^ d ^ f« ?£ ^
Ï1 m
E3 M-
JOURNAL
OF THE
COLLEGE OE SCIENCE,
IMPERIAL UNIVERSITY,
VOL. IV.
^ m :J^ m W ^n m v^ -ti- ra ^
PUBLISHP]!) BY THE UNIVERSITY.
TOKYO, JAPAN.
1891.
iq x^
CONTENTS.
Page.
On the Fœtal Membranes of Cbelonia. (Coutributious to the Embryology
of Eeptilia II.) by K. Mitsukuri, PA. D., rti(jalcultakiishi, Professor of Zoology, Imperial University. (With I'lates I~X.) 1
On the Development of Araneina. By Kamakichi Kishinouye, lUyaku^shi,
Science College, Imperial University. (With Plates X-XVI.) 55
Observations on Fresh-water Polyzoa. (Pectinatella gelatinosa, uov. sp.)
by A. Oka. Imperial University, Tokyo. (WitJi Plates XVIl-XX.J 89 On Diplozoon nipponicum, n. sp. By Seitaro Goto, Pigalcushi, Post- graduate Student in Zoology, Imperial University. (With Plates XXI~
XXIII.J 151
A New Species of Hymenomycetous Fungus Injurious to the Mul- berry Tree. By Nobujiro Tanaka. (Witli I'lates XXIV-XXVIIJ... 193 Notes on the Irritability of the Stigma. By M. Miyoshi, Piijai.-usJn.
(With Plates XXVIII-XXIX.) 205
Notes on the Development of the Suprarenal Bodies in the Mouse.
By Masamaro Inaba, Pii(jakushi. (Witli Plates XXX-XXXIJ 215
On some Fossil Plants from the Coal-bearing Series of Nagato. By
Matajiro Yokoyama. (With Plates XXXII-XXXIV.j 239
Comparison of Earthquake Measurements made in a Pit and on the
Surface Ground. By S. Sekiya, Professor, and F. Omoei, Riijalciishi, Imperial University, Japan 249
Laboratory Notes. By C. G. Knott., D. Sc, F. E. S. E. Professor of Phy- sics 287
Diffraction Phenomena produced by an Aperture on a Curved Sur- face. By H. Nagaoka. Piii/akiishi 301
Effect of Magnetization on the Permanent Twist of Nickel Wire.
By H. Nagaoka. Wnakushi (With Plate XXXVIII.) 323
On Certain Thermoelectric Effects of Stress in Iron. By C. G. Knott,
D. So., F. E. S. E. Professor of Piiysics, Imperial University and S. KiMURA, Pd(jakushi 311
On some Cretaceous Fossils from Shikoku. By Matajiro Yokoyama.
(With Plate XL.) 357
PRINTED AT THK SEISHIBUNSHA, TOKYO.
Publishing Committee.
Prof. D. KikuChi, Ri^akulmkuslii. IV!. A., Director of the College (ex oßcio).
Pi'of. J. Sakurai, Rié^kuhakushi. F. C. S.
Prof. K. Milsukuri, Rièakulmkushi, Ph. D.
Prof. C. G. Knott, D. Sc, F. R. S. E.
From July, 1891.
Prof. D. KikuChi, Rièakulmkushi, M. A., Director of the College (ex oßcio).
Prof. E. Divers, IVI. D., F. R. S., etc.
Prof. K. Yamakawa, Ri^akuliakuslii, Ph. B.
I'l-of. K. Mitsukuri, Ri^akuliakuslii, Ph. D.
On the Foetal Membranes of Chelonia.
(Contributions to the Embryology of Reptilia H-')
by
K. lYIitSukuri, Ph. D., Riéakuhakushi. Professor of Zoolofry, Imperial University.
With Plates I— X.
Om- k'iio\vl('<luc ()(■ Hie I'd'tnl iiicirilii-;m('> <»f Kc))tili:i is conrrsycdly slill very impovfoci. It is o'onenilly assimu'd that they rosoiiil)lt' luoi'c or less closely tliosc of liirds. K;)IIikor is nlt<\oothci' silcMit, I'.aliniir oivcs very ine:»ure information, on the siihjeet in thrii' respec- tive treatises on Enil)ryoloo-y, wliilc llert\\iii- in liis Lelirluich treats Reptilia thronglioiit as |)resentin,ii- the sanic appearan<'es as liinls on this point, Ueeently Strahl (Xo. ô), llollnian (Xos. i] & 7). Kavn (Xo. 0) ami IV'ivnvi (Xo. K!) have toin-lic«! on the siihjeet hut their ohservations are eoniined mostly to the earlier stages.
Whilst eollectiim- eml)ryos of Chelonia, I beenme aware of the fai't that there are sonu- very notal)le ieatures presented hy the fœtal )uem1)ranes of these animals which, so far as T am aware, liave hitlua-to heeii entii'ely o\ crlookcil. These features a) )peared to me so remai-kahle and interesting tiiar I thought it wortli while to inves-
* I shall consider th«^ article on " the Ponnation of tlie Germinal Layers in Chelonia '' by Mr. Ishilcawa atul uiyself, and iiuhlishe<l in tliis .Tournai Vo|. 1 and also in Quart. .Tnnr. of Micro. Sei. Vol. 27 as the first of this series of C(.n(rilintion.« to llio Euil.ryoh)oy of Ifeptilia.
Z K. MITSTTKUHr.
tio-ate the whole history of these nicmbraiu's in thi« oroup. The following embodies the resiihs of my sf udy km\ tliis subject.
The species which I have iiivestigatxMl are C le mm y s (or Emys) Japonica, Gray, and Tri onyx Ja))onicus , Schlegel. In earlier stages, the fetal meml)ranes of these two species are very much alike ]3ut in later stages they present differences which, in my oj)inion, are highly significant. F«H' convenience of trentment. I shnll divide the present article into three parts, ns follows : — I. Earlier Stages of the Amnitin, 11. Origin of ihe Allantois. ni. Later Stages of the Fœtal Membranes.
And in (»ach part, 1 shall tivat the two spe(äes sej)aratel y, generally giving th<' description of CI em my s first, as that species seems to have more primitive relations in its fœtal membranes. At the conclu- sion, 1 have put together some suggestions on the theoretical bearings (»(' the Cacf^ l)foii<jli( fordi inidef tlie liead of (General Considerations.
I. Earlier Stages of the Amnion.
a. Clciiwni^ Japonica.
The first stage of which 1 shall give a description is re))resented in siirfi<e view in Figs. ]. and 1 a. Fl. I. There is at tins period a deep horse-shoe shaped groove bounding the anterior end of the em- bryonic region — the "Vordere (Jrenzfurche " of Cerman authors* The posterior wall of this groove is the head of the eml)ryo, while its anterior wall is the first rudiment of the anterior fold of the amnion. T'he structure and relations of these parts will become clear from the sections to be described directly. The medullary groove is still open thoughout its length, its posterior pai't being wi<ler apart than its anterior poi'tion. The dorsal opening of the
ON THE FOETAL MEMBKANES OF CHELOXIA. 3
l)l:iwr(jpor(' is \ery distinct. At tiie posterior end of the eniljryonio region, there is, in the specimen figured, îi h)vv semilunnr fold bound- ing the embryo from behind. It gives one the impression of its being the posterior fold of the amnion. Such folds are not, however, found by any means in all the embryos, and even when present, are not always of the same figure and distinctness as in the figure. As the subsequent history shows, these inconstant folds ut the posterior end of tlie eml)ryo take no share wliatever in the formation of the permanent amniotic sac.
Hound the head-end of tlie embryo, there is an irregularly semi- circular transj)arent area of the blastoderm. In this area, there is usually an opaque line also semicircular and concentric with the cephalic grooxe (Fig. 1). Kound the postei-ior end of the embryo, and along its sides, there is a brcjad h(jrse-sh<^e shaped opac(ue streak which is caused by the abundant accumulation «jf yolk-granules — the germinal wall. The mesoblast, at this stage, extends into the head of the embry«) [)r<jper, but anteriorly, laterally, and postei'iorly the opaque liorse-slioe shaped streak mai'ks the limit of its extent. Hence the transparent area in front of the embryo is as yet free from the mesoblast .
In Fig. n.S, IM. \ll. (See also Diag. 1. IM. X.), a median longi- tudinal section of the head end of the embryo is represented. It is evident from this section that the deep horse-shoe shaped groove at the anterior erid (a. /../.) is bounded posteriorly by the head (H. F.) of the embryo, while its anterior wall forms the first rudiment of the anterior fold of the :tmnion (Anin). The anini(jn is thus laid in the region into wliidi the mesoblast has not yet found its way, and ihcTefore. of nercssitN , consists at lirst only of the <'|)iblas( and hypo- blast. In Fig. 59 (Fl. VII.), a transverse section of the same region is represented. From this and Fig. 58 (PI. VFT.). the characters
4 K. MIT«UKUKI.
of the two layers in the niniiioii will Ik- easily understood. Where the layer« reaeh the le\el of the _ueiieral surface of the ])lastoderin, the epiblast presents a thickened ridu'e aloni;- the whole u|>|)er ed^e of the ii'i'oove. As it i.s hy the _ü'rowth backward of this cdu'e that the amnion comes to co\'er the endjryo, tliis ridge of the epihlast must he the seat of an active i^row th. There is also in the mcthan line a thickened rid_ue (Fig. 51:), (•.)oftlie epildast which starling from the hottcjm of the groo\e reaches as far a.s tlic lexel of the hlasloderm, litling in its ujjward course the still oj»en medullarv !jroo\ e of the head of the endjryo.
In the semicircular tI•an^])arent area in front (jf the anterior liorse-shoe shaped groo\e, the epihlast consists of two layers of pave- ment cells, of which the up|)er is especially Hat and seems to be of stitf consistency. The hypoblast in the region directly in front of the groove consists of polygonal cells. The o[)aque semicircular line in the transparent area already spoken of seems to be due to a special acGimiulation of the hypoblastic (Fig. 58.) cells. A little in front of this line, the hyjjoblast becomes suddenly a mass of live yolk granules with nuclei scattered among them. At the periphery of the transpai'cnt area this passes rather abruptly into a 1)ed of large y«>lk spherules.
The fact that the amnion in Kept ilia, consists, when Hrst laid, only of the two primai-y layers was made known by IStrahl (No. 5), Hoffman (No. (i), Ferenyi (No. 16), and Kavn (No. 9). Hoffman pointed it out as a point of great difference between the amnion <jf l\e{)tilia and that of lîirds, but it is now well kno\\n lliai, in Jîirds also, the amnion consists at first only of the epihlast and hypoblast. Kijlliker refers to the fact in his classical work (zweite Auf. j).l.SS. and Fig. 85). and Ka\n (No. 8) has woi-ked out the point ehdiorately. \ an Beneden and I'h. dulin (No. 11) also ob>erved the same fact in the
ON THE i'uETAL MEMBIIANES OE OHELONIA. •'>
|{,;il)1)ir ;iti(l lîats und iiaiacl the two-layered amniotic cap the •' Tro- amiii(jij."' Fleischmann ha.s also found the s«ame state of things in the eat. It seems tlierefoi'e an estabhshed faet that the head-fold of the amnion, when iirst laid, consists throughout the Amniota only of I he epiblast and liypoblast and is therefore of the natiuv of Pi-oam- nion. In liei)tilia, this point is made perha])s more conspicuous hy the sid)se<pienl histoi'y of the fœtal membranes than in other groups.
It will be seen fr«jm this stage tliat the head ot" the embryo sinks fr(jm the Iirst I)eIow the leNel of the blastoderm. Apart from any ])hylogenetic significance, there is mechanical necessity for its sink- ing in this manner. As soon as the development begins, the white of the egg is rapidly absorbed from the part over the blastoderm which becomes adherent to the innei- surface of the shell membrane. There is therefore no space into whicli the head can grow except towards below. In removing endjryos from the eggs, I availed myself of the llict of tlie ijlastoderm ])ec«;ming adherent to the shell membrajie. for. with a stout pair of scissors, I could easily cut a watch-glass shaped piece of the shell with theshell mendjrane and the embryo adherent io it, and inverting it, I coidd jxjur the preservative iliiid into it, thus using it like a veritable watch glass, (jnly excelling it ill this that it keeps the end)ryo and the Ijlastoderm stretched in their natiu'al positions.
I am inclined to thijik that the sendlunar ridge at the posterior end (I'ig. 1) i'*^ also caused l)y the posterior heavy end of the embryo sinkini!' int<j the s})ace below . Its section is almost exactly like that of the lateral foM of the [»ermanent amnion (Figs. oO and oOa, PI. V.). Such adventitious ridges seem to be produced here and there witlnnit any regularity (••f. also Fig. 2). They are of a transient nature and take no part in tlie foi'ination of the anmion.
As later staijes will show, the wliole amniotic sac is
6 K. MIT.SUKUKI.
}) V ( ) duce d solely 1j y t li e g r u w t li h a e k \v a r d o f t h e an t e r i o r fold in conj unction with the lateral folds which ri«e grad- uall\ from before backward.
In the «taiie with two or three ]ne>s(jbla.stic somites, a> shoxNU in Figs. 1> and 1^«, IM. 1. (see also Diag. II. and 11'. Tl. X.), the am- niotic fold has extended nearly lialf o\er the body of the embryo Avhose anterior pari has sunk meanwliüe more and more below ilie level of the blastoderm. The jjosterior ii'dge of the amniotic hood presents a horse-shoe shajjed outline, being caused by the lateral f )ld of each side extending more posteriorly Ihan the median p;irl. fhere are ;igain some irregidar folds (a) in the posterior parts (jt I he embryonic region.
Figs. o0-o3 (1*1. \'.) show a series of transverse sections selected from différent parts of this embryo, Fig. oO being the most j>ostei'ior and Fi"". o3 the most anterior.
