to warm ocean currents, This is
a difference of 11 degrees. The flora of the Jackson was, moreover,
a coastal flora, and I have not the slightest doubt but that had the
Mississippi embayment extended five degrees farther North, its shores
would have been clothed with the same Jackson flora, for at that time
similar floras are found in the Paris Basin in Latitude 49° North,
in southern England in Latitude 51° North, and along the expanded
Mediterranean sea of the Old World.
The southern limit of the contemporaneous “ Arctic flora”’ is about
Latitude 45° North in North America (British Columbia), and about
57° North in Europe (Isle of Mull). It seems to me that the essential
concordance of these facts is significant, and whatever may be thought
of them, it would certainly seem to be difficult for any one to claim that
these various Eocene floras mentioned do not show a climatic change
in passing northward from the equator toward the pole. Moreover, at
present—a time of, in many ways, an abnormal climate in a geologic
sense ; with rather sharp zoning, although not nearly so sharp as the
textbooks would have us believe; a time of almost, if not quite, un-
precedented land expansion in the Northern Hemisphere, which I
believe expresses a casual relationship—the reliable members of these
Eocene Arctic floras range much farther southward than they did
in late Eocene time.
EXISTING ARCTIC FLORAS
Greenland is the most illuminating of Arctic Lands because it is
much the largest, and therefore more likely to preserve endemic
species, and to receive immigrants from other Holarctic lands. Al-
though mostly covered by ice which rises to an altitude of more than
8,000 feet in the interior, it has island peaks (nunataks) with recent
plants. Moreover the northeastern part appears never to have been
glaciated.
About 400 species of recent vascular plants have been recorded
from Greenland and at the south trees may reach heights of 10 or
12 feet. North of the Arctic Circle the number of plants is fewer,
but Ostenfeld (1925) records 125 species north of Latitude 76° and
108 between Latitudes 78° and 80°, including 2 equisetums, a lycopod,
3 ferns, 32 monocotys and 70 dicotys, including Salix and Vaccinium.
In an earlier paper (Ostenfeld, 1923) this author describes the flora
of the north coast and records 70 species of plants from Latitude 82°.
NO. O PAST CLIMATE OF NORTH POLAR REGION——BERRY L7.
This brief statement will be sufficient to indicate that there are other
and more important factors than cold. The almost entire absence
of vascular plants (a single species as I recall it) from Antarctica
shows the part geography plays in the problem. The absence of trees
in Lapland (Kihlman) shows the part taken by cold desiccating winds.
The northern limits of many tree species in coastal Alaska and Nor-
way will indicate the ameliorating climatic effects of warm ocean cur-
rents and humidity.
EXISTING ARCTIC CLIMATES
This is a complex subject which cannot be discussed in this con-
nection beyond pointing out certain observed facts which support the
thesis of the present discussion. These are the slower heating and
cooling of water bodies as compared with land areas, with their respec-
tive influence on air temperatures and pressures, their influence on
the amount of water vapor in the air and the resulting effect of
humidity on equability.
The climatic influence of the northward drift of oceanic waters
may be illustrated by the course of the present day isotherms over the
north Atlantic, a somewhat hackneyed illustration but nevertheless the
most striking. I am showing a few of the isotherms for January and
July in figures 5 and 6. Those for January which show the full effect
of the rapid radiation and quick cooling of the land, contrast most
markedly with the slow radiation and cooling of the ocean. At this
time the zero isotherm reaches Latitude 35° in Asia and about Lati-
tude 74° north of Norway, a difference of 39°. Much the coldest place
is in northern Siberia which is 10° to 20° colder than at the pole itself.
The — 30° isotherm reaches almost to the pole north of the Atlantic
and swings to approximately Latitude 55° in Siberia—a difference of
about 35° of latitude. The midsummer isotherms naturally smooth
out these curves somewhat but even at this season the isotherm of 5°
swings from about 62° in southern Greenland to 80° just west of
Spitzbergen and the oceanic effect is clear as far eastward as Nova
Zembila.
A few figures quoted from Sir John Murray’s calculations will
serve to emphasize the relations referred to. The energy radiated
by the lowering of the temperature of a cubic meter of water I° is
sufficient to raise the temperature of more than 3,000 cubic meters of
air 1°, and a second calculation shows that the heat released by lower-
ing by 1° a stratum of water 200 meters deep and of 700,000 square
kilometers area would suffice to raise the temperature of a stratum
18 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82
of air 4,000 meters deep over the whole of Europe on an average
Of 1O=,
I have not attempted to evaluate the effects of the present ice cap
on Greenland or of the present altitude of the land surface, as all
ce
Ss
NJ
I wish to do in this brief discussion is to emphasize in a graphic way
the major thermal effect of land and water.
The Arctic is an oceanic basin and shows a remarkable climatic
contrast with the elevated glacier-covered Antarctic continent. A few
of the probable climatic effects which would follow if the Arctic re-
NO. 6 PAST CLIMATE OF NORTH POLAR REGION—BERRY 19
ceived ocean waters from the Pacific or across Eurasia from ancient
Tethys, or became ice free during the summer are discussed very
briefly in a subsequent section of this paper.
Fic. 6.—Midsummer isotherms at the present time.
SOME PALEOBOTANICAL MISCONCEPTIONS
Although I have on previous occasions emphasized the lack of
climatic value of most of the plant types which paleobotanists have
relied upon as indicating tropical climates, this subject should not be
passed over without some comment in the present connection.
The principal evidence upon which tropical climates have been pred-
icated falls into three somewhat dissimilar categories. First it rests
upon tradition which never had any basis. For example the concep-
20 SMITHSONIAN MISCELLANEOUS COLLECTIONS voL. 82
tion that the flora of the Carboniferous grew in a supertropical
climate with a humid atmosphere charged with carbon dioxide, of
which Koppen and Wegener make such specious use, had as its
original basis the 18th century idea that the strange plants associated
with the coal had been swept to Europe from the tropics by Noah’s
flood and the further fact that the habit and venation of certain fern-
like Carboniferous plants, now referred with strong probability to
the Pteridosperms, resembled certain existing tropical ferns.
Kuropean students accustomed to the modern accumulations of
peat in high latitudes concluded quite as illogically that peat could
not accumulate in the present equatorial region because of the rapid
oxidation there, so added carbon dioxide to make growth extraor-
dinarily rapid and great moisture to prevent rapid oxidation. The
carbon dioxide stimulation would also conveniently account for the
enormous size of some of the calamites and lepidodendrons as com-
pared with their diminutive survivors the equisetums and clubmosses.
Then Koorders and Potonié described a peat bog from Sumatra and
others have been subsequently described from other tropical lands,
and there has been much readjustment of views, which might have
been accomplished much earlier if the experts on geological climates
had ever visited the tropics or even consulted the report on the peat
deposits of Florida published by the Geological Survey of that state.
There is not space at my disposal to follow the vagaries of opinion,
but it may be stated in the most positive way that temperature or the
position of any region with respect to the equator,’ that is between
hot or cold climate, is not a factor in the formation of either peat or
coal. Second the tropical idea relies on representatives of long lived,
vigorous groups with very many species, which either in the past or
in the present have become adapted to a variety of habitats, as is
usually the case in large vigorous groups of all kinds of organisms.
As outstanding examples I may cite just a few types such as the
palms, and figs, or such genera as Cinnamomum and Zizyphus. The
great bulk of the existing palms are tropical and they are one of the
first types of plants visualized when we think of tropical climates,
whether we picture the Arab and his date palms or the South Sea
Islander and his cocoanut palms. Nevertheless certain palms extend
to approximately 39° South in Chile, 44° South in New Zealand,
34° North in California, 35° North in North Carolina and 36° North
in Japan, and commonly are hardy several degrees north of their nat-
ural limits, as in the Sacramento valley in California, or in southern
* Not considering the subtropical arid belts of high pressures.
No. 6 PAST CLIMATE OF NORTH POLAR REGION—BERRY 21
France. The greater limits of cultivated forms is usually not a result
of cultivation so much as it is of selecting the species that will grow
in a particular environment. In nature the proper species is subject
to the historical factor of there having been ancestors in the region
or in a region offering access to the particular region. For example our
native Californian palm (Neowashingtonia) is a plant of sandy alka-
line soils whose range seems to be conditioned by the geologically late
submergence of the Colorado Desert area, and to bear no relationship
to latitude. In the present tropics certain palms range upward to
nearly 10,000 feet, as in the wet parts of the northern Andes
(Ceroxylon, Geonoma, etc.).
The genus Ficus, to which the cultivated fig belongs, is one with
upwards of 600 existing species of a great variety of habitats, and
with probably as many fossil species, extending back to the dawn of
the Upper Cretaceous. Various members range well into the temper-
ate zone, both geographical and altitudinal. The cultivated fig gener-
ally ripens its fruits in Baltimore. I have seen it in the temperate
altitudinal zone in Bolivia, and Weberbauer* records an altitudinal
range for it through 8,255 feet in Peru.
Cinnamomum is the genus to certain members of which the names
cinnamon and camphor trees are applied. The genus is large and
ranges from the Upper Cretaceous to the present. Although the ma-
jority of existing species are confined to the tropics some extend for
considerable distances into the Temperate Zone, in fact the com-
mercial supply of camphor comes in large part from Formosa and
Japan, and the tree is hardy in the southern parts of the latter country.
Introduced into Florida it has been widely seeded by birds and is
perfectly hardy throughout that state.
Zizyphus is a large genus also going back to the Upper Cretaceous,
whose present center of population is southern Asia and the Sunda
Islands. The new world species are practically confined to the tropics,
but in the old world there are distinctly temperate species in southern
Europe and eastern Asia. It has run wild in Louisiana, and charac-
teristic fruits occur in the Pleistocene of the Atlantic coastal plain as
far north as Long Branch, New Jersey. Obviously as a fossil.
Zizyphus entirely lacks a tropical significance.
A third source of error is the common assumption that because a
particular type of plant has its home in the equatorial zone it is neces-
sarily a tropical plant. The type most frequently alluded to in fossil
Arctic floras as indicative of a once tropical climate is the tree ferns,
the term embracing a variety of species in several genera.
* Weberbauer, A., Archiv. Asoc. Peruiana Progreso Ciencia, tomo 2, p. 60, 1922.
22 SMITHSONIAN MISCELLANEOUS COLLECTIONS voL. 82
As a matter of fact tree ferns reach their maximum development
in temperate rain forests, as in New Zealand (Lat. 40° S.), or in
similar situations in tropical uplands, as was pointed out by Alexander
von Humboldt over 100 years ago. They reach their greatest pro-
fusion in South America in the temperate part of the montafia zone
of the eastern Andes. They grow luxuriantly on the mountains of
central Africa at altitudes where they are buried in snow for part of
each year, and as fossils their climatic significance is wet temperate
and not tropical.
There are a great many other genera or species in the same category.
I have seen Anonas and Ingas (cultivated) at 10,000 feet in the Andes
perfectly hardy, and a large number of generic types that are com-
monly thought of as lowland tropical above the tropical altitudinal
zone—such things as Dodonaea viscosa, Sapindus saponaria and
Swietenia mahagoni. In fact it was my own observations in the Andes
that first turned me from the paleobotanic tropical tradition.
Another misinterpreted type is the Gleichenia type of ferns (now
segregated in several genera) very common in the Cretaceous floras
of Greenland, but largely absent from the northern hemisphere in
recent floras. Although commonly confined to low latitudes at the
present time, it is by no means confined to the tropical altitudinal
zone ; in fact, where I have seen it (Yungus of Bolivia) it is promi-
nent above the tropical zone, as it is also in Hawaii, Peru, Ecuador,
Asia, etc. Representatives reach 54° South in Chile and 40° South
in New Zealand.
All this is related in any account of fern distribution (e.g., Die
naturlichen Pflanzenfamilien, 1902), and still Gleichenias, along with
palms, cycads, and tree ferns always appear in the paleobotanists
tropical repertoire.
I suppose that constant reiteration of facts like the foregoing will
have to be continued over many years before the news reaches those
who write on paleoclimatology, and at least another generation will
elapse before writers of geological text books cease to talk about the
tropical climate of Tertiary Greenland.
Juniperus communis Linné is found as far north as the North Cape,
which is at least 20° farther north than any other member of the
family Cupressinaceae is found in the Eastern Hemisphere (Nat-
horst, 1911). Sassafras, of the mostly tropical family Lauraceae, ex-
tends northward to southern Maine, or about 13° beyond the bulk
of the family. Diospyros, of the mostly tropical family Ebenaceae,
extends northward to southern Connecticut, or about 12° beyond the
bulk of the family.
No. 6 PAST CLIMATE OF NORTH POLAR REGION—BERRY 23
Nor must it be lost sight of that at those times in the past when
certain groups were varied and abundant, as were the seed ferns in
the Paleozoic or the cycads in the Mesozoic, they were quite likely
to have shown the features of dominant organisms, both plant and
animal, and to have occupied more environmental niches than the
depleted survivors of the cycad phylum do at the present time.
In Newfoundland and western Labrador the larch (Larix ameri-
cana), the balsam poplar (Populus balsamifera), the paper birch
(Betula papyrifera), and the balsam (Abies balsamea) fail to reach
the Straits of Belle Isle (52°) whereas they all extend far above
Latitude 60° in Alaska and the first crosses the Arctic Circle. Podo-
carpus just fails to reach the Tropic of Cancer in Cuba. A Chilean
species reaches 42° South Latitude in Chile. The northern limit of
forests crosses the Arctic Circle in Alaska and reaches 70° North
Latitude in Norway, the latter 20° north of the tree line on the
Atlantic coast of North America.
BAPLANATION OF PAST ARCTIC CLIMATES
It is perhaps fatuous to point out that climate, either present or
past, depends upon a variety of factors, both cosmic and terrestrial.
Of the former the only one that is of practical importance is solar—
that is, radiant energy from the sun, since it is inconceivable that
other heavenly bodies or the introduction of kinetic energy by meteor-
ites exert any appreciable effect.
The amount of solar energy reaching the earth depends upon the
sun’s activity, which is variable; on the distance of the earth from the
sun, which is also variable ; and more practically in so far as terrestrial
climates are concerned, on the condition of the earth’s atmosphere,
especially with respect to the amount of ozone, water vapor, carbon
dioxide, and dust present, all of which again are variable. The lati-
tude, determining the angle of incidence of the sun’s rays, is an obvi-
ous factor, as is also the geographic pattern and the topography, in-
cluding altitude under the latter. The geography determines whether
the sun’s energy falls on the land or the water, it determines the
temperature gradient between the equator and the poles and the con-
sequent force of the planetary winds and ocean currents, and in less
obvious ways is of the greatest significance, as the following illus-
tration will make clear.
The North and South Equatorial currents in the Atlantic are so
situated that the South Equatorial, the stronger and the larger of the
two, is divided by Cape San Roque into a larger, northern or Guiana
current; and a smaller, southern or Brazil current. Some authors,
24 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82
e. g., Guppy, are inclined to consider the South Equatorial as bipartite
throughout, calling the Guiana current the Main Equatorial current.
The point is immaterial in the present connection since all I desire
to show is that the shape of eastern South America and the latitude of
Cape San Roque are purely fortuitous in so far as their relation to
climate is concerned, and yet if the latter had happened to lie a few
degrees north of its present position much of the water that ultimately
contributes to the Gulf Stream would have turned southward to aug-
ment the Brazilian current, and the climate, especially of Europe and
the Arctic, would be profoundly modified. It has been estimated that
if Cape San Roque were 2° north of its present position there would
be a shift of 40% of the [Equatorial current which would be deflected
southward instead of northward. The same results would be attained
if the southern trades were not stronger and more constant than the
northern trades, because of the relative amounts of land and water
in the northern and southern hemispheres.
Scant attention will be devoted to the various theories that have
been advanced to explain geological climates. These range from that
of Croll, in its original or modified form, based upon the eccentricity
of the earth’s orbit and the obliquity of the ecliptic, which was doubt-
less a factor at all times, but hardly a controlling one ; through those
theories that rely on changes in the atmosphere, such as alterations
in the amount of carbon dioxide (Tyndall, Arrhenius, Chamberlin)’
amounts of volcanic dust (Humphreys), to the extreme form of the
hypothesis advanced by Manson, and elaborately defended by Knowl-
ton, that a combination of cloudiness progressively diminishing dur-
ing earth history, and a terrestrial control due to a cooling earth,
instead of a solar control as at present, are the primary factors which
explain past climates. Finally there are those highly speculative
hypotheses such as Chamberlin’s reversal of the oceanic circulation,
and a group which predicate a wandering of the poles in various
ways, now fashionable in the revived form put forward by Wegener.
I have quite possibly omitted other proposals that might be men-
tioned, and I] have now to mention the theory, if it can be called a
theory, which is the main thesis of the present paper, namely: that
it seems to me possible to interpret geological climates in the light of
demonstrated changes in topography and geography, including under
the latter differences in the distribution of land and water and the
transfer of energy by currents.
* It is of interest to note that Neumayr in 1883 pointed out that excesses of CO,
would be impossible since the absorption by the oceans would maintain an almost
perfect balance.
i
No. 6 PAST CLIMATE OF NORTH POLAR REGION
BERRY 25
This idea, as applied to the Pleistocene glaciation, was first advanced,
I believe, by Lyell, and in its more general application has been re-
cently put upon a scientific basis by Brooks, with whom I am in perfect
agreement to the extent of the evaluation of these as major factors,
but also in my firm conviction that arm chair philosophy with its
fondness for highly speculative and catastrophic hypotheses, has no
place in a uniformitarian world or in 20th century science, but be-
longs in the medieval age of human thought.
Climate, in a uniformitarian geology, occupies a somewhat anoma-
lous position, which the scientific world has been slow to recognize,
namely, that the history of the human race has been run under cli-
matic conditions which, from the point of view of earth history, are
exceptional. Man was evolved subsequent to the relative elevation
and the great extension of the continents which ushered in the Pleis-
tocene glaciation, and therefore what is normal in human experience,
is abnormal for the bulk of geological climate.
While, therefore, we recognize that the climatic factors and the
meteorological elements are the same now as always, their combina-
tion to form actual climates has depended upon a great many factors,
among the chief of which was the size, shape, position, and relative
elevation of the land masses. It may be remarked parenthetically
that numerous theories of the causes of, or descriptions of geological
climates have been advanced by students ignorant of meteorology,
and also usually ignorant of the relationship of organisms to their
environments, and the last is strikingly true of Koppen & Wegener's
recent Die Klimate der geologischen Vorzeit (1924).
In attempting, a few years ago, to explain the extension of floras
nearly to the poles during the late Eocene, I relied chiefly on the sub-
mergence of continental areas in the middle Eocene and the resulting
free oceanic connections at that time between equatorial and Arctic
waters, pointing out that these Arctic floras were coastal floras and
therefore under the régime of an oceanic climate.’ Essentially the
same explanation was put forward independently in connection with
Jurassic climates a few months later by Kerner von Marilaun.* An
additional and important factor has since been brought forward by
3rooks,’ who points out that the temperate gradient is a simple func-
tion, whereas the influence of the ice increases as the square of the
* Berry, Edward W., A possible explanation of upper Eocene climates. Proc.
Amer. Phil. Soc., Vol. 61, pp. 1-14, 1922.
* Kerner von Marilaun, F., Sitz. k. Akad. Wiss. Wien, 1922.
* Brooks, C. E. P., The problem of mild polar climates. Quart. Journ. Roy.
Meteor. Soc., Vol. 51, pp. 83-94, 1025.
26 SMITHSONIAN MISCELLANEOUS COLLECTIONS vol. 82
radius. Hence a coincidence of minor factors sufficient to effect an
overturn in the one or the other direction, that is, toward ice forma-
tion or melting, would suffice to induce a wide extension of polar
ice, or to prevent the polar regions from maintaining a permanent
ice cap. If this is true then it seems quite probable that there was little
polar ice during those times already enumerated when temperate
floras invaded the polar regions. This would mean profound changes
in the distribution of barometric pressures and consequent wind cir-
culation, and in fact, in all of the elements which constitute climate.
It would mean that in western Greenland, for example, where the
most extensive late Eocene Arctic flora has been found, the present
day glacial anti-cyclonic winds would be replaced by westerly or south-
westerly winds blowing from the relatively warmed waters of Baffins
Bay, and this would satisfactorily explain the details of the floral
facies. This does not mean that there would be tropical climates
in the Arctic or that the region would not be ice bound in the winter
season. The protective effect of snow, and cold sufficient to cause
_acessation of plant activity during the Arctic night are a physiological
necessity. Otherwise most vascular plants could not maintain them-
selves. They tend to die either if active in darkness or if exposed
to desiccation by air and wind when the ground water is frozen.
Regarding the general history of discussions of geologic climates
I believe that most paleontologists who have written on this topic,
especially those dealing with the pre Cenozoic periods, have had little
basis in fact for their speculations. They seem to me to be utterly
oblivious to the great amount of modern work on the distribution
of marine organisms ; and their ideas of the climatic significance of a
trilobite, eurypterid, or ammonite is purely a tradition inherited
from the distant past when all strange organisms were associated with
torrid climates.
In stating my belief in a greater uniformity of climate during the
past than obtains at the present I do not wish to be understood as
advocating such unsound beliefs as the entire absence of zonation,
such as many paleobotanists have defended (Jeffrey, Knowlton), or
a similar uniformity throughout all time. Both are equally disproved
both by geological observations and meteorological principles. Jeffrey,
for example (Anatomy of Woody Plants, Chapter XXX, 1917), holds
that the more ancient the epoch the warmer the climate, and that there
has been a gradual and progressive refrigeration during geologic
time ; that the organization of secondary wood in extinct plants furn-
ishes the most reliable evidence of climatic conditions; that toward
the end of the Paleozoic, growth rings appeared in woods in high
latitudes ; that in the Triassic, growth rings were developed ten degrees
No. 6 PAST CLIMATE OF NORTH POLAR REGION——BERRY 27
nearer the equator than had been the case during the Paleozoic ; that in
the Jurassic, the tracheids first developed tangential pitting which
was at the end of the annual ring, and accompanied by storage ele-
ments (wood parenchyma).
None of the statements in the foregoing paragraph are facts of
observation. There is no geological or paleontological evidence indi-
cating a progressive climatic cooling during geologic time, and the
Permo-Carboniferous glaciation was admittedly more extensive than
that of the Pleistocene. The presence or absence of growth rings
exhibits what might be called constitutional variations quite indepen-
dent of climate, not that they really are independent, but two associated
species under an identical climate will behave differently with respect
to this feature of their anatomy. Growth rings appear in some Pale-
ozoic woods many degrees nearer the equator than Jeffrey admits,’
and in marine formations deposited off low coasts so that they cannot
be considered to have been upland types. Several Lower Carbonifer-
ous examples have already been cited. The Paleozoic genus Mesoxy-
lon shows tangential pitting, which, according to Jeffrey, first appeared
in the Jurassic; and the citation of a wood from the Triassic of
Arizona as an argument for the advance equatorward of cooler cli-
mates during the early Mesozoic is particularly disingenuous, as it
is perfectly clear that the growth rings in this case have nothing to do
with temperature, but are due to periodic lack of moisture in that
region, as exemplified by the contemporaneous gypsum deposits.
Similarly in the recent elaborate work on geologic climates by Kop-
pen & Wegener, already alluded to, these authors offer explanations
to account for climates during the successive geologic periods, which
climates have not been proved to have ever existed.
As I have pointed out on previous occasions, paleobotanists in
general have entirely lacked objective experience outside the temper-
ate zone, and have invariably overestimated temperatures. They have
been prone to use the present distribution of the fancied or real rela-
tives of their fossil forms as if temperature were the sole factor in the
environment, and have stopped with the geographic occurrence, with
the apparently simple trust that all lands in the equatorial zone were at
sea level and wet tropical. A sojourn in the Arctic climate beneath
the equator on the backbone of South America would do much to
correct this misapprehension, as would also some experience in the
temperate rain forests of different regions.
I had intended to indicate current conceptions of contemporaneous
paleogeography on the maps showing the plant localities but have
* Several have been named in the preceding paragraph devoted to Mississippian
Arctic plants and others could be added.
28 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. $2
not done so although I did publish such a map for the Eocene in 1922.
This intention was abandoned for the reason that it was not possible
to compile maps that did not cover too much time nor in which the
extrapolation was not so great as to destroy any real value.
Arldt has compiled maps which represent a synthesis of opinions
and showing the areas of agreement and disagreement among special-
ists and to these the reader is referred. The debatable North Atlantic
continent and the Gondwana continent would, if they ever existed,
have had a profound effect on climate. Whether or not they were
ever realities I am not prepared to say. I can, however, make the
following statements with a considerable degree of certainty, namely:
That there was a wide extent of land in the Northern Hemisphere from
late Mississippian through the Permian. That the Arctic was land-
locked in early and middle Triassic and that there was a wide trans-
gression of the sea in the Neo Triassic. That the maximum Jurassic
transgression was about Oxfordian ; that of the Lower Cretaceous was
in the Neocomian ; that of the Upper Cretaceous was in the Emscher-
ian; that the late middle Eocene was a time of wide sea transgression
and low lying lands; and that during the Miocene, the age to which
Heer assigned the Arctic Tertiary floras, the amount of land in the
Northern Hemisphere was nearly as great as it is at the present time.
It will be seen that there is a correspondence between times of sea
extension and Arctic floras and times of land extension and no traces
of Arctic floras. This correspondence is not exact, and so little of
paleogeography is objective, that I would not want to appraise it for
more than it is worth, but in so far as it is known it does offer
corroboration of my thesis.
I had expected to attempt an estimate of the meteorological condi-
tions at the various times at which fossil floras are found in the Arctic,
but after abandoning any hope of getting reliable paleogeographic
data I have also abandoned the former. Brooks has published some
interesting meteorological estimates using as a basis those parts of
Arldt’s maps where authorities agree, but it should be pointed out that
majorities are quite as likely to be wrong in science as in politics, and
if generalizations are valid (which of course they are not) then
minorities are usually right.