F^iiJ". 30 is from the region co\ered only bv the lateral lind),s of the horse-shoe shaped posterior margin ol the amniotic hoixl. F'rom this and Fig. oO« (PI. V.") (the latter representing the left half of Fig. oO under a much higher powei" of magnilication) it will be seen tliat the lateral f »Id of tlie amnion, when first laid, presents two peculiarities: (1) it is purely epiblastic, ;uid the mesoblast has no shave whatever in it ; (2) the fold is solid and not composed of I he inner and outer limbs as re])resented in ordinary diagrams.
F^ig. ol is just in front of the point where the two lateral am- ni<jtic folds have united. One half of it i> shown under a hierher power in Fig. öl</ (PI. \ .) j'he whole amnion here is composed of a solid sheet of the e[)il)l:i.s|, I he mc>oi)I;ist insinuating it sell' between the epiblast cells only later on. The cells of this part of the amnioji are in se\ eral layers, and of these, the cells of the outermost layer have under- gone some process of hardening and their nuclei are stained dee] 'est.
O.V THE FOE'I'AL MEMBRANES OE I^HELOXIA 7
Fii;-. 'A'2 is irniii the point where the lien<l-eiid «»1' the embryo is }uM ])Vii\ii\\']])<x ^" ><\nk Inflow tlie level of the Idàstodcriii, Tlie meso- hlast of the liody hns .^epiij-jited from the extr:i-emhryoTiie \mri . The amiiioii is mostly epibl.istic, ;xlthoiio-h lined hy the hypolilasl iiir n short distnnee on en<-li side.
Imù". .').') is froiii the liead reo-ion whidi is completely snnk below the level of tlie hinstoderm. As em|)hnsized bv Motfmnnn, the bead aj)pears in the cr«»ss section Ix-low. instead of above, the blastoderm. The aiiinioii is eom]>ose(l of the epiblast and hypoblast, eaeli heino- only one-eell layered.
These sections show that the amnion at this sta^'e eonsists, in the region ol* the sunken head, of the epil)last and hypol)last, and in the (h)rsal ren-ion, of the epil)last only. The mesoblast as vet has no share in it.
In the stajii'e with t! or 7 mesoblastie somites (Figs. )> and .') a PI. I. See also Diag. TIF. and TIT. PI. X.), the amniotic hood has ex- tended to the posterior end of the eml)i'yo, leaving (jnly the region round the neurenteric canal exj)osed. The mesoblast has also very much increased in its distribution and has become, thoughout, split into the somatic and splanchnic layers. The cœlom has thus appeared not only within the body of ihe cnibi-v«» proj)er but lias extended itself into the cxti'a-embrNonic porti«)ji ol' the blastoderm. Although the mesoblast has originally s])read IVom behind foi'ward, the cœh^inic cavity appeal's first in the neck region of the embryo and s])reads graduall}^ backward — as was pointed out by Strahl (No. 5). In the stage represented in Pig. o, when seen through from above, the extra-embryonic coelomic cavities of tAvo sides, extending into the amniotic folds come close together (but are not fused) in the median dorsal line along a considerable distance in the anterior part of the dorsal region, but separate from each other before the posterior
8 K. MITSÜKURT.
eclo"e of tile aiiuiinii is roachod, and, oradn.'illy Icssciiiiif^' in \hv\r height, arc lost too'ethor with tin- uratliially lowcrini;' lat^-i-al iolds of tlie amnion. Tlius the niosohlast now has a consi(]('ral)l<' share in the formation of the amnion.
Fio-s. 34-38 (PK V.) are a series of transverse .sections selected from different regions of tliis embryo.
Fip-. 34 is from the reo-ion where the lateral folds of tlie amnion are still Ioav. When we compare this with Fio-. 30. we see that in this stage the somatic layer of the mesoblast is f<^ldetl and pushing itself into the hitherto solid epiblastic amniotic folds.
Fig. 35 is from the region where the mesoblastic folds or, wliat amounts to the same thing, the extra-embryonic cœlomic cavities are still some distance from the median line. Fig. 35 a represents the median dnfsal portion •»!' the amnion in the same section under a liiiidier ])owei-. It is evident that here also, a somatic fold ol' the mesoblast insinuating itself, so to speak, on each side into iho ori- ginally solid epiblastic amnion is separating the latter into two liml)s of which the inner is the true amnion and the outer the false amnion* or serous envelope.
In Figs. 36 and 36 a, the mesoblastic folds have reached furtlier dorsahvard, but the amnion aiid the serous envelo])e are unite(l in the mc^dian line. \n Fig. 3(! /*, a few >ections forwai-d ol" Fig. ."»(!. the mcsolilastic folds have readied still fiirthcj' dorsal ward— the most (h)rsalward at this stage — but still there is a distinct connection be- tween the amni<m and the serous envelo])e.
The mesoblastic folds inaintain themselves at the level given in Fig. 36 /' for many sections forw^ard, and the comiection between the
UTl'
* In futniv, I shall avoid iisint;- tho t^riii " fais.- amnion "" to d.'iiotu the strurtnit' 1 indicated and shall call it tlip sorons .'nvelope, as tlio tonn -'fnlsi' nniiiinTr' is appli.'d \>> tu very different structures }jy GJerman and Enolish authors.
ON TUE FOETAL MEMBRANES OF CHELONIA. 9
aiTinion and the serous enveloj)e is also iuvariahly jn-eseiit. (Coinjtare Fig. 3, PI. [.).
In Figs. 37 .'ind o7 a, which arc froii) the region of the he;irt, where the head-end is heuiiiniiig ti) sink heh)\v tlic sm-face of the I)histo- derm, the mesoblastic folds have again receded fi-om each other and the connection l)eMveen the amnion and the serous enveioi)e is a^ain liroad.
Fig. 38 is from tlie .legion of the head sunk l)e]o\v ihe le\el of the bhist()der!n, which therefore ;i|)])ears above tlie liead in this s(^ctiorj. Tiie amnion or proamnion consists only of the epildast and hypoblast.
The relations of different parts will become clearer, when studied in a longitudinal section.
Fig. 41 (PI. V.) is such a section slightly out of the median dorsal line so that the extra-embrvonic cœlomic cavity fcœl') of one side appears in the amnion. This section shows that the epiblastic amniotic fold reaches nearly to the neiu-enteric canal, while the hypcjblastic fold extends only to the neck region. The triangidar space between these two f(jlds as seen in this section is occupied, for the most part, by the mesoblast enclosing a porticjn of the extra-embryonic cœhjmic cavity. A little earlier there would have been no mes(jblast in the amnion which then consisted, in the dorsal region, of the epiblast only, and in the sunken head part, of the epiblast and hy|)oblast. The meso- blast is now ])ushing itself into the solid epiblastic sheet of the amnion, dividing it into an outer and an inner lindo. In Fig. 41, the posterior ])art of the epiblastic fcjld is, however, still solid. Anteriorly the mesoblast is insinuating itself between the epiblast and hypoblast. The cœlomic cavity in the mesoblast is widest in the anterior part.
One of my most important results is in regard to the connec- tion between the amnion and the serous envelope, seen in Figs. 35-37. Contrai-y to what is hithert(3 known, the extra- em b r y o n i c c ( e 1 o ni i c c a V i t i e s of t w (j sides a r e n e v^ er united
10 K. MITSUKÜRI.
across with each other over the dorsal region of the em- bryo. A C(mnection — quite elongated and definite in later stages — between the amnion and the serous en- velope separates them to the very end of the develop- ment. That this structure causes great peculiarities in the fœtal membranes is to be expected and will become clear as later stages are described. This connection, I shall call hereafter the sero- amniot i c connect] on . It does not extend to the sunken head part where the amnion cojisi.st.s of the ejnblast and hyp(jblast, and is con- fined to the region l)ehind the neck representing the original solid epiblastic sheet of the amnion oi- its prolongation behind.
While Fig. 3 (PI. I.) Tio doubt represents the conunonest and noi-nial form in which the amnion s])rea(]s backward, it seems by no means to l)e the exclusive «jne. Fig. 14 (IM. II.) shows one in which the posterior f)ld is present but a part of the left lateral fold is absent, so that the hcjrse-shoe shaped postei'i<jr margin of the amnion is open toward the left. I have also another embrjo in which a part of the right lateral fold is absent.
Now comes the most i'emarkal)le point in the development of the amnion in C I em my s . According to what is hitherto known al)out the amnion, one would expect that when it has reached the stage shown in Fig. 3 (PI. 1.) the |)osterior fold will be produced or the lateral folds will convei-ge toward each other and thus the amniotic sac wnll be completely closed. Such is not the case in Clemmys. The anteri(n- and lateral Iblds which stalling from the head have gradual!}^ extended backward over the whole embryo do not stop at the posterior end of the embryo but continue to grow back- ward, although diminished in their width, until final- ly there is produced a tube extending backward from the posterior end of the embryo, almost as long as the
ON THE FOETAL MEMBRANES OF CHELONIA.
11
body o f t h e embryo itself, connecting' the amniotic sac with the exterior. A reference to Fig".s. 4-7 (PI. I.), will make the growth of this posterior tube clear. In Fig. 4, the folds have extended slightly beyond the posterior end of the embryo. Beyc^nd this point, they snddenly come near each other, and being diminished very much in width, their continued growth backward produces a tube (Figs. 5 and 6). It will be seen that the extreme posterior point always presents a horse-shoe shaped outline, as it did when growing over the body of the embryo itself. Fig. 7 shows the stage of the greatest development of this tube in my possession. Tn three embryos of this stage whose lengths are 8, 8, and 8 \ millimeters, the length of the posterior tube of the amnion is respectively 6, 8, and 7 ^ millimeters. The posterior opening is s(^me distance beyond the edge of the vascular area.
The sections of this tube show that the relations of the different layers are in all essential respects exactly as in that part of the amnion )»roper enclosing the einbryo as shown in Figs. 39 and 40 (PI. v., from the embryo given in Fig. 5) of which Fig. 39 is froni the anterior part of the tube near the embryo and Fig. 40 from about the middle of the tube. In the surface view, there is often seen a streak along the median line of the tube, which is shown by the sections to be a thickenino- on the floor of the tube. The structure of the similar tube in Tri onyx is gi\en in a more enlarged scale in Figs. ô3-r)o (PI. VI.).
What the function of this remarkable tube connecting the am- niotic sac with the exterior is, -^whether it has any active function at all or is only of the nature of a remnant (-»rgan, I am unable to tell. I think it probable that it serves for conducting into the amniotic sac the nutritive matter from the Avhite, with whose gradual disappearance from over the embryo the backward grow^th of the .
12 K. MTTSUKURI. -j
posterior amniotic tube seems to keep pace.
The condition of the amniotic sac proper at this stage when the posterior tube has ah'early been developed is shown in the series given in Figs. 42-47 (1^1. VI.) from an emln-yo with twenty mesoblastic somites. An inspection of these figures shows rliat. over the ])osterior part of the embryo (Figs. 42 and 43), the amnion and the serous enveh)pe are still adhei-ent to each other for a considerable space : hence the extra-embryonic rœlomic cavities (cœl') of the two sides are separated from each other by a wide interval over the dorsal region. As we proceed forward, the mesoblastic folds gradually push toward the median line se])arating the amnion from the serous envelope, until, over the middle region of the embryo, they are separated only by a thin partition (Figs. 44 and 44a). This partition — the sero-amniotic connection^ — -has now become vertically somewhat elongated and unlike Figs. ?)(vi and b (PI. V.) ])resents a string of cells in a cross-section (Fig. 44a). This represents the greatest vertical elongation of the sero- amniotic connection at this statte. Further forward, the mesol)]astic folds becoîne again separated by a considerable interval (Fig. 45). An- teriorly to the point wluu-e the head-end l)egins to sink beneath the surface of the l)lastederni, the cœlomic cavities of two sides which arose separately have l)econie united across, there being no sero- amniotic connec'tion from the beginning in this part (P'ig. 46). In the head which is freely pi-ojecting into the cavity below the Ijlastoderm, the amnion still consists only of the e])iblast and hypoblast (Fig. 47).
Fi'oin what has been given above, it iollows that the extra- embryonic cœlomic cavities of two sides are separated from each other over the dorsal median line by the seio-amniotic connection from t\\c n«M'k region to the very tip of the posterior tube. In front of the neck region, i.e., in the siuiken head regicm, the cavities become early united across. It is important to
ON THE POETAL MEMBRANES OP GHELONIA. 1«^
reineinb(>r this fact in order t<i understand the relations of some parts in later stages.
In a slightly older embryo, the sero-amniotic connection has increased more in its vertical extension. Figs. 48 and 48a (PI. VI.) are from the tail region, Figs. 49 and 49^/ (PI. VT.) from the middle of the body. Tn the latter, the sero-amniotic connection is of a con- siderable length, becoming quite definite.