There are, however, a few considerations that may be put forward
as having a high degree of validity, namely the importance of ice as
a third factor, added to the long recognized rotational (planetary) and
geographic (distribution of land and water and altitude) factors
in influencing the distribution of pressures and consequently of pre-
vailing winds. And also the effect of the volume of fresh water car-
=
oo
No. 6 PAST CLIMATE OF NORTH POLAR REGION——BERRY 29
ried into the Arctic basin by rivers in the formation of ice and the
effect of current-borne ice in maintaining subnormal density and con-
sequently the identity of the present day cold currents as they move
southward. Once they become of normal density they disappear below
the surface and lose their climatic influence.
Another factor of considerable importance climatically, especially
in connection with the theory of Brooks, is the amount of reflection
from the earth’s surface. I do not have the exact figures, but estimates
given to me orally by W. J. Humphreys, are about 7 per cent from
land or water and about 70 per cent, or ten times as much, from the
surface of snow and ice. If there has been the wide fluctuations in
polar ice as Brooks predicts, then reflection is a factor which can not
be safely neglected.
At the present time in high latitudes the prevailing wind circula-
tion is easterly with a southward moving component at the surface.
If the ice cap were gone we would have westerly winds in high lati-
tudes with a poleward component at the surface.
If Bering Strait was open and less shallow, a great volume of warm
Pacific water would pour into the Arctic and greatly ameliorate the
climate, as would also be the case if a Cretaceous seaway bisected
North America, or a Devonian or Eocene seaway bisected Eurasia,
such as are shown on current paleogeographic maps. If the best avail-
able sources are utilized in plotting Eocene seaways nearly all the
Tertiary coal occurrences and floras in the Arctic range themselves
along the easterly coasts of such seaways.
CONCLUSIONS
The major factor in the polar extent of temperate floras is
not primarily the direct effect of temperature so much as it is the fact
that above 32° F. water is a liquid and below 32° F. it is a solid. Asa
Gray said “ Plants are the thermometers of the ages.” I have no
doubt that terrestrial vegetation when properly interpreted is the safest
guide to geological climates, but as thermometers they are pretty
poor and we have no means of calibrating them,
There is no unequivocal botanical evidence of tropical or subtropical
climates at any time in the Arctic. There is no evidence from paleo-
botany of a lack of climatic zonation at any geological period from
which fossil plants are known, although at such times the evidence
points to a relative mildness and a lack of sharp zonation, as com-
pared with the present.
The distribution of the known fossil Arctic floras with respect
to the present pole proves conclusively, as Seward pointed out in
1892 (p. 53), that there could have been no wandering pole.
SMITHSONIAN MISCELLANEOUS COLLECTIONS
VOLUME 82 NUMBER 7
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SMITHSONIAN MISCELLANEOUS COLLECTIONS
VOLUME 82, NUMBER 7
THE ATMOSPHERE AND THE SUN
BY
H. HELM GLAYTON
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THE ATMOSPHERE AND THE SUN
By, H. HEEM ‘CLAYTON
CONTENTS
PAGE
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INTRODUCTION
This paper is the fifth of a series giving the results of investiga-
tions of the relation of solar activity to atmospheric changes. The
earlier ones were published as Smithsonian Miscellaneous Collec-
tions, Vol. 68, No. 3; Vol. 71, No. 3; Vol. 77, No. 6; and Vol. 78,
No. 4. The author has been stimulated to continue these researches
because he believes in their great importance. The interest of
Dr. C. G, Abbot and the sympathy and aid of Mr. John A. Roebling
have encouraged him in the task and enabled him to undertake much
work that otherwise would not have been possible. Miss M. I. Rob-
inson has aided in the calculations needed for the discussion.
i SOLAK CHANGES
It has long been known that spots appear on the surface of the
sun and that the number and size of these spots varies from day
to day, from month to month, and from year to year. More recently
it has been discovered by Dr. C. G. Abbot and his associates that the
radiation coming from the sun varies ; so that, in general, it is known
that the sun is hotter when there are many spots on its surface than
when there are few or none.
There is also evidence that the heat of the sun varies from day
to day and from week to week in short cycies of change. The most
convincing evidence of this fact is the comparison of measurements
SMITHSONIAN MISCELLANEOUS COLLECTIONS, VOL. 82, No. 7
2 SMITHSONIAN MISCELLANEOUS COLLECTIONS voL. 82
of solar radiation made at observatories thousands of miles distant
from each other, one in the northern hemisphere and the other in
the southern hemisphere; so that the chance of both being affected
by the same weather changes becomes very small. The solar radia-
tion reaching the earth is measured in calories per square centimeter
per minute, and averages about 1.940 calories. Table 1 shows a com-
parison of observations of solar radiation made simultaneously in
northern Chile and in the United States (first in California and then
in Arizona) during the years 1918 to 1924. The table shows the
frequency of different values observed in the United States for each
increase of .010 calorie in Chile.
TABLE 1.—Comparison of Solar Radiation Values in Chile and the United States
(Number of Cases)
Values in Values observed in Chile
United — A
States I1.910-9 1.920-9 1.930-9 1.940-9 1.950-9 1.960-9
MWSOO=On eae ee I 6 6 6 O 0)
MOOO—Os es ome eee ec II II I (0) Ce) oO
BO LOO ays eta eraees 20 25 II 5 4 (6)
1.02050) eyno.citer ere 18 38 21 5 4 D
TO30—Os sane one 7 23 29 II II 0
TQAO=Ol ai bene Ate 4 6 12 15 16 4
TO5O=Oi. Sieve Sietecos he (6) 4 10 10 13 6
TQ0O=Oiane ak Saeweios (a) I 3 4 7 5
1 O7FO—O mise eee (0) I oO I 3 2
If there were no relation between the measurements at the two
stations, the observed values would be scattered through the dif-
ferent classes at random. The tabulation shows that a random dis-
tribution does not exist ; but for each group of observations in Chile,
there is a maximum near the same values in the observations in the
United States. There is, therefore, a progressive displacement of
the maximum frequency as the solar values increase from 1.910-9
to 1.960-9, or nearly three per cent of the mean value. The probable
error of the measurements is +.006 calorie; so that the solar varia-
tion during the interval covered by the observations was more than
eight times the probable error of each group of observed values.
Since variability in solar radiation has been questioned by some
investigators, it is well to state that the evidence of this variability
rests on three fundamental and independent facts:
(1) The changes in radiation are alike when measured at two
widely separated stations, allowing for variations from a middle
value due to errors of observation.
NO. 7 THE ATMOSPHERE AND THE SUN—CLAYTON 3
(2) The changes both of short period and of long period in solar
radiation are related to visible changes in the number and area of
spots, faculae and flocculi seen on the sun.
(3) The changes in solar radiation are correlated with other phe-
nomena such as certain changes in terrestrial magnetism, in radio-
receptivity, and meteorological changes which are known by other
evidence to be related to solar conditions.
The critics of solar variability have pointed out that the measured
variations have decreased as the accuracy of the observations in-
creased and that in the earlier observations the effects of water vapor
Zee BEFORE DAYS AFTER
eee a
Fic. 1—Calcium flocculi and solar radiation. The mean values of solar
radiation received at the earth in calories per square centimeter per minute on
days before and days after the passage of calcium flocculi across the central
meridian of the sun. 1918-1920. Flocculi of 400 or more on the Ebro scale of
values.
in the air, of dust, of ozone, and of turbidity were not entirely
eliminated ; but they have in no manner destroyed or impaired these
fundamental evidences of variability.
Abbot and his associates’ have given evidence of the relation of
solar radiation changes to solar contrast and to groups of spots on
the sun, Fowle* has shown a relation to groups of flocculi, and I°
have shown a relation to faculae. Bauer * has shown a relation to cer-
tain changes in terrestrial magnetism, and Austin® has found a
* Smithsonian Misc. Coll., Vol. 66, No. 5, 1916.
*Idem, Vol. 77, No. 5, 1925.
* Idem, Vol. 77, No. 6, p. 53, 1925.
*Terr. Mag., Vol. 20, pp. 143-158, Dec., 1915.
* Smithsonian Misc. Coll., Vol. 80, No. 2, p. 13, 1927.
4 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82
marked parallelism between radio-receptivity and changes in monthly
values of solar radiation.
In order to study further the relation of clouds of calcium and
hydrogen as seen in faculae and flocculi to solar radiation I took
from the publication of the Ebro Observatory all days on which
the area of observed clouds of flocculi exceeded 400 millionths on
the Ebro scale. The day on which this area crossed the central
meridian of the sun as seen from the earth was called zero day.
Then, the solar radiation measured on that day and on each of the
seven days preceding was averaged. The same was done for each
of the following days up to 21 days later. The mean values for each
day are shown plotted in figure 1. This plot shows that the radia-
tion from the sun averaged lowest when the flocculi were near the
center of the sun. This fact indicates changes of transparency in
the sun’s atmosphere and is interpreted to mean that the clouds of
calcium and hydrogen in the flocculi cut off the radiation from the
surface of the sun, just as water-vapor clouds cut off radiation from
the surface of the earth beneath them. When near the limb of the
sun, however, these clouds add to the total radiation.
IJ], LATITUDE. EFFECT OF SOLAR CHANGES ON THE EARS
ATMOSPHERE
Studies of the relation of solar radiation changes to meteorological
changes have been published in four preceding papers in this series.
The results of recent researches and deductions drawn from the
whole mass of data follow. Some readers may be inclined to think
that the generalizations given are based on too small an amount of
data, but in reality they are based on a large amount of data accumu-
lated during 20 years of research. Where one example is given, many
others might have been presented.
In the earlier papers of this series the first finding of importance
was that there was a marked latitude effect of solar radiation changes
on the pressure and temperature of the earth's atmosphere. Accom-
panying or immediately following short-period changes in radiation,
there was an increase in temperature and a fall of pressure in equa-
torial regions, a rise of pressure and a fall of temperature between
40° and 60° latitude, while at latitudes above 70° the pressure fell
and the temperature rose. These conditions hold true for both the
northern and southern hemispheres. The chart illustrating this fact
is reproduced in figure 2.
Figure 3 shows how, in the average of many cases, day to day
changes of pressure at Honolulu are associated with simultaneous
NOD THE ATMOSPHERE AND THE SUN—CLAYTON 5
changes of pressure at Nome and also with day to day changes in
solar radiation. During the interval covered by the data from which
eZ
INNA |
Ay
ims
ln, ZZ if
YL SOF,
Fic. 2—Zonal effect of increased solar activity. Shaded areas show regions
where the pressure falls and the temperature rises with short period changes of
solar radiation. Unshaded areas show regions where the reverse conditions occur.
these curves were constructed, January to April, 1928, the pressure
at Nome followed the solar radiation changes directly, and the pres-
sure at Honolulu followed inversely. The changes are nearly simul-
DAYS BEFORE DAYS AFTER
2
Pole
Fic. 3—Maxima of pressure at Honolulu compared with pressure
at Nome and with solar radiation.
taneous except that the solar minimum and maximum appear to
occur slightly earlier.
6 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82
A later investigation disclosed that there were also latitude dif-
ferences in pressure correlated with changes in the monthly num-
ber of sun spots.’ Using the data from about 200 stations, the aver-
age pressure when sun spots were near their maximum frequency
was compared with the average pressure in the same latitudes when
the sun spots were near a minimum of frequency and differences
obtained. These differences are plotted in figure 4.
Figure 4, shows that when sun spots are more frequent in num-
ber, the pressure is lower in the equatorial region from about 30°N.
to 30°S., while from about latitude 35° to 65° in both hemispheres,
the pressure is higher when the sun spots are most numerous. This
result is in good agreement with that found for short period changes
NORTHERN HEMISPHERE EQUATOR SOUTHERN HEMISPHERE
2077 3500 (40% SO BEGOE
ap alkene |e ees Ee Hea 2 8 SS)
oP ok a a eS a ae a a ie
Fa a a Sa
Ce ae a a ee ee
Fic. 4—Mean difference of pressure at sun-spot maximum from that at
sun-spot minimum.
of solar radiation and with the fact disclosed by the measurements
of the Smithsonian Astrophysical Observatory that more radiation
from the sun reaches the earth when sun spots are more frequent.
A recent research by Ekhart* shows clearly the opposing oscilla-
tions of the pressure in high and in low latitudes. When the pres-
sure falls in low latitudes, it rises in high latitudes and vice versa.
In order to investigate this relation further with the data which
appeared in ‘ World Weather Records,” * 24 cases were selected in
which solar activity was above normal as shown both by the Wolfer
sun-spot numbers and by the Smithsonian values of solar radiation ;
and 24 cases where the opposite condition prevailed, namely, a small
monthly sun-spot value and a low value of solar radiation. Where
* Clayton, H. H., World Weather, p. 262. New York, Macmillan & Co., 1923.
* Ekhart, E., ‘‘ Untersuchungen der jahrlichen Schwankungen der atmosphar-
ischen Zirkulation,’ Meteorologischen Zeitschrift, Heft 2; February, 1930.
* Smithsonian Misc. Coll., Vol. 790, 1927.
NO. 7 THE ATMOSPHERE AND THE SUN—CLAYTON yi
no values of solar radiation were available, only sun-spot numbers
were used and an equivalent value of solar radiation was derived
from Abbot’s * plots of equivalent values and placed in parentheses.
Since both sun-spot numbers and increased ‘solar radiation are
considered in forming this table, the results derived from a compari-
son of the data in the table with meteorological conditions rest on
TaB_e 2.—Kelative Sun-spot Numbers and Average Values of Solar Radiation
Used in Study
High solar values
ve a
——— —
Low solar values
Date Sun-spot Solar Date Sun-spot Solar
summer number radiation summer number radiation
NDE TOLO. 15.0.0 GP (1.952) AN(is LOI2= yee ee 4 (1.928 )
SESTOU ONS 3 Rei, < 8 1.953 H OHOUA or a I (1.925)
Nitaiys OL = sec - 114 1.956 May= 1OTOs. 4445. 22 1.916
ee OQ 20K ss os 34 1.953 ee LOM ere Co) (1.923)
Jine “O05 ><2.::. 40 1.968 MINE MTOOO ssa: 23 1.930
SS SIGHT) 5 eae III 1.955 mL OT2) wcrc syerae 4 1.930
ily TO06......- 103 1.962 Wahi WONG cococe 14 1.013
SS NOUY Areata 120 1.989 sa ee LOLI, Revoneye 3 1.Q17
IATRES T01G 25-0 aeeee 154 1.956 [NOV MOO) 6 ob ane 23 1.926
PMO MG sty: say.0.c, 102 1.954 Oe TORO cee II 1.912
SEOs OL 25.0 5 cc: 120 1.948 Septs 1000ss 5. . 39 1.908
ee TOUS s \.acy. 80 1.944 aC mOTOR Aon: 26 I.915
NIGENTS Se aereene ene 05.7 1.958 Mean ene 8.3 1.017
Winter Winter
Oc Ol7. v.21. 72 1.952 OVS WON oe obee 3 1.915
PeMPLOT GO cicxrate's i 85 1.939 She TORS eae « 3 1.866
INO, Gy tye eee 96 (1.954) ING TOW coco nee 4 1.903
SB OMTGLO. <6 a5. 42 (1.953) LOTG ee sae I 1.866
DEG TOIT. aes. 129 (1.957) Dect TOT. 4... 2 (1.926)
Bee TO2ZOS- cus 6. 40 1.955 eS STOUBR nes 4 (1.928 )
iene LOLS. .....: 96 (1.954) WEIS WOW Gs okose 3 (1.927)
Re TOZO rss cs x: 59 1.904 Goin Wa Ohi te eee 2 (1.925 )
Bebe TOUS)... ... 65 (1.951) IGE “WOW 5 Soon (a) (1.923 )
RETO 2Z0 Ses c c2-5 51 1.956 SO LG Reet 3 (1.927 )
Mite TOUT: oc ..-« 05 (1.954) Mare 1OU2s5 62-4 5 (1.929)
pee TO2ZO ms «320. 72 1.945 LOU SC ei k 5 - oO (1.923 )
MICE eee View 1.955 MiGaTI tt eee iee 2.5 1.913
Values in parentheses are derived from sun-spot data_and are taken from Abbot’s curve
of equivalent values, Smithsonian Misc. Coll., Vol. 80, No. 2.
increased solar activity, whether measured by sun spots, faculae and
flocculi, or by an increase in solar radiation reaching the earth.
Solar radiation values are missing for a number of the spring and
winter months because no observations were made during these
months in the earlier years. These months are included because it
* A group of solar changes, Smithsonian, Misc. Coll., Vol. 80, No. 2, p. 8, 1927.
8 SMITHSONIAN MISCELLANEOUS COLLECTIONS
VOL. 82
was desirable to have an equal distribution of the observations
throughout the months in order to study and to eliminate seasonal
influences. If, however, only those months had been used in which
both values were present, the main conclusions which follow would
TaBLe 3.—Mean Departures of Pressure from Normal in Millibars with High
Solar Activity
Winter Hali-Year
180°-120° W. 120°-60° W. 60°-0° W. o°-6o° E.
80°-70° N. (—0.5) (+1.0) 7.2 —1.7
70 —60 ALi (E115) —0.6 —0.7
60 —50 +0.6 SEG 11.4 +1,2
50 —40 1.6 +0.4 +1.0 +I.1
40 —30 +0.5 +0.2 +1.5 +1.0
30 —20 —o.8 +0.4 +o.2 0.1
20 —10 (—0.4) +0.4 +0.3 +0.2
10 -O (—0.3) 0.0 +0.3 0.0
Summer Half-Year
80°-70° N. (—2.0) 0.0 +0.2 —0.6
70 —00 —1.8 (5); -0.7 +3.8
60 —50 +12 L.5 +tI.1 +0.7
50 —40 +0.6 1.1 +0.5 +0.3
40 —30 +0.1 +0.3 +0.4 0.0
30 —20 Or +-0.2 =OL7/ —0.2
20 —10 (—0.3) --0.2 -Lo.I —Oo.1
10 -0 (—0.2) 0.1 = 017 0.0
Year
80°-7o° N. (—1.2) (+0.5) +0.7 —I.2
70 —00 —0.3 (+1.3) +0.1 +1.6
60 —50 -+0.9 +1.6 +1.3 -++0.9
50 —40 sir +o.8 +o.8 0.7
40 —30 +0.3 +0.3 +0.9 +0.5
30 —20 —o0.6 +0.3 —0.3 —0.1
20 —10 (—0.4) +0.3 +0.2 0.0
10 -O (—0.2) 0.0 +o0.8 0.0
60°-120° E.
(—I.0)
+0.5
+0.6
-+-0.7
+0.1
—o.1
—o0.6
—0.3
0.5
+2.4
—o.I
—0.7
—0.3
0.0
—0.2
—o0.1
+0.2
+1.4
+0.3
0.0
—0.2
—O.1
—0.4
(0k)
120°-180° E.
(0.0)
+0.2
+TI.1
+0.2
0.4
+0.2
—0.6
—0.6
(—I.2)
—I.4-
+0.2
—O.1
—0.2
—0.:2
—0.2
+0.1
(—0.6)
—0.6
+0.6
+0.1
+0.1
0.0
—0.4
—0.3
Values in parentheses are interpolated from a synoptic chart (polar projection).
Mean
—022)
+0.4
+1.1
+o0.8
+0.6
0.0
—(8),1
—— OL
—0.4
+0.8
+0.8
{0:3
+0.1
—0.2
—0.1
+0.1
—0.3
+0.6
+0.9
+0.6
+0.3
—O.1
—0.1
0.0
not have been greatly impaired, although the quantitative values
would have been different.
The monthly values of pressure for the months when solar activity
was above normal were separated into zones of 10° of latitude,
namely all between 80°N. and 70°N., between 70° N. and 60° Nemec:
Because the stations were not equally distributed, but were mostly
NO. 7 THE ATMOSPHERE AND THE SUN—CLAYTON 9
land stations, a further selection was made by grouping the stations
into areas of 20° of longitude and 10° of latitude and taking means
for each group. Finally, the means for the different groups were
obtained for each 10° of latitude. The average departures of the
TABLE 4——Mecan Departures of Pressure from Normal in Millibars with Low
Solar Activity
Winter Half-Year
180°-120° W. 120°-60° W. 60°-0° W. 0°-60° E. 60°-120° E. 120°-180° E. Mean
80°-70° N.(+0.7) (—o0.5) —3.9 —2.6 (—2.0) (—1.2) (—1.6)
70 —60 +1.2 (0.0) —4.6 —2.3 —2.3 —1.6 —1.6
60 —50 +11 —0.2 —2.8 —1.3 —2.5 +0.4 —0.9
50 —40 +1.3 --Lo.8 —0.6 0.5 —0.4 —Oo.I +0.2
40 —30 +0.3 --0.9 0.7 +1.3 0.0 +0.2 +0.6
30 —20 +0.7 +0.6 -_T.o +0.4 +1.7 +0.4 +08
20 —I0 (+0.5) +1.0 0.7 +0.8 +0.4 +0.7 +0.7
10 -O 0.0 —0,.2 7.3 +0.7 —o.1 +0.6 +0.4
Summer Half-Year
80°-70° N.(--1.5) (-+1.0) +0.1 +1.3 (—0.3) (—1.0) (+0.4)
70 —60 1.0 (+0.6) 40.6 +0.8 —0.6 —1.5 +o.1
60 —50 +0.5 +0.4 +1.1 +o.1 +0.6 —2.4 —o.I
50 —40 +0.4 +0.8 —0.5 —0.7 +0.4 —0.4 0.0
40 —30 +0.4 +o0.8 +0.7 —0.2 —0.2 —0.7 +0.1
30 —20 +0.8 +0.6 —0.2 —0.2 —0.3 —0.7 0.0
20 —10 (+0.7) 0.7 +0.4 +0.1 0.0 +0.2 +0.4
10 -O +0.6 +0.2 +0.3 —0.3 —0.5 +0.3 +o.1
Year
80°-70° N.(+1.1) +0.3 —1.9 —0.6 (—1.1) (—1.1) (—0.53
70 —60 +11 +0.3 —2.0 —o.8 —1.5 —1.6 —0.7
60 —50 +o0.8 -Lo.1 —0.9 —0.7 —1I.0 —I.0 —0.5
50 —40 +0.8 +o.8 —0.6 —0.2 0.0 —0.3 +o.1
40 —30 +0.4 +o.8 +0.7 +0.5 —o.I —0.2 +0.3
30 —20 +0.8 -L0.6 +0.4 +0.1 +0.7 —o.I +0.5
20 -10 +0.6 +0.8 +0.6 -+0.5 +0.2 +0.5 +0.5
10 -0 +0.3 0.0 +0.8 +0.2 —0.3 +0.5 +0.3
Values in parentheses are interpolated from afsynoptic chart (polar projection).
pressure from normal, in millibars, with high solar activity are shown
in table 3, and the average departures from normal with low solar
activity are shown in table 4.
The means in the last columns of these two tables show clearly
that with high solar radiation there is a defect of pressure in the
equatorial belt from the Equator to 30°N. latitude, an excess of pres-
IO SMITHSONIAN MISCELLANEOUS COLLECTIONS voL. 82
sure from 40° to 70°N., and a defect in the vicinity of the pole, while
the opposite signs are found in the same latitudes during low solar
activity.
MEAN MONTHLY DEPARTURES FROM NORMAL PRESSURE WITH HIGH AND
WITH LOW SOLAR RADIATION.
cee Age Re
40
+ +e HIGH SOLAR RADIATION *———-* LOW SOLAR RADIATION
Fic. 5—Mean monthly departures from normal pressure with high and
with low solar radiation.
Figure 5 shows a plot across the pole of the means for the year in
each case. The dotted line connects the values for high solar activity,
and the broken line connects the values for low solar activity. Data
are missing from points north of 80° so that the part of the curve
near the pole is interpolated.
EQUATOR LATITUDE NORTH POLE rea as NORTH es,
10) 10 20 «30 40 50 60 7 80 90° 80 70 20 10
PAE iy
SEA B Ie
CCRRCH RC
PORTE OE ee
CCA oo
De eae ee ye ee, (ee
NORMAL Gee a AT es LATITUDES
MEAN PRESSURE WITH HIGH VALUES OF SOLAR RADIATION
——-—-— MEAN PRESSURE WITH LOW VALUES OF SOLAR RADIATION
Fic. 6.—Mean pressure at different latitudes with different solar conditions.
This diagram brings out clearly the opposite oscillation of the
pressure in latitude with high and with low solar activity.
Figure 6 shows how these departures appear when they are added
to the normal distribution of pressure. In this figure the normal dis-
NOw/, THE ATMOSPHERE AND THE SUN—CLAYTON II
tribution of pressure with latitude is shown by a continuous line.
The dotted line shows the distribution with high solar activity. With
high solar activity the equatorial low pressure belt and the high pres-
sure belts in middle latitudes are both intensified and the polar
anticyclone diminished. This clearly means an intensification of the
Peeent r
$e
Sp eeeig, Meare
Fic. 7.—Differences in pressure with change from low to high solar activity.
Shaded area shows increased pressure, unshaded areas decreased pressure.
(Difference between yearly means in tables 3 and 4.)
normal atmospheric circulation. The decrease in the polar anticy-
clone is attributed to the increased circulation around the pole, the
centrifugal action developed in the circulating winds causing a fall of
pressure in the polar basin. The effect of the earth’s rotation on the
wind increases with latitude, and for this reason the fall of pressure
in the equatorial belt is greater at latitude 20° than at the Equator.
(See fig. 5.) The broken line shows the distribution of pressure with
12 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82
low solar activity. The opposite conditions are here found ; the pres-
sure is higher in the tropics and near the pole, and lower in middle
latitudes than the normal pressure.
Another fact to be noted is that the maximum of pressure between
30° and 40° latitude and the minimum of pressure between 60° and
70° latitude are nearer the pole when solar activity is high than when
solar activity is low. This same condition prevails in both the north-
ern and southern hemispheres.
The changes of pressure due to a change from low to high solar
activity are shown in figure 7, where the changes for each 20° of
longitude and 10° of latitude are plotted on a chart of the northern
hemisphere with a polar projection. This map shows a decreased pres-
sure all around the world in latitudes of 0° to 30° with increased solar
activity. It shows increased pressure between latitudes 40° to 60°
and diminished pressure in the polar basin. But there is evidently
a longitude effect also. The excess of pressure in latitudes 40° to
70° is greatest over the Eurasian continent and least over the Pacific
Ocean.
If the values in tables 3 and 4 are corrected for latitude effect by
subtracting the mean values in the last column of the tables, there
is seen to be a distinct tendency for the pressure in all latitudes to
be low over the Pacific and high over Eurasia, with increased solar
activity. Subtracting the yearly means in table 4 from those in table 3
and correcting for the latitude effect, the data were obtained from
which figure 8 was drawn. The tabulated results are shown in
table 5.
TABLE 5.—Longitude Differences. Differences in Millibars between the Yearly
Means in Tables 3 and 4 Corrected for Latitude
180°-120° W. 120°-60° W. 60°-0° W. 0°-60° E, 60°-120° E. 120°-180° E.
80°-70° N. : dais sitet ee Beat stele
70 —60 —2.7 ee +08 -+-1.0 +1.6 —0.3
60 —50 —1.3 +o.1 +08 +0.2 Lo.1 +0.2
50 —40 —0.2 —0.5 +0.9 +0.4 — (O25 —0.I
40 —30 —O:1 —0.5 0.2 0.0 —-Oel +0.3
30 —20 —o.8 +0.3 —O0.I +0.4 —0.2 10.7
20 —-10 Ge cic +0.1 +0.2 +0.1 0.0 —O.9
10 -0 sien +0.3 +0.3 —O:1 +0.4 —0.5
Figure 8 brings out clearly an excess of pressure over the Eura-
sian continent with increased solar activity, the maximum being in
latitude 50° to 80°N.; while a defect is evident over the Pacific
Ocean and North America, the greatest depression being in high lati-
NO, THE ATMOSPHERE AND THE SUN—CLAYTON 2?
tudes over the North Pacific. This longitude distribution is appar-
ently another effect of centrifugal action developed by increased
atmospheric circulation with increased solar activity. In regions
where the air flows more freely, as over the great expanse oi the
Pacific, the centrifugal force developed tends to lower the pressure,
especially in high latitudes, more over the water surfaces than over
the land areas.
Fic, 8.—Longitude differences between high and low solar activity.
The primary cause of the general atmospheric circulation is be-
lieved to be the contrast in temperature between equator and pole.
This circulation and all its attendant phenomena changes in unison
with changes in the amount of solar radiation received by the earth,
just as the regulator on a steam engine varies with the amount of
heat received by the boiler.
Once in operation there are at least four modifying forces of
importance acting on the general atmospheric circulation:
14 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82
The first of these modifying forces is the earth’s rotation. The
effect of this rotation is to cause a high pressure belt in middle lati-
tudes and a diminished pressure in the polar basin, although it can-
not entirely destroy the central high pressure at the pole due to
increased cold without stopping the circulation. Hence, any increase
in solar radiation should intensify the pressure belt in middle lati-
tudes and lower the pressure in the polar basin, and the reverse with
decreased solar radiation. This is exactly what happens.
A second modifying force is the change in cloudiness caused by
increased or decreased atmospheric circulation. Clouds and water
vapor’ have an important influence on incoming and outgoing radia-
tion, so that the belts of cloudiness near the Equator and near 60°
of latitude have an important influence on the temperature and pres-
sure and thus should aid materially in maintaining the latitude effects
of changes in solar radiation reaching the atmosphere of the earth.
A third modifying force is the movement of ocean water under
the influence of wind. An increase in the general circulation should
cause.an increased flow of ocean waters, with all the modifications in
weather which such an increase implies.
A fourth modifying force is the distribution of land and water.
The influence of all these modifying causes can be seen in the lati-
tude and seasonal effects, with differences in solar activity.
Ill. SEASONAL INFLUENCES
When the influences of solar changes on the pressure are worked
out separately for each month of the year for different places, it is
found that the effect is different at different seasons of the year.
At continental stations in high latitudes, such as Dawson, the pres-
sure increases much more in mid-winter with increased solar radia-
tion than at other seasons, and at mid-summer the effect may even be
the reverse of that in mid-winter. Figure 9 shows the annual period
in the effect of increased solar activity at Dawson. At other stations
such as Stykkisholm in the North Atlantic and Nome in the North
Pacific there is a dominant semi-annual period in the solar influence.
(See fig. 9.) The dotted curves in figure 9 are sine curves derived
from the first and second terms of the harmonic formula in a
* Simpson, G. C., Further studies in terrestrial radiation. Mem. Roy. Meteor.
Soc., Vol. 3, No. 21, 1928. Manson, M., The evolution of climates, Baltimore,
Md., 1922. Angstrém, A. K., On radiation and climate, Geogr. An., Vol. 7, p. 122,
Stockholm, 1925. Brooks, C. E. P., Climate through the ages, p. 138, London,
1926. Abbot, C. G., The radiation of the planet earth to space, Smithsonian Misc.
Coll., Vol. 82, No. 5, 1929.
NO. 7 THE ATMOSPHERE AND THE SUN—CLAYTON 15
12-month period. The 6-month period and the annual period in pres-
sure were computed in this way for stations all over the northern
hemisphere from the data in “ World Weather Records” for the
OCT. NOV. DEC. JAN. FEB. MAR. APR. MAY JUN. JUL. AUG. SER OCT.
is 9 es ee
le Ae DAWSON eat
64°N., 139°W.
Le A nee
HAH SSR
i (eit cai
ee
65°N., ee W.
NOME
64°N., 165°w.
Fic. 9.—Departure from normal pressure by months with high solar
activity.
months when solar activity was high and for the months when solar
activity was low as given in table 2. The results for the 6-month
period when solar activity was high at the epochs April and October
are shown in figure 10 plotted on a map of the northern hemisphere.
16 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82
It is seen from this map that the latitude effect as pictured in figure 7
is increased twice a year when the sun crosses the Equator in March
and October. At that time the effect of high solar activity on the
pressure is accentuated. The decreased pressure at the Equator, the
increased pressure in middle latitudes and the decreased pressure at
the poles are greater than at other times of the year.
Fic. 10.—Excess or defect of pressure at the Equinoxes (March and
September) with increased solar activity.
On the other hand, when the sun is at the solstices in June and
December the latitude differences are diminished and effects due to
contrasts between land and water are accentuated. The greatest
increase of pressure with increased solar activity is over the con-
tinents in winter and over the oceans in summer. This is an annual
change in contrast to the semi-annual period in latitude effects. The
annual effect is shown in figure IT.
NO. 7 THE ATMOSPHERE AND THE SUN—CLAYTON 17.
This chart is derived from the annual period in pressure as com-
puted from the data by harmonic analysis. The areas outlined on
the chart show where the maximum increase of pressure occurs
at different seasons when solar activity is greater than normal. In
mid-winter the excess of pressure is greatest over the continents
in high latitudes. There is a defect in the same regions in summer.
\
AO
‘ o>
ISNy
TS TIS
2
As p7 x7
LAY
192
Bees wee \y
== AUTUMN 7
es
Fic. 11.—Regions in which highest pressure occurs at different seasons
with increased solar activity. Annual period.
In spring the greatest excess occurs over the North Atlantic and
North Pacific, and there is a defect in autumn. In autumn there is
an excess in middle latitudes and a defect in spring.
The results both for the semi-annual period and for the annual
period were checked by an analysis of the data during periods of
low solar radiation which give in general the opposite effect.
The shifting in position of maximum effect on the atmosphere in
the annual period is clearly related to surface conditions and may be
18 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82
explained by changes in the balance between incoming and outgoing
radiation. In summer the land masses in high latitudes absorb solar
heat and this absorption increases with increased solar radiation.
There is also an increase of cloudiness at that time which should play
an important role in determining the effect of increased solar radia-
tion on the atmosphere. In autumn an increased atmospheric cir-
culation causes an excess of warm water and of cloudiness in the
North Atlantic and North Pacific with an accompanying diminution of
pressure. The same increase in atmospheric circulation determines an
increased flow of cold water along the north coast of Africa and of
Western Mexico and thus determines the opposite annual period in
these regions to that in the northern part of the same oceans.
The seasonal shifting in the centers of maximum solar action in
the atmosphere are thus plausibly related to changing physical con-
ditions in the atmosphere and in the surface conditions of the earth.
IV. ATMOSPHERIC WAVES
When atmospheric changes, whether of pressure, temperature, or
wind movement are analyzed into oscillations of different lengths
they are usually found not to be stationary but to progress from
point to point. The short oscillations move fastest and the longer
oscillations progress more and more slowly with increasing length.
They thus have some analogy to ocean waves and are frequently
called waves.
Meteorological data may be analyzed into longer and shorter oscil-
lations by means of smoothing, by means of using changes of suc-
cessively greater length, by means of sine curves derived from indi-
vidual periods, or by the process of averaging successive periods,
using trial periods of different length. These processes are described
and illustrations given in ‘ World Weather.” *
The method adopted for the present research was to select from
plotted curves the cases where an oscillation of some particular
length was unusually strong and then to get the average of several
successive oscillations, so as to eliminate oscillations of longer period.
This process was repeated successively for each particular oscillation
selected, dropping one and adding another later in time. An example
of the method is shown in table 6 for St. Paul, Minnesota. The data
were obtained from the Washington 8 a. m. weather map.
The consecutive means of four successive periods, obtained as
shown in table 6 for the months of November and December, 1927,
are plotted in figure 12 for a series of stations running from Nome,
‘Clayton, H. H., World Weather, p. 114. New York, Macmillan & Co., 1923.
NO. 7 THE ATMOSPHERE AND THE SUN—CLAYTON Ig
Tasie 6.—Means of 4 Periods of 7 Days Each, St. Paul, Minnesota
Consecutive means of 4 periods,
Observed pressure, 29.00 + inches 29.00 + inches
Day I 2 3 4 S 6 7 1 2 3 4 5 6 7
boy, 4 601.02 1.32 1-24 1.16" 1.26 86
Te RGOt LAS leo D. Tdi 02" 5.3828. 188) 1.12) 0.08. 68) .86* 1.29: ~ 1.13
Ths 2S - 2O4, cSAhC.04.. 1.26.-1.02. 1.06; 1:24 1.57, .87 281" 1.18 3.22
eee Cee M70. 11S! 370) Ag" 21.26 (1.36) 508 “1.20 2.15) .79°..70* 1.12 1.04
Bee. 2) 1.40 -1.45 1.30 GS8* 06 82 1.20) 102 1.10. %1.22 .94 .8o* 1.13 1.14
Oniesteles Ifo) 1040 <7O" Ris 56 L1G 1.26 1.260.10 105 | 03%: 07
16 .46* .88 1.20 1.46 1.48 1.32 1.40 etc.
oe Td 1.42 11.38. P32" 1.08. <42*° "68
* Minimum.
NOV.10,1927 15
od TTT Te BSA TTT TTT
nara Nel OF IS VIN
a PEEPS SSCA
NUNIT Altea eT)
yn Nt LRN j de JAS
sot “a eoovalie etic HALAL Snn\\G7 an8
ole PERCE NG eA aie JEN
aii UAUISUPNITT irl
Te Ariba hub | NL
sof PAE PERM LUCCA
oakode ii TTT
nnd cena ch BEEBE EEE
Srna tit
30. a HEN SHH
all NCEP
TTC EET can
soit p= =Sannnnne Ee ae sear
: ‘iin
aed ea ala
Fic. 12.—7-day pressure wave.
20 SMITHSONIAN MISCELLANEOUS COLLECTIONS voL. 82
Alaska, southeastward to Key West, Florida, and to Colon, Panama.
It is evident from the plot that the maxima and minima occur later
at southern stations, so that at Williston, North Dakota (not shown
in fig. 12), the oscillations are opposite in phase to those at Nome ;
TAA TTT
BECCA NG is APA ND
LY IY AR
LAT
Aap | ow | | IM
ASP
aeti
ii
AAT Sell
hed || Sle A pe
I~ MY
SN a i N
PERE CARY TA a7 NT
Fic. 13.—14-day pressure wave.
but further southward at Key West they are in the same phase as
at Nome, although much diminished in intensity.
Figure 13 shows an oscillation of 13.6 days averaged in overlap-
ping two-period intervals. The continuous lines were plotted from
NO. 7 THE ATMOSPHERE AND THE SUN—CLAYTON 21
the averages ; sine curves computed from the data by harmonic analy-
sis are shown by dotted lines. Here, again, it is found that the
maxima and minima of the oscillations occur later at the more south-
ern stations and the phase is inverted at St. Paul, showing that the
progressive movement is only about one half as rapid as the 7-day
period. In other words the ratio, rate of progress divided by length
of period, is the same for both periods and apparently for all periods,
as will be shown later.
That atmospheric pressure and temperature may be analysed into
waves or oscillations which move at different speeds inversely pro-
portional to their wave length was advanced by me in the monthly
Weather Review, April, 1907, and has been confirmed by a num-
ber of research workers, Defant, Vercelli, Danilow,’ Clough,’ Weick-
mann, and others. These waves do not always move from the same
direction, as Danilow and Weickmann have pointed out; but the
dominant direction of motion is from northwest to southeast in the
northern hemisphere and from southwest to northeast in the south-
ern hemisphere.”
The rate of progress for all classes of moving atmospheric waves
appears to follow a very simple law. This may be illustrated by the
progress of the 7-day wave. Using the data from about 16 sta-
tions, the progress of the wave from Alaska is illustrated in figure 14
by a series of heavy lines giving the wave front on successive days
as it passed across the North American Continent. Small circles show
the positions of the stations used. It is seen that the wave moved
from about 180° W. longitude at a rate which would carry it half
around the world in one period of oscillation, namely in seven days,
and hence entirely around in two periods. At the same time the
wave front advanced from the Arctic Circle near Nome to the Tropic
of Cancer near Key West also in a period of seven days or at a rate
which would carry it, from pole to Equator in the time of two periods
of oscillation.
If, however, the rate of progress is taken not along the wave
front but along a meridian—in this case the goth meridian west is a
good example—the rate of progress southward from the Arctic
Circle to the Tropic of Cancer takes place in 34 days, or at a rate
‘Wetterwellen, Podoleschen Abtheilung des Ukrainischen Meteorologiches
Dientes, 1926.
* Monthly Weather Review, Vol. 52, No. 0, p. 436, Sept. 1924.
*Weickmann, L., Das Wellenprobiem der Atmosphare. Meteor. Zeitschr.,
2AT. 1027.
* Clayton, H. H., World Weather, p. 111. New York, Macmillan & Co., 1923.
22 SMITHSONIAN MISCELLANEOUS COLLECTIONS voL. 82
which would carry it from pole to Equator in one period of oscilla-
tion. This is evidently a law which applies to wavelike changes of
all lengths.
_ WAVE FRONT SHOWING SPEED OF
Sm MOVEMENT IN A 7-DAY WAVE
Jays.
\ eo Tye
Nes es,
en >
‘
Date.
Explanation _—
PO ON OF STATION
HOWN BY SMALL CIRC
Fic. 14.—Wave front showing speed of movement in a 7-day wave.
In Dr. Weickmann’s? able analysis of the 24-day wave of pres-
sure of the winter of 1923-24, it is shown that the wave originated
1 Petermanns Mitteilungen, Erganzungsheft No. 191, 1927.
NO. 7 THE ATMOSPHERE AND THE SUN—CLAYTON 23
in the polar basin and spread southward toward the Equator. Fig-
ure I5 is derived from a plot made by Dr. Weickmann. The plot is
made to show the wave at successive dates along the meridian of
45° E. longitude. The dotted curve No. I in figure 15 shows that on
December 10 there was a minimum of pressure in the arctic basin
north of Spitzbergen and a high pressure over Central Asia about
60° N. Six days later, on December 16, as shown by the broken
curve No. 2, the low pressure was about 70° N. and a high pres-
sure about 45° N. Twelve days later on December 22, as shown
by the continuous curve No. 3, the period was in opposite phase and
are DEC. WO) ===" DEC. 16 ——--DEC Pe, 1925.
Fic. 15.—Pressure departures in 24-day period (data derived from diagram
by Weickmann).
the low pressure is found at 60° N. with a high pressure south
of 30° latitude and also in the polar basin. Eighteen days later, on
December 28, as shown by the dotted curve, No. 4, the low pres-
sure is at 45° and a high pressure is advancing southward.
The plot brings out clearly the decrease in amplitude of the oscil-
lations with decreasing latitude. Owing to the decrease of ampli-
tude with latitude the velocity of progress of the wave is best
obtained from the points where the curve crosses the zero line.
The first zero point is at 72° latitude and the second about 30°
latitude. This is the distance traversed by the wave in 12 days, a
rate which would carry it from pole to Equator in about one period
of 24 days.
In Mr. Clough’s* study of a period of about 24 years in pres-
sure he says: ‘‘ The epochs of the short period for St. Paul, St. Louis,
*Monthly Weather Review, Vol. 52, No. 9, p. 436, Sept., 1924.
24 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82
Memphis, Vicksburg and New Orleans have been derived and it is
found that there is an average lag of 0.19 year from St. Paul to
St. Louis and a lag of 0.37 year between St. Paul and New Orleans.”
The distance from St. Paul to New Orleans is 15° of latitude and
0.37 year is about one-sixth of the period, so that the rate of prog-
fue
SCHEIN ma/auiSi
Hi BR Ss)
UR canon
Bee Pane NZ NAL
ae Bs as ===
an
aa aN NB
fas)
AN a ‘BY4NOe
ey _ a eeat ame VT vee
| man é| al |
a oA NS a
oa
mun
Fic. 16.—Pressure in 3.77-year period.
ress here indicated would carry the wave from pole to Equator in
one period.
In figure 16 is found a period in which the unit of time is years
instead of days. The period of oscillation in pressure is about four
years. It was taken to be 3.75 years, or one-third of a sun-spot
period of 11.3 years, and averages were made for each three suc-
cessive oscillations of 3.75 years. The continuous curves show the
Noe 7 THE ATMOSPHERE AND THE SUN—CLAYTON 25
averages. The letters a, b, c, etc., show successive maxima. The data
were derived from “ World Weather Records” and cover the con-
tinent of Asia where the data are more complete for different lati-
tudes than in North America.
t is seen from the plot that the maxima and minima of the period
occur first in high latitudes and successively later at stations nearer
the Equator, at least down to about 30° latitude, taking about three
years to move from Obdorsk, 66° N., 66° E., to Ley, 34° N., 77° E.
In the equatorial belt between 20° N. and 20° S. the maxima and
minima occur simultaneously at all stations as shown by the results for
Madras and Batavia. However, from figure 16 it is seen that the
pressures at Alma Ata, 43° N., and at Batavia, near the Equator, are
opposite in phase, which is further evidence that this wave traversed
go° of latitude in one period of about 3.75 years.
A recent study of 2- and 33-year waves in temperature by Ernest
Rietschel * shows a rather complex movement indicating a combina-
tion of standing and moving waves.
That the law of wave progress quoted above holds true in the
Southern Hemisphere as well as in the northern is shown by the
rate of progress of a temperature wave of about 18 days shown
plotted on page 223 of ““ World Weather.” “ This wave progressed
from Santa Cruz, 50° S., to Cuyaba, 16° S., in seven days, a rate
which would carry it from pole to Equator along a meridian in one
period of 18 days.
The rate of progress of a 7.5-year wave is indicated in figure 22
where the maxima and minima of the waves occur successively later
at Stykkisholm, Rome, and Calcutta, the minima and maxima at
Calcutta being about 7 years later than at Stykkisholm.
These facts render it evident that the rate of latitude displace-
ment is a general law for periodic oscillations of all lengths. This
law may be stated as follows:
Law of latitude displacement of periodic waves.—Periodic oscil-
lations in atmospheric conditions progress in latitude from point to
point along a meridian at a rate that would carry the wave from
pole to Equator in one period, whatever the period of oscillation.
It is probable that the law of displacement in longitude is equally
simple. Figure 14 shows that the 7-day wave progressed in longi-
tude about 180°, or half around the world, in seven days.
*Die 3-34 jahrige und die 2 jahrige Temperaturschwankung, von Ernst
Rietschel. Geographical Institute of the University of Leipzig, Vol. IV, No. 1,
1920.
VoL. 82
EOUS COLLECTIONS
SMITHSONIAN MISCELLAN
2 a
4
Hi
QO
et
eee
:
hi
NOS 7 THE ATMOSPHERE AND THE SUN—CLAYTON 27
A proportional rate of progress appears to occur in the periodic
wave of about 7.5 years. Figure 17 shows the centers of oscillation in
a 7.5-year wave on a world map. This map is derived from har-
monic values computed from groups of three periods between 1883
and 1913 at 117 stations scattered over the world. It shows the
centers of oscillations at the epochs, 1885, 1893, 1900, etc. Con-
tinuous lines show equal values above normal and broken lines show
equal values below normal. It is not possible with available data
to follow the progressive movement of all the centers, but the center
over Greenland shows a distinct progress from west to east. This
progress will be evident from figure 18 which shows the centers of
oscillation in the area between 50° W. and 120° E. north of the Equa-
tor when the epochs are taken successively two years later. The
results in figure 18 are derived from the data of 48 stations taken
from “ World Weather Records.”
In 1885 there was a marked excess of pressure over Greenland
(see fig. 17) ; in 1887 this center of excess pressure is displaced to
Norway; in 1889 this center is over the northern part of central
Siberia; two years later, in 1891, it is over the northern part of
western Siberia. The progress of the centers is shown by small cir-
cles in the upper chart of figure 18. The circles show that the center
was displaced eastward about 180° in a period of 7.5 years or at a
rate which would carry it around the world in two oscillations of
this period.
In his study of the 23-year period Mr. Clough’ found that the
epochs at Portland, Oregon, preceded those at Toronto by about
0.75 year. The difference in longitude is 43°. At that rate the epoch
would move about 150° of longitude in one period, or approximately
around the world in two periods.
The charts given by Dr. Weickmann in his study of the 24-day
period referred to previously do not show the drift in longitude so
clearly as the drift in latitude. However, in his charts there are
found centers of maximum departure which show a drift in longi-
tude. A center in the Aleutian Islands on December 10, 1923, moved
eastward across Canada to Labrador in 11 days, which is at the rate
of about one period for 180° of longitude; but a center near Green-
land moved eastward to northern Siberia and then retreated.
The longitude drift of the waves is, hence, not so clearly defined
as the latitude drift ; but there is undoubtedly a trend which may be
stated as follows:
*Monthly Weather Review, Vol. 52, No. 1, p. 30, Jan., 1924.
SMITHSONIAN MISCELLANEOUS COLLECTIONS VoL. 82
oo t/_F TERA 2G a af bed
APE ea
Naa
Ce ai i
INO e7 THE ATMOSPHERE AND THE SUN—CLAYTON 29
Law of longitude displacement of periodic waves.—Periodic waves
tend to drift eastward at a rate of 180° of longitude in one period,
whatever the length of the period. The centers of greatest departure
are found in high latitudes, 60° to 80° from the Equator.
There are several factors which make this drift toward the east
difficult to follow. First there are the factors depending on solar
changes described in the latitude effect and which are nearly instan-
taneous with solar changes. There are also seasonal factors and
probably others which influence the results.
Examining the successive charts in figure 18 it is found that the
magnitude of the departures in the 7.5-year period decreased rap-
idly as the central areas passed into Siberia and increased again
over Kamchatka. This enhanced intensity in the departures coincided
with a maximum of solar activity as will be seen later.
Another disturbing factor is the formation of centers of distur-
bance moving at right angles to the normal waves. When waves of
high pressure and low temperature are advancing from the north-
west, low pressure areas form in front of them and advance from
southwest to northeast. These disturbances advancing toward the
northeast are particularly frequent over the warm ocean waters to
the east of Asia and of North America. These cross currents greatly
complicate the normal movement of atmospheric waves and make
analysis of the data difficult.
V. RELATION OF THE WEATHER WAVES TO SOLAR CHANGES
If the values of solar radiation observed by the Smithsonian
Astrophysical Observatory simultaneously with the pressure waves
are treated in the manner just described they show in each case
wavelike changes of the same length as the pressure waves.
Figure 19 shows the successive means of four periods of seven
days in solar radiation during November and December, 1927, com-
pared with the atmospheric pressure observed at the same time at
Eagle, Alaska, and treated in the same manner as in table 6. The
dotted curves in each case show the harmonic values of the 7-day
wave computed from the data. Compare this diagram with the plots
in figure 12.
Figure 20 shows the means of successive values of a period of 13.6
days in solar radiation and in pressure derived from the means of
two periods. This diagram may be compared with the plots in fig-
ure 13. The dotted curves in figure 20 show harmonic curves com-
puted from the data.
30 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82
NOV. 5, 1927
AIS
Fic. 19.—7-day period in solar radiation and pressure.
MAR. 21, 1927 APR.10 MAY 10
ne i i re + 1,2
FA Sea
Ce ae
SSURE
ee Ne =
Rik, tN Es Nags
Fic. 20.—13.6-day period in solar radiation and pressure.
EAGLE , 65 IN., 141 Ww.
NO. 7 THE ATMOSPHERE AND THE SUN—CLAYTON 31
Figure 21 shows the observed values of solar radiation during
December, 1923, and January and February, 1924. These values are
compared with the observed values of pressure at Spitzbergen and
at Hamburg. A 24-day period of oscillation is evident in each case
and this oscillation is shown by the dotted curves computed from
the data in each case by harmonic analysis. Pressure data from all
DECEMBER 1923 JANUARY ss FEBRUARY
i 2! 3) 10 9
SO|LAR RADIAT
CRT he then
Stee ay
ee be
ASSURE IN SPITSBERGE
Fic. 21.—24-day period in solar radiation and pressure.
over the northern hemisphere were treated in this way for a period
of 24 days by Dr. Weickmann and showed a systematic wave
movement from the polar basin southward.
For the study of long periods, no values of solar radiation are avail-
able; but the 7.5-year period shows a distinct relation to sun-spot
changes. Figure 22 shows a plot of consecutive means of three
periods of 7.5 years. This period is one-third of Hale’s sun-spot
period of 22.5 years, and the mean of the three periods eliminates
the I1.3-year sun-spot period which is one-half of Hale's period.