As to the fate of the posterior amniotic tube. At the stage (Fig. 7, PI. I.) when it is in its highest development, the axis of the tube is the same as that of the embryo, i.e., the embryo and the tube are in the same straight line. Beyond this stage, the tube begins to become curved, at first slightly, then more and more. In Fig. ISa (PI. IT.) the curvature is very slight ; in Figs. 13/> and 8 (PI. II.) it has increased greatly ; in Fig. 9 the distal portion of the tube is bent at a right angle to the proximal basal part ; in Figs. 10 and 15 (PI. [[.), the tube has become very irregidarly curved. It will be seen that the tail end of the embryo which is at first far in front of the horse-shoe shaped distal end of the posterior amniotic tube (Fig. 7) gradually approaches the level of the latter (Fig. 9) until in Figs. 10 and 15 it has pushed itself far behind. It is now the distal end of the tube that is in front. This change of the relative positions is no doubt due to the flict that the embryo and the amniotic sac proper grows more rapidly than the posterior amniotic tid)e which they push aside, so to speak, in oi'der to gi-ow beyond it. As the eurvature be- comes greater, ])arts of the tube become fainter and fainter in appearance. For instance, in Fig. 10, a large |)art of the tube excepting the dist;d horse-shaped end and the proximal basal jmrt, was very difficult to recognize (being represented too distinctly in the Figure). In Fig. 15 I could detect only faint traces of the tube, hei-e and there excepting the proximal l)a,sal part which is always
14
K. MITSUKURI.
distinct. The oldest stage in whif^h I detected any portion of the distal half of the posterior amniotic tube i>; that ^iven in Fig. 67 (PI. VITL). I found there the horse-shoe shaped distal eîid of the tube and the portion contignoiis to it, hnt after n most cnrefnl sf^arch. I could not connect it with fhe proximal part. From tliese facts, it appears that the largest part of the posterior amniotic tidie disappears entirely, and that oidy the proximal |»art — the ])art nearest the amnion proper (prox pt. Figs. 9, 10, and 15, PI. II.) — remains permanently. It will he remembered that the scro-amniotic connection extends from over the neck regi(^n of the embryo to the tip of the |)osterior tube. As the proximal part of the tidoe remains permanently this marks in all later stages the posterior end of the sero-amniotic connection. As fur- ther growth in size of the amnion proper (accommodating itself to the growth of the embryo within it) takes place mostly behind the rem- nant of the posterior tube, the latter and the sero-amniotic con- nection come to lie in the anterior part of the amnion in older embryos. The growth in size of the amnion after being closed on<-e is therefore due mostly to the enlargement of that part which is placed behind the posteriiM- tube enclosing the tail end in a sî;ige like Fig. 11 (PI. IL).
In all the stages hitherto described, the head of the eml)rvo projected below the level of the blastoderm covered l)v the proamnion which consists only of the epiblast and hv})oblast (Fig. 41. PI. V.). On this accoinit, in sections of this region, the head is found Ix'low the general level of the blastoderm (Figs. ^3, 88, PI. \'., Fig. 47, PI. VI.). The manner in which this anomalous state of things is brought to a close, and in which the head covered by the tunnion «-on- sisting of the epiblast and the somatic mesoblast comes to lie above the hypoblast as in other |)arts (^f the body, has been described by Strahl (No. 5) and Hoffman (No. 6) and c^uite recently by Ravn (No. 9).
ON TEE FOETAL ICEMBRANES OF CHELONIA. 15
The last named author ÇS(^. 8) hns also studied the process in the chick and found it to he alike. My own ol)servations jiuive in all essential points with the account gi\en hy these authors. The process briefly stated is as folhjws : As stated before, the extra- embryonic cœlomic cavities of the two sides become early united across iîi the he;id re^'ioii, there being no sero-amniotic (.'onnection here. This united caxitv or its niesol)hist \\;dl. in spreading itself, in- sinuates itself hetween the epibhist and hyo]toblast of the bhistoderm and thus |)Ushes the hy|>oljlast forward and downward. A com- parison of Figs. 41 and 41(/ (PI. \'.) aii<l Diags. III., I\'., \'. (I 1. X.) will make this jxnnt cI(Mu-. In Fig. 41. the head is still entirely covered by tlie proamnion; in Fig. 4h/,, the extra-embryoiiic cœlomic cavity (cad') in enlarging itself, has ])ushed the hypoblast forward and peeled it otf, so to s])eak, from the greater part of the proamnion covering the head, so that now tlie proamnion is found only on the ventral part of the head. Meanwhile, the emliryo turning on its longitudinal axis comes to lie on its left side. These movements brinR- about the state of things as shown in F'in's. 11 and 11(/(P1. II.) In Fig. 11 the end)ryo lies evitirely on its left side, and a small anterior part of the head is covered by the now much reduced pro- an.nion. In th(^ ventral \ iew of the same (Fig. IP/) the proamnion is very conspicuous, because it is transparent and without blood- vessels. A section from the head of this embryo is shown in Fig. 85 (PI. X.). Lt shows how the proamnion extends now only for a short extent.
The final disappearance of the proamnion is bn^ught about by the continued extension of the mesoblast. Although the encroach- ment of the proamnion takes place to some extent from behind and before, it takes place most actively from tlie two sides. Pig- 86 (Id. X.) is a se<'tion sinvilar to Fvj;. 85 Iron! a somewhat older embryo.
16 K. MITSUKURI.
How the proamnion hns been eneronched upon from both sides and has all but disap'H'ared is \ ery clear, if we compare these two ügures. These two figures show also that the k^ft \'itelliiie vein (Y va) becomes much larger than the right.
h. TrioHijx Japonicus.
Earlier stages in the development of the Amnion in Tri onyx are verv much as in Glemmys. There is in fact n<j point of any impcn'tance which is different in the two species. As, however, tlie Trionyx embryos in ni}' possession show very well in surface views how the extra-embryonic cœlomic cavities arise first in the neck region and gradually spread backward, I shall introduce here some figures which illustrate that point among others.
Fig. 16 (PL III.) is the stage closely resembh'ng Fig. 1 of Clemmys (PI. I.). The anterior horse-shoe sha})ed groove (" die vordere (Trenzfruche "), the still open medullary canal, and the trans- parent area in front of the embryo are all very similar to the Clemmys embryo < )f the corresponding stage.
In Fig. 17 (PI. III.) the amnion has extended over the anterior half of the embryo. When seen from the ventral side the whole anterior end of the embiyo covered by the proamnion is projecting below the level of the blastoderm, as shown in Fig. 17^. In the neck region where the emljrvo gains tlie level of the blastoderm, one is able to recognize distinctly the extra-embryonic cœlomic cavity on each side of the embryo appearing as a vesicle which bulges out the dorsal and ventral surfaces of the blastoderm (Figs. 17 and 17a). The level of its poster- ior limit is the same as that of the posterior limit of the amnion, and the growth backward of the cœlomic cavities progresses hand in hand with the backward growth of the amnion. fhese t\vo cavities, one on each side of the embryo, are (jf course the same as Strahl's '' Mesublastische
ON THE FOETAL MEMBliAXES OF CHELOXIA, 17
Schliiiiclie " (Of. Struhl Xo. 5). The section« of this embryo show that in the reo-jon where the hitenil fjlds of the amnion have not yet united in (iie median line (Fig". 50 l*L \ I.), the fold is purely e[)iblastie and sohd. and tlie mesol)hist has no share in it at all. In the region where (he extra-emhryonie l)udy ea\"ity is jjresent (biii". •M). tlie mesobhistie fokls have ah'eady pushed themselves eon- sideraljly into the epiblastie amniotic sheet, dividing it int<» two limbs: tlie amnion proper and the serous envelope. In the embryo of Clem my s given in Fig. 2 (PI. I. ), the mesol)iast has as yet no share whatever in the formation of the amnion. It follows therefore that the mesublastic folds begin to push themselves into the epiblastie amniotic sheet somewhat earlier in Trionyx than in Clenimys. Fig. b'2 is lr(jm the head region of the embryo given in I'ig. 17. The head is surrounded b^• the proamnion conn)osed for the most part of the epi blast and hypoblast, and appears beneath the blastoderm instead of aboN e it.
Figs. 18 and U) (PI. III.) show that the amnion is gradually spreading backward, and with it the extra-end)ryonic cœlomic cavities are urowinn- laru'er and lart^er. In Fiu'. 18, the cavities of the two sides are still wide apart over the doi'sal region of the embryo; in Fig. 11) they aluKjst touch each (jther along the median dorsal line in the anterior dorsal pari of the endjryo. but are considerably apart ui the posterior region. A section tivjni the anterior region (Fig. 57) shows that thev are separated l)y the sero-amniotic connection which aj)j)e;u's, however, still very short in a section.
In the embryo given in Fig. 23 (PI. 1 \ .) the amnion has covered the eml)ryo entirely and has even extended a short distance behind it. The c(elomic cavités are correspondingly enlarged.
In the stage gi\ en in Fig. 24 (PI. \\ .). the ])osterior amniotic tube has become alread}' (piite elongated. Its ])os(erior opening is
IS
K. .Ml'I'SUKUi;!.
iKtw jtisl ;il flic cdiic (»1 tlic \as(;iilar area. Tli«' I'Xl fa-ciiilirvuiiic (j(i'loj)iic cavities have now ('xteiided so iniicli thai llicv ar<' no Jouter recogiiizahle a.s \'esicles in a sin'faee view. I'iu's. oo-of) (I'h ^'I.) ai'e tlirce sections from (liHci'cnt parts of" llu' ])()stci'inr ainnit)tic tiil)e (ti this emljrxo. 1' ii^s. ').") lieini!' near the jxisteriol" openini:' and others ijcino- in trout of it, Huh \]\c c])il)hist and somatic ]iies<;h]ast ai'e re{)resented in tlicse hüuix's. the i(cIoui. the s])hinciinic niesolihi>t and yolk licini:' left out, as a comparison willi Fii;'». .")0 iind iO (I'l. \ .) \\ill show, Fiu'. .")(! is the median ]>ai't ol" the auinion from o\(;r the middle re,Lii<)n (jf the body of the emljrv«' :njd shows the 2"reîitest encroaehment at this stiige of the extni-endjryonic co'loniie cavities, reducini:' the sero-amniotic connection to a meiv sej»tum-]ike ])artition,
rigs. 21 a, h, c, and d. (IM. III.) she)w the [)osferior amniotic tuhe of foui- embrvos of the staii'e a little older than that i;-i\en in Tig. '24. hi a the tube is still straight, in h it is slightly c^r^('d, and in r and il more curved. hi a the embi-yo is (! mm. h»i)g, while tlie ])osterior amniotic tulie is only o -g mm. As this is no doubt the stage of the highest development of the tube, it follows that the ])ostei-ior tube in Trionyx is not as long relatively to the l)ody of the embry« > as i t is in C 1 e m m y s .
In f'igs. 'J'J (I and h (PI, Iir,) tlie posterior amniotic tube is becomijjg very irregularly cur\ed.
Iji Fig. 27 (PI. I\'.). most of the jiosterior amniotic tube has already disappeared or at least is unrecognizaljle. The ])roximal or basal part of it is, however, veiy distinct. At this stage, the sero- amniolic connection exists from the neck-region to the tij) of the renmant of the ])osterior amniotic tube.
The maiuier in which tlie proamnion coiisisting oidy of the epiblast and hy|)oblast is graduallv ri'])laced bv the amnion consisting ol the e))i1jlast and mesoblast is exactlv as in Cleminys.
ON 'I'lIK Foi: TAL M EM IJüAXKS Ol' CllELONTA. !'•
II. Origin of the Allanlois.
lu'siilcs KitpH'rr who (U'i'ivcs tlu- allantois tVoiii iho lU'inviitoric onnal. the one wlio has most can-l'iilly studied its origin in Kcjiiilia is Strahl (Xos. 1 and 2). Acc(n'dinp; in this anth»n'. tlie allantois is laid, in Fvaccrta, as a solid knol) at the post<'rior end of the emhrvo, suhsequentlv hollows itself out, and only then comes to eonnniinicate with the hind-gut hy an independcMitly formed allantoie stalk. Ft then tiu'ns rciiind the tail end and comes to lie in lV<Mit of. anil lielow, the latter.
After Strahl, llotl'niann (Xos. (! and 7) and I'ereiiyi (Xo. l(i) have studied the oi"igin of the alhintois in lve])tiria. The \ lews whieh Holfmaim expresses in his lirst papei- (Xo. (5) mainly support Strahl's ohservations. while in his se<'oiid. paper (Xo. 7) lie seems to have somewhat modified his idea. For the exact details in which his later ideas difler from those of Perenyi(Xo. 1 ()), T must refer the reader to the original papers themselves, as I have to confess my inahiliiv lo grasp them ))recisely. Xotwifhstaniling Perenyi's sfateiiuMit that thev dilfer, it appears to me that they are deserihing snl)stan(ially the same process. Under the circumstances, I am unahle to sa\' wdiether my results agree with the view of either or IxHh of these aiitliors, although I think we have arrived at^ nearly the same results, Hoffmann says that the origin of the allantois in Reptilia is tlu'onghoiit the same as in lîirds (X'o. 7. ji. ISO). Such is the eon- elusion r too have arrived at, after a eareful study oi' ("helonia. In fact, ihis is so much so that (Jasser's figures (Xos. \'2 atid l."!) oi- lîalfoiir's deseriplioii (Comp. Emhrvol. \'ol. If.) on the origin of the allantois in liii-ds tnight lie hodil\ adopte(l to desia-iiic tiie same process in ('lielonia.
As I lia\'e a more f'oinplete sei'iev of the 'frionvx emhryos
20
K. MITSUKURT.
illnstratiiiri- lliis ])r)i]it lliaii those, of ('Iciniiiys, I sliall hcoin with the former species.
Figs. 60-63 (PI. VII.) aiKl Figs. S7 mid 87« (Fl. X.) give successive stages in the development of the ullantois in Trionyx.
Fig. 60 is fr<:»m an embryo very simihir to the one represented in Fig. 23 witli about seventeen mesoblastic somites. The sjjhmch- noplenre has not vet l)een folded under to form the hind-gut. The first trace of the allantois (All.) is, however, already visible as a shallow notch in the posterior ]iart of the tail- lobe. In a surface- view, this notcli appears as a shalh^w transverse slit as re))resented in Fig. 20. Fi'om the first, tVic {)osterior wall of the allantois is lined with a distinct epitlielium of the hy|iol)last. Its anterior wall is no doubt also of the hypoblastic nature, but is her(^ fused Avith \\\v indifferent cell-mass alx^ve it.
Figs. CA-G?^ (IM. Vll.):uid Figs. 87 and 87« (Fl. X.) s])C'A suf- ficientlv foi- themselves :ind need tioI be miiiutelv exphn'ncd to those who ai'e alreadv familial' wiih llic (•<»! I'espoudiiig shigcs iii j>irds. ]jv the gradual f )lding of the spianclmi^pleui'e on the ventral face, the hind-gut is j)roduced, and on its ventral floor the allantois becomes esta])lished as a vesicle at first wide open ahme (Figs. 62-63) but with its gradual growth constricted at the neck (Fig. 87). Fig. 87« represents a cross-.se<'tioii of the alhuitoic region from an embryo of the same stage as that represented in Fig. 87. It shows that the cavity of the allantois is at this stage two-lobed.