32 SMITHSONIAN MISCELLANEOUS COLLECTIONS vot. 82
Pressure curves are plotted for five widely separated stations. These
plots show distinctly an oscillation in the atmosphere of the length of
7.5 years and a progress southward from high latitudes.
1870 1880
ACA ted
PREISSURE
STYKKISIHOLM , 65°'N , 23 W.
6 Gs aw a ag
Fie ALA e ALE am Ve
i ek SY anal ees cea ~—V|¥—“¥- nee
7. ae
is aeby ee”
ene ON ae eye
ee
ge
TES eal
LAY
Fic. 22.—7.54-year period in sun spots and pressure means of 3 periods.
VI. SOLAR CYCLES AND WEATHER CYCEES
From the preceding investigation it is evident that atmospheric
and solar conditions show wavelike changes of a periodic nature,
The question has long been a challenge to investigators, as to whether
there are fixed and regular cycles in weather and in solar changes.
If such regular cycles could be found, it would greatly assist in
unraveling the complexities of the weather and in forecasting future
occurrences. There is a dominating period of about II years in sun-
spot numbers, and many efforts have been made to find this same
NO. 7 THE ATMOSPHERE AND THE SUN—CLAYTON 33
dominating period in weather changes. Such a relation has not been
found and the reason appears to be that weather changes follow
changes in solar radiation more closely than they do sun-spot num-
bers, and solar radiation is more variable and shows a more complex
periodicity than do sun spots.
When the 11-year period 1917 to 1928 is analysed harmonically
for sun spots and solar radiation, the results in table 7 are obtained.
TaB_eE 7.—Harmonic Terms for 11%-Year Period in Sun Spots and Solar
Radiation
Sun-spot numbers Solar radiation
or A 2S
Amplitude Amplitude
Epoch 1917.5 in numbers Epoch 1917.5 in calories
Ax = 104° Gi = 35.3 AG == 640 a1 = .009
Ne —— oa a—70 As = 238° 2 = .004
As = 305° az = 10.6 Az = 50° az = .008
Ne 333° a: = 6.0 AG 339° ds = .005
These results show that in a general way the oscillation in the num-
ber of sun spots and in the intensity of solar radiation are in the
same phase—that is, when one increases the other increases ; but the
amplitudes of the changes are very different. The amplitude of the
primary oscillation, a, in the sun spots (the 114-year period) is
decidedly predominant while in the solar radiations the amplitudes
of the harmonics of 4, 4, and 4 of 11.3 years, ds, a3, and a, are almost
as large as the primary a,. The pressure data for tropical stations for
the 11 years 1917 to 1928 are not available at present, so that a com-
putation of pressure changes was made by going back two periods of
_I14 years to January, 1890, and computing the harmonic terms from
the mean pressure of nine equatorial stations extending from Quix-
eramobim in Brazil eastward across Africa and the Indian Ocean to
Malden Island in the Pacific. The data covered two 11-year periods,
1890-1913, and the epochs were taken at 1895.0= 1917.5.
Taste 8.—Harmonic Terms for 111%4-Year Period in Pressure, 1890-1913
Mean Pressure of 9 Equatorial Stations
Epoch 1895.0 = 1917.5
Agi 8250 a1 = 0.36 mb.
1 — 29° dz = 0.32 mb.
As = 265° ds = 0.25 mb.
AT — 50" a4 = 0.35 mb.
This comparison indicates that in the 114-year period in pres-
sure in the Tropics, the phase is in general terms opposite to that
of sun spots and solar radiation, and hence when these increase the
34 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82
pressure decreases. This fact is also made very apparent by com-
paring the individual periods in sun spots with pressure from 1870
to 1920. It is also evident that the amplitude a, of the 11-year period
is not dominant as in the sun-spot period ; but as in the case of solar
radiation the subharmonic terms a2, @3, and a4, are almost as large as
the primary ay.
In order to compare the harmonic terms of the 114-year period in
pressure in equatorial regions with those in other latitudes, the mean
pressure was obtained for each 10° of latitude in the northern hemis-
phere for each year from 1890 to 1913. A period of 23 years was
taken because from Hale’s observations of magnetism in sun spots
the complete period of the sun spots is about 22.6, so that 11.3
years becomes the second harmonic of this period. From the data
thus obtained harmonic terms were computed for each zone of lati-
tude and are given in table 9. The phases of the periods varied for
TABLE 9.—Amiplitudes of the Harmonics of a 22.6-Year Period in Pressure
a2 as a4 a6 ag 24 a4s a7z2
Zones of No. of 11.3 7.54 5.65 3 e7e7, 2.83 11.3 AG 3.8
latitude sta. r yr. yr. yr. yr mo. mo. mo
airs < ; 4
70°-80° N. 2 0.60mb. 0.65 mb. 0.94mb. 0.92mb. 1.12mb. 2.40mb. 2.50mb. 3.75 mb.
60°-70° 14 0.59 0.61 0.77 0.88 0.86 2.09 2.78 ALB
Orso Api ONS 0.38 0.46 0.61 0.76 1.32 1.60 1.28
40°-50° 25 0.32 0.42 0.43 0.45 0.51 Te22) 1.10 1.23
30°-40° 30 0.24 0.33 0.40 0.31 0.31 0.67 1.02 0.88
20°—30° 13) 10:30 0.21 0.29 0.24 0.23 0.62 0.63 0.53
10°—20° 15 0.42 0.25 0.35 0.21 0.33 0.42 0.45 0.40
0°—I0° 6 0.36 0.27 0.32 0.25 0.35 0.39 0.25 0.38
Nore.—In computing the harmonics in Table 9 the means of three or of four periods
were used in each case except the case of a2 where two periods were used. The observed
values from which a2 were computed covered the entire interval of 22.6 years, while the
values from which az. were computed covered only one twenty-fourth of this interval.
each latitude as it was evident they must do from the preceding inves-
tigation of wave movement. The striking facts brought out are:
(1) The amplitudes of the periods increase greatly in high latitudes
where they are much greater than in low latitudes and, (2) the
amplitudes of the smaller subharmonics in high latitudes are much
greater than that of the period of 11.3 years.
This last finding is of the utmost importance to meteorology,
because it shows that the shorter periods are of much more impor-
tance in the meteorology of high latitudes than the longer periods of
II years or more. These meteorological and solar periods are all
believed to be harmonics of longer solar periods.
Clough found solar periods of 300, 11.3, 7, and 2.5 years, and an
analysis of the sun-spot data by Schuster disclosed a number of other
NO: 7 THE ATMOSPHERE AND THE SUN—CLAYTON 35
periods besides the 11-year period. Turner found evidences of a
period of 260-280 years from a study of tree rings, Nile floods, Chi-
nese earthquakes, and sun spots. (Mon. Not. Roy. Astron. Soc., 1919
and 1920.) According to a recent analysis of the Wolfer sun-spot
data made by Dinsmore Alter, published in the Monthly Weather
Review of October, 1928, there are solar periods of more than 200
years in length, and the 11-year sun-spot period is a subharmonic of
much longer periods. This view agrees with that put forward by
Ellsworth Huntington and S. S. Visher in “ Climatic Changes,”
1922, p. 45. My own investigations are in accord with this view, ex-
cept that recently the longer periods seems somewhat greater than that
given by Alter.
Beginning with a period of 90 years, instead of 84 as given by
Alter, I find periods of approximately the following length: Length
of solar periods in years: 90, 56, 45, 35, 30, 28, 22.5, 18, 15, 12.9,
114, 10, 9, 8.2, 74, etc. All of these shorter periods are subharmonics
of 90 years, except 56, 35, and 28, which are harmonics of a longer
period.
They agree very well with meteorological cycles found by Prof.
A. E. Douglass* from rings indicating the annual growth of trees in
the southwestern part of the United States where rainfall is the most
essential factor in growth. The periods found by Professor Douglass
ame+.35, 31, 25, 22.5-24.0, 20.5, 17.2, 14.2, 11.2-11:7, 10.2, 8.6, 7.6, 6.8
years.
A study of periodicities in the Nile floods by C. E. P. Brooks
leads him to pick out the following periods in years: 76.8, 64.6-67.4,
Paes... 33-40, 24.42, 21-81-2243, 18.32, 16.68, 14.87, 12.50, 10.86-
11.36, 8.33, 7.33, 6.83, 5.52, 3.66, 2.86. It is pointed out that 11 out
of 16 of these periods are multiples or submultiples of a period of
22.12 years. This period is somewhat shorter than Hale’s period of
22.6 years; but the difference may be due to the fact that the period
actually was shorter during the intervals covered by Brook’s data
which go back to the year 641. His data indicate a systematic varia-
tion in the phase of this period, so that at the end of about 200
years the phase is inverted as regards epochs 200 years earlier.
The researches of D. Brunt” also indicate that there are a great
many meteorological cycles, or else there are none. His periods in
years derived from the Greenwich temperatures are: 23, 17.5, 15, 8.17,
2
* Climatic cycles and tree growth, Vol. 2, p. 123. Carnegie Inst. of Washington,
1928.
*Mem. Roy. Meteorol. Soc., Vol. II, No. 12, 1928.
* Quart. Journ. Roy. Meteorol. Soc., Vol. 53, No. 221, Jan., 1927.
36 SMITHSONIAN MISCELLANEOUS COLLECTIONS VoL. 82
7.34; and in months, 64, 60, 42, 37, 26, 25, 21%, 19.3-19.5, 14:5-
14.7, 13, 124. The researches of Dinsmore Alter* published in the
Monthly Weather Review also bear testimony to the multiplicity of
meteorological cycles.
My own researches have dealt largely with shorter periods of days
and months rather than years, principally because there was a much
larger mass of data available for discussion. In my earlier studies
of pressure and temperature data in the United States.” I found the
following periods in days: 3, 3.6, 4.6, 5.45, 6.14, 7.24, 9.1, 11, 18, 22,
29, 44, 58, etc. My recent studies indicate that there are many more
cycles and that all are probably harmonics of the sun-spot cycle.
A. Defant* in a world-wide study in 1912 found the following
periods in days: 4.4, 7.9-8.7, 12.0-13.0, 16.8, 24.5, 31.2-31.5. Are-
towski, Turner, Simpson, Wallén, Myrback, Wasserfall, Schosta-
kowitsch, and Kidson have all found short meteorological cycles of
various lengths Even the short period cycles of a few days are
probably submultiples of much longer solar cycles, the most promi-
nent of which is the 11-year sun-spot cycle, or its double value, the
22.5-year cycle.
In most cycles the subharmonics of small length are not important,
but it has been shown in table g that in high latitudes the subhar-
monics of the I1-year period in meteorological cycles are of greater
amplitude than the primary period of 11 years and that the ampli-
tude increases with decreasing length of the harmonic. The sequence
has not been followed through for the entire Northern Hemisphere
beyond the period of about four months, but the amplitudes of
meteorological cycles at stations in the northern United States and
Canada apparently increase down to a length of about three days.
These shorter periods determine the origin and movement of the
ordinary cyclones and anticyclones seen on the weather map.
Most investigators of meteorological cycles assume at the begin-
ning of their work that any cycle which may exist is constant in
amplitude and phase and may by repetition be separated from other
changes by which it is masked. This belief is the basic assumption
underlying the analysis by the Fourier series or the Schuster peri-
odogram. Prolonged investigation usually convinces the research
worker that this assumption cannot be maintained. I early became
*Monthly Weather Review, Vol. 54, p. 44, and Vol. 55, pp. 60 and 263.
* Amer. Meteorol. Journ., Feb., 1895, p. 3760; also Amer. Journ. Sci., March,
1894.
* Sitzungberichte d. Wiener Akad., Bd. 121, Heft 3.
NO. 7 THE ATMOSPHERE AND THE SUN—CLAYTON 37
convinced that meteorological cycles change both in amplitude and
phase. (Science, 1898, p. 243.)
Figure 23 shows an analysis of the Wolfer sun-spot numbers
between 1890 and 1913 into a period of 22.6 years and its harmonics.
It is seen that the chief period is one of 11.3 years, but some of the
other periods show a fairly large amplitude of oscillation.
1890 1895 {900 1905 1910
PPE
Ca LUCE LCS a euaee
fo
_ wR ARR e eee
EEE EE Pee EE EEE EE
Fic. 23——Harmonic analysis of 22.6-year sun-spot period, 1890-1913.
The meteorological data at more than a hundred stations in various
parts of the world were analyzed in the same manner. Figures
24, 25, 26, and 27 show lines of equal departure of pressure for the
various periods at the time of maxima of the solar periods of the
same length. A chart showing the departures at the time of the
solar maxima of the 7.5 year period is given in figure 17.
38 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82
Certain common features stand out clearly in all these charts. )
First, in the equatorial belt, except possibly over parts of the Pacific
Ocean, the pressure is lower than normal at the time of maximum
A CES
ZZ. Bae aot eS ASN
es TN BROS
bat S55 EERE
je | EES VAN
tat tS (gd ON
Sy -SUGtenc® ee ele
oS SK renee : Ee. QT
“a Z
Fic. 24.—11.3-year period i in pressure = 4 of 22.6 years. Departures at time
of maximum of solar period of same length.
solar activity in each period. Second, in middle latitudes of the
Southern Hemisphere there is a tendency to a belt of pressure above
normal which cannot be well outlined on account of insufficient
raat
Le See hes <<
KET
= —; Sigs wate ve, s—\ i A
Bie es
fone fT
era K {
Fic. 25.—5.65-period in pressure = } of 22.6 years. Departures at time
of maximum of solar period of same length.
observations. Third, in the Northern Hemisphere in high latitudes
there is a tendency for the departures to form centers of positive and
negative departures, usually two centers of positive departure, and
NO: 7 THE ATMOSPHERE AND THE SUN—CLAYTON 39
two centers of negative departure. Fourth, these centers are not in
the same geographical position for the different periods and do not
remain fixed for successive epochs of the same period. The reasons
HEE
em IG
KGS
OT LISA TKN TIE WN at Sek
f PMT tit] eS
sanebenemistea Tels
A eae
f enh an ~
Me Nae)
ok,
Fic. 26.—3.77-year period in pressure = } of 22.6 years. Departures at time
of maxima of solar period of same length.
for these shifting centers are not clear. They are associated with
changes in the phase and amplitude of the cycles.
Changes in amplitude are both apparent and real. Apparent
changes occur where two periods of nearly the same length first
a Ney SA BPs a TS
ey
Xe HIS LSLLLEE :
SWAY zz
ann
Fic. 27.—2.82-year period in pressure = § of 22.6 years. Departures at time
of maxima of solar period of same length.
strengthen each other when they are in the same phase and then
weaken each other when they are opposed in phase. This change will
be familiar to most readers from diagrams to illustrate beats in sound
40 SMITHSONIAN MISCELLANEOUS COLLECTIONS VoL. 82
waves. The beats are even more complicated when there are three or
more periods of nearly the same length. In such a case there may be
an apparent change of phase in one of the periods.
Real changes in amplitude are brought about by the influence of
longer periods on shorter periods. An example of this is the influ-
ence of the annual period on shorter weather cycles. All weather
changes are most intense in winter, because then the contrasts in
temperature between Equator and pole, between ocean and continent,
and between adjacent bodies of land and water are at a maximum
intensity and the general atmospheric circulation is increased.
Also all periodic changes in the atmosphere are more intense when
solar activity increases. The reason for this increased intensity will
be clear, first from the fact shown in the early part of this paper
that increased contrasts of temperature and pressure in the atmos-
phere result from increased solar activity, and second from the fact
that the amplitude of the solar cycles increases with increased solar
activity.
An example of the increased amplitude of solar periods with
increased solar activity is shown in figure 22 where the amplitudes of
the 7.5-year sun-spot period is distinctly greater during the inter-
val 1865 to 1875, when the general level of solar activity was higher,
than during the interval 1885 to 1895, when it was lower. The
increase of amplitude during the first of these intervals and decrease
during the second was also evident in the sun-spot cycle and in its
harmonics of 5.65, 3.75, 2.82 years, etc.
An example of increased amplitude of meteorological cycles with
increased solar activity is shown in figure 28 where a period of 73
months in pressure at Chicago shows a marked increase in ampli-
tude at the time of maximum of sun spots in 1917 and a diminished
amplitude during the intervals of minima of sun spots in 1913 and
1923-1924. The data for this curve are the means of 10 overlapping
periods of 74 months obtained in the manner indicated in table 6.
The dotted curves are sine values computed for each individual
period.
That meteorological cycles change in phase as well as in intensity
is also evident. These changes of phase appear to arise from several
different causes. First, the solar periods themselves change phase. In
most cases this change occurs suddenly and appears to be about 180°
—_—
AI
SUN—CLAYTON
AND THE
THE ATMOSPHERE
NO.
“(tunuxeu jods-uns 1vou apnyzydwe jo asearoul sutmoys) OSeoryD Ul aanjzetoduioy ur potsod syjuowl-¢Z— gz “OI
\ | |
bel ee fa aa ae
LM AAU ADP PAA TP PA a
EE Pid i? Vy WA
[2 eS ee bee Lae ee ee
ee SS See ee
[a7 a ea) a (A) (AAC TA (AT PR R11 SA“ 2 TT MT}
42 SMITHSONIAN MISCELLANEOUS COLLECTIONS VoL. 82
or a complete reversal in phase. Figure 29 shows what appears to be
a reversal in phase in the sun-spot cycle. The average length of this
cycle is about 11 years, so that two cycles occur in 22.5 years. If the
cycles are plotted in 22-year periods as in figure 29 it is seen that in
the period 1770 to 1792 the cycle is nearly inverted in phase to the
cycles occurring 22 years earlier and 22 years later. It is, however,
quite possible that this result is due either to interference of periods
of different lengths, or to lack of accuracy in the early observations.
No such apparent inversion has occurred since 1800.
B 9 10 1 12 13 14 15 16 17 18 19 20 2i 22
rea e
PTT
Fic. 29.—1I-year sun-spot cycle, showing apparent inversion of phase.
In figure 30 is given what appears to be a reversal of phase in the
74-year period. This cycle was in one phase from 1848 to 1870,
as shown by the broken curve in figure 30, but appears to have been
in an opposite phase from 1825 to 1847, as will be seen by the con-
tinuous curve in figure 30. This type of change is found in every solar
and meteorological period. Brooks and Clough seem to think that
shiftings of phase are gradual; but my own researches lead me to
the opinion of Professor H. H. Turner that the changes are sudden
and of the nature of discontinuities.
The change of phase in meteorological cycles is not brought about
entirely by changes in phase of solar cycles; but is in part, at least,
due to shifting of centers of action in the atmosphere. In the case
NO. 7 THE ATMOSPHERE AND THE SUN—CLAYTON 43
of pressure, when it rises in one part of the world, there is an equiva-
lent fall in other parts. These centers of rise and fall are not fixed
in position, but shift their position to some extent as illustrated in
the case of a 25-month period in a preceding paper of this series.’
The variations in intensity and phase of solar and meteorological
cycles makes the investigations of the separate cycles difficult. The
use of the Fourier series and of the Schuster periodogram are not
well adapted to such work. In order to meet these difficulties I
devised the correlation periodogram* which is to a considerable
extent independent of variations in intensity of the periods; but
does not overcome the difficulty of shifting of phase. The best
EAR 2345 67 8 9 10 ll 12 13 4 15 16 17 18 19 20 21 22
Niet tact
TAS CPLR EEL
Ne seas e EE ee E
vi N
Fic. 30.—74-year sun-spot cycle. Means of 3 cycles, showing apparent inversion.
method appears to be to use trial periods of successively greater and
greater length and harmonic analysis for each individual oscilla-
tion; then to combine the results for each period into groups of
3, 5, 10 or more. By this method the curve in figure 28 was
obtained. This method of research, using groups of 10, has made it
possible to analyze and to follow the changes of a great number of
meteorological periods and to recombine them by synthesis for a
trial in practical forecasting. Such analyses of more than Ioo cycles
have convinced me that these cycles follow solar cycles of the same
length and that they are, mostly at least, harmonics of long solar
cycles.
"Smithsonian Misc. Coll., Vol. 78, No. 4, p. 48, 1926.
* Smithsonian Misc. Coll., Vol. 71, No. 3, p. 15, 1920.
* Clayton, H. H., World Weather, p. 376, New York, Macmillan & Co., 10923.
44 SMITHSONIAN MISCELLANEOUS COLLECTIONS voL. 82
VII. THE USE OF WEATHER CYCLES IN FORECASTING
Having developed methods of separating and studying various
conditions which make up the weather, it seemed important that a
test be made of the possibility of using them in practical forecasting.
Forecasting future weather conditions in the present state of knowl-
edge may be undertaken in at least three different ways: (1) By
tracing out the results which follow the increase or decrease in the
general circulation of the air with changes in solar activity. (2)
By analyzing and following weather waves of different classes. (3)
By computing the amplitudes and phases of different cycles found
in solar and weather changes and projecting these forward into the
future.
In regard to the use of the first method, since increased solar
activity is attended by a fall of pressure in equatorial regions and
by increased contrasts of pressure in higher latitudes, there is brought
about an increased atmospheric circulation and certain general con-
ditions follow:
(1) The cloudy and clear belts of the world are intensified and
thus alter the incoming and outgoing radiation.
(2) The increased air circulation means an increased flow of ocean
waters which brings an increased northward flow of warm water
along the east coast of the United States and Japan and an accumula-
tion of warmer water in the North Atlantic and North Pacific. The
accumulation of warmer waters in these regions especially in autumn
brings increased cloudiness and increased rainfall. The increased
cloudiness reacts by diminishing radiation losses from the earth and
thus further modifying weather conditions. On the other hand
the increased oceanic circulation brings increased cold water to the
shores of North Africa and southern California, and produces a
chain of atmospheric conditions which affect the northern shores of
South America and the West Indies and extend well out into the
Pacific. A parallel set of changes is produced in the Southern Hemis-
phere in an opposite way on the east and west sides of the con-
tinents. When solar activity diminishes the reverse conditions
prevail.
(3) Increased solar activity brings also an increased flow of air
over the continents and with it an increased rainfall in certain regions
and a decreased rainfall in other regions. The distribution of pres-
sure and attendant conditions is to a large degree influenced by the
seasons.
NO: 7, THE ATMOSPHERE AND THE SUN—CLAYTON 45
Hence, to follow the sequences of weather resulting from increased
solar activity it is necessary to consider the month or seasons sepa-
rately and to work out expected conditions for different intensities of
solar activity.
In regard to the use of the second method, forecasting weather as
ordinarily practiced at the present time depends on anticipating for
a day or two at a time the drift of weather conditions. Such fore-
casts can be improved and extended in time by analyzing weather into
waves of different lengths and forecasting the progress of the
stronger waves. Even long range forecasts can be made on this basis,
as I have demonstrated by actual tests.
The third method of forecasting is by means of the periodic
vibrations in the sun and atmosphere. Any pulsation in solar condi-
tion will be attended by similar pulsations in the earth’s atmosphere.
The shorter pulsations will be felt relatively more in high latitudes
of the earth and the longer pulsations relatively more at low lati-
tudes, but all will be repeated to some extent in every part of the
atmosphere. An analysis of the periodic terms in the weather at any
point on the earth would make it possible to project the periodic
terms ahead to any length of time desired, were there no variations
in the amplitude and phase of the periods. But there are variations
and for this reason it is necessary to redetermine the periodic terms
at short intervals and to limit the time in advance which they are
made to cover. When these variations in the periodic terms become
calculable, this method of forecasting will probably replace all others.
Already considerable progress has been made along this line.
In practical forecasting at present it is desirable to consider all of
the three methods mentioned and to use them as checks on each
other. Forecasting in words has but little meaning to the average
expert, because the meanings of words can be interpreted in various
senses and there are no accepted rules for verifying such cases.
Quantitative forecasts can, however, be verified by accepted stand-
ards; so that from the beginning of my experiments in forecasting,
both verbal and quantitative forecasts were made. These quantitative
forecasts were made first for about a week in advance, then for
longer intervals up to a month. Figure 31 gives one of the more
recent of these forecasts of pressure made on November 24, 1929, for
27 days in advance beginning on November 26 and ending on
December 21. The forecast was made up from a combination of
cycles varying in length from 3 days to 13 days. The correlation of
the forecasted with the observed pressure is 0.64 + 0.06.
46 SMITHSONIAN MISCELLANEOUS COLLECTIONS VoL. 82
By computing pressure in this way for a network of stations,
weather maps bearing unmistakable resemblance to observed weather
maps may be computed in advance. In March, 1929, values of pres-
sure were computed for one week in advance for 23 selected sta-
tions forming a net over the United States and from these computed
values lines of equal pressure departures were drawn, The maps
NOVEMBER, ee DECEMBER
26 27 28 29 30 2.3 4.5 6 7 8 9 10 WIA IS 14 15 6 N6nigk2orel
CHICIA
PRES|SU
AG
Fic. 31.—8 a. m. pressure.
thus forecasted are compared with the observed pressure distribu-
tion in figure 32. The close resemblance of the two sets of maps is
apparent. This degree of accuracy can be obtained, however, only
when the meteorological cycles are comparatively steady. It is never-
theless the goal toward which research is leading and to which it
will undoubtedly attain.
In April, 1929, a diagram was sent to a number of persons,
including the Secretary of the Smithsonian Institution, giving a fore-
cast of departures from normal temperature by weeks from April 2
to September 3 for New York City and for two other stations. Fig-
ure 33 gives a copy of this plot for New York City. The broken
curve shows the forecast and the continuous curve shows the ob-
served departures from normal. The correlation coefficient for the
23 weeks is 0.37+0.12. This correlation taken alone is inconclusive
as to the possibility of such forecasts, except in the light of other
data indicating its possibility. It is believed that forecasts by months
and years are feasible on the same basis and by the same methods,
but no prolonged test is yet available.
If the conclusions presented in this paper are verified and accepted
by other research workers, as I feel they must be in time, it will
—_—
NOS 7 THE ATMOSPHERE AND THE SUN—CLAYTON
47
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14 SMITHSONIAN MISCELLANEOUS COLLECTIONS voL. 82
are slightly too high for those insects which did not respond readily ;
but the figures given under the heading “ difference” are practically
the same as those when all the insects counted in section I were
eliminated.
ce
Usually during the afternoon similar tests were conducted four
times, using the same beetles, but no light was used. In this case,
without the use of light, the geonegative response was 5.27+0.177
more than the geopositive one, while with the use of light it was
only 2.40+0.120 more (table 1), 10.00 being equal to a 100 per cent
response.
On later dates the preceding tests were again repeated, using two
other sets of overwintering beetles. The general average and prob-
able errors of the three series were therefore obtained by using the
12 means and the mean of them. Thus, for active, overwintering
beetles the geonegative response, when light was used, was 2.56+
0.140 more than the geopositive one; but when no light was used, it
was 5.40+0.119 more, indicating that when the beetles were forced
downward by the light this stimulus overcame about one-half of the
geotactic one. In two of these series of tests the light was used
during the forenoon, but in the third series during the afternoon. The
sequence in which these insects were tested, therefore, had little or
no. effect on the results obtained.
The preceding tests were repeated by using one set of old beetles
of the second brood. These insects were not so active as they were
when younger and did not respond so readily to light and gravity
as did the more active overwintering beetles. Their lower responses
were due mostly to the fact that the insects soon became tired of
being forced to respond.
Two sets of larvae were likewise tested in the photo-geotactic box
and were found to be photopositive and geonegative (table 1). Com-
pared to the adults they were sluggish and three times in four did
not respond as readily to light and gravity. Larvae of the third
instar reacted weakly to light and gravity, while the larvae of the
fourth instar responded strongly to light but weakly to gravity.
The reader has doubtless noted that the writer has designed his
experiments and discussed his results from the point of view that
rate of movement is a measure of tropic response. After an animal
is oriented, some writers claim that the rate of its movement toward
or away from the source of excitation is not a measure of its tropic
response. If a tropic response includes nothing more than the mere
act of orienting, the preceding results then have little to do with the
subject of tropisms. The writer in various publications has dis-
No. 18 SENSE ORGANS OF COLEOPTERA—McINDOO 15
cussed the subject of tropisms from a broad point of view, and has
not yet accepted any definition nor does he know exactly what a
tropic response includes, but he believes that it includes more than
orienting in a certain direction.
In conclusion, bean beetles and their larvae are usually found on
the upper portions of their host plants, because they are photopositive
and geonegative ; but since direct sunshine in warm weather is harm-
ful to them, they are usually found on the lower surface of the leaves.
II. CHEMOTAXIS
I. REVIEW OF LITERATURE
Most of the information regarding chemotaxis found in the widely
scattered literature pertains to the subject of baits. Scores of refer-
ences have been consulted, but only the more important ones will be
cited.
(A) BAITS FOR WIREWORMS AND TENEBRIONIDS
It is not known when the practice of using baits for beetles was
first begun, although this is an old control method. The Japanese
growers, according to Treherne (85), were probably the first ones
to use baits for catching wireworms, the larvae of elaterid beetles.
After roasting dry rice shorts or rice bran, the Japanese then mois-
tened the roasted material with water and made it into small balls,
which had a strong odor said to be attractive to wireworms. The
Japanese claimed that a single ball would catch 100 or more wire-
worms, but when this method was tested by Treherne a single bait
buried in heavily infested soil never yielded more than go larvae.
Treherne (86) also tells about the old-fashioned way of attracting
wireworms, which is still recommended as one of the few control
measures. Pieces of cut potatoes, to which white wires have been
attached, are buried in the infested soil. Upon visiting the infested
area the potatoes are pulled from the ground by means of the wires,
the wireworms are removed and destroyed, and then the potatoes are
buried again. In Canada attractive baits, consisting of potatoes, balls
of dough, shorts, meal, or rice bran, are set in the soil. The addition
of molasses or other attrahent (“attractant”) in these bran baits
does not improve their attractiveness, nor has the inclusion of ar-
senicals been of any practical value.
Weldon (95) reports that small pieces of potatoes were planted
between rows of beans in California. This bean crop was saved, while
30 acres of beans nearby, not thus protected, were entirely destroyed.
2
16 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82
Borodin (6) reports that in Russia the best remedies for wire-
worms are various baits, consisting of sliced potatoes, carrots, beets,
oil cakes, cabbage stalks, etc., buried 3 or 4 inches in the soil. Those
poisoned with Paris green or arsenic need no further attention.
The unpoisoned ones must be inspected weekly. Poisoned maize baits
are also recommended.
French (15) says that in Australia poisoned baits consisting of
cut-up turnips, carrots, etc., soaked in lead arsenate, have given good
results.
Lovett (38) states that in Oregon poisoned-bran mash may be
placed under stones or boards in the fields as a control measure for
wireworms.
Masaitis (39) reports that in Siberia baits of horse dung, poisoned
with sodium arsenite, appeared to be considerably more effective than
those of poisoned linseed or hempseed cake.
More recently special attractants have been given serious attention.
Comparative tests, conducted in Washington State by Spuler (83), in
which rice flour, graham flour, graham flour and sugar, bran, graham
fiour and oranges, graham flour and lemons, potatoes, carrot roots,
carrot tops, and apples were used as baits gave a descending order
of attractiveness as listed. Other tests, in which baits consisting of
germinating Alaska peas, beans, corn, graham flour, and potatoes
were used, indicated that the seeds and flour were about equal in at-
tractiveness, but that the potatoes were far inferior. For practical
control work use baits, particularly germinating seeds, to allure the
wireworms to definite spots, and then the worms may be easily killed
with a soil fumigant, such as calcium cyanide. When the worms have
gathered around the bait, spaced about four feet apart, to partake of
the feast prepared for them, all that remains to be done is to bury
a little of this granular fumigant near the bait. Shortly the deadly
fumes send the banqueters to their happy hunting ground and all is
ended.
Federal entomologists (1) at Clarksville, Tenn., have recently made
an interesting discovery in connection with poisoned-bran bait fed
to tobacco wireworms, which have hitherto stubbornly resisted all
efforts at direct control. These worms were easily attracted to bait
flavored with ordinary nitrobenzene. In five series of large-scale ex-
periments in tobacco fields these worms were reduced from 50 to 60
per cent by the use of this chemical as a bait flavoring. Other en-
tomologists (2) at the Florida experiment station remark that a
flavoring of nitrobenzene added to poisoned-bran bait is very attrac-
tive to a variety and large range of insects, and they found it quite
No. 18 SENSE ORGANS OF COLEOPTERA—McINDOO 7,
attractive to the celery leaf-tier. If it is attractive to such diverse
insects as wireworms and caterpillars it is quite possible that it will
be found of value against a large number of insects.
Melander (50) states that a dough made of flour or bran proved
very attractive to wireworms, but the addition of sugar, oranges,
lemons, etc., added little to the drawing power of the baits.
Since the larvae of certain tenebrionid beetles are destructive, why
not attack the evil at the source by destroying their parents? This
was the way Wakeland in Idaho reasoned during the season of 1921.
After discovering that these beetles feed greedily for a month before
egg-laying time, he next found out that they could be easily killed
during this period by feeding them poisoned-bran bait, thus largely
eliminating them before they had a chance to start a new generation.
The following season he (93) continued his experiments and states
that the bait used consisted of bran, Paris green, amyl acetate, and
water. It was distributed broadcast or in the bottom of furrows,
plowed at regular intervals, over an area of 18,000 acres. This method
is said to be practical and economical, because the beetles were ef-
fectively killed at a cost of about two and a half cents per acre for
materials, and the labor involved was not a large item.
In 1920 Jack (29) in Rhodesia poisoned the adults of certain
tenebrionids by using the bait recommended against cutworms.
Swenk (84) remarks that a promising remedy against the adults of
Eleodes opaca is a bait prepared by mixing, dry, 25 pounds of coarse
wheat bran and 1 pound of Paris green, to which is added # ounces
of amyl acetate in enough water to make a stiff mash. This quantity
is sufficient for several acres when put in furrows.
Other species of tenebrionids in the United States (8), Russia (73),
and Rhodesia (30) are more or less controlled by poisoned baits. In
Southern Rhodesia several formulas have been used (31) success-
fully against so-called wireworms (tenebrionids). One of them is
made of chopped green stuff, dipped in a solution consisting of 1
pound of sodium arsenite, 8 pounds of cheap sugar or 1 gallon of
molasses, and 10 gallons of water. This bait may be broadcast or
applied like bran bait.
(B) BAITS FOR STRAWBERRY-ROOT WEEVILS
During the past 25 years strawberry growing in the western parts
of Washington, Oregon, and British Columbia has been handicapped
by strawberry-root weevils. For 20 years or more many efforts have
been made to develop a remedy for this serious pest, but not until
recently has a satisfactory control measure been discovered. An
18 SMITHSONIAN MISCELLANEOUS COLLECTIONS VoL. 82
attractive poisoned bait was developed by M. J. Forsell of Seattle,
Washington, who, at the suggestion of the present writer, attacked
the problem through the weevil’s sense of smell. In the preliminary
experiments dried ground apples were found to be the most attractive
substance tested, and magnesium arsenate was the most satisfactory
poison. It is further claimed that the discovery and perfection of this
bait marks an important horticultural step in the fruit industry of
the State of Washington, as these weevils had become so serious in
many places that the strawberry-growing industry seemed doomed.
Melander and Spuler (51) report their results concerning the
poison-bait remedy for the strawberry-root weevils in Washington.
They say that these destructive weevils can be satisfactorily, economi-
cally, and practically controlled by the distribution of a poisoned bait
immediately at the close of the berry harvest. This bait consists of sun
or oven dried sliced apples, ground into pulp or granules, to which
an arsenical is added, magnesium arsenate being the most satisfactory.
The bait is broadcast over the strawberry plants at the rate of about
70 pounds per acre.
Mote and Wilcox (57) tell about the bait method used in Oregon.
They remark that a homemade bait consisting of 95 pounds of ground
dried apple waste, mixed with 5 pounds of calcium arsenate, kills the
strawberry-root weevils. A commercial bait is also reported to be
efficient.
Downes (13) further experimented with baits for strawberry-root
weevils. He states that apple waste containing about 20 per cent of
moisture was found more attractive than super-dried bait, and that
sodium fluosilicate was the most suitable poison to use with apples
containing that percentage of moisture. Two applications of the bait
are recommended, the first in April and the second in June.
(Cc) BAITS FOR THE JAPANESE BEETLE
A study of the chemotaxis of the Japanese beetle was begun in
1922 at the Japanese Beetle Laboratory in New Jersey, and since that
date several persons have worked on it, but some of them have never
received credit in the published papers on this subject. This is par-
ticularly true of F. J. Brinley, who did the work in 1923 and dis-
covered that geraniol was the most important attractant used. Rich-
mond and the present writer continued the work in 1924, the former
doing the field-work and the latter the laboratory work. Some of
Richmond’s results have been published, but since those of the writer
were only preliminary they still remain unpublished.
no. 18 SENSE ORGANS OF COLEOPTERA—McINDOO 19
The first authentic report on this subject is by Smith (76), who
states that in chemotactic studies it has been found that Japanese
beetles are strongly attracted by geraniol, and nearly 50,000 beetles
in 1924 were collected from baits containing this substance. Bait
mixtures, containing bran, molasses, and geraniol retain the odor for
a long time if protected from the rain. Eugenol, citral, and citronellol
as attractants, and tar oil as a repellent, appear to have some value.
Richmond (66) gives a detailed report on this subject and tells
about the earliest experiments conducted. Since the beetles were
known to have favored food plants and were strongly attracted to
ripening fruit, various chemicals were tested in 1922 to ascertain if
the fruit odors might be imitated. To determine whether beetles could
be attracted to the sources of odors, a number of essential oils were
sprayed on foliage. The results indicated that the oils of sassafras,
hemlock, mustard, and lemon, and iso-amyl valerate were somewhat
attractive. More detailed experiments were conducted in 1923 and a
large number of compounds were studied: Bran-bait mixtures, put in
cans which hung in trees, were used. Among the oils, sassafras and
clove were easily the leaders, while ethyl alcohol, geraniol, and eugenol
proved to be the most important constituents. In 1924 greater detailed
studies were undertaken. The adult beetle was found exceedingly
susceptible to the influence of color, odor, temperature, humidity, and
light. The six leading chemicals tested are geraniol, eugenol, cit-
ronellal, citral, citronellol, and diphenyl ether. Geraniol proved to be
far superior to the other five. In other experiments emulsions were
tested. When cloths (1 foot square) were dipped in a 10 per cent
emulsion of geraniol and suspended in orchards (pl. 1, A), beetles
were drawn as if by a magnet and 13,000 beetles were collected on
12 cloths over a period of 5 successive days. In 1925 and 1926 this
project was much expanded so that it included the testing of various
types of bait cans and bait traps. The best type of trap devised
was cylindrical in shape. A single one of these caught over 13,000
beetles in 8 hours. Richmond’s summary follows:
Geraniol is clearly the primary .attrahent of the Japanese beetle but its com-
bination with eugenol materially lowers the cost and increases its effectiveness.
During the summer of 1924 over 65,000 beetles were actually collected from the
bait can experiments. Nearly 50,000 of these beetles were present on geraniol
baits alone. The results of experimentation in 1925 and 1926 were in keeping
with these remarks, but, inasmuch as more extensive tests were conducted, the
number of beetles collected was proportionately greater. The activities of the
adult varied with temperature, humidity and vapor pressure. Females are
attracted approximately one-third more frequently than males when geraniol
and most other chemicals are employed. Molasses has only a slight attractive
20 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82
value. Satisfactory traps have been evolved and it seems possible that they will
have considerable value in reducing the number of beetles in a given orchard.
Bran retains odors over long periods if protected from the rain. Geraniol has
been satisfactorily incorporated in poison sprays although its odor is not retained
for a long enough period. To this end experiments on the absorption of this
chemical on charcoal, clays, ete., are under way. The value of geraniol, when
used in connection with a contact spray, has been demonstrated. Eugenol, citral,
citronellol and citronellal.follow geraniol as attractive agents.
It is further stated (3) that methods have been devised whereby
geraniol may be used to concentrate the beetles in a relatively small
area. It was found that by spraying less than an acre of orchard
with geraniol, beetles could be drawn on the leeward side of the or-
chard for a distance of nearly one-half mile within the first 15 minutes
after the spray had been applied. This makes it possible to destroy
large numbers of beetles with a comparatively small quantity of a
contact spray.
Van Leeuwen and others (87, 90) determined that acetic acid, an
accumulation of beetles, geraniol, and fermented apple juice attract
these beetles. It was discovered that the beetles would gorge them-
selves upon foliage sprayed with a mixture of lead arsenate and re-
fined sugar, on trees to which they had been attracted by geraniol
(pl. 1, B). More beetles fed on this foliage than on unsprayed leaves,
and consequently the mortality was greater than ever before obtained.
Smith (78) more recently reports that a combination of lead arsenate
and refined cane-sugar sirup has been found useful as a spray on non-
economic plants. The beetles are strongly attracted to it and eat it
readily. He says that this preparation is probably one of the most
effective lethal sprays yet devised for the Japanese beetle. Owing to
its tendency to injure foliage it is not recommended for use on
economic plants.
Metzger (52) and Richmond and Metzger (68) describe various
types of traps, one being called the standard bait trap. Each kilo-
gram of the standard bait contains 500 grams of bran, 455 grams
(350 cc.) of molasses (refiners’ sirup 75 per cent), 44 grams (40 cc.)
of glycerine, and a quantity of an attractant. With geraniol as the
attractant making 5 per cent of the prepared bait, the bran-glycerine-
molasses mixture does not deteriorate to any marked degree when
exposed to the weather, and its attractive odor has been retained more
than three years in some traps. In practice, baits were renewed twice
a month, 150 grams of the prepared bait being put in each trap. The
best bait, however, was found to be a technical geraniol, 58.8 per cent
pure, used in the proportion of 2.5 per cent with eugenol in the pro-
portion of 0.25 per cent of the total material. The total number of
No. 18 SENSE ORGANS OF COLEOPTERA—McINDOO 21
beetles caught in 39 traps in 1926 was about 2,000,000, one trap
catching 13,476 in one day. These traps were used also in connection
with ecological investigations, and to obtain data on the degree of
infestation at different points in different years. Beetles are caught in
the traps before any are observed in the immediate neighborhood. As
a result of these investigations various types of traps have been put
on the market by commercial firms. In the 1929 report on the Japa-
nese beetle, Smith (78) has the following to say about geraniol and
traps:
Several years ago chemotropic investigations revealed that geraniol, one of
the higher alcohols, was extremely attractive to the Japanese beetle. Few, if any,
other insects have been found to be attracted to any degree by this chemical and
it is apparently a specific for this insect. In commerce it is commonly used as
an ingredient in the cheaper perfumes. Geraniol has been utilized in several
ways in the control of the beetle; these include combining it with poisoned baits,
as a means of concentrating the beetles in a small area where they may be killed
with contact sprays, or more often as a constituent of baits used in mechanical
traps. The Japanese beetle traps have come into wide use by residents in the
suburban area around Philadelphia. In conjunction with spraying, the traps are
useful in capturing large numbers of beetles. During the summer of 1929, 500
traps were placed on a 15-acre estate in the heavily infested district near
Roxborough, Pennsylvania. The record of collections in these traps during the
period between July 9 and August 23 gives a total of 1,8745 pounds of adult
beetles and represents approximately 10,000,000 individuals. Many types of
beetle traps are now on the market, ranging in price from 10 cents upward.
The traps have not yet become sufficiently effective to warrant their use on
farms. In fact, the presence of large numbers of traps may attract many
beetles which are not captured, with the result that the grub population in the
soil, in the vicinity of the traps, is greatly increased over what it would have
been had the traps not been used.
During the past few years traps have come into general use for
catching large numbers of Japanese beetles, but for various reasons
a large percentage of the insects attracted to the traps are not caught ;
therefore, Mehrhof and Van Leeuwen (49) devised and perfected
an electric trap (pl. 2) which not only attracts the beetles but kills
practically all of them that come to it. This trap, in the form of a
hollow cube, is 3 feet on each side, with parallel wires, inch apart,
on all four sides and on the top. The most effective bait was geraniol
emulsion, sprayed on peach foliage which was suspended in the center
of the trap. By this method beetles were at times attracted from a
distance of one-fourth mile.
Siegler and Brown in 1927 (74) first published on the idea that
attractive baits might be used advantageously in scouting for in-
jurious insects. During the season of 1929 the Federal Plant Quaran-
22 SMITHSONIAN MISCELLANEOUS COLLECTIONS VoL. 82
tine and Control Administration made practical use of this idea by
installing bait traps along the edges of the Japanese-beetle infested
zones. So far little has been published on this particular phase of the
work. According to the report of Secretary of Agriculture Hyde (27)
the use of beetle traps at Baltimore and Washington, and in Alexan-
dria County, Virginia, has resulted in the collection of great numbers
of beetles. The possibility of substantial control at such isolated points
by this method will thus be given. It has already been demonstrated
that enormous quantities of beetles can be collected by trapping. In
fact, on a single property in Pennsylvania (not New Jersey as re-
ported) nearly a ton of beetles were thus collected in 1929. In the
heavily infested areas, such trapping is of little value unless the em-
ployment of this method is general. Van Leeuwen (88) states that
25,000 of the Government standard traps, which he illustrates, were
used by the Plant Quarantine and Control Administration during
1929 in its scouting work to determine the presence of beetles. Rex
(65) illustrates and briefly discusses these traps and gives the bait
formula recommended by the Japanese Beetle Laboratory in New
Jersey. Van Leeuwen and Metzger (89) give the very latest informa-
tion about traps for the Japanese beetle. They recommend the follow-
ing formula for one baiting of a standard trap.
Geraniol (at least 58 per cent pure)............. I5 grams (4 teaspoonfuls)
Bucenoli (U2 SiR) zae neti hete cee ree eleanor 1.5 grams (4 teaspoonful )
Brant: paste coin aS Se ea Ene eer 75 grams (13 cups)
Water 0508 fel hee Soe ae [Ns ee tee ed yan 13 cc. (1 tablespoonful )
MOLASSES) se ies ea oo ae he GR Ee ee 39 cc. (24 tablespoonfuls)
Glycerine(G Boia Ae hone case hoaee Seas 6 cc. (14 teaspoonfuls)
Figure 4 was drawn by the present writer and illustrates the
various parts of one of the standard traps.
At this place a few more remarks concerning the attractiveness
of geraniol should be made. The effort is usually made to correlate
attractive odors either with the food or opposite sex of an animal;
but in some cases it is questionable whether food, or sex, or some
unknown factor, is involved. For example, why should the banana-
like odor of amyl acetate attract grasshoppers, or certain beetles?
And why does the odor from the catnip plant attract members of
the cat family? In regard to the attractive power of geraniol, a food
odor is probably involved, although we know little about it. Smith
(76, p. 59) and Smith and Hadley (79, p. 58) in two of their earlier
reports remark that several of the essential oils were found to be
highly attractive to the Japanese beetle, and that on studying these
oils, it was discovered that one of the higher alcohols, geraniol, was
No. 18 SENSE ORGANS OF COLEOPTERA—McINDOO 23
; N Bait Container
-SOF
Fic. 4.—Japanese beetle trap, used by the Federal Plant Quarantine and Con-
trol Administration, showing parts of it in a cut-out perspective view. It is one-
fourth natural size and was drawn by the writer by using a 1929 trap and a
drawing of a 1930 trap, the latter being furnished by Mr. Courtney. The beetles,
attracted by the odor from the bait in the bait container, fly directly into the
funnel or strike the baffle and then fall down through the funnel into the fruit
jar, where they cannot escape because they can neither fly out nor climb the
walls of the jar.
24 SMITHSONIAN MISCELLANEOUS COLLECTIONS VoL. 82
a constituent of all the oils found to be distinctly attractive. Tests were
made of a series of the preferred food plants, and in all cases these
plants contained geraniol in varying quantities. The present writer
has seen no report by a chemist concerning the last statement; but as
regards fruit, Power and Chesnut (61) found geraniol in apples. They
used only the parings of the McIntosh, one of the most fragrant
varieties of apples, and say that geraniol, either in the free state or in
the form of esters, is probably contained in varying quantities in all
the numerous varieties of apples, although to the greatest extent in
those which possess its distinctive odor. Power and Kleber (62) tell
us that the two oils, one from sassafras bark and the other from
sassafras leaves, are fundamentally different in regard to their chemi-
cal compositions. Oil from sassafras bark contains eugenol but no
geraniol, while oil from sassafras leaves contains geraniol but no
eugenol. There are also other differences. The fact that Japanese
beetles were observed to be fond of sassafras leaves led to tests in
which the oil of sassafras was used; after learning that oil from
sassafras leaves contains geraniol it was only natural to continue
using geraniol in bait mixtures. |
A popular impression is that Japanese beetles are fond of geraniums
and that our supply of geraniol comes from these plants, but this is
far from the truth. Ballou (4) informs us that these beetles do feed
upon the flowers and to a limited extent upon the foliage of cultivated
geraniums (Pelargonium spp.), but with deleterious effects to them-
selves, because this food is toxic to them. Most of our commercial
supply of geraniol is said to be derived from the oil of citronella,
but in perfumery much of it also comes from the oil of palmarosa or
Turkish geranium. Geraniol also occurs in the oils of lemon-grass,
geranium, rose, sassafras leaves, and other essential oils.
(D) BAITS FOR OTHER BEETLES
Since 1916 it has been reported in numerous publications that cer-
tain sugarcane cockchafers in Australia can be attracted by odors
from various chemicals and by the aromas distilled from their food
plants, but it seems that so far no practical results have been obtained.
Other reports by Jarvis (34, 36), however, indicate that poisoned
baits have a practical value in helping to control the grubs of these
beetles.
For years it has been known that poisoned-bran baits are of con-
siderable value against the common May beetles and more recently
Vickery and Wilson (92) used a bait consisting of 20 pounds of
No. 18 SENSE ORGANS OF COLEOPTERA—McINDOO 25
wheat bran, 1 pound of Paris green, I quart of sirup, and the juice
of 3 lemons or I teaspoonful of anise oil successfully against a wing-
less May beetle.
McKinney and Milam (48) and Gilmore and Milam (19) have
successfully used a poisoned-bran bait against the grubs of the green
June beetle in tobacco-plant beds and in a tobacco field.
A large white grub of a dynastid beetle is the most serious pest of
sugarcane in St. Croix. The control recommended in 1916 by Smith
(80) was a poisoned bait.
Poisoned-bran mash was the best control used by Cooley (10) in
1917 against the spinach carrion beetle.
Using a poisoned-bran bait in 1916 Scholl (71) destroyed the
striped blister beetle on alfalfa and tomatoes.
Newman (59) in 1929 reports that a poisoned-bran bait gave ex-
cellent results against a subterranean clover weevil.
Jack (32) in 1928 reports that over 95 per cent of certain weevils
in a maize field were killed by one application of a bait consisting
of 1 pound of sodium arsenite, 8 pounds of sugar, and 10 gallons of
water on chopped fodder.
During the seasons of 1926, 1927, and 1928, over 1,000 traps, con-
taining fermenting sugar or molasses, were used in a peach orchard
in Pennsylvania for the purpose of trapping oriental fruit moths.
Frost and Dietrich (16) report that incidentally 4o families of
beetles, including 188 genera and 258 species, were also caught in
these traps.
Snapp and Swingle (81) have recently tested a large number of
aromatics, including various steam distillates and other odorous ma-
terials derived from the food of peach insects. A large number of
chemicals were found, under orchard conditions, to be slightly at-
tractive to various peach insects, as well as to the plum curculio, but
none showed much promise of being valuable from the standpoint of
control.
Garman and Zappe (18) have also recently conducted many tests,
trying to find attractants and repellents for the plum curculio. They
remark that curculios are very sensitive to odors. Acetaldehyde and
malic acid were the only substances used in the laboratory which
showed much attractive power, but when these substances were tested
in the field no curculios were trapped.