Figs. 64-66 (1^1. VII.) are three successive stages in the develop- ment <^f the allantois in Clcuniiys. Althougli these do not give as complete a series as in Trionyx, they are }'et sufficient to show that the process in Clemmys is in all essential res])ects similar to that in Trionyx.
In none of my series of sections can I detect any trace of an
ox 'I'lIE FOETAL MI'rMl'.K'AXI'lS OF t'llELOXFA, 21
iii(lc|)('iulfiitlv i'ufiiK'd vc'sick' which aricfwiinls puts itself in ((tm- niiinicatinii with ilic liiinl-f|'iit hv an iniii'|)cii(l('nl Iv locincil sfalk. The fiii'nres üiven ab<)\e siitticiently wai-ranl us in oouchidin^' that in Clielonia at least, the allantois arises as a d i verti e u I u iii of the hinrl-o'iit and is from tlie first (;o7i t i ii no us witli it.
III. Laler Stages of the Foetal Membranes.
hi tiie urecediuii" tuo sections \vc lollowcd sc[i;(r;ncl\- i he L;r<iwth of I lie anuiion aiid (){' I he allantnis uji loa certain <tau('. It will he more e(jn\ »nient to treat the later .stages of these meiidiranes together. As tlie develo[)ment advances, they begin to differ in the two genera (demmys and Trionvx, until, wlien completed, they ])resent important dillcreiices in their struct tu'cs. As those in (demmys ])resent in mv cijiinion more primitive relations, I hegin with tliat species.
(I. i 'h'Uimijs J(lj)<tH/nl.
As llie aliantois pushes itself out as a vesicle into the; extra- eml)r\'onic C(elomi<' ca\itv. tlie allantoic hlood-Ncssels ai'e soon found distrihiited in two groups (('ompare f'ig, 27 Tl. \\ .). One (the right) s(M of arteries and veins is ]>laced in that part <d' the \esiele fa<'ing antei"iorly while the otlici" (llie lel'l) set is placerl on the posterioi' external aspect of tluî V(îsic]e. The mannei- of distrihiition of the blood-vessels exerts a consid<'ra1)Ie influence on the fut lu'c shape of the aliantois.
As the aliantois spi-eads itsell' over the emhrvo as well as over the y<dk in the extra-emla-Noni*; Cd-lomic ca\it\', it assumes a peculiar shape represented in iM"g. ()7 (IM. Virt.). 'l'he vesicle now flattened is divided by two peculiar constrictions into two [)arts of une<pinl sizes. The larger part is again subdivided into two lobes by the posterior set
22
K. Mfl'SUKlTi,'!
of blood-vessels. These two lohcs of flu- hii'u'i'i' |>:H't ni:i\- In- ciilUnl respeetively tin* ri^-ht, and the left lobe, wliilc the smullci- linlf of the allantoic vesicle may be called the niidillc lobe.
The 1 wo constrictions that divide the middle lobe from tlic larger half of the allantoic vesicle are caused in two different ways. The anterior constriction is ^ery easy to explain. It was mentioned above that one set of the allantoic vessels runs on the anterior side of the as yet small allantc^ic vesicle. Now, in the rapid growth of the vesicle, the lines along which blood-vessels run cannot, on account of their presence, keep up in their growth with the rest of the vesicle, aiid ai'c iicccssaiMl V left behind until along these lines f hei-e are pi'odn(_'ed groo\es at tlie bottom of whicli the blood-vessels rim. When the allantoic vesicle is flattened, these grooves necessarily produce notches Ol' bays ill the margin of the \esicle, more or less deep according to tlie size of the bl<x)d- vessels. In the case of the anterior set of the allantoic \essels, the gi'oove luis bec(^me so deep that the right lobe and tlie middle lohe on the two sides of it have met again and become llrndy a])])ressed with each other, so that praeticallv these blood- vessels are sup))orted in tlieir course by a mesentery- like i'old of the allantoic \esicle. This explains the origin of the anterior constric- tion ol' the allantois. In a similai' way the notch tliat divides the larger part of tlie allantois into the right and left lobes is prodiice(l bv the ])osterior Ol' lel't set of lilood-vessels, althongh th<' iiot<h is not as deep as in the anterior constriction and consists ol two or tliree minor indentations.
The jiosterior constriction of tlie allantoic- \esicle given in fig, B7 is also not very difficult to explain. There can be no d(»ubt tliat it is due in the main to the fact that the vesiele finds itsell' iinalile to spread freely over the eiubrvo on account of the sero-amniot ic connection. The only thing it can do is to grow round tin; sero-
()-\ THE FOETAL MEMJJKA.NE« OF CUELOXJA. -io
;iiiiiii()tic <'()iiiiccTi(jii, thus piNjduciii^' ;i (lee]» incision in its oiitliiu'. riie postcfini- ((»list I'ictitjii OWL'S its orii^'iii to tljis circuiiistaiKX'. niid llms liL'twt'cii tlic mid.lle. and the left. IoIk' there is always interposed tlie sei'o-aniiiiot ic coimeetion. There ;ire some details of" tin's poste- ri(.)r (j(jnst rietion wlndi lam not altle to imderstand. The allantois [irepares to meet the sero-aniniotie eonneetion. sometime before it reaches in its lirowtli the latter struetnrc (/. c, before there is, so fai- as I see, any mechanical necessity for a consti'iction) by folcbni^- itself and pi'odncinii' a constriction. Thus in Tig. G 7 îhe apex of the [)osterior const I'iction is some distance from the remnant of I lie posterioi' tube <»f the amnion (which marks the ])()sterior end <>f the sero-amniotic connection), and is nnu'ked by fohfs of the allantois slioAvinu' tliemselves as wln'te streaks. The result of this is that in later stau'es (Fi.i;'. VJ^) the jnjsterior ctjnst rictioii is. near its head, divided into two liml)S : one contains the sci-o-anniiotic connection and its termination, the remnant of the jjosteritir tube of the amnion, and the othei' is simj)lv an incision in the margin of the allantoic vesicle. In still later stages, the latter is much the deeper of the two aïid becomes (juite <;ons])icuous (ligs. (ÎS and 71. Tl. \ III.). I am unable to see an\' nei^essity for tlie existence of this incision. 1 can not detect anv one large bloo<l-ve^seJ or set of blood-vessels, wliich might cause it, as the anterior constriction of the allantois is caused by the right set of allantoic vessels. It aj)pears t() be a congenitally acquired character.
The nearl\' circular shape of the middle lobe is produced ])y iVie fact tliat if is necessarily limited in its gi'uwth l.»_y the sero-amniotic connection which obstructs its front. In fict it is the right and left allantoic lobes that grow to cover the larger part of tlie yolk-sac.
The right and middle lobes are suj)plied mostly by \\n' I'iglit set «•f bl(H)d-vessels. while the left IoIjc is sn[)plied by the left set.
24 k. MLTSUKUl.'!.
TIk' ullantui.s Ims not yet in this ^tnge entirely covered the amnion and the eml^ryo from above so that tlie amnion witli its sero-amniotie eonnection, and the anlei'ioi" dorsal part of the eiiilirvn are visible beyond the margin of the middle allantoic lube. Tiie amnion at these stages does not iit itself ti^btlv over tlie embrvo but leaves a spacious amniotic cavity arcnind ilie embi-vo. ]']speci;ill\ there is a remarkable snout-like prolongation of the amnion extend- ing in front of the head.
Fig. ()8 represents an embryo about forty days old. The allantois has now spi-ead over a lai'ge part of the uj)per half <jf the Volk, and this extension is due mostly to the right and left lobes and iKJt to the middle lol)e. A j)eculiarly sharp demarcation between the middle and left lobes of this stage is due to the fact that the sero-amnioti<' c(»nnection is placed between them. The remnant of the posleri<jr tube of the amnion appears as a white triangular ])alch extending to the left at the head of the ])osterior incision. The long white streak extending from the same point ol)li(jUely backward over the back of the endjry»j i^ the sim[)le incision of the allantois referred to above in Fig. 12 (PL TL). The allantoic vesicle being of some thi<'kiie>>. the walls of tin incision which extend from the iiiiM'f tii the outer limb of the allantois are of some depth, and beim: pressed from abo\c are bent down and show as a wliite conical streak of peculiar a p})eara nee. Note also the deep anterior constric- tion with the right set of allantoic vesseU at its bottom.
ll may be remarked in passing that the position of the embr\o on the Volk is not necessarily as in Fig. 68. fhe embryo is formed at ai]y jjlace which liappens to be up[ierm!)st when the egg is dej'(),xitcd. ll' an egg haj»pens to stand on it> end, the embryo Avill (jccupv the eml oj' the oljlong yolk.
Fig. Gl' (^I'l. \ 111.) giA'cs a side \iew of a somewhat oldi'r
ox THE FOETAL MEMBliAXES OF CHELOXIA.
25
I'uiljryo. The aljunluis hus spread over the larger part of the yolk ï>u that, ill the tigure, the latter show.s bare only at the posterior part of the ventral .--ide. The figure shows the left lobe of the allantois, the sero-ainiiiotic (-«Mjiiection with peculiar structures at its posterior cud. and the left set of allantoic Aessels with the corresponding incision in the margin of the alhnitoic vesicle.
ViiS. 7(1 gives a, \ entrai \iew of an cjj;^^' of aliout the same stage. Tlie rlifee lo1)es of the allantois have n<.)W spread themselves over a jiart of the lower half and are here \ ery conspicuous. The lol)e that a])prar> to ilie ol)server's right is tlie left allantoic lol)e. Xext to it is the middle lobe and finally at the o]>server's left is the i-ight allantoif lobe. The incision between tlu' middle and the right lobes is the anlei'ioi- constriction of Figs. ()7 and 68, and at its dorsal end is found the I'iuiit set of* alhnitoic vessels. The incision between the middle and the Icfi lohes passing o\er the head of the embryo correspontls to ihc postcrioi- constricrion of the; earlier stages, and has the scro-anmiotic connection placed in it. While in Figs. 67 and C)S the cnd)rvo is coiihned to the space l)elow the middle loljc, in this hgiirc ihc head <d' the end;ryo appears below the left lobe lo the left of the sero-amniotic connection. This is brought about by the following circiuustances. In Fig. 67, the embryo lies on its left side and, the sero-amnioti(.- connection l)eing a[)proximately over its dorsal median line, we are viewing it. so to s[)eak, from the side. As the embryo and with it the amnion gi'ow, the embryo comes again to lie on its ventral surface, a> in the earliest stages, and the seroamniotic connection ag;iin accomipanying the dorsal surface <^f the eml)ryo is tiu'ned toward the obser\'er. 'Idle amnion is thus free to grow to the left of it, under the left allantoic lobe. The amnion being spacious, the eml)ryo is aT)le to mo\e within it, and the head may now be seen to the left, or to tlie right, or directly under, the
26
K. MITSUKUlii.
sero-nmniolic connection, altliouuli the ])osition .sliown in Jnu". 71 appears to l)e tlie most normal.
The l)ho(3cl-vessels that pass thi'ono-h the umbilicus at tliese later stages, are arranged as in Fig. 75 (PI. IX.). The most anterior is the vitelline vein, then comes the \itelline artery, after it tlie allantoic artery and last of all the allantoic vein. The last three di\ ide int(j two, the right and left brandies, soon after their exit from the umbilicus. The vitelline artery is distril)uted over the surface of the yolk, but the vitelline vein is somewhat peculiar: it is much larger than the vitelline artery and while it receives branches from the surface of the yolk, the main liulk of it enters right into the substance of the yolk. This no doubt makes the acquisition of nutriment from the yolk much easier.
I may now proceed to describe the relations of the embryo, the foetal membranes and the yolk shortly before hatching. (Figs. 71 and 71a PI. \U\. and Diag. VI. Pi. X.).
Tlie yolk sac (Fig. 71«) is now reduced considerably in size and the three lobes of the allantois have entirely enclosed it. These three lobes never fuse witli one another, but are permanently sejiarate. The seams that sejiarate them are roughly speaking tri-radiite, the center being at the anterior end of the yolk-sac slightly to the left (to our riglit as we view it from the ventral surface) of the median ventral line. The seam that extends transversely from the center towards (he right (to the left of the observer) se]>arates the middle (phi«.'e<l in front of it) fivtm the right allantoic lobe (jilaced behind it) and corresponds to the anterior constriction in Pig. 67. Hence, at its distal end. is found the rio-ht set of the allantoic arteries and veins. The seam that runs back from the center nearly parallel with the median ventral line separates the left lobe (placed to its left or to the ol)server's right) iVoni llic right lobe, and corresponds to the
ON THE FOETAL MEMBRANES OF CHELONIA.
i>7
shallow notch prorluced by the posterior (the leff) set of blood-vessels in Fig. 67, or to the inrision in Fig. 60. Hence, at its distnl end the posterior or left set of allantoic vessels is found. The seam that separates the middle fi'om the left allantoic lobe is difterent from the other two, for here the two lobes of the allantois cannot come into contact, being separated bv the sero-amniotic connection. Ft passes over to the dorsal side of the embrvo (Fig. 71), and its dorsal end has the triangidar i-emnant of the postei'ior tube of the amnion, and the peculiar conical white streak caused by the simple incision of the allantois. (Compare Figs. 68. PI. V[TT., and 12, PI. 11.).