In conclusion under this heading a few remarks may be made about
the present writer’s (45) results obtained when testing potato beetles
in an olfactometer. In this study no baits were actually used, but it
was proved for the first time that plants (not flowers) attract insects
26 SMITHSONIAN MISCELLANEOUS COLLECTIONS VoL. 82
by emitting odors. Since odors from the steam distillates and emana-
tions from 4 or 5 species belonging to the potato family attracted
potato beetles, it was then suggested that the chemist tell us what
constituent or constituents, common to these plants, did the attracting.
If we had this information, we might be able to use these substances
in poison baits.
(£) REPELLENTS USED AGAINST BEETLES
Onder this heading many repulsive substances are regarded as
repellents, but for some of them a more appropriate word would be
deterrents; nevertheless, there is little distinction between these two
words. Let us define a repellent as an odorous substance, which by
means of its unpleasant exhalations repels insects before they have
touched it; and a deterrent as an inodorous substance which repels
insects after they have touched it. Thus defined, a deterrent repels
mostly, if not entirely, through the sense of touch; while a repellent
operates either through the sense of smell or, if its exhalations are
poisonous, then through the breathing pores. These definitions are
easily made, but it is perhaps almost impossible to have a deterrent
which is totally inodorous to insects; and furthermore, other factors
are often involved. These terms have been used loosely by various
writers, and since this subject is yet confused, the present writer will
still continue to use them without attempting to explain how the
enumerated substances repel, deter, or otherwise keep insects away
from plants. The following remarks by the writer’s reviewers help
to elucidate the subject.
In regard to the Japanese beetle, Doctor Van der Meulen and Mr.
Van Leeuwen believe that there should be another subdivision of
repellents to include those substances which mask attractive odors;
for example, those from geraniol. We might call these “ maskers ” or
“neutralizers,’ because they repel from a short distance merely by
covering up or neutralizing the attractive odors. Relative to “ in-
odorous” materials, Japanese beetles may also be repelled before
touching dusted or sprayed food by means of the sense of sight. In
regard to the repellency of the arsenates, the subject of toxicity should
also be considered; but at present we are not able to evaluate the
various factors, including the senses of sight, smell, touch, taste, and
probably a general sense connected with the digestive system.
After reading the preceding definitions, Dr. F. L. Campbell pro-
posed that attrahents, now usually called attractants, should be di-
vided. The odor from geraniol causes the Japanese beetle to orient
and to move toward this substance; therefore, geraniol is a true
No. 18 SENSE ORGANS OF COLEOPTERA—McINDOO 27
attractant. In the course of random movements certain other insects
may come upon sugar, for example, which holds them after they
have touched it. In this case, Campbell says that sugar might be called
a true “arrestant.’’ If insects have true senses of smell and taste,
an attractant then attracts through the sense of smell and an arrestant
arrests through the sense of taste.
Since entomologists already know much of the following informa-
tion, only the more important references consulted will be cited here.
The substances inodorous or slightly odorous to us, which have been
found repulsive to insects, may be briefly discussed as deterrents.
Whitewash may be considered the first deterrent used. White-
washing the bases of fruit trees has been practiced for years. It is
still questionable whether such a practice is of any real economic
importance, but its advocates claim that the lime in it has a tendency
to drive away noxious insects and may be slightly injurious to in-
sect eggs. The most improved and best mixture of whitewash, as
recently recommended in France, consists of lime, calcium arsenate,
lime sulphur, and water. In this case the lime might act as a deterrent
and the lime sulphur, which has a strong disagreeable odor, as a
repellent. One of the most efficient deterrents used in the United
States is air-slaked lime, which is employed extensively for dusting
melons and cucumbers to prevent the attacks of the striped cucumber
beetle. It is also said to prevent injury to stored beans by the bean
weevil. In Germany a mixture of white sand and hydrated lime has
recently been used to deter flea-beetles. Paints, particularly white-
lead paint, are recommended for preventing boring beetles from
entering wounds on fruit trees. The coat of paint covering the fresh
wound preserves the wood and also acts as a mechanical barrier to
the beetles. Lead arsenate, when sprayed or dusted on foliage, deters
a number of insects, including the Japanese beetle, western cabbage
flea-beetle, desert corn flea-beetle, and striped cucumber beetle. Most
of the arsenicals deter the Mexican bean beetle. Bordeaux mixture
sprayed on the leaves of eggplant and potatoes deters flea-beetles and
the potato leafhopper, which causes the disease called “ hopperburn.”
In regard to repellents used against beetles, the first ones used
were probably decoctions of certain poisonous plants. As early as
1848 leather waste from tanneries, when put among plants in Germany,
was found to be a repellent against flea-beetles, and more recently in
France sawdust coated with coal tar when placed among the plants
repelled these insects. The most successful repellent used against
these tiny insects and the striped cucumber beetle in the United States
28 SMITHSONIAN MISCELLANEOUS COLLECTIONS voL. 82
is nicotine dust. Since it is almost impossible to kill flea-beetles by
using arsenicals or other insecticides, the repellent method is an im-
portant control measure.
In Europe there has been considerable experimenting with repel-
lents to keep beetle larvae, particularly white grubs, from attacking
the roots of plants. The odorous substances were usually worked into
the soil around the bases of the plants, but it is doubtful whether
much protection ever resulted. In France and Belgium crude naph-
thalene mixed with sand was used. In France three other repellents
were found more or less effective—first, residue of glue; second,
naphthalene and kerosene mixed with sawdust; and third, crude oil
mixed with lime, plaster of Paris, and feces. In Germany sulphur was
worked into the ground around strawberry plants. In England
naphthalene was successfully used against wireworms in gardens,
and in Australia crude naphthalene was effective against wireworms
injuring sugarcane.
McColloch and Hayes (40) have recently reviewed the methods
and enumerated the repellents used to protect germinating seeds and
roots and to prevent the invasion of the soil by underground insects,
particularly beetles. Numerous substances have been recommended
as repellents, including crude carbolic acid, turpentine, naphthalene,
paradichlorobenzene, creosote, coal tar, oils of lemon and tansy, kero-
sene, and phenol. They state that no satisfactory repellent has yet been
found which can be depended upon under varying conditions existing
in the soil. They believe that this subject needs further investigation.
Since the Japanese beetle is fond of ripening fruit, particularly
apples and peaches, and since it is not advisable to spray early fruit
with arsenicals, ripening fruit should be protected by other means.
Therefore, much experimental work has been done to develop an
effective repellent to take the place of the arsenicals. Metzger and
Grant (54) have developed smudge candles, which, when lighted
and hung in peach trees, give off ill-smelling smoke for a period of
five to eight hours. The mixture, to be burned slowly without pro-
ducing a flame, was put in a wire-screen cylinder, 31 inches long and
2.25 inches in diameter. In conclusion they say that wood flour and
potassium nitrate, when properly mixed, form a satisfactory base for
smudges. The fumes from pine-tar oil, Dippel’s oil (bone oil), and
a commercial mixture of chloronaphthalenes, when given off from
burning smudge candles, are definitely repellent to Japanese beetles.
Air currents in the orchard, however, prevented the repellent smoke
from giving satisfactory control of beetles on early peach trees.
No. 18 SENSE ORGANS OF COLEOPTERA—McINDOO 29
Metzger (53) describes five methods used in testing 430 materials,
alone and in combination, as repellents for the Japanese beetle.
Under method 1, “testing material in comparison with a known
attrahent,” 306 materials were tested, and 45 of them decreased the
attraction of the geraniol-eugenol combination. Beginning with the
one most repellent, the first ten in the list are o-cresol, pine-tar oil,
phenol, Dippel’s oil, high boiling tar acids, coal-tar neutral hydro-
carbon oil, trichlorobenzene, crude dichlorobenzene No. 1, alpha
chloronaphthalene, and crude dichlorobenzene No. 2.
Another difficult test has been to find a successful repellent for
wood-boring beetles. The first object is to prevent them from enter-
ing the living trees, lumber, or manufactured wooden articles, and
the second object is to kill them or drive them out of their burrows
-after they have once entered. Little success has yet been accomplished
along this line, but it is easier to prevent their entrance than to con-
trol them later. In Brazil a mixture consisting of crude carbolineum
I part, quicklime 10 parts, and water 40 parts is painted on the trunks
of citrus trees to prevent the entrance of borers. In the United States
carbolineum and creosote are often applied to the trunks of aspen
trees in forests to prevent the entrance of the aspen borer. A suc-
cessful repellent has recently been recommended by Pettit (60)
against flat-headed borers which do considerable damage to apple
trees. Following a special procedure a thick solution is prepared by
using 50 pounds of laundry soap, 3 gallons of water, 25 pounds of
flake naphthalene, and 2 pounds of flour. After warming and thin-
ning this mixture to the consistency of heavy cream, it is applied
several times with a brush to the trees.
The Lyctus powder-post beetles, which cause much damage to
hardwood lumber, implement handles, furniture, etc., throughout the
world, may be deterred and repelled by several substances. In the
United States, according to Snyder (82), the usual method recom-
mended is to immerse the lumber, already infested or liable to in-
festation with these borers, in vats of kerosene, or in a mixture of
creosote and kerosene, or in one of creosote and naphtha. The writer
has recently been told that these beetles may be repelled by using
coal-tar creosote and orthodichlorobenzene. The lumber and handles
which can not be treated by the vat method may be stored in closed
sheds and close-fitting houses and then sprayed at intervals with these
chemicals. In Great Britain lumber stacked in the open is often
treated with cold paraffin mixed in equal parts with oil of cedar,
linseed oil, or a heavy mineral oil. To lumber stored in sheds or-
thodichlorobenzene is applied with a brush or sprayer, or paradichlo-
30 SMITHSONIAN MISCELLANEOUS COLLECTIONS voL. 82
robenzene is scattered on top of: the stacks and suspended in bags
from the roofs of the sheds.
Carpet beetles, also called ‘“ buffalo moths,” often do considerable
damage to carpets, woolens, furs, feathers, and upholstered furniture.
One of the control measures is to prevent them from coming in con-
tact with these articles by using repellents, such as naphthalene in
the form of flakes and moth balls, paradichlorobenzene, or camphor,
or by the use of red cedar chests.
,
2. ORIGINAL WORK ON MEXICAN BEAN BEETLE
In 1928, Mr. J. E. Graf, Assistant Chief of the Bureau of Ento-
mology, handed the writer a manuscript entitled “ Some chemotropic
responses of the Mexican bean beetle,’ by Wallace Colman, who tested
over 200 materials, but found only a few to be attractive while a
larger number were repellent. According to the results in this un-
published manuscript, which deals with the sense of smell alone, the
following seemed to be attractive: banana peel, amyl acetate, vanillin,
coumarin, corn sirup, honey, and molasses of the higher grades ; while
certain lead and arsenic compounds, including lead arsenate, seemed
to be repellent. Using different methods the present writer tested
all of the above supposed attractants, but found only the corn sirup
and molasses to be attractive, while lead arsenate proved to be re-
pellent.
(A) SEARCH FOR ATTRACTANTS AND REPELLENTS, USING AN OLFACTOMETER
Using the writer’s (45) olfactometer, with the plant chamber dis-
connected, no important results were obtained, but the following re-
marks may have some theoretical interest. On several occasions fresh
bean leaves were put in the small bottle, used for holding the odorous
substance to be tested. In each test in which only a few leaves were
used the odor or exhalation from the leaves was attractive to the
bean beetles, although the highest attraction was only 57.9 per cent.
In two other tests the bottle was filled full of leaves. The results
(61.8 per cent and 72.5 per cent), instead of showing attraction,
showed repulsion, indicating that attractants when concentrated be-
come repellents. The odors from table molasses (1 part molasses and
I part water) and the water extract (diluted juice) of bean leaves
were also found to be slightly attractive.
The following, used in minute quantities, were repellent: oil of
peppermint, creosotum, nicotine sulphate, banana peel, amyl acetate,
and geraniol.
No. 18 SENSE ORGANS OF COLEOPTERA—McINDOO 31
(B) SEARCH FOR ATTRACTANTS AND REPELLENTS, USING FEEDING METHOD
A search for attractants and repellents was begun in 1928, but dur-
ing that year no important results were obtained. The following re-
marks, however, may be of some interest. A liquid, highly scented
with skatol, when sprayed on bean foliage in the laboratory did not
delay the eating of the leaves. A piece of cotton, scented with oil of
peppermint, was put among some bean leaves. The leaves were
eaten as usual. Four odorous powders were prepared with the aid
of heat by using (1) nicotine sulphate and lead arsenate; (2) nicotine
sulphate and lime; (3) tar and lead arsenate; and (4) tar and lime.
When these powders were mixed with soap solution and sprayed on
bean foliage in the laboratory the sprayed leaves were eaten almost
as readily as were the untreated leaves nearby.
A wire-screen cage, 4 feet long, 3 feet wide, and 3 feet tall, con-
taining hundreds of adult beetles, was put in the insectary. A pan
containing bran bait was suspended in each corner. The first bait
was flavored with black-strap molasses ; the second, with amy] acetate ;
the third, with vanillin; and the fourth contained only bran and water.
The second and third baits each attracted only a few beetles; the
fourth, many; while the first, more than twice as many as the fourth.
It thus seems that the molasses bait was slightly attractive.
The preceding test was repeated by putting a pan containing black-
strap molasses and water in each corner, an aromatic being put in
each of three pans. The pans containing coumarin and vanillin at-
tracted practically the same number of beetles; the pan containing
amyl acetate, several more; and the pan-containing only molasses and
water, a few more, but the attraction was not significant.
The foregoing test was repeated by putting three pans in the cage.
One contained the juice from bean leaves; the second, the remaining
pulp of the leaves and diluted table molasses; and the third, diluted
table molasses. The first and third attracted beetles in equal number,
while the second attracted three times as many, not a sufficient number
to appear significant.
A pan containing fermenting table molasses was next put in the
center of the cage. For five days the beetles in it were counted, but
no striking attraction was noticed at any time.
Not yet having found any substance which seemed promising as
an attractant, the writer in 1929 decided to test a large number of
materials. After spending much time, 104 aromatic chemicals, 3
brands of molasses, 2 varieties of canesugar, and 1 highly scented
honey were tested. The method consisted of testing 8 substances at
one time in a small wire-screen cage. This method was found to be
3
32 SMITHSONIAN MISCELLANEOUS COLLECTIONS voL. 82
faulty, yet the writer believes that if a strong attractant in the proper
concentration had been used striking results could have been obtained
quickly. No important results were really obtained, but the follow-
ing remarks may be worth recording. Using water as a control, methyl
anthranilate, benzaldehyde, methyl benzoate, terpinyl acetate, di-
benzyl ether, tertiary amyl alcohol, and ethyl iso-valerate seemed to
be more or less attractive, but not sufficiently so to be significant. The
most promising chemical, methyl anthranilate, was tried in the bean
patch but attracted no beetles. In the preliminary tests while using
water and portions of bean leaves as controls, a good grade of table
molasses diluted with water was nearly always preferred to the con-
trols. Fermenting table molasses was attractive up to the vinegar
stage of fermentation, after that its attractiveness ceased. During
warm weather when the beetles were thirsty, a long series of tests
was conducted to ascertain their preferences when given water, mo-
lasses, sugar, and honey. The final results showed their preferences
to be: (1) water alone; (2) corn sirup and granulated sugar, practi-
cally the same; (3) table molasses and sugar sirup, the same; (4)
brown sugar; (5) honey; and (6) black-strap molasses. The sugar
sirup consisted of boiled brown sugar and water (about 1 to 1). The
brown sugar was a saturated solution. Each of the others was half
sweet substance and half water. On August 5 and 12, pans contain-
ing table molasses, corn sirup, and black-strap molasses were put
between rows of beans in the garden. Observations were taken there-
after for several days, but not a bean beetle was seen in the pans,
although many moths and certain other insects were caught in the
baits.
(c) SEARCH FOR ATTRACTANTS AND REPELLENTS, USING AN IMPROVED
FEEDING METHOD
In order to obtain comparative results which could be treated
statistically, four cages were constructed. Each cage was 8.75 inches
square, 0.75 inch deep (inside dimensions), and had a wooden bottom
and a top of wire-screen and glass (fig. 5, A). The substances to
be tested were put on pieces of cardboard (W, X, Y, and Z),
1.75 inches square, which were arranged in a row, being equally
spaced between themselves and the sides of the cage. From left
to right the positions of the cardboard were numbered 1, 2, 3, and
4. In the first series of tests the substances were arranged in the four
cages as indicated by the first row in the four diagrams (B, C, D, and
FE.) ; in the second series, as indicated by the second row; in the third
series, as indicated by the third row; and in the fourth series, as
No. 18 SENSE ORGANS OF COLEOPTERA—McINDOO 33
indicated by the fourth row. According to this arrangement of food,
no two rows in the same cage were exactly alike ; likewise, no two rows
of all 16 rows were identical, although the distribution of food was
not so complete. These four series of tests were conducted during
the forenoon, and then usually repeated in the afternoon. Each
2d_ |Series
Zs x W v4
3d |Series
W V6 ZA xX
4th |Series
Xx W We Z
D E
Fic. 5—Diagrams of wire-screen cage (A) and arrangement of substances (B,
C, D, and E) to be tested by bean beetles. See text, p. 32, for further
explanation.
Series
Ni
Series
individual substance used was therefore tested 16 times in the fore-
noon and usually 16 times in the afternoon.
It was difficult to decide whether tests of this kind should be con-
ducted in the dark-room or in the well-lighted laboratory. After try-
ing the dark-room it was observed that the bean beetles did not eat
freely either in artificial light or in total darkness. So it was de-
cided to place the cages on a table by a south window, but not in the
34 SMITHSONIAN MISCELLANEOUS COLLECTIONS vot. 82
direct sunshine. As suspected under these conditions, the number of
beetles counted in the four positions varied greatly. More beetles
were always counted in the outer positions (Nos. 1 and 4) than in
the inner ones (Nos. 3 and 4). This was caused largely by the beetles
following the sides of the cage while moving toward the window.
In 40 series of tests, selected at random, 67.04 per cent of the beetles
were counted in the outer positions and 32.96 per cent in the inner
positions. The following percentages were counted in the four posi-
tions: 37.06 per cent in position I; 17.01 per cent in position 2; 15.95
per cent in position 3; and 29.98 per cent in position 4. Since each
substance used lay in all four positions during any one series of tests,
these large differences did not supposedly change the arithmetic mean,
but they greatly affected the probable error, because each number of
beetles counted on a substance was considered a statistical item. Since
the beetles ate more freely during the forenoon than during the after-
noon, the probable errors were further affected.
In addition to the preceding statements, the general plan in con-
ducting these tests was to put 60 beetles of approximately the same
age and physiological condition in each cage. The number of beetles
on (or touching) the food was counted at intervals of 45 minutes,
and this number was considered a statistical item. The food was re-
newed whenever necessary to keep it in an appetizing condition, and
to prevent contamination it was usually put on unused pieces of card-
board. Since the beetles had a tendency to congregate at the ends of
the cages nearest the window, the cages were often turned end for
end, thus causing the insects to scatter more evenly. The daily tem-
perature and relative humidity in the laboratory were recorded, and
a record of the outside climatic conditions was also kept. In brief,
everything possible was done to obtain reliable data which could be
treated statistically. The arithmetic mean and probable error are
stated in tables 2 to 11 for reference in connection with the following
discussion. Since the statistical items were never less than 16, the
following formula for calculating the probable error was used—
oC
P, E.m=+0.6745 VN
(1) Beetles can distinguish differences between water and salty
liquids —To determine whether Mexican bean beetles “ like ”’ or “ dis-
like’ the four classes of substances which produce the four human
attributes of taste, many series of tests were conducted. The results
obtained are given in tables 2 to 5.
To ascertain whether these insects “like” salty water, sodium
chloride, potassium nitrate, and magnesium sulphate (epsom salts)
No. 18
SENSE ORGANS OF COLEOPTERA—McINDOO
os)
TABLE 2.—Tests to determine whether Mexican bean beetles can distinguish
differences between water and salty liquids
Se : vg ~ n
2 58 Fe a dere 5
Ooh) is s Oy, Pu Hy, wa
On 8 o e c s ou &
oo 3 al ~
Seg Eg Pee Sfa| 98 J
age ge Gu Seeule ae 2 Fe
222 ofa) ae o38| 38 z 5
iF a = Nae ra Z A 7,
Water on cotton (con-
HCN O) eateect als yous \s fecal, evs 106 |3.31 £0.44] 1.00
Sodium chloride on
QO OST, brane o.cOOr 13) | |On4te==10712)1 0; 02
Potassium nitrate on 16 | Aug. 29-30) 32
SOUEOI ote ie) arte ote ales ove 30 | 0.94 + 0.28} 0.28
Magnesium sulphate on |
GOETOM Me scosars ters clap ese 56) Deo == OL 27) 0553) |
TABLE 3.—Tests to determine whether Mexican bean beetles can distinguish
differences between water and sour liquids
‘so A es ~
, ae re 2 z
Ss ro) a iS
c= fe: 3s ray eee
DW wy so =e oY uo
S58 Beas ieee ee ae
S32 re ae ws E
% a ~ fa) —
eae oS os CRees 3S
a o a fo Z
Water on cotton (con-
BRO) MEN acts. Serer atyeeeae | 150 |9.38 £1.12] 1.00
. e |
Acetic acid on cotton. | 360, 2225 == 0700 |, 0.24 ck
. . | -
Hydrochloric acid on) |
| |
COG) Me tererateior pes & 21 OAH = 0747 | O. 20
Lemon juice on cotton. 27 | 0.60 == 0: 44)| 0.18
Number of tests
Date
Aug. 31 16
TABLE 4.—Tests to determine whether Mexican bean beetles can distinguish
differences between water and bitter liquids
-) , n ~ 5
Z SS un 3 wee | 8 =
2 gos S Se es 2
we
os 258 ~§ age Rr “s
tp | e vo ~
Sie 22s a5 ga |. 33 3
aa Bes as me E 2 E
e22 B28 oa ose | 5% = 5
Pe ee = = [A Z a) vA
Water on cotton (con- |
REGh) ecko eee 171 | 10.69 £0.84] 1.00
Strychnine on cotton.| 102 | 6.38+0.78)| 0.60 14 Aug. 16 16
Quinine on cotton.... S37 ebro = s72)| "O240 |
Picric acid on cotton. AG | 2e00 == 0. 20) NOL ey, |
Leaves, sprayed with
water (control) ..| 198 | 6.19 0.29) 1.00
é 20 Sept. 14 32
Leaves, sprayed with
bectievextracty aa... fe ky een 5530:-=10-30)||1 0.07
36 SMITHSONIAN MISCELLANEOUS COLLECTIONS VoL. 8&2
were used at the rate of 1 gm. of salt to 25 cc. of water (table 2).
Pieces of cotton of equal size were wet with tap water and with the
three salty solutions, and then they were put on the pieces of card-
board, as already described.
(2) Beetles can distinguish differences between water and sour
liquids—To ascertain whether the above statement is true, three
TABLE 5.—Tests to determine whether Mexican bean beetles can distinguish
differences between water and sweet substances
8% g 265 3 eon Sy ae)
ELE Bgl ae) Ve Ea ass :
253 ae a ae a2 go 2 2
che BeEL 22 0 | gee es | eae
Water on cotton (con-
trol) acres roe 845 106'== 002341 1300
Cane sugar on cotton.. | 307 |9.60+0.75| 9.03 16 | Aug. 29-30 32
Grape sugar on cotton.| 87 |2.72+0.35| 2.56
Saccharine on cotton. . 15 |0.47+0.12| 0.44
Leaves, sprayed with
water (control) ....| I41 | 4.41 +0.36| 1.00
Leaves, sprayed with
Canessucat een eernee 254 |7.04+0.41| 1.80
Leaves, sprayed with = epiata a2
grapesugab ase eoe ee 202) 16330 ==0s44 tes
Leaves, sprayed with
Saccharine een. sa ELS | 325320027) 0.60
Leaves, sprayed with
water (control) <.. | ro08 | 3.38: 0133] 1-00
Leaves, sprayed with
table molasses .. ss -261 |8.16+0.51| 2.42 ee Seta a
Leaves, sprayed with
(COIs Hiab) Soconoac 174 |5.440.40| 1.61 |
Leaves, sprayed with
black-strap molasses.| 203 | 6.34 0.41] 1.88
sour liquids were used, each of two being prepared at the rate of 4 cc.
of glacial acetic acid (99.5 per cent) or hydrochloric acid (85.9 per
cent) to 25 cc. of water, and the third at the rate of 4 cc. of lemon
juice to 21 cc. of water (table 3). |
(3) Beetles can distinguish differences between water and bitter
liquids —To determine whether the above statement is correct, four
bitter liquids were used, each of three being prepared at the rate of
No. 18 SENSE ORGANS OF COLEOPTERA—McINDOO 37
50 mg. of picric acid, quinine sulphate, or strychnine sulphate to 25 cc.
of water. The fourth was prepared by adding 25 cc. of water to the
macerated bodies of 20 live bean beetles. The resulting liquid, when
filtered, was yellowish and to the writer had a bitter taste and an
unpleasant odor. It was sprayed upon bean leaves, which when dry
were cut into pieces, one inch square, then put on the pieces of card-
board, and finally fed to the beetles (table 4).