There is one featnre in an e^»; tliiis advanced which deserves special notice. The white of the egg which disa])peared vei-y early iVom over the embryo continues to grow smaller and smaller in rpiantity. But it persists up to a very late date, if it ever disappears entirely. There is alwavs, even in very much advanced eggs, a small mass of the white just at the point where the three lobes of the allantois meet at the lower pole. This mass seems t(^ have undergone some change in its chemical composition for it is now much denser, slightly yellowish in color and sticky. To receive this mass the mend^ranes are often shallowly depressed. Into the center of this mass of the white a thick low ])rocess of the membranes penetrates (shown in Fig. 71« on the left allantoic hdie, just to the right of the sero-amniotic seam), so that when the membranes are removed, the mass of the white with the central part hollowed out appe;u-s like a bowl. The cells of the serous envelope on the surface of this process are peculiarly modihed. They are more columnar than in other parts (Fig. 21», PI. IV.). Their nuclei are larger, irregular in shape, and stained deeper. In these cells are found many large vacuoles which remain unstained. There can l»e n<^ doubt that these cells are absorbing albuminous particles from the
28 K. MITSUKUKI.
ninss of the wliitc. It seems to me that here wehnve in a very primiti\e condition the strnctiu'C described by Duval (No. 10) as the placenta in Birds.
'I'he amnion in tliose later stages seems to envelope the embryo tolérai)! V closely, and its cavity is no longer spacious.
In hatching, the yolk-sac passes into the interior of the body whei-e it lies for a long time — in fact for several months, for I found it in young tortoises late in the spring of the year following that in which they were hatched. I'he amnion is torn into shreds, but the allnntnis seems to be spbt o])en by the anterior limbs of the emerging embr\(> along the sero-amniotic scam — if not nlwavs, at least in some cases, for I have specimens in which ihc adantois has been cast away iii this manner and is uniiijinvd. The outer shell whicli has Ijccomc \er\' brittle is easily In-okcn throngli and the young tortoise emerges into the worhl.
We maA' now cxaiiiinc tlie mi<'roscopic striu-tures of these mend^ranes. \\e left the scro-amniori«' connection in tlic condition represented in Fig. 41) (I'l. \'L). Aftci- ihat stage, as tlu; distance between the amnion and the serous envelope increases and th<' con- nci'tion 1)ecomes accordingly elongated in its vertical extension, the epiblast cells in it become flattened in the direction perpendicidar to the plane of the eoinie<M ion. Fig. 7ß (PL IX.) represents a pai'i of a section of the sei-o-aininotic' connection from the saine embi-yo as that from which Fig. S(i (l*L X.) is taken, 'fiie cells show decidedly the flattening referred to al)ove.
This flattening goes on more and moi'e. but I omit the inter- mediate stages and proceed to tin- descri])ti(^n of the sero-amniotic connection in the finished fœtal metnln-anes (Fig. 71, PI. \ II f.) Figs. 78-80 (PI. TX.) are selected seclions iVom an embryo of the same stage as thai rejn'csented in Figs. 71 and 71^/ (PI. \'fT[.). All
ON THE FOETAL MEMBRANES OF CHELONIA.
29
three are from the region of the remnant of the posterior tube of the amnion, Fig'. 78 beinc; the most anterior, and in order to facilitate the imderstandini>- of these sections, I have introduced a diagram of this region in Fig. 77. In this diagram, the serous envelope is represented as spread over all the structures ; the amnion is below it and is indicated <wly by the line from which the sero-amniotic con- nection arises. The remnant of the posterior tube of the amnion has before this stage been modified into a solid eompressed string of (•('lis and is shown l)y the hea\iest dark line whioli stretches from tile amnion to the serous envelope. The sero-amniotic connection is r('])resent('d shaded by parallel dotted lines. Throughont the largest ])art of its length (froîii its anterior end to near its posterior end) this structure lies in one plane and is sinijily a membrane stretch- ing between the amnion and the serous envelope. Bnt on coming to the r(^gion of the posterior tube (^f the amnion, it makes a sudden turn of over 90° to the left and goes to the serous termination <>f the posterior tu1)e, wliicjh latter structure it connects (m its way with the serous envelope. It will of (jourse be undersiood that the sero- amniotic connection from its anterior to its posterior end was originally in one straigiit line and that its |)C(MiIiar bent termination at this stage was Iii'ouglit about bv its a('(;oin|)an ving the posterioi* anuiioti(.- tube in all its (.•liang(\s of r(îlîtti\(' position. It is this peeidiar bent pai't of tlie s(M'o-amniotie (Connection wliich is seen as the ti'iangidar white ])atch at the dorsnl end of t he sero-:unniotic seam. (Figs. (18, 61), 71, IM. \'T[l.).
Fig. 78 is from the regi'^'i '*f ^'i^' simple sero-amniotic connection (the line 1-1 in Fig. 77). in such a section, the sero-amniotic con- nection is regally a striking structure, forming a broad and con- spicuous connecti(W lietween the serous envelope and the amnion. The e])il)last cells in it are now very flat and closely packed. riie
30
K-MITSUKTJRI.
îillantoic lobes become closely applied agjiiiist the mosoblii^t of tbe connection but nre permanently sepnrate from on<'h other. The epiblast of both the nmnion and the serons envelope consists of tAvo layers of cells. The inner la\er of the former and the outer Inver of the latter consist of very much flattened cells with hirge nuclei — which, in the case of the serous envelope at least, nre much laru-erand stained deeper than those of the second layei-. It is the cells of the outer layer which become specially laro'e in the reo-ion of the placeiitn. The second or underlying layer consists of cubical cells which in some places may be present in more than one layer. It is this inner second layer alone that forms the sero-;nnriiotic connection, the outer taking no part in it. As reçfards the allantois, the outer limb is generally much thicker than the iiiner litnb and has many more blood- vessels distributed in it. The thickness of the allantoic walls is crossed in all directions by slender spindle-shaped cells.
Fig-. 79 corresponds to the line 2-2 in Fig. 77 just through the anofle of the bend w^hich the sero-ainniotic connection makes. The sero-araniotic connection goes here on one side to the amnion and on the other to the remnant of the posterior tube of the amnion, which, being now reduced to a thick compressed and somewhat con- voluted sti-ing of cells, shows in section as lobated cell-masses.
Fig. SO corresponds to the line 3-3 in Fig. 77. The sero- amniotic connection is no longer continuous with the serous envelope but goes to the remnant of the posteri<n' tube of the amnion. To the rigfht of the sero-amniotic connection, the two lobes of the allantois meet but are not fused. This is the section of the conical white streak that stretches over tlie dorsal region of the embryo and (V)rres- ponds to the simple incision of the allantois given in Fig. 12 (PI. Tl.).
In a few more sections, the sero-amniotic connection disappears. The two lobes of the allantois, however, keep separate and meet in
ox THE FuETAii MEMBL'ANES (JE CHELuMA. 31
a sieaiii for many more sections, a>; the .simple incision of the alhmtois extends considerably further postericjrly than the most posterior point of the sero-amniotic connection. Finally, however, the allantoic cavitv is continued across. As the incision is deeper in the iimer liml) of the allantois than in the outer, the allantoic cavity first becomes continuous near the external surface and then u'radually extends tcjward the inner surface.
h. Trknujx Jaitonieu.s,
As in Clemmys. the allantoic blo(jd-\essels group themsehes into two sets : the antei'ior (or the right) and the posterior (or the left), while the allantois is still a small vesicle (Fig. 27 PI. l\.). AVhen the allantois has advanced simiewhat in its de\'elopment, it presents the shape represented in Fig. 72 (PI. VIII.). This cor- responds to Fig. 67 of Clemmys but presents some important differences. The allantois consists here of two lobes marked off from each other bv two constrictions. One of these is just l)ehind the eve and the other is directly opposite the first on the opposite side of the ^•esicle. Pnlike Clemmvs, both these (/«jnstrictions are pi'odiiccd in the same way. That is, the line along which each set of blood-vessels jwisses from the inner to the outer liml) of the allantoic Aesicle is left behind in its growth, and the parts on each side of" the >anic hni' growing faster and meeting each other sotjn pnjdiice a mesenterv-like f)ld slingiiig these blood-vessels. In tjther uords, Ixjth the constrictions of Tri onyx are of the same nature as the anterior constriction of Clemmys (Fig. 67). The posterior constriction of Tri onyx is not well-marked in Clemmys: it corresponds to the shallow notch caused by the posterior or left set of blood-vessels. ( )n the contrary, that corresponding to the
32 11. MlTSUKUKi.
pD^tcrior (•(»ii.'^t ricli(jii of" (Icniiny.s — tu that caitsoil Ijy the prij.seiice of the .seru-iiiJiuiutic (oiiiiectinii — is never [)roduced iii Ti'ioiiyx, iilthough at the .spot whei'e it (ju;Li'ht to lie ])roduced, \\z., opp(jsite the remuant of the posterior tul)e of the amnicjii, the alhiiit(jis is draw ii out to a peculiarly ,siiape<l point as if it were trying;' to uo round the senj- amniotic (•onneeti<ju. From these considérât ions, it follows that that part of the Trionvx allaiitois in fi-oiit oï the aiilerioi- constriction corresp(jiids to tiie ri<^"ht loljc of (I em m vs, the part fronî the anterior (•onstrictitjn to the ptjint op])osite the I'emnaut of the posterior lid»e of the amnion to the middle lobe, and the part lTo]n I lie same point to the j)osteri<jr constriction to the left loljc. flic middle lohe faces, as in (demmys, the sero-aniniotic conne<'tion.
Unlike ( ' 1 e ni m y s . h o w <ô\ e r . t h e if r o \\' t h of t li e middle lohe pushes, so to speak, the sero-am n i oti c connection before it, so that the amnioii comes gi'ad u a I - Iv to assume the shape of a bag «jf which the sero- am- niotic connecti<jn forms the puckered month. Keference to Fias. 25 and 2(5 (1^1. lA.) will make these ])rocesses clear.
In Fi"'. 25, the sero-amniotic connection is still directly over the dorsal side of the embryo and it is still straight. The allantois is pressing on it.
In Fia'. 26, the arowth of the amnion has removed tlie jnain j)ortion of it from the sero-amniotic connection. The Avhole amnion has now assumed the shape of a l)ag hanging ])cndant by the sero- amniotic connection. The allantois is still pressing on the sero- amniotic connection, and its i)ressure, so to speak, has bent the hitherto straiafht sero-amniotic connection like the letter \. Moreover the a'eneral axis of the sero-amniotic connection which has hitherto been parallel with the axis of the embryo is now at right angle with the latter. The general appearance of the c^^g at this stage as seen from
ox THE FOETAL MEMBRANES OF CHELOXIA. OO
tlie \eijti-al sfide is gi\ eii in Fig. 7o (1*1. \'JII.). The allautoi.s ha.s covered a larger j)arl of the yulk >a<'. lea\ iug ojiIn an oxal .s|»ace at the lower [)n\r mieovered. Thi.s o\al .space i.s hounded anteriorly hv the sero-aniniotic connection hent hke the letter \ , and from tliis is seen stretching" tbrwai'd tlie anterior prolongation of the amnion whicli unites the main portion of the latter with the sero-amniotic connection (Comp. J)iag. VIL. IM. X.). The two constrictions or meseuterydike folds of tlie allantcjis caused by the two sets of blood-vessels are also seen distinctly in the tigure.
The final shape <jf the fœtal membranes is seen in Tig. 74 (1^1. \ Jli. Comp. Diag. V'JL, PI. X.), and tliat part of the ventral surface where the lobes of the allaiitois finally meet is represented in a more enlarged scale in J: ig. 81 (1*1. IX.). The space left uncovered by the allcintois in Tig. 78 is now mostly grown over by the growtli from the posterior side. There is however a small space still left uncovered by the allantois. It is triangular in shape; the apex of this triangle is bounded anteriorly by the sero-amniotic connection, now com- pressed to an irregidar horse-shoe shaped opaque streak. On two sides of the triangle is the anterior allantoic lobe (which equals the middle and left lobes): posteriorly, it is limited by the posterior allantoic lobe (which e({uals the right lobe). From the lateral angles of this triangle the mesentery-like fold of the allantois stretches on each side to each set of the allantoic vessels. These correspond to the two notches in F^ig. 72. The view fr<jm inside of this reofion is given in FTg. Sla. In this there is a ridge across the middle of the triangular area. This is the line of junction of the yolk-sac and the amnion, as will become clear from the sections to be described directly. It appears in the external view as an opaque line across the horse-shoe shaped sero-amniotic connection (F'ig. 81). The anterior [n'olongation of the amnion connecting the main body of
34 K. MITSUKUitl.
the latter with the .sero-anmiotic coiiiiectioii is now ,so dispropor- tiunatelv small (-(Jtupared with the aiiiiiiou itself that it appears as a small irivi;-iilai'ly triaiiuuhir white pateh (l"'i,u". 8L(f, Aiit. Proloiiii'. Amii., and 1' i;L:. <Sl). Its oaA itv. n(3w ahiKJst ohliterated t)\' the aj)pres- sion of its two walls, js still ('ontiniKjiis with the amniotie cavity throiiiih n narrow slit (see Via;, (ila and Diaii'. A'll). It leads to the sero-anmiotic connection. I'ig«. 82-85 (PI. IX.) are a series of sec- tions of this region, the plane of sections being in the antero-posterior direction. Fig. 82 is from the left side of the triangular unc(jvered area, in Fig. 81« (or from tlie right side in Fig. 81). The two allantoic lobes, the anterior and posterior, are only slightly apart from each other. Attention is called specially to the section of a part of the anterior prolongati(jn. Figs. 83 and 84 are from the triangular area itself. Here the two allantoic lobes are wide a})art. The interspace is tilled up mostly by the growth of the somatic mesoblast of the serous envelope. The sero-anmiotic connection in Fig. 83 is of a very complicated figure. This arises from two reasons. Jn the first place, the section being taken in the antero-posterior direction, it cuts ()ne lindj of the horse shoe shaped sero-amniotic (.-onnectioji more or less longitudinally. In the sectjnd place, the sero-amniotic connection is not in a simple straight line as in (Jlemmys, but being compressed and rultled. ap])ears as of an irregular ])attern in a section. In Fig. <S4, the sero-amniotic (•onnection is cut nnjre directly across. To give an idea of the structiu'e of this region. I have gi^ en a. part of Fig. 84 on a more enlarged scale in 1 ig. 84(/. In Fig. So. wlii<-li was hi-oken by accident, the two allantoic lobes have again a])j)roached eiicli other, the section being out of the triangular area. The\" are, however, distinct and continue distinct until the sections reach the allantoic vessels.
In Tri onyx, the renuiant of the posterior tube of the allantois
ON THE FOETAL MEMBRANES OF CHELONIA. 35
is not to be olearly distino-ui.slied. The ])]ace where it should be present is drnwn ont to ;t point (Fio-. 26, PI. IV.): thnt seems to be all the indication I'emninino- in later stao-es of rhe posterior rube (tf the amnion.
The white remains to the last in Tricmvx ns in (MeniTnys. !ind is found opposite the triana'idar area of the \entr;d |iole left un- covered by the allnntois. This |)nrt is o'enerally more or less depressed to receive the nr^iss which is sticky niid yellowish. The outermost cells of the serons enxelope in this area imdero'o modificn- tions similnr to those of the corresponding' spot in Clemmy s . Tlie\' become taller and lar^'er and contain large vacuoles, their nuclei become larger and irreo-nlar in shape and stained deeper (Fig. S4(f., Comp. Fig. 29, PI. ÎA'.). In Tri onyx howe\ er. there appears to be no process that penetrates into the white as in Clem my s .
The yolk passes inside the embryo in hatching.
Of the completed fœtal membranes of Clemmy s and Tri onyx above described, there can be no doubt that Clemmy s has retained more primitive relations. The main ground for this (Conclusion is that, starting from the same ipoint, (bfferent structures (above all, the sero- amniotic connection) retain in Clemmy s tlieir original positicni and arrangement, while in Tri onyx various structures are disturbed from their first arrangement, the sero-amniotic connecticm being pushed forward, l)ent and C(^m])ressed into a secondary shape. If the process begun in Tri onyx were to go one step further, no spot would be left uncovered by the alia uteris, the sero-amniotic coiniection might be pressed out of existence, the two allantoic lohes might come in (^ontact with each other, and then the condition liitherto accepted as occurring in Birds would be the result.
3^! K. MITSUKURI.
General Considerations.
The notewi^rthy features in the history of the foetal meniliranes of Chelonia as given above are : —
1. The presence of the Proamnion and the manner in whicli it is replaced by the jiermanent Amnion.
2. The presence of a pecnliar tube stretchinis- posteriorly from the posterior end of the Amnion e o n n e c t i n g the c n v i t y of the latter with the ex- terior— the Posterior Tube of the Amnion.
3. The permanence of the Sero- Amniotic Con nee -
t i O 71 .
4 . T h e d i tf e r e n c e s in the fa te of t h e S e r o - A m n i o t i c Connection in Tri(^nyx and CI em my s ,
5. The presence (^f the rudimentary "Placentn." Of these, the iirst point has been noticed in nearly all tlie
amniotn wliose development has lieen carefully studied within reeent years. The only new feature is the fact thnt the dorsal part of the proaniîuon consists at tirst solely of a solid sheet of epibhist cells. The second, thii'd, and foiu-th points are. so far as I am aware, broiiuht out for the first time in the coiu'se of the present investigatioji. They certainly are vovy I'emarkable features, and, so fai" as (»ur present knowledge goes, might be looked on as distinctive of tlie ("heloniati fietal ]n«'inbi'anes. 1 think it, however, highlv |)rol)aMe that if other gi-oiips of |{e|»riHa aii<l lîirds are careful] V gone o\('i' again, maiiv struct ures wliicli are liighh sio-ui- ficant in the light of the facts now <)btaine(l will lie found to have hitherto escajied notice oi- been laid aside ;is iniim|>ortaiii . l^'or instance, in the sections of Lacei'ta gi\(Mi bv se\(M"al antliors. the sero-aiiiniotic connection is (listinetively lii^iu'ed v.xrw up to comparatively late
ON THE FOETAL MEMBRANES OF CHELONIA. 37
stages. Being possessed with the idea obtained fi-om the study of Birds thnt it is soon to disappear, different writers have not thought it worth theii- while to follow its history further. Nevertheless I ran not but think that the sero-aniniotir- connection rmis a similar course ill other groups of Re))tili;i as descril)e(| now for Ohelonia. I also think that the posterior tube of the amnion is not such an unique structure as it appears to V)e at present.
The fifth point, the pi-esence of the rudimentary placenta, is certainly very interesting. If the depression into which the white is received shoidd Ijeconie deeper, ajid the allantoic folds -should be produced to enclose it, we shall have exactly the same structure as "the placenta " described by Duval in Birds.
The Re])tilia, being the lowest group of the Amniota, are of great importance in tlic (•<)niparative study of the foetal membranes. What light dc^cs the history of the Chelouian fœtal membranes as given aliove throw on the phvl<\f;"eny of those membranes in the \'ei-febrat;i ? Witliout going into a o'enet'a.l disiiis- sion of this difficidî prol)letu. I think T might offer here a few suggestions which have |)f(-sented themselves to me in the course of the present investigation. T strongly incline to the \ iew thnt the amnion was originally descloped by mechanical cjuises. In Ohelonia, when the head fold is |»ro(bicetl. there are two reasons why it should sink into the yolk helow. fn the first place, the yolk is very Inro-c and licpiid. especially just beneath the blastoderm, so that a slight weight is enough to sink any struetiu'e into it. In the second place, the white rapidly disappeai's from oNcr the blastoderm, which adheres then firmly to the sh<'ll-niembrane : hence there is no space fo)* Ihe head-fold to grow except towards l)elo\v. Without asserting tluit these are the very same causes that produced the anterior
38 K. MITSUKTJRr.
fold of the amnion, I think it reasonahle to assume that it was prodiieed by some such meehanical means. En this relati(^n, I think, those inconstant adventitious folds ns o-iven in Fiu's. 1 and 2 (PI. T.) are hio-hly significant. These iind(^ubtedly arise l)y the neio-hhorino- parts sinkino- heh)w. We mit>ht suppose that in tlic earlier stufj-es of development many such folds are produced, different in different emhrvos aeeording to their individunl idinsynerar-ies, and the anterior inid of the amnion may be looked upon merely as one of these. Oidv the canse that ))rodnces it being present in all the embryos :ind acting permanently and augmenting steiidily, finally gnve rise to the structure whieh we call the ninnion, heredity (-)f course helping a great deal.
The anterior fold of the amnion, when produced, consists only of the hypoblast and epiblast, nnd is called the Troamnicm. AVe now know that this is fonnd in all the groups of the Amniota, and I think we ought to add the stage of the proamnion as of normal occurrence n the development of the amnion. In Chelonia. the dorsal part of the proamnion is for some time entirely epiblastic. Should this be looked upon as a |)rimitive feature or as a secondary one? I am inclined to adopt the former view for two reasons : —
(1). The inconstant adventitious folds are, as previously stated, always pui-ely e])iblastic and exactly like the lateral folds of the proamnion (Fig. 80a, PI. A'.): hence, it is reas<^nable t(^ conclude that all such folds produced on the surface «^f the blastoderm are ;it first always purelv epiblastic, and the solid epiblastic dorsal sheet of the Proamnion produced by the coalescence of the lateral folds of two sides have reason to be simply epiblastic.
(2). Tn Olemmys, whose deNt'lopmetit is certaitdy more pruni- tive than that of Tri onyx, the solid dorsal sheet persists for a longer time than in the latter genus, and thei-e is a ccmsiderahle interval of
ON THE FOETAL MEMBRANES OF CHELOXIA. o!^
time before the meso})lastic folds insinuate theniselves into the epi- blastic sheel. I think, hijvvcver, thai ahliDUg'h these folds are solid and \vith<.)ut any cavity, they ought t(.) he regarded as consisting of t\V(j Jinibs, the inner and outer, which are hrinl\' ap|)ressed against each otlier : otlierwise there is no reason \N'hy the .sero-anini(.)tic connection, which ought to be regarded as the seam al«jng which the folds of the two sides have met. should remain permanently and sej)arate the mesoblastic idlds of the two sides to the end.
If the doi'sal part of tiie proanuiic.n consisted primarily of t he e[)ibhist ahjne, why sliouM the meso]>lastic folds afterward insinuate tliemsehes between tlie two limbs of that ])art, thus extending tlie extra-eml)ryonic c<r']omic ca\it\ into that region? For the explana- ti(jn ofthat process, I adopt Jxdfour's view. To give efücac\' to the aliantois as a respiratory organ, it is desira])le that it should l)e spread as extensixely as possibk^ chjse under the surface of the egij!; ; hence the extra-em Ijrycjnic «-adomic cavity must ha\e spread pai'i- jHissii willi the gradual growth of the aliantois. The extension of tile folds of the somatic mesobiasf into the epiblastic fdds of the [)roaninion is. I think, due ])rimai-i]y tn this caiise. That the mesohJast s))reads itself at present long Ijetore the aliantois, is to be ex])lained as a case of precocious dc^eh^j^nent.
rile sero-amiiioidc coiiiiection is, in m\' oitiiiion, decidedly a pi'imitixe structure The manner in which t he aliantois sjU'eads itself in (Memniys hy r»junding the sero-amniotic connection can also be explaine(l only on ])hylogeiiet ic grounds. The manner in which the allantoic blood-vessels -are slung <jn mesenter\ -like folds of the aliantois, is, i think, also a primitive feature. The manner in which the sero-amniotic c<jnnection in Trionyx is pushed forward, bent and compressed, points out, I think, the way in which that structure historically disappeared in higher forms. As i have stated
40 K. Mi'J'ISUKUlll.
;ibo\e, if tlic proce.-s.s liegiiii in Triuuyx i.s ("irried jn.sit une ste}» litrther, the seru-ainniutic conne(.-ri<)n would ceu«e to exi.sl. Wluit i« the cause which Ijrouulit about this di«a])[)earance? So far a« I can «ee, the .sei'o-amniotic coiinectioii serxef- no |)ractical purpose in Ciem- uiys and its presence is only to be accounted for phylogeneticaJly. If such is the case, it would be undoul)tedly ecoiiomical to skip over the roundabout iiiaiiner by which the aUantois spreads itselt in Clem in \ s round the sero-anniiotic c(jnnecti(jn. Hence its dis- appearance at last in higher forms. Whether the innnediate agent of its forward shifting is the force exerted solely by the growing edge of the aUantois i cannot tell. It is no doubt partly due to that, but in addi- tion I oiler the following as a suggestion. In T r io n y x , the alhiiitoic vessels come out synunetrically on each side; in Clemniys, the symmetry is disturbed, the right set is found more anteriorly than the left. As I have often remarked, CI em my s presents on the whole more primitive relations, but I cannot regard this asymmetry of the allantoic blood-vessels as a |)riiniti\ e (•(jndition : something being- present in Clemmys has disturbed the <n-iginal symmetry and being- absent in Tri onyx no longer intereferes with it and this something I think is the presence of the sero-amniotic connection. May not the tendency of the blood-vessels to assume a symmetrical arrange- ment help to push the sero-anmiotic connection forward in Triony x?
ON THE FORTAL MEMBEANÇS OP CHELONIA. 41
List of Works referred to.
1. H. Strahl : — Ueber die Entwiclvlung des Canalis Myeloentericiis
u. d. Allantois der Eideclise. Arch. f. Anat. ii.
Physiol. 1881. Aiiat. Abth. 2. : — Beiträge zur Entwicklung von Lacerta agilis.
Ibid. 1882. 3. : — Beiträge zur Entwicklung der Reptilien. Ibid.
1883. 4. : — lieber Canalis neurentericus u. Allantois bei Lacerta
viridis. Ibid. 1883. 5. : — Ueber Entwickluno'svorträno'e am Yorderende des
Embryos von Locerta agilis. Ibid. 1884. 6. C. K. Hoffmann : — Beiträge zur Entwicklungsgeschichte der
Reptilien. Zeit, für Wiss. Zoöl. Bd. 40. 1884. 7. : — Weitere Untersuch uneven zur Entwicklunocssfe-
schichte der Reptilien. Morph. Jahrb. Bd. 11. 1886. 8. P]d. Ravn : — Ueber die mesodermfreie Stelle in der Keimscheibe
des Hiihnerembryos. Arch. f. Anat. u. Entwickl.
1886. 9. : — Bemerk, ueber die mesodermfreie Zone in der
Keimscheibe der Eidechse. Anat. Anz. IV. 1887
No. 5. , . ,
10. M.Duval: — Etudes histologiques et niurphologiques sur les
Annexes des Embryons d'Oiseau, Journ. de l'Anat. et delà Physiol., XX. 1884.
11. E. Van Beneden et C. Julin : — Recherches sur la Formation des
Annexes fœtals chez les Mammifères (Lapin et • Chéiroptères) Arch de Biol. V. 1884.
12. E. Gasser : — Beiträci^e zur Entwickluno^so^esch. der Allantois der
42 . K. MITSUKUKI.
Miiller'schen gänge u. des Afters. Frankfurt 1874.
13. : — Der Primitivstreifen bei Yogelembryonen (Hiihn u.
Gaus) Cas sel. 1879. . .
14. K. Mitsukuri and C. Ishikawa : — On the formation of the Germinal
Layers in Chelonia. Quart. Jour, of Micros. Sei. 1886. Also Jour, of Science College. Imp. Univ. Tokyo, Japan. Vol. 1.
15. A. OstromiiotF: — Zur Entwickhmofsg'eschichte der Eidechsen
Zoöl. Anz. Nr. 292.
16. Jv. Perenyi : — Entwicklung des Amnion, VVolff'schen Gauges u.
der Allantois bei den Reptilien. Zoöl. Anz. Nr. 274.