TABLE 6.—Tests to determine whether bean foliage sprayed with sweétened
arsenicals 1s more attractive to Mexican bean beetles than
uns prayed foliage
os 2 vs oD 2
bokes| ue £ 4 = a o
eas oo ei a ‘So fe
cS: Bo ole) x eae °
see a3 Bg 280 | 3? y
Cr SNES oo ZOO sy 2
ane g2 3 au aa hn e
os Su & 3 st 2 SI
oS 05.8 ats OSL 55 3 5
a =a = oa ae Z A 2
Unsprayed (control).. TA 231 ==10535) LOO
Calcium arsenate and
QURTIO Bt os Onn: TOO 3031 == 0.50) 0.43
Magnesium arsenate 18 Sept. 5 32
ANGUSUPAR . occa. s EGY 4etO== 0533) 1577
Lead arsenate and
SU Oi rere co Sieuars ctevate 132s Pele ==0, 30) tao
Unsprayed (control)... | 131 | 4.10 =0.38| 1.00
Magnesium arsenate
and table molasses..| 194 |6.06+0.40| 1.48
Magnesium arsenate
and corn sirup...... 157 |4.90+0.49| 1.20
Magnesium arsenate
and black-strap mo-
ASSES Bale ectreretcie se 113 |3.530.40| 0.86
22 Sept. 25 32
(4) Beetles can distinguish differences between water and sweet
liquids ——To determine whether the above is correct, 24 series of
tests were conducted by using six sweet solutions, each of five of them
being prepared at the rate of I gm. or I cc. of granulated cane sugar,
grape sugar (dextrose), a high quality table molasses, corn sirup, or
black-strap molasses to 25 cc. of water; and the sixth at the rate of
20 mg. of saccharine to 25 cc. of water (table 5).
From the information given in tables 2 to 5, with additional notes,
it may be concluded that Mexican bean beetles exhibit “likes” and
“dislikes ’ when fed substances which produce the four human at-
38 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82
tributes of taste. They “disliked” water containing salts, acids,
bitter materials, and saccharine, but “liked” the other sweet sub-
stances, including cane sugar, grape sugar, table molasses, corn
sirup, and black-strap molasses, and even showed preference between
them. To the writer the saccharine solution was sweetest, but dis-
tasteful; the cane sugar, less sweet, and tasteful; and the grape sugar,
least sweet, and less tasteful. The beetles showed “ dislikes’ and
TABLE 7.—Tests to determine whether bean foliage sprayed with arsenicals,
is repellent to Mexican bean beetles
aS = 7
us bE a ae dee E
uF cr 3 = og 8
ohgo} Cal au oO a
SoS S38 33 S62 | 3s 8 5
5 = Ss 4 Z, la zi
Unsprayed (control) .| 191 |5.97 0.49! 1.00
Calcium arsenate ....| 160 |5.00+0.62| 0.84 |
Magnesium arsenate..| 177 |5.53+0.56| 0.93 » SB Sie
Meadwarsenates meee. DUC e4 7 = 02401 Onss
Unsprayed (control)..| 275 |8.59+0.67| 1.00
Calcium arsenate .... | 177 115.53 = 0:50) mou6s
Magnesium arsenate..| 122 | 3.81 +0.42| 0.44 > Sena 32
Lead arsenate ....... 1228 Shor 0749) On4a
Unsprayed (control)..| 172 |5.38=0.46| 1.00 |
Calcium arsenate ....| 159 |4.07 +0:35| 0.02 |
Magnesium arsenate..| 104 | 3.25 +0.25| 0.60 “4 Sept 27 ae
eadRarsenatesee eerie HO Go S=O.22)|! O50). | |
SuMMARY of above:
Leaves, unsprayed
(controls), Secession. 638 | 6.64 +£0.33] 1.00 :
Calcitim arsenate ....| 406 |'5.17 20:20) 027 Aho cis ih hcnecesel eta above
Magnesium arsenate..| 403 | 4.200.26) 0.63 96
Lead arsenate: ho aan05 S84 Seto = 04221 Ons |
“likes” in somewhat the same order. To the writer the picric-acid
solution was most bitter, the quinine less bitter, and the strychnine
least bitter. The insects ‘‘ disliked” these solutions in about the same
order. To the writer the solutions containing acetic acid and hy-
drochloric acid had practically the same degree of sourness, while the
diluted lemon juice was sourer. The beetles also showed only slight
differences between them. In regard to the salty solutions, the writer
disliked only the magnesium sulphate sclution, but the beetles pre-
ferred it to the other two.
No. 18 SENSE ORGANS OF COLEOPTERA—McINDOO 39
(5) Bean foliage sprayed with sweetened arsenicals is more at-
tractive than unsprayed foliage——To ascertain whether the above is
correct, 16 series of tests were conducted. The arsenicals were pre-
pared as stated on the following page, then 1 gm. of granulated cane
TABLE 8.—Tests to determine whether bean foliage sprayed with sweetened
magnesium arsenate is more attractive to Mexican bean beetles than
foliage sprayed with non-sweetened magnesium arsenate
é e3 Se eee :
$5 Bs oe ose | 3s = =
4 = = a Z A =
Magnesium arsenate
(aot) coaeococe FAC || DG SE (o)6)|| 1000
Magnesium arsenate
and table molasses
(GEtOASO) i. eens 102) |(6+00)==0, O11 2-70
Magnesium arsenate 23 Sept. 26 a2
and corn sirup (2 to
50) Sa eeaeee pees 114 |3.56+0.39| 1.60
Magnesium aresnate
and black-strap mo-
lasses (2 to 50)....| 122 | 3.81 +0.43| 1.72
Magnesium arsenate |
(CoOnttol) essere |) 82.1) 2556 c= 0.28). 100
Magnesium arsenate
and black-strap mo-
fasese(2) tow50)) panel elgen inl 2)== Ons) ener
Magnesium arsenate
and black-strap mo-
lasses (I to 50)....
Magnesium arsenate
and black-strap mo-
lasses (3 to 50))..... | 134 |/4.19 320.32) 1.63
25 Sept. 30 32
|
|
|
|
|
105) 32 50/==020)))) 140) ||
sugar or I cc. of a high quality table molasses, corn sirup, and black-
strap molasses was added to 25 cc. of the spray mixture (table 6).
According to the results given in table 6, it is again shown that
these beetles like their food sweetened.
(6) Bean foliage sprayed with arsenicals ts repellent—To deter-
mine whether bean foliage sprayed with arsenicals is eaten as readily
as are unsprayed bean leaves, 24 series of tests were conducted. The
4
40 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82
leaves were sprayed with calcium arsenate, magnesium arsenate, and
lead arsenate at the rate of 1 pound of powder to 50 gallons of water.
The calcium-arsenate mixture also contained lime at the rate of 1.5
pounds to 50 gallons of water (table 7).
The results given in table 7 clearly show that arsenicals are repel-
lent, but not sufficiently so to prevent the foliage from being eaten.
Lead arsenate was most repellent, magnesium arsenate was less so,
and calcium arsenate was least repellent. The word “ deterrent” is
probably the better expression in this case.
TABLE 9.—Tests to determine whether water extract and steam distillate of
bean leaves are attractive to Mexican bean beetles
é 2 ey eae g
= Bes 2 5° i g
we Ug io} ° ay > aie G4 a
ets Eas Ze onee AW ere ‘Se
eS 28 a eis eae ,
Oy gat. dv ‘Sae . 2° a ie
Bos S455 os oeeS| Se = I
= ep = eA Zz A 7,
Leaves, unsprayed
(contro!) ieee. TOO 58 O4)==10430) OO
Water on cotton.... 20H ORG 7,== 04044 Om Ls
Water extract on cot- a Sept. 18 :
| ept.
OM Hetausteceherierslasctetete 107) | Se22 = =OA0l OG P 3
Water extract and
cane sugar (1 to
25))) son) cottons. | 677) 2,06 == 0.82)" 3), 56
Water on cotton ]
(control) Meee lars | 6.48 = 0.41 | 1.00 2!I Sept. 19 64
Distillate on cotton..| 436 | 6.81 +0.43)| 1.05 [
(7) Bean foliage sprayed with sweetened magnesium arsenate 1s
more attractive than foliage sprayed with non-sweetened magnesium
arsenate-—To determine whether the above is true 16 series of tests
were conducted by using magnesium arsenate (1 pound to 50 gallons
water) with molasses added at the rate of 2, 1, and } gallons to 50
gallons of the spray mixture (table 8).
The results given in table 8 once more show that sweetened food is
preferred to non-sweetened food.
On September 30 four small bean plants, each bearing six leaves,
were sprayed. Two of these were sprayed with magnesium arsenate
alone and the other two with a mixture of magnesium arsenate and
black-strap molasses (1 to 50). One plant sprayed with the non-
sweetened mixture and one with the sweetened mixture were put to-
la rae aan
No. 18 SENSE ORGANS OF COLEOPTERA—McINDOO 4!I
gether in one end of a cage, and the other two sprayed plants were
arranged likewise at the other end of the cage. Soon after placing
100 beetles in the cage the insects climbed upon the sprayed foliage,
paying apparently no more “attention ” to the sweetened leaves than
to the non-sweetened ones, but after a few hours and thereafter until
October 3, when the experiment was ended, the sweetened leaves
bore the more beetles and were the more eaten. The final result
TABLE 10.—Tests to determine whether chemotaxis or phototaxis is more
important in the finding of food by Mexican bean beetles
ong eo. 36 ain o 8 Be
owe 23 o, a5 vy | ge 5o
onc vv aa nese as Q
soy Sone as S ae] & & ee]
eee SHo 9 ord yews 3 A 35
aol fH be ones a 4 eq
sn Ee tS Ee le ee
Bean leaves, not |
sprayed (control). 65.5) e2ar2)-Siosn 100 |
Apple leaves not 32 tests.
BBEAVEU (ale as ows ahe-6 4 | 0.12+0.02| 0.06 a2 | Seppe) Beetles
Green water on cot- “| in direct
(WEIN! Games A ORS 196) || 6,12) == 0.70) 2.88 sunshine.
Green sugar water (I
to 25) on cotton..| 635 |19.84+0.99| 9.34
Bean leaves, not
sprayed (control).| 116 | 3.62+0.24/ 1.00
Mulberry leaves not |
SPLAVER, sci scrseic LO) | O.50/== 0) 10 | 0-16
Mulberry leaves,
; 22 Sept. 24 32
sprayed with sugar | |
water (I to 25)... 78. 2528'22102 30) |) 0163
Bean leaves, sprayed
with sugar water
GH 45. 25) Skeets 221 | 6.0% =='0342)| 1-60
| |
showed that the sweetened leaves bore 69.7 per cent of all the beetles
counted on the four sprayed plants.
(8) Water extract and steam distillate of bean leaves tested —To
test the diluted juice of bean foliage, a water extract was prepared by
adding 50 cc. of water to ro gm. of leaves, cut into small pieces. After
macerating the pieces and decanting the liquid through cheesecloth,
50 cc. of a greenish liquid was secured. To test the steam distillate
of bean foliage, 100 cc. of water was added to 30 gm. of leaves, cut
into small pieces, and then 50 cc. of a clear and odorous distillate was
collected (table 9).
42 SMITHSONIAN MISCELLANEOUS COLLECTIONS voL. 82
The results given in table 9 show that when water extract of bean
leaves was compared to unsprayed leaves it was about equally attrac-
tive, while sweetened water extract was about 3.56 times as attractive.
Steam distillate from bean leaves was not attractive, but gave practi-
cally the same result as did water, indicating that its faint odor had
no attractive influence.
(9) Chemotaxis more important than phototaxis in the finding of
food. Sixteen series of tests were conducted to ascertain whether
phototaxis or chemotaxis, or possibly thigmotaxis, is the more im-
portant in the finding of food. Squares of bean leaves, apple leaves,
TABLE 11.—Tests to determine whether repellents would protect beans from the
Mexican bean beetle
: = ze | ¢ g
Bshee} us & os o
a GS ie) ry > uw Fi
gas = 2 ne S = oi
ae oe, | "28 ie | 3F ;
i oo oe 2
cae ge Ee mata tele 2 E
8 ma cee s 3 2 Os 2 iS) ra 2
Unsprayed (control)..| 226 | 7-06 == 91,A0)|/ 00), |
ikanmance limes ee 216 6-75 ~0.53} 0.96 |
Nicotine sulphate and | t 19 Sept. 9 32
Airmerng ste oss vie aal ores |) £o6) |\o-12 2 0747 0.87 |
Derns product ).-... - | £20") 3275 == 0.47.) 10.53
Unsprayed (control)..| 256 | 8.00 £0.64) I.00
| |
kona ees aiece uals g 7 5e4==)0) O.
oo iy KZ ot 0-22) Be 19 Sept. 10 32
Nicotine sulphate ....| 219 |6.84=0.56| 0.85
Beta naphthol™ 3...) f 142 14.440.47| 0.55
and mulberry leaves, all of the same shape and size (1 in. square),
but some bearing a film of cane sugar, represented practically the
same color, form, and texture, but differed chemotactically. Cotton
wet with green water and with green sugar water (a green dye being
used) also somewhat resembled the leaves in color but differed in
other respects (table 10).
The results given in table 10 show that sweetened food is preferred
to non-sweetened food and that chemotaxis is more important than
phototaxis in bringing about the results obtained.
(10) Repellents would probably not protect beans—To ascertain
whether certain substances, usually known as repellents, would keep
the beetles away from the treated leaves in the four small cages,
bean foliage was sprayed with the following: Tar and lime, combined
as a dust; nicotine sulphate and lime, combined as a dust, a com-
NO. 18 SENSE ORGANS OF COLEOPTERA—McINDOO 43
mercial Derris product, consisting mostly of pyridine; cresol, U. S.P.
(1 cc. shaken in 400 cc. water); 40 per cent nicotine sulphate in
water (I to 400) ; and beta naphthol (1 gm. powder in 400 cc. water ;
powder not all in suspension) (table 11).
The results given in table 11 show that the repellents more or less
protected the leaves, but not sufficiently so to prevent them from
being eaten. The Derris product and beta naphthol were the only ones
which might be considered promising, yet their protective value was
about equal to that of lead arsenate, as already shown in table 7.
III. THERMOTAXIS :
After having searched the literature for references on other
tropisms not yet discussed, the writer found a few more concerning
Coleoptera, but only two of these references pertain to the orientation
of beetles to temperature. Much experimental work on various tem-
peratures, particularly as control measures, has been done, but very
little of it can be discussed from the tropic point of view.
I. REVIEW OF LITERATURE
Fulton (17) devised a crude temperature gradient with which he de-
termined that the choice of temperature of adult click beetles is much
below the usual maximum temperature in open fields during summer.
He also says that negative phototaxis causes the beetles to seek dark
hiding places during the day. Wireworms, or the larvae of these
beetles, were found more resistant to heat than were the adults, but
they did not voluntarily seek higher temperatures. Seasonal move-
ments of the larvae may be closely correlated with changes in soil
temperature.
Grossman (21) tried three methods to determine the orientation of
cotton boll weevils to heat stimuli, but decided that only the results
obtained by using a new apparatus were reliable. This apparatus was
constructed by using 16 copper bars $ inch wide and 3g inch thick, with
gz inch insulating space between each two bars. Using only two
variables, temperature and light, 126 boll weevils were tested 1,993
times. The average temperatures to which they reacted definitely were
130° F. at the hot end of the apparatus and 26° F. at the cold end.
B. Sensory RECEPTORS
Since tropic responses are brought about largely by external stimuli
affecting either the special sense organs or others not definitely known
and localized, called the general sense organs, it is only natural to
discuss the tropic responses and sensory receptors in the same paper.
44 SMITHSONIAN MISCELLANEOUS COLLECTIONS VoL. 82
I, PHOTORECEPTORS
According to the phototactic responses of the Mexican bean beetle
and its larva, already discused, the compound eyes and ocelli in this
species are normally developed and seem to function adequately, so
far as beetles are concerned. It is recalled that the adults are always
photopositive and that the larvae up to the time of pupation are photo-
positive, too, but when ready to pupate they become photonegative.
Whether the negative reaction is caused by a change in the structure
of the ocelli is not known.
Since the morphology of insects eyes has often been discussed and
as the writer (46, 47) has recently cited reviews on this subject, no
further discussion is needed here. Also, the other sense organs and
senses of beetles will be discussed only briefly.
Il. CHEMORECEPTORS
Chemoreceptors include both olfactory and gustatory organs, but
we are not absolutely sure that insects have true chemoreceptors, al-
though their organs certainly belong to the same category.
I. SO-CALLED OLFACTORY ORGANS
(A) ANTENNAL ORGANS
The organs on the antennae of the Mexican bean beetle are com-
paratively few; that is, these antennae are nearly bare in comparison
to most antennae (fig. 6). Only four types of sense organs were
found on them. They are as follows: (1) Two groups of tiny hairs
(St) ; and (2) three or four pores (P), called olfactory by the writer,
lie on the base of the first antennal segment; (3) the Johnston organ
(J) lies at the distal end of the second segment; and (4) five areas
of thin-walled hairs (OHr) were found on the distal ends of the ninth,
tenth, and eleventh segments. All of these structures are sense organs,
because sense cells were found connected with them, while the larger
hairs (Hr), usually called sense bristles, were found to be non-
innervated.
Of these four types of sense organs only the olfactory pores and
thin-walled hairs may be regarded as so-called olfactory organs. -The
thin-walled hairs are numerous and most of them lie on the dorsal
surface of the antennae (fig. 6, OHr). Under a high-power lens they
appear long and slender, have thin, almost transparent walls (C, OHr),
and are connected with sense cells.
From the preceding it is evident that pore plates, found only on
the antennae of aphids, bees, wasps, and on some beetles, are totally
absent on the antennae of the Mexican bean beetle. The pore plates,
No. 18 SENSE ORGANS OF COLEOPTERA—McINDOO 45
when present, are considered the olfactory organs by most writers.
Figure 7 illustrates the antennal organs of a water beetle, copied from.
Hochreuther (25). The pore plates (PP), hollow pit pegs (HPPg),
and massive pit pegs (MPPg) might be called olfactory organs, but
Hochreuther regarded only the hollow pit pegs as probably olfactory
in function. If they really act as olfactory organs, then the mouth
parts, thorax, legs, and sexual organs must aid in receiving odor
stimuli, because Hochreuther found them also on these parts of the
anatomy.
Fic. 6.—Drawings of antennae of adult Mexican bean beetle, showing organs
on them. A, ventral surface, and B, dorsal surface, showing location of follow-
ing: Hr, noninnervated hairs; J, Johnston organs; P, pores called olfactory
by the writer; OHr, so-called olfactory hairs; and St, tactile hairs. C, a semi-
diagrammatic drawing from a section through tenth segment, showing structure
of so-called olfactory hairs (OHr) and their sense cells (SC). A and B, X 53;
and C, X 500.
(B) OLFACTORY PORES
The writer (46, p. 1105) in 1926 cited references pertaining to
these organs in beetles and in 1929 he (47, p. 27) stated why they
were called “ olfactory pores.” In 1915 (41) he made a comparative
study of them in 50 species of beetles belonging to 47 genera and rep-
resenting 34 families. In that study only the legs, elytra, and wings
were examined for these pores. A group of pores (fig. 8, A and B, r)
was always found on the peduncle of each elytron. The number of
pores in it ranged from 12 to 310, and the more pores in the group
the smaller they were and the closer they were together. Of the 47
46 SMITHSONIAN MISCELLANEOUS COLLECTIONS VoL. 82
Fic. 7.—Antennal organs of a water beetle, Dytiscus marginalis, copied from
Hochreuther (25). A, longitudinal section through a hollow pit peg (HPPg) ;
B, longitudinal section through a small massive pit peg (MPPg) and 2 pore
plates (PP). This drawing is a combination of Figs. 32 and 58 from Hochreuther,
slightly modified. C, a small tactile hair from first segment, total preparation;
and D, portion of Fig. 12 from Hochreuther, showing 4 small sense bristles
from second segment. NF, nerve fiber; SC, sense cell; SCG, sense cell group;
and SF, sense fiber.
Fic. 8.—Portion of left elytron (A and B) and left wing (C) of Mexican
bean beetle, showing position of olfactory pores as indicated by numbers 17 to 4
and letters a to d on dorsal surfaces. A shows relative sizes of peduncle of
elytron and group 1 when compared with size of basal margin (BM) of elytron;
A and C, X 12; and B, & 67. The lower side of A and B is the outer margin
of the elytron. C, costa; MD, muscle disk; Me, media; FR, radius; RP, radial
plate; Sc, subcosta; ScH, subcostal head.
No. 18 SENSE ORGANS OF COLEOPTERA—McINDOO 47
winged species examined, 11 had only one group of pores on each
wing, 21 had two groups on each wing, 12 had three groups on each
wing (C, 2, 3, and 4), and 3 had four groups on each wing. The
Fic. 9.—Position of sense organs on legs of adult beetles; dots, marked 5
and 6, and ¢ and f, being olfactory pores; and St, tactile hairs. A to F, legs of
Mexican bean beetle, 12; and G, distal end of tibia from front leg of Epicauta
marginata, showing 5 olfactory pores on tibial spine. The drawing of each leg
in which the tarsus is shown represents the outer surface and the portion of leg
without tarsus represents the inner surface of the same leg. A, right front
leg; B, left front leg; C, right middle leg; D, left middle leg; E, right hind
leg; and F, left hind leg.
number of pores on a pair of wings ranged from 130 to 982. The
number of pores counted on all six legs of an individual ranged from
49 to 341. There were usually two groups of pores on each trochanter
(fig. 9, 5 and 6). Sometimes a pore was found at the proximal end of
48 SMITHSONIAN MISCELLANEOUS COLLECTIONS voL. 82
the femur. A few pores were always found at the proximal end of
each tibia (e and f), and sometimes pores were found in the tibial
spines (G) and on the tarsi.
In regard to water beetles, the better the legs are adapted for loco-
motion in water, the fewer pores they have. The smallest winged
species examined had 273 pores, which is the smallest number counted
of all the species, and the largest species had 1,268 pores which is the
largest number of all the species examined. The wingless species had
more pores on the legs than usual. As a rule, the smaller the species,
the fewer its pores and the larger they are, comparatively speaking.
As a rule, no generic and specific differences were found, except vari-
ations in number of pores, the amount of variation depending on the
sizes of the individuals compared. There were no individual and
sexual differences other than slight variations in number of pores.
The pore apertures or pits are round, oblong, slitlike, or club-
shaped. On the elytra and wings (fig. 10, A and B, Ap) they are al-
ways round or oblong. On the legs (C) they have all four of the
enumerated shapes.
The spindle-shaped sense cells (fig. 10, C, SC) of most beetles lie
in the lumens of the appendages outside the pore cavities. A small
chitinous cone (Co) is always present. It is formed by the hypoder-
mal cell at the mouth of the pore after the insect has emerged from
the last pupal instar, and at the same time when the chitinous integu-
ment is being considerably thickened. The sense cells are fully devel-
oped when the insect emerges into the imago. The sense fiber pierces
the cone, and comes in direct contact with the outside air. This state-
ment is denied by other writers. In the legs of the lady-beetle Epi-
lachna borealis the pore apertures lie in the center of domes (fig.
10, C) above the general surface of the legs.
A large nerve and a large trachea run into each elytron (fig. Io,
A, N and Tr) and wing. In the peduncle of the elytron they run
through the radial plate just beneath the group of olfactory pores.
Branches from the nerve are given off which connect with the sense
cells. The large nerve and trachea passing into the wing soon divide
so that a smaller nerve and a smaller trachea (B, N and Tr) run
through each main vein. The largest trachea passes through the sub-
costa, and the largest nerves pass through the veins bearing the ol-
factory pores. These nerves give off branches which connect with
the sense cells. The sense cells (C, SC), wherever found, are always
surrounded by blood (1).
In a study of the sense organs of the cotton boll weevil, the writer
(46) found the olfactory pores common to both the adult and larva;
——
No. 18 SENSE ORGANS OF COLEOPTERA—McINDOO 49
Fic. 10.—Diagrams showing portions of elytron, wing, and leg of adult beetles,
to illustrate internal and external anatomy of these appendages and of olfactory
pores and hypodermal glands. A, oblique transverse-longitudinal view of portion
of peduncle of Epilachna borealis. The transverse portion passes through group
1 of the olfactory pores and radial plate (AP) in the direction of the line marked
X in figure 8 B. B, transverse-longitudinal view of portion of wing of Orthosoma,
passing through pores on radius (R) and media (Me). C, transverse-longitu-
dinal view of proximal end of trochanter belonging to right hind leg of E.
borealis, passing through group 6 of olfactory pores (4 pores on right) and
group 5 (3 pores at left). Ap, pore aperture, BI, Blood; Co, chitinous cone;
GC, hypodermal gland cell; Hr, noninnervated hair ; N, nerve; Po, pore of
hypodermal gland; SC, sense cell; SF, sense fiber; and Tr, trachea.
50 SMITHSONIAN MISCELLANEOUS COLLECTIONS voL. 82
but the other so-called olfactory organs, which are nothing more
than ordinary innervated hairs, are common only to the antennae of
the adult, although similar innervated hairs are also found on other
parts of both adult and larva. In the adult the olfactory pores were
found on the head capsules, legs, elytra, wings, and mouth parts, and
at the base of the antennae; in the larva, on the head capsule, base
of antennae, mouth parts, clypeus, and second thoracic segment. The
individual and sexual variations found in the pores were small, al-
though the females have 13.7 per cent more pores than have the
males.
Fic, 11.—External view of single olfactory organs and noninnervated hairs
on larva of Cotinis nitida, & 320. A, 4 organs from trochanter, showing pore
border (PB), pore aperture (Ap), and pore wall (PW). B, 2 organs and a hair
from hypopleural region; C, 2 organs from maxilla; D, 2 organs and a hair
from labrum; E, 2 organs from labium; F, 2 organs and a hair from epicranium;
and G, a hair from first antennal segment.
On the larva of the green June beetle (Continis nitida L.) the writer
(44) found the olfactory pores unusually numerous and consisting of
two types. The single olfactory organs are isolated pores, not arranged
in groups. They were found on the antennae, all mouth parts, head
capsule, thorax, and legs, and average 1,359 pores per individual
larva. This number is slightly more than the total number of pores
found on the elytra, wings, and legs of an adult of the same species.
Their external anatomy is unusual in that the pore border (fig. 11,
PB) is radially striated, while the border around the hairs never
shows striae. The compound olfactory organs (fig. I2) are variously
shaped plates, each of which bears many apertures. They were found
only on the distal halves of the last antennal segments. Figure 13
illustrates the internal anatomy of the single and compound organs.
ee
No. 18 SENSE ORGANS OF COLEOPTERA—McINDOO Sl
Fic. 12.—External view of compound and single olfactory organs and olfactory
pegs on distal half of last antennal segment of larva of Cotinis nitida. A, 9 com-
pound organs and 3 single ones on ventral side of antenna, viewed from a flat
surface, < 100; 2 of the compound organs at extreme tip are not shown. B, 6
compound organs, 4 single ones, and I group of olfactory pegs (Pg) on dorsal
side of antenna, viewed from a flat surface, X 100. C, external view of a com-
pound and a single organ, 320; the small circles represent pore apertures.