17. A. A, W. Hubrecht : — The Placentation of Erinaceus Europeus,
with Remarks on the Phylogeny of the Placenta. Quart. Jour. Micros. Sei. Vol. XXX. 1889.
18. J. A. Ryder : — The Origin of the Amnion. Amer. Natur. 1886.
19. A. Fleischmann : — Mittelblatt und Amnion der Katze. Erlan-
gen. 1887.
Explanation of Figures in Plates I — X. List of Reference Letters.
* a. (Fig. 2) iucoustaut tidveutitious folds, a. I. f. anterior limiting fuvrow= vordere Grenzfarche. All. Allantois. Amn. Amnion, b.v. blood-vessels. Coel. coelom witliin tlie embryo. CoeV. extraembryonic coelom. vh. notochord. Ej>i. Epiblast. H. f". head-fold. H///^ hypoblast. Lrt^/. J )wt. Lateral fold of Amnion. Mes. mesoblast. ^V. R. Can. neureuteric canal. Post. Ta. Amii. Posterior tube of Amnion. j)ro.v. />t. proximal part of posterior tube of Amnion. Proam. Proamnion. Reimiatit. Post. Tu. Amn. Renmant of posterior tube of Amnion. Ser. Knv. Serous envelope. Sero-Amti-Conn. Sero-Amniotic connection, v. v. a. anterior vitelline vein. yk. yolk.
In colored figures of sections, the epiblast is always colored red, the mesoblast blue, and the hypoblast yellow. In PI. IX. blue stands for the somatic mesoblast, and green for the splanchnic mesoblast.
ox THE FOETAL MEMBKANES OP CHELONIA. 43
Plate. I.
Fig. 1. Dorsal view of a Clemmys embryo 2 days old. Zeiss aa X 2. ^"^ '
Fig. la. Ventral vie\v of the same, aa x 2.
Fig. 2. Dorsal view of a Clemmys embryo 4 ^ days old, with 2-3 mesoblastic somites, aa x 2. rxxxsix.)
Fig. 2a. Ventral view of the same.
Fig. 3. Dorsal view of a Clemmys embryo 4 days old, with 6-7 mesoblastic somites. Extra-embryonic cœlomic cavities of two sides distinctly seen almost touching each other ov(!i" the median dorsal line of the embryo, aa x 2. ^"^^-^
Fig. 3a. Ventral view of the same, aay.2.
Fig. 4. Dorsal view of a Clemmys embryo 7 days old. aa x 2.
(xxxxi.)
lug. Ö. „ „ „ 8 „ „ aa x 2.
(XXXXIII.)
Fig. 6. „ „ „ 9 „ „ aa x 2.
(xxxix.)
Fig. 7. „ „ „ 4 ^ „ „ aa x 2.
(LIII.)
Plate. II.
Fig. 8. Clemmys embryo slightly older than Fig. 7. Enlarged.
(1.)
Fig. 9. Clemmys embryo 13 days old. aa x 2. (xxvm.)
44 K. MITSUKÜßl.
Fig. 10. Posterior tube of the Amnion higlily convoluted, from a Clemmys embryo 14 days old. aa x 2. ^'''"'•^
Fkj. 11. Dorsal view of a Clemmys embryo, 10 days old, 6^^ mm. long. Enlarged about 17 times. ^"'"'^
Fig. 11a. Ventral View of another embryo from the same deposit. Enlarofed about 17 times.
Fig. 12. Semi-diagramatic view^ of the posterior constriction of the AUantois in a Clemmys embryo 31 days old, seen from outside the serous envelope, ca x 7. ^"'^'^
Fig. 13. Two Clemmys embryos 18 days old. Slightly enlarged.
(xxxxv.)
Fig. 14. Dorsal view of a Clemmys embryo whose amnion is open toward the left. '^^^""•'
Fig. 15. Posterior tube of the Amnion disappearing. From a Clemmys embryo 13 days old, 8 mm. long.
Plate. III.
Fig. 16. Dorsal view of a Trionyx embryo 34 days old. a« x 2.
(126.)
Fiq. 17. Dorsal view of a Trionyx embryo o.i It y old, 3 mm.
long, witli 5-6 mesobl. somites, aa x 2.
(128.)
Fig. 17a. Ventral view of the same.
Fig. 18. Dorsal view of a Trionyx embryo 74 days old, 3t\ mm.
long, with 7-8 mesoblastic somites, aa x 2.
(141.)
Fig. 19. Dorsal view of a Trionyx embryo 8^ days old, 4 mm.
long, aa x 2. ^'"'-^
Fig. 19a. Ventral view of the same, aa x 2.
Fig. 20. Ventral \'iew of the posterior part of a Trionyx embryo
ON THE FOETAL MEMBRANES OF CHELONIA. 45
8 dnys old, showing the beginning of the Allantois. A A x2.
(112.)
Fig. 21. Posterior tube of the Amnion in four Trionyx embryos 13 days old. Slightly enlarged. ("--^
Fig. 22. Posterior tube of the Amnion in two Trionyx embryos 16 days old. aa x 2. <i6^-)
Plate. IV.
Fig. 23. Dorsal view of a Trionyx embryo IOt days old. aax2.
(157.)
Fig. 24. Dorsal view of a Trionyx embryo 114 days old, 5^ mm.
long. Posterior Tube 2 + mm. long. *^"'
Fig. 25. Trionyx embryo 38 days old, seen from the side of the
yolk-sac which has however been removed. (^"^•'
Fig. 26. Trionyx embryo 53 days old. The yolk-sac removed and
the embryo seen from the ventral or yolk-sac side. x3.
079.)
Fig. 27. Trionyx embryo 10^ days old. ^^''^•>
Fig. 28. Same embryo seen from its dorsal aspect, with the serous
envelope lifted up, showing the sero-amniotic connection
and the remnant of the posterior tube of the Amnion. Fig. 29. Cells of the serous envelope in the region of the " placenta "
in the Clemmys embryo represented in Figs. 71 and 7la.
DD X 4.
Plate. V.
Fig. 30-33. (5-8). Selected transverse sections from the Cleinmys embryo represented in Figs. 2 and 2a. CC x 1. Fig. 30. From the region of the lateral limbs of the Amnion.
46 K. MITSUKURI.
Fig. 31. From the region where the two lateral limbs have just
united. Fig. 32. From the region where the head is partly sunk below
the level of the blastoderm. Fig. 33. From the region of the head which is wholly sunk below the level of the blastoderm. Fig. 30a. Region of the left amniotic limb in Fig. 30. under a higher
power. BD x 4. Fig. 31a. Left half of the amnion in Fig. 31. DD x 4, Figs. 3-1-38. Selected transverse sections from the Clemmy?^ embryo represented in Fig. 3 and 3rt. CG x 1. Fig. 34. From the region of the lateral limbs of the Amnion. Figs. 35-36. From the dorsal region. Fig. 37. From the region of the heart. Fig. 38. From the region of the liead. Fig. 3ôa. Median dorsal part of the Amnion in Fig. 35. under a
higher power. DD x 4. Fig. 36a. Median dorsal part of tlie Amnion in Fig. 36. under a
higher power. DD x 4. Fig. 361). The same region a few sections in front of Fig. 36.
DD X 4. Fig. 37a. Median dorsal part of the Amnion in Fig. 37. under a
higher power. DD x 4. Fig. 39. Transverse section of the posterior tube of the Amnion from the embryo given in Fig. 5. near its proximal end. OCxl. Fig. 40. Do. from about its middle. (70 x 1.
Fig. 41. Longitudinal Secti<ju, slightly out of the median line, of a Cleuunys embryo from the same stage as that represented in Fig. 3. BB x 2.
ox THE FOETAL MEMBRANES OF CHELONIA.
47
Fig. 41a, DiagTammatic longitudinal section of a Clemmys embryo somewhat older than that o;iven in Fig. 41.
Plate. VI.
Figs. 42-47. Selected transverse sections from a Clemmys embryo
6 days old with 20 mesoblastic somites. CC x 1. '^^^"•> Figs. 44a. Median dorsal part of the Amnion in Fig. 44. under a
higher power. D.Z) x 4. Figs. 48-49. Selected transverse sections from a Clemmys embryo 9 days old. CC x 1. Fig. 48. From the tail-region. ' Fig. 49. From the dorsal region. Fig. 48a. Median dorsal part of the Amnion in Fig. 48. under a
higher power. BD x 4. Fig. 49a. Median dorsal part of the Amnion in Fig. 49. under a
higher power. DD x 4. Figs. 50-52. Selected transverse sections from the embryo repre- sented in Fig. 17. CC X I. Fig. 50. From the region of the lateral limbs of the Amnion. Fig. 51. From the dorsal region of the Amnion. Fig. 52. From the region when the head is sunk almost entirely below^ the level of the blastodem. Figs. 53-55. Selected transverse sections from the posterior tube of the Amnion in the embryo represented in Fig. 24. Only the epiblast and somatopleuric mesoblast are represented, the hypoblast and splanchno})k'uric mesoblast being omitted. DD x 4. Fig. 53. Near the posterior opening of the tube.
48 K. MITSUKÜEI.
Figs. 54-55. At various distances in front of Fig. 53. Fig. 56. Median dorsal part of the Amnion in a section from the
middle dorsal region of the Trionyx embr3o represented
in Fig. 24. DD x 4. Fig. 57. Median dorsal part of the Amnion in a section from the
dorsal region of Trionyx embryo represented in Fig. 19.
DDx4.
Plate. VII.
Fig. 58. Longitudinal section of an embryo from the same stage as
that represented in Fig. 1. DD x 2. Fig. 59. Transverse section of the embryo represented in Fig. 1.
DD X 2. Fig. 60. Longitudinal section of the Trionyx embryo shown in
Fi^. 20. OCX 2.
Fig. 61. Longitudinal section of a Trionyx embryo lOj days old.
GG X 2. ^'"-^
Fig. 62. Longitudinal section of a Trionyx embryo 9 days old.
GG X 2. *"'-^
Fig. 63. Longitudinal section of a Trionyx embryo IH days old.
GG X 2. ^'''•'
Fig. 64. Longitudinal section of a Clemmys embryo 4 days old
with 16 mesoblastic somites. BB x 2. ^^^^-^
Fig. 65. Lorjgitudinal section of a Clemmys embryo 6 days old
with about 20 mesoblastic somites. BB x 2. ^^^^"^
Fig. 66. Longitudinal section of a Clemmys embryo 9 days old.
BB X 2. ^^""'^-^
ox THE FOETAL MEMBRANES OF CHELOXIA. 49
Plate. VIII.
Fig, 67. Surface view of a Clemmys embryo 28 days old. Seen from outside the serous envelope. x 4^. ^''^^'•*
The upper transparent membrane is the serous envelope» The lower opaque membrane with blood-vessels is the yoîk-membraiie. Between these two membranes are placed the enihnjo, the allantois &c. Different divisions of the allantois are sufficiently explained in the text. The white line close to and parallel with the median dorsal line oi the embryo is the sero-amniotic connec- tion. : traced posteriosly, it bends sharply to the left, this short liml) being the remnant or proximal part of the posterior tube of the amnion. Over the posterior part of the embryo, is a clehcate, irregularly curved white tube : this is the distal part of the posterior tube of the amnion with its horse-shoe sha[)ed posterior opening. It has no connection with the proximal part.
Fig. 68. Dorsal view of a Clemmys egg, with the embryo, the fetal membranes, and the yolk-sac. About 40 days old. x 2.
(LXSII.)
Fig. 69. Side view of a Clemmys egg with the embryo, the fetal membranes, and the yolk-sac. 51 days old. Nat. size.
(lxxiii.)
Fnj. 70. Ventral view of a Clemmys egg with the embryo, the foetal membranes and the yolk-sac. 55 days old. Blood-vessels on the yolk-sac omitted. Nat. size. a-ssv.>
B'ig, 71. Dorsal view of a Clemmys embryo, shortly before hatching with the fœtal membranes. 45 days old. ^''^'^•*
50 K. MITSUKURI.
Fig. 71a. Ventral view of the same.
A low lobate process of the membranes situated close to the left of the tri-radiate allantoic seams penetrates into the mass of the white.
Fig. 72. Surface view of a Tri onyx embryo 15f days old. X 5^.
(1-7.)
This corresponds to Fig. 67. of Clemmys, and the ex- planation of the latter is applicable to this. The white line stretching from the neck of the embryo to its posterior end is the sero-amniotic connection. Its slight posterior expansion marks the remnant of the posterior tube of the amnion. Fig. 73. Embryo represented in Fig. 26. with the yolk-sac and the
foetal membranes. Blood-vessels on the yolk-sac omitted.
Slightly enlarged. ^^^^'^
Fig. 74. Ventral view of a Trionyx embryo 42 days old with the
yolk-sac and the foetal membranes. Slightly enlarged.
(ISl.)
Plate. IX.
Fig. 76. Blood-vessels that pass through the umbilicus. Fig. 76. Part of a transverse section through the sero-amniotic connection of a Clemmys embryo 13 days old. DD x 4.
(LIX.)
Fig. 77. Diagram of the region of the posterior tube of the Amnion.
Figs. 78-80. Selected transverse sections through the posterior part of the sero-amniotic connection and the remnant of the posterior tube of the Amnion in the Clemmys embryo represented in Fig. 71. CC x 2.
ox THE FOETAL MEMBRANES OP CHELOXIA.
51
Fig. 78. Through the line 1-1 in Fig. 77.
Fig. 79. „ „ „ 2-2 in Fig. 77.
Fig. 80. „ „ „ 3-3 in Fig. 77.
Fig. 81. Region on the non-embryonic pole of the yolk-sac where the allantoic lobes meet. From a Trionyx embryo similar to Fig. 74. Seen from outside the serous envelope, x 3.
(182.)
Fig. 81a. The same region seen from inside.
Figs. 82-85. Selected sagittal sections through the region repre- sented in Figs. 81 and Sla. aa x 2. Fig. 82. is to the extreme left of Fig. 81a. and the sections gradually proceed toward the right. Fig. 84a. Region of the sero-amniotic connection in Fig. 84. more highly magnified. DD x 2.
Plate. X,
Fig. 85. Transverse section from the head-region of the Clemmys
embryo represented in Fig. 11. aa x 2. Fig. 86. Similar section from the head -region of a Clemmys embryo
13 days old. aa x 2. *""*
Fig. 87. Longitudinal section of a Trionyx embryo 16 days old
(the same embryo as that given m Fig. 2'1). CG x 1. ' '■'> Fiq. 87a. Transverse section through the allantoic vesicle of an
embryo of the same stage. CC x 1. Diags. I~VII. Give a summary of the development of the fœtal
membranes in Chelonia. Diags. I-V. Applicable to both Clemmys and Trionyx. Diag. I. Corresponds to Fig. I. (PI. I.) and to Fig.
^2 . K. MITSUKURI.
58 (PI. VIL). The head-fold of the embryo is sunk below the level of the blastoderm and enveloping it is the proamnion ns yet only slightly developed.
DIag. 11 and II'. Corres])ond to Fig. 2 (PI. I.). The aioniotic hood prot'ceding backward has covered the anterior half of the embryo. Its cephalic portion con- sists of the hypoblast and epiblast ; its dorsal portion of the epiblast alone. IT represents a cross-section of the dorsal region. It shows clearly that the mesoblast has as yet no share whatever in any part of the amnion (or more properly proamnion).
Dwg. Ill and III'. Correspond to Fig. 3. (PI. I.). The amniotic hood has extended nearly to the posterior end of the embryo. The extra-embryonic cœlomic cavities of two sides are nnited across in the head-region. The mesoblastic f )lds have also insinuated themselves into the hitherto solid epiblastic dorsal part of the amnion (HT.) A partition — tJie sno-amniotic couiicc- tion — in the median line, however keeps the cu'lomic cavities of tw(^ sides separate in the dorsal region.
IJiag. IV and IV'. Represent the stage when the posterior tube of the amnion is fully developed. The sero- amniotic connection in a cross-section (IV'.) is now closely invested on each side by the mesoblastic fold, and is longer than in III'. The mesoblastic fold is peeling the hypoblast otf the proamnion covering the head. (IV.).
Diag. V. TAH but a small proximal part of the posterior tube has now disappeared. The sero-amniotic connecticm is more developed. The mesoblastic fold has now entirely
ON THE FOETAL MEMBRANES OF OHELONIA. 53
peeled the hypoblast off the proamnion, and the head is now enclosed in the amniotic cap consisting of the epiblast and mesohlast. Although these diagrams (III, IV and V) show the encroachment of the mesoblast on the proamnion as taking place from before backward, it in reality takes place mostly from two sides. In Diags. IV and V, the gradual development of the allantois is shown.
Diag. VI. Shows the fœtal membranes of Clemmys as com- pleted.
Diag. VII. Shows the foetal membranes of Trionyx as com- pleted.
Jour. Sc. Coll. Vol. IV PI. /,
K. Nagahara del.
Jour Sc. Coll. Vol. IV PI. II.
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i: V,h:.h„r, .r K .V„„.-,li„ra del.
On the Development of Araneina.
by
Kamakichi Kishinouye, Rigakushi.
Science College, Imperial University.
With Plates XI— XVI.
The following' observations où the development of Araneina were made in the Zoological Laboratory of the Imperial University during- the academic session of 1888-9. S<mie of the results I have arrived at seem to be not without interest, l^efore going further I wish to express my thanks to my teachers, Dr. K. Mitsukuri and Dr. I. Ijinia for their kind and valuable advice during my work.
The materials used for the investigation were all collected by myself during the summer of 1888 in the grounds of the university. The genera that have been most carefidly studied are Lycosa and Agalena, while Theridion, Epeira, Dolomedes, Pholcus were more or less examined for comparison. A species of Lycosa which is very abundant among grasses breeds constantly from the end of March to the latter part of September, and carries about the cocoon so that we are able to obtain its eggs in various later stages with great ease. It, however, failed to breed in captivity, and for this reason, in the study of earliest stages recourse wns had to the eggs of a species oî Agalena which breeds very freely in captivity. The statements made in the following pages refer to all the species examined unless otherwise specified.
56
K. KISHINOUYE.
A few words about the methods of investigation may be of use. Eggs of later stages were killed by heating in water to 70-80°C., while segmenting eggs were plunged directly in hot water. Heating was stopped when the eggs became somewhat opaque and white. They were then allowed to cool and transferred to 70% alcohol. After 24 hours, they were examined one by one under a dissecting microscope and those with unburst egg-membranes were perforated with the point of a needle to facilitate the penetration of reagents. They were then hardened in ascending grades of alcohol. I have always found this method to be excellent for all spider eggs.
Staining was done with alcoholic cochineal, picrocarmine, alcoholic carmine, or hasmatoxylin. Alcoholic cochineal and picro- carmine have given best results. It is a remarkable fact that j)araffin penetrates into eggs stained with picro-carmine more easily than into those stained with any other reagent. Alcoholic cochineal proved to be especially good for staining sections on the object glass. Imbedding for section-cutting was done in paraffin.
Composition of the Freshly Laid Egg.
The egg has two investing membranes, the inner of which is the vitelline membrane, and the outer the chorion. The external surface of the latter is covered with a crust of minute spherical granules, insoluble in alcohol. In a species of Epeira, these granules are com- paratively large and closely encrust the surface of the eggs, in some places in two or three layers, making the examination of the inside almost impossible. They were easily removed by gentle rubbing with the fingers. In species of other genera examined, the granules were tolerably crowded in one layer, but being smaller than those of Epeira did not seriously obstruct the view of the inside.
ON THE DEVELOPMENT OF ARÄ.NEINA. ,57
The conipositicjji of a freshly hiid egg has been tolerably ac- curately described l)y previous writers, their opinions differing oidy in some points of details. Tt may be conceived of as a scanty network of protoplasm in the wide meshes of which yolk granules are im- bedded. There is always more or less concentration of protoplasm toward the centre which may be called the centroplasm. An ex- tremely thin layer of protoplasm is fnind on the external surface of the egg, directly inside the vitelline membrane and may be dis- tmguished as the periplasm. The centroplasm and periplasm are no doubt connected with each other by a scanty protoplasmic network, although not always ajoparent in sections. The space between the centroplasm and periplasm is almost entirely taken up by large yolk granules which are arranged in characteristic radiate columns. In each column the yolk granules are in several rows, one placed outside another, and in each row there are generally two granules abreast. The granules near the centroplasm are much smaller than those placed more to the outside. In a freshly Jidd egg I was unable to detect the germinal vesicle in any part. The first segmentation nucleus appears in the centroplasm a few hours later. In Lycosa, the so-called yolk-nucleus of tha usual appearance was distinctly seen in the centroplasm. In Agalena, I could not find it.
The periplasm when seen from the surflxce presents the appear- ance of being divided into irregular polygonal areas (PI. XI, tig. 1). The cause of this appearance has lieen a point of dispute, Ludwig* even maintaining that there is no such. That the peri- plasm is marked out into irregular polygonal arears, there can be jio doubt. I agree with Locy** in assigning the cause of this marking to a pressure whicli is exerted on the periplasm and presses it against
* Ludwig— IJ.'ber die Bildung d"s Blastodermes bei den Spinnen, Zeit, für wiss Zool XXVL
** Looy— Observations on the Development of Agelena naevia, Bull. Mus. Couip. Zool. XII-
58 K. KISHINOUYË.
the peripheral end of the underlying yolk columns, thus causing the former to receive the impression of the latter. The fact that in freshly laid eggs the polygonal areas correspond with the underly- ing groups of yolk granules favours tliis view. I must, however, differ from Locy as to the cause of this pressure brought to bear on the periplasm. Locy ascribes it to the contraction of the egg. This can hardly be, for I could find in no case any trace of contraction, the eggs being always very closely covered by the two membranes. I think it much more probable that the polygonal markings are the effect of the pressure to which the eggs are subjected as they pass through the narrow oviduct. Locy states moreover that at an early stage a number of faintly marked areas made their appearance at the animal pole, ^vhile they could not be detected upon the opposite hemisphere. I can not corroborate this statement, for I found the polygonal marking covering the whole surface of the eggs from the earliest period after l^eing laid. It should be stated that after a while when segmentation begins, the yolk granules more or less shift tlieir places ; hence we no longer find the coincidence of polygonal areas with groups of yolk granules. The polygonal areas do not seem to change their positions nor do they vary in number after they are once formed.
From the Segmentation of the Ovum to the Formation of the Germinal Layers.
According to Ludwig*, who gives a detailed description of the segmentation of the ovum in Philodromus, the nucleus and the yolk divide simultaneously first into two, then into four, eight, sixteen, nnß. so on. Morin** who studied Theridion, IMiolcus. Drassus and
* Ludwig — loc. cit. ** Moïin — Zur Eutwicklungsgeschichte dey Spinnen, Biolog-. Centralbl. VI.
ON THE DEVELOPMENT OP AKANEINA. 59
Lycosa, «ta tes that there is no division of the yolk before there are formed eight nuclei. In the species studied by myself, the yolk columns are grouped into as many masses (yolk-pyramids or rosettes) as there are nuclei, from the time when there are only two of the latter.
In PI. XII, fig. 8, I have represented a section of an egg in which there are two nuclei. It will be seen that the yolk is already evidently divided into two masses or segments. In the lower seg- ment, the nucleus is distinctly seen. In the upper, the nucleus does not happen to be in the section, but there is seen the yolk-nucleus (//. n). The latter does not divide and was often found even in eggs of the 4 cell stage, always by the side of one of the segmentation nuclei. The segmentation cavity (^seg. cav) is already present. The yolk granules immediately adjoining the perinuclear protoplasm are split up into small particles at whose expense the protoplasm evidently seems to increase in bulk (PI. XII, figs. 8, 9, 10). This process of assimilation is no doubt continued during the whole process of segmentation.
From this stage on, as the nuclei divide, the yolk masses also divide, assuming characteristic rosette or pyramidal shape (PL XI, fig. 2). Strictly speaking, the segmentation is not total but syncytial, as the periplasm remains undivided. Nor is it entirely regular, as stages with 3, 11, 22, 34, 85 &c. nuclei were found. Nevertheless the nuclei, after repeated division, are distributed fairly uniformly in the egg.
As the process of segmentati(3n goes on, the segmentation cavity which was already present in the 2 -cell stage gradually enlarges so that iu stages represented in figs. 9 and 10 the centre of the egg is occupied by a large cavity.
Side by side with their increase by division the nuclei together
60 K. KISHIXOUYE.
with theii' «ur rounding protoplasm gradiuilly travel toward the periphery of the egg through the yolk pyramids (PI. XII, tigs. 8, 9, 10). When about 30 in number, they all reach the surface. \Vhen they are almost at the surface, the continuity of the perinuclear protoplasm with the periplasm by means of pseudopodia-like processes can be demonstrated on surface views. Figs. 3, 4, PI. XL are tw<^ figures giving such views in which the radially arranged processes of the perinuclear protoplasm (represented in the figures as dark lines) become lost in the peri[)lasm whose polygonal markings are still visible. Soon after such a stage the perinuclear protoplasm and the periplasm are entirely mixed together forming a nucleated layer at the surface. So far as my observations go, the nuclei emerge simultaneously all over the surface of the egg — not, as Locy states, earlier at the animal pole than at the opposite pole. When there are formed about a hundred nuclei, this nucleated layer separates itself from the underlying yolk, and then by the continual division of the nuclei the one-cell layered blastoderm is established (PI. XIII, fig. 15). Coinciclently the poly- gonal markings disappear and the egg recedes from the investing membranes. Probably this is due to the swelling of the membranes and not to the contraction of the egg.
Whether the yolk still contains nuclei or is entirely free from nuclei when the blastoderm is established has been a matter of dispute. In my own sections, I could not at this stage detect an}- nucleus at all in the yolk, thus confirming the views of Morin in opposition to lîalfour's.* Yolk granules are, however, still aggre- o^ated into masses.
The change that comes next is of great importance. The cells of the blastoderm when it is at first established are of uniform spherical shapu throughout its extent. While; these cells gradually assume a
* Balfour — Notes ou the Development of the Araneina, Quart. Jouru. Micr. Sei. XX.
ON THE DEVELOPMENT OF ARANEINA. 61
flattened shape over the greatest part of the blastoderm, there is one spot where the nuclei become conspicuously spherical and mnlti])ly rapidly. The spot may be distinguished by reflected light as a round whitish area (PL XI, fig. 5, j)rim. th). It is often a little depressed at first ; but it soon becomes flat and eventually a little elevated. Sections through this spot show a large accumulation of blastodermic cells about seven cells deep (PL XII, fig. 11). I shall call this thickening the pririiary thickening.
Shortly after this another thickening appears, close to the pri- mary thickening, on the future median line (PL XI, fig. 6, PI. XII, fig. 12, sec. tJi). This is also slightly elevated above the general surface of the blastoderm (PL XII, fig. 13). I shall call it the secondary thickening. The primary thickening now gradually ex- tends itself in all directions and forms a whitisli disc-like area of the blastoderm, the centre of which is thicker than the periphery (PL XI, fig. 7). This white area is the first trace of the ventral plate. The primary thickening as it spreads out surrounds and pushes away the secondary thickening, so that the latter now lies at the margin of the white area but is further from the centre of the primary thicken- ing than before (PL XI, fig. 7).
There has been much confusion in regard to the nomenclature of these two thickenings of the blastoderm. The secondary thicken- ing corresponds to the primitive cumulus as described by Claparede,* This appears at least very probable when we compare my fig. 7, PL XI, with figs. 