Fic. 13.—Internal anatomy of sense organs on antenna of larva of Cotinis
nitida. A, longitudinal section through tip of antenna, showing innervation of
compound (P/) and single olfactory organs (FP), and tactile hair (St); two-
thirds diagrammatic, * 100. (At this magnification the pore apertures are never
discernible). B, cross section through single olfactory organ from antenna,
x 500. Ap, pore aperture; Hyp, hypodermis; NB, nerve branch; NF, nerve
fiber; SC, sense cell; S/, sense fiber; and Tr, trachea.
52 SMITHSONIAN MISCELLANEOUS COLLECTIONS voL. 82
The olfactory pores on several males and females of the Mexican
bean beetle were examined, but they were actually counted on only
one female, and these are illustrated in figures 6, 8, 9, 14, and 15. In
this study only one totally new fact was learned. In all the previous
studies on beetles, no olfactory pores were seen on the ventral side of
the peduncles of the elytra, but in this position on the bean beetle 7
pores were seen on one elytron and 6 pores on the other. The groups
Fic. 14.—External view of chemoreceptors of adult Mexican bean beetle. A,
noninnervated hairs and group 5 of olfactory pores on trochanter of front leg,
< 500. B, ventral surface of distal end of maxillary palpus, showing numerous
noninnervated hairs (Hr) with their gland pores, isolated olfactory pores (P),
group 7 of olfactory pores (7), and a plate bearing numerous so-called taste
hairs (THr), X 100. C, group 7 of olfactory pores, markings on chitin, hairs,
and gland pores, X 500.
of pores are numbered, as usual, from 1 to 7, and small letters are
used to indicate the position of some of the isolated pores. Group I
on the elytra (fig. 8, A) contains 58 pores on the left peduncle and
65 on the right one. Groups 2, 3, and 4 on the dorsal surface of the
wings (C) have as follows: Group 2, 58 and 64 pores; group 3, 43
and 38 pores; and group 4, 70 and 64 pores. Isolated pores on the
wings are as follows: At a, 2 on the ventral side; at b, 8 on the dorsal
side; at c, 1 on the dorsal side; and at d, 12 on the dorsal side and 8
on the ventral side. The number of pores in groups 5 and 6 and at e
No. 18 SENSE ORGANS OF COLEOPTERA—McINDOO ne
and f on the legs (fig. 9) can be counted by inspection. Group 7, con-
sisting of 8 slit-shaped pores, lies on the ventral surface of the ter-
minal segment of the maxillary palpus. All the’ remaining pores
counted are isolated ones found on the antennae and mouth parts.
The total number of pores on all appendages of the same bean beetle
are as follows: Wings 397, elytra 136, legs 95, maxillae 32, labium
14, antennae 8, mandibles 6, and labrum 4, making 692 in all. The
Fic. 15.—Internal structure of sense organs on adult Mexican bean beetle,
* 500. A, an olfactory pore, gland cell (GC), and sense hair from dorsal surface
of labrum. B to G, olfactory pores; B, from mandible, C, from maxilla; D,
from elytron; E, from trochanter; F, from tibia; and G, from wing. H, sense
hair from trochanter. I, drawing, two-thirds diagrammatic, from longitudinal
sections of distal end of labial palpus, showing innervation of so-called taste
hairs (THr), tactile hairs (St), and olfactory pore (P). J, semidiagrammatic
drawing from 3 cross sections through base of first antennal segment, showing
tactile hairs (St), gland pore (Po), olfactory pore (P), trachea (Tr), and
nerve (N).
fact that this number is small for an adult insect might be correlated
with the fact that the bean beetle is “ stupid ” when the olfactory re-
sponses are considered.
The olfactory pores on several individuals of all four instars of
bean-beetle larvae were examined. Since no differences in number
and position were observed, the pores were carefully studied on only
individuals of the fourth instar. They are illustrated in figure 16.
The total number of pores on all appendages and the head are as
follows: Legs 30, maxillae 12, head capsule 6, antennae 4, labrum 4,
54 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82
labium 4, and mandibles 2, making 62 pores in all. The fact that this
number is extremely low for any insect may help to explain why these
larvae did not respond readily to odor stimuli.
is
Cc D
Fic. 16.—Position of olfactory pores, (dots), 12 to 15 so-called taste hairs
(Thr) at tip of each maxillary palpus, 8 tactile or so-called olfactory hairs
(St) at tip of each antenna, and ocelli (Oc) on larva of bean beetle, X 32.
A and B, inner and outer sides respectively of right front leg. The number of
pores on the legs is nearly constant, and they shift only slightly in position.
C and D, dorsal and ventral surfaces respectively of the head and head appen-
dages. On the base of each antenna one pore is on the dorsal side and one on
the ventral side. On each terminal maxillary segment there is a slit-shaped pore.
2. SO-CALLED TASTE ORGANS
Several writers, particularly Nagel (58), have described certain
tiny peglike hairs on the mouth parts of insects as taste organs, but
no one has ever demonstrated that they perform such a function.
Hochreuther (25) found many “ Tast- und Geschmackszapfchen ”
on the maxillary and labial palpi of the water beetle Dytiscus margi-
no. 18 SENSE ORGANS OF COLEOPTERA—McINDOO 55
nalis. The earlier papers concerning the chemoreceptors of Coleoptera
are reviewed by Deegener (see Schroder (72, pp. 150-151). Since
Minnich’s papers on the taste organs of butterflies and flies have
recently been reviewed by the writer (47, pp. 36-39), they will not be
discussed here. The reader should know, however, that according to
the experiments conducted by Minnich certain butterflies bear so-
called taste organs in their tarsi, and certain hairs on the proboscis of
the blowfly serve as gustatory organs. The most recent paper by
Minnich (55) discusses the chemical sensitivity of the legs of a
blowfly.
The writer (46) described and illustrated many tiny peglike hairs
found on the cotton boll weevil, but did not attribute a gustatory
Sui
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————
6
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4 |
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Ay
¢ , ai y.
bs bf i S Ps 2 Jaf By\ | oy
3 y LA Vie/. ZA (ay
‘| LY r y Ziff “tp 4G; Hi tl | r
é f 1 SG, Sd, _ hey 4 j
CHI LLM SYS LZ WA ial HRS
my TALL DB ke G : : ves 4 h
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Fic. 17.—Internal anatomy through tip of maxillary palpus of adult Mexican
bean beetle, showing following: Hyp, thick hypodermis; PH, pseudohairs; PI,
soft plate; Po, gland pore connected with gland cell, which lies some distance
from pore; SC, sense cells; St, tactile hairs; and THr, so-called taste hairs. A
drawing, two-thirds diagrammatic, < 300; and B, semidiagrammatic, 500.
,
function to any of them. According to position, and possibly to struc-
ture, the ones on the tips of the labial and maxillary palpi are best
suited to be taste organs. The same type of hairs was also found at
the same place on both adult and larva of the Mexican bean beetle
(figs. 14-17, THr). The ones at the tip of the maxillary palpus of
the adult (fig. 14, B) are the most numerous and most conspicuous
of any yet observed by the writer, and consequently they would appear
to have some function other than that of touch. These tiny, thin-
walled, and transparent hairs arise from a slightly convex plate, which
is soft, flexible, and transparent. The number of hairs on the organ
illustrated in figure 17 is about 447. An oblique cross section through
the fourth or terminal maxillary segment is represented by figure 17,
5
56 SMITHSONIAN MISCELLANEOUS COLLECTIONS voL. 82
A. The transparent plate (P/) is bordered by tiny pseudo-hairs (PH)
and the hypodermis (B, Hyp) just beneath the plate is very thick.
Each hair is connected with a sense cell (SC) and these cells almost
fill the lumen of the segment. The sense cells are very long and
slender and have conspicuous nuclei.
Now, if aqueous solutions can pass quickly through the walls of these
sense hairs in order to stimulate the nerves inside, these structures
would be excellent taste organs. Or, if air can pass quickly to the
nerves, they would then be olfactory organs. The fact that the bean
beetle possesses two of these highly developed sense organs helps
to explain how these insects were able to distinguish so readily between
the various aqueous solutions and insecticides fed to them.
III. AUDIRECEPTORS
Since the writer (46, p. 1119; 47, p. 39) has already reviewed the
literature on the sense of hearing in insects, no further review is
necessary here, other than to cite the recent book by Eggers(14).
I. JOHNSTON ORGANS
In caustic-potash preparations of the antennae of the adult bean
beetle the location of the Johnston organs may be determined by
focusing downward with the microscope when looking at the distal
end of the second antennal segment. A serrated structure (fig. 6, A
and B, J) will be observed to encircle the segment. The distal ends
of the sense cells are attached to this structure. In longitudinal sec-
tions the Johnston organs appear about as shown in figure 18, A. At
the base of the second segment the nerve divides into two branches,
which run directly to the sense cells (SC). Formerly the Johnston
organs were assumed to be auditory in function, but more recently
they have been called muscular receptors or statical-dynamic organs
to register the movements of the antennae.
2. CHORDOTONAL ORGANS
Chordotonal organs very often accompany the Johnston organs,
as illustrated by the writer in the cotton boll weevil; but none was
found in the Mexican bean beetle. Many sections through the larvae
were also made and studied, but no chordotonal or Johnston organs
were found.
Since the writer has never reviewed the literature on the so-called
auditory organs in larvae, the reader is referred to the paper by Hess
(24) who gives a brief history of the chordotonal organs and de-
No. 18 SENSE ORGANS OF COLEOPTERA—McINDOO 57
scribes them in cerambycid larvae. Hess determined that the pleural
discs in these larvae are the points of attachment of abdominal
chordotonal organs. Two of Hess’s drawings (fig. 18, B and C) were
copied to illustrate the internal structure of these organs in-coleopter-
ous larvae.
Fic. 18.—Internal anatomy of so-called auditory organs of beetles. A, draw-
ing, two-thirds diagrammatic, from longitudinal sections through second an-
tennal segment of an adult Mexican bean beetle, showing Johnston organs con-
sisting of groups of sense cells (SC), * 500. B and C (after Hess), longitudinal-
vertical section of the pleural zone and chordotonal ligament from a larva of
Ergates spiculatus, showing following: AF, axis fiber; C, chitinous cap; CC,
cap cell; EC, enveloping cell; EK, end knob; F, fibrils of cap cell; N, chordo-
tonal nerve; Sc, scolopale; SC, sense cell; TL, terminal ligament; and l’, vacuole.
IV. THIGMORECEPTORS
I. TACTILE HAIRS
Hochreuther (25) made a thorough study of the sense hairs on
a water beetle (Dytiscus marginalis). On the basis of external
structure, he separated them into five divisions. Vom Rath (63, 64)
found sense cells connected with all the small hairs on the maxillary
palpi of Coccinella septempunctata, Melolontha vulgaris, and Tenebrio
58 SMITHSONIAN MISCELLANEOUS COLLECTIONS voL. 82
molitor, and also with all the small hairs on the labial palpi of the
last species. The present writer (46) found tactile hairs on the cotton
boll weevil as follows: Sense hairs (Sensilla trichodea) on the head
capsule, antennae, mouth parts, thorax, legs, wings and abdomen;
sense bristles (S. chaetica) on nearly the same parts; and sense pegs
(S. basiconica) on the head capsule, mouth parts, and genitalia.
In regard to tactile hairs on the Mexican bean beetles, all parts of
the integument were not searched for them, but practically all the
innervated hairs already discussed might be considered as touch
hairs; however, the sense hairs (Sensilla trichodea) are considered
to have no function other than that of touch. On the base of each
antenna lie two groups of these hairs (figs. 6, B, and 15, J, St) and
each trochanter bears one or two groups (fig. 9, C, and 15, H, St).
They were also found on the maxillary and labial palpi (fig. 1 5» tS)
of the adult and on the head (fig. 16, C, St) of the larva.
C. ScENT-PRODUCING ORGANS AND REFLEX ‘“ BLEEDING ”’
The study of scent-producing organs follows as a corollary to that
of tropisms and sensory receptors, and reflex “ bleeding ” is closely
related to them. Since the sense of smell is such an important means
of communication among insects, it is probably true that all insects
have structures for producing odors. In fact these structures have
already been described for most insect orders, and particularly for
Coleoptera.
The writer (43) in 1917 reviewed the literature on this subject.
A brief summary of that review concerning beetles follows: The
simplest type of a scent-producing organ in beetles is composed of
unicellular glands distributed over the entire body surface. In some
beetles these unicellular glands are grouped and thus form glands
varying considerably in complexity. In Malachius two pairs of car-
uncles serve as the scent-producing organs; unicellular glands lie in
the walls of these structures. In Dytiscus, Gyrinus, and Acilius two
different kinds of liquids issue from unicellular glands situated in the
articular membranes between the thoracic segments. The liquid
emitted at the femoro-tibial articulation during reflex “ bleeding ” of
certain beetles seems to be secreted by two types of unicellular glands
at this location. The highest type of scent-producing organ among
insects is the anal glands of beetles. These have been found in several
families.
In regard to the Mexican bean beetle, no careful search was made
for the purpose of finding scent-producing organs other than the
No. 18 SENSE ORGANS OF COLEOPTERA—McINDOO 59
unicellular glands distributed over the entire body surface. In fact
this type of scent organ is the only one in lady-beetles known to the
writer. The bean beetle, like other coccinellids, is well supplied with
these glands. All parts of the body surface are covered with com-
paratively large hairs. Near the base of each hair there is usually one
and sometimes two gland pores (figs. 6, 10, 14, 15, 17-19, Po). The
large gland cells (figs. 10, C, and 15, A, GC) are variously con-
structed, but are always connected with reservoirs lying in the integu-
ment. In some of the smaller appendages, for example the maxillary
palpi, where the available space is limited, the gland cells lie some
distance from their pores and often nearly fill the lumen of the
appendage.
The writer (42) in 1916 reviewed the literature on reflex “ bleed-
ing” in beetles and added further information by using the squash
lady-beetle, Epilachna borealis. When disturbed certain coccinellid
and meloid beetles fold the antennae and legs against the body, eject
small drops of liquid from the femoro-tibial articulations, and feign
death. There has been a controversy as to how the liquid is expelled
so quickly and as to whether the liquid is blood or is a glandular se-
cretion. The writer has now shown that in regard to the squash lady-
beetle and the Mexican bean beetle (£. corrupta) the phenomenon is
a true reflex, but that instead of the liquid being blood, it is a secretion
from two types of hypodermal glands and that it passes to the exterior
through innumerable tubes opening near and in the articular mem-
brane. The gland pores of the first type, with reservoirs, lie in groups
on the tarsi and around the femoro-tibial articulations. Two groups
of these are located at the extreme proximal end of the tibia and two
at the distal end of the femur around the articular membrane (fig. 19,
A, Po). The gland pores of the second type, without reservoirs, lie
in the articular membrane, marked a in figure 19. The discharge of
the amber-colored secretion is accomplished by putting the gland cells
under a high blood pressure. This is made possible by a muscular con-
traction in the femur whereby the blood is forced into a specially de-
vised chamber containing the gland cells which belong to the pores in
and near the femoro-tibial articulation. The glandular secretion is
bitter and has an offensive odor. Its chief purpose is that of pro-
tection, but it probably also aids the beetles in recognizing the different
individuals and sexes of the same species.
Hollande (26) in 1911 wrote a large paper in which he reviewed
the literature on the phenomenon of discharging “ blood ” in insects
and on the toxicity of this substance. He also added new information
on these subjects. He reports that self-bleeding has been found in
60 SMITHSONIAN MISCELLANEOUS COLLECTIONS VoL. 82
Orthoptera, Hemiptera, Coleoptera, Diptera, Lepidoptera, and Hy-
menoptera. Under his general conclusions he states that some authors
believe that the discharged liquid is blood, while others think it is a
glandular secretion. The manner in which the liquid is discharged
is little known, except in a few cases. In general it is admitted that
the blood is discharged by a reflex action, being a means of defense.
He discusses four methods in which the blood is discharged and gives
MUCH Re Seana =
a
. & Jak, Biel
Se
tt a mn iff Ps
ml
U7
i
hi
Fic. 19.—Drawings, illustrating reflex “ bleeding” in lady-beetles. A, diagram
of a section through femoro-tibial articulation of Epilachna borealis, showing fol-
lowing: a, pores of gland cells without reservoirs; BS, blood sinus; H, mem-
brane dividing lumen of leg into two chambers; Po, pores of gland cells having
reservoirs; and St, sense hairs. B and C, portion of tubercle on larva of bean
beetle; B, distal end of tubercle having 6 branches (Br), each of which is
terminated with a hair (Hr), * 32; and C, distal end of a branch, showing hair
arising from a socket, which is surrounded by 5 processes (Pr), only 2 being
shown, X 320.
examples of insects for each method. He further remarks that the
ejected blood is usually very toxic.
While discussing coleopterous larvae, Hollande shows how coc-
cinellid larvae protect themselves by discharging blood. As an example
he used Epilachna argus, whose body is covered with chitinous tu-
bercles, which in turn bear many smaller branches, each of which
is terminated by a hair. The discharged blood is accomplished by a
rupture of the chitin near the base of the hair. When one seizes the
ee
no. 18 SENSE ORGANS OF COLEOPTERA—McINDOO 61
larva with the fingers, the hairs pierce the epidermis on the fingers
and are then broken off, causing the blood of the larva to exude as
small drops.
The larvae of the bean beetle are likewise covered with hairlike
tubercles (fig. 19, B), which bear many branches (Br); each of which
is terminated by a hair (Hr). While picking up the larvae the writer
observed a yellowish liquid on his fingers. This liquid was bitter and
very distasteful. After carefully examining the larvae under a bi-
nocular, it was learned that the bitter liquid came from the tips of the
branches (C, Br). Using a needle it was possible to touch the hairs
(Hr) lightly, so that they broke at their weakest point; that is, at the
socket which is surrounded by five processes (Pr).
SUMMARY
This paper is written as a-complement to the writer’s (47) former
one entitled ‘ Tropisms and Sense Organs of Lepidoptera,” and con-
tains information of a similar nature, but dealing with Coleoptera
alone. A large mass of literature on the sense organs and tropisms
of beetles, including papers on light traps, attractive baits, and repel-
lents, has been consulted; but only the more important information
found has been briefly summarized.
The Mexican bean beetle was selected to represent the Coleoptera.
When tested to odor stimuli alone this beetle was found to be an un-
favorable insect ; but when the adults were allowed to come in contact
with the substances to be tested as foods, the beetles clearly demon-
strated their “likes” and “ dislikes’; and when tested to light and
gravity in a dark-room, the adults proved to be almost ideal for this
purpose. In order to obtain comparative results which could be treated
statistically, new technique and apparatus were devised, and the more
important experiments were repeated many times under controlled
conditions. The more important results obtained are as follows:
When tested in a phototactic box, which lay on a table by a south
window in bright light, although not in direct sunshine, larvae of the
first and second instars were weakly photopositive or indifferent to
light. Most of the larvae of the third instar and the more active ones
of the fourth instar were strongly photopositive. As a rule, the larvae
up to the time of pupation were found to be photopositive, but when
ready to pupate they became photonegative. Whether the negative
reaction is caused by a change in the structure of the ocelli is not
known. Hundreds of adult bean beetles were also tested and all
proved to be photopositive, most of them being strongly so.
62 SMITHSONIAN MISCELLANEOUS COLLECTIONS VoL. 82
In a dark-room in which the temperature and relative humidity
were fairly constant many tests were conducted to determine the differ-
ence between the phototactic and geotactic responses of adult bean
beetles and their larvae, with and without the use of light. The in-
sects were confined in a photo-geotactic box, just above or below
which lay a water screen to prevent the infra-red or heat rays from
reaching the beetles. Under these conditions the following results
were obtained. For active, overwintering adult beetles the geonega-
tive or upward response, when light was used, was 25.60.20 per cent
stronger than the geopositive or downward one; but when no light
was used, it was 54.6+0.17 per cent stronger, indicating that when
the beetles were forced downward by the light this stimulus overcame
about one-half of the geotactic one. Old beetles of the second brood
did not respond so readily, yet their geonegative responses were
stronger than their geopositive ones. Larvae of the third instar did
not respond readily and they went up only slightly more than down.
When light was used, active larvae of the fourth instar reacted as
readily as did the overwintering adults; but when no light was used,
they did not respond so readily, although they went up more than
down.
While searching for attractants and repellents an improved feeding
method was devised. The adult bean beetles were confined in four
small wire-screen cages, each of which contained a row of the same
four foods, but differently arranged. This series of tests, with the
foods differently arranged each time, was then repeated three times in
the forenoon, and usually the four series were again repeated in the
afternoon. Each individual food used was therefore tested 16 times
in the forenoon and usually 16 times in the afternoon. According to
the arrangement of food, no two rows in the same cage were exactly
alike; likewise, no two rows of all 16 rows were identical, although
the distribution of food was not so complete. This plan was adopted
in order to equalize the number of beetles counted on the same food
which lay in all four positions during any one series of tests; and
furthermore, everything possible was done to obtain reliable data
which could be treated statistically. Using this plan the following
results were obtained.
To determine whether bean beetles “like” or “ dislike” the four
classes of substances which produce the four human attributes of
taste, many series of tests were conducted. It was soon learned that
they have “likes” and “ dislikes” in regard to food. They “ dis-
liked ” water containing salts, acids, bitter materials, and saccharine;
but “liked” the other sweet substances tested, including cane sugar,
eS
No. 18 SENSE ORGANS OF COLEOPTERA—McINDOO 63
grape sugar, table molasses, corn sirup, and black-strap molasses, and
even showed preferences between them.
Bean foliage, sprayed with arsenicals, was repellent, but not suffi-
ciently so to prevent the leaves from being eaten. Lead arsenate
was most repellent; magnesium arsenate was less so; and calcium
arsenate was least repellent. Bean foliage sprayed with sweetened
arsenicals was more attractive than unsprayed foliage. Bean foliage
sprayed with sweetened magnesium arsenate was more attractive than
foliage sprayed with nonsweetened magnesium arsenate. This would
indicate that it might be of economic importance to use sweetened
arsenicals in control measures, particularly to poison the overwinter-
ing beetles early in the season.
In regard to the tropic receptors of the bean beetle, the following
may be stated. The structure of the compound eyes and ocelli was
not studied, but these organs are normally developed and seem to
function adequately, so far as beetles are concerned.
Two kinds of so-called smelling organs—certain hairs on the an-
tennae, and pores, called olfactory by the writer—are fully described.
These hairs appear long and slender, have thin, almost transparent
walls, and are connected with the sense cells. They are numerous and
lie in five groups on the distal ends of the ninth, tenth, and eleventh
segments. The olfactory pores on the adult beetle were found as
usual on the elytra, wings, legs, mouth parts, and antennae. The total
number counted was only 692. The pores on the larva lie on the head,
antennae, legs, and mouth parts. The total number found was only
62. The fact that the total number of pores on both adult and larva
is comparatively small might be correlated with the fact that this
species is “ stupid ” when olfactory responses are considered.
A so-called taste organ was found at the tip of the maxillary palpus
of the adult. It is a soft plate which bears about 447 tiny, thin-walled
sense hairs. The fact that the bean beetle possesses two of these
highly developed sense organs helps to explain how these insects were
able to distinguish so readily between the various aqueous solutions
and insecticides fed to them.
The only so-called auditory organ found in the bean beetle lies in
the second antennal segment. These structures, called Johnston or-
gans, were formerly assumed to be auditory in function, but now are
believed to be muscular receptors to register the movements of the
antennae.
The remaining receptors described are the tactile hairs, which are
widely distributed over the surface of the beetle.
64 SMITHSONIAN MISCELLANEOUS COLLECTIONS VoL. 82
In connection with the receptors the scent-producing organs and the
phenomenon of reflex “bleeding”? were studied. The only scent-
producing organ found was the unicellular glands, which are dis-
tributed over the entire body surface. The bean beetle, like other
coccinellids, is well supplied with these hypodermal glands. The chief
purpose of the secretion is that of protection, but it probably also aids
the beetles in recognizing the different individuals and sexes of the
same species. When disturbed the adults eject small drops of a
glandular secretion from the femoro-tibial articulations, This is called
reflex “bleeding.” The larvae of the bean beetle also protect them-
selves in a similar manner. When they are handled or even touched
the yellowish and bitter “ blood’ exudes from ruptures at the bases
of the hairs, which terminate the branches on the tubercles.
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EXPLANATION OF PLATES
PLATE I
Photographs taken at the Japanese Beetle Laboratory in New Jersey, show-
ing hundreds of Japanese beetles attracted by geraniol; 1, loaned by the Japanese
Beetle Laboratory, and 2, by Van Leeuwen et al.
1. When cloths (1 foot square) were dipped in a Io per cent emulsion of
geraniol and suspended in orchards, beetles were drawn as if by a magnet.
Some of the attracted beetles, shown in the photograph, are on the cloth,
but most of them lie on the peach tree.
2. It was discovered that the beetles would gorge themselves upon foliage,
sprayed with a mixture of lead arsenate and sugar, on trees to which they
had been attracted by geraniol.
PLATE 2
Photographs taken at the Japanese Beetle Laboratory, showing an electric
trap which attracts and kills Japanese beetles. (After Mehrhof and Van
Leeuwen. )
1. The trap rests on supports 4-1/2 feet high. A 250-Watt step up transformer,
a resistance coil, and a condenser lie in the box under the trap. Several
dead beetles may be seen below the trap. The danger sign was placed
on the trap to prevent outsiders from molesting it.
2. Near view of the trap, showing its construction and the bait inside. The
most effective bait was geraniol emulsion, sprayed on peach foliage which
was suspended in the center of the trap.
VOEC 82 NO. Asha
SMITHSONIAN MISCELLANEOUS COLLECTIONS
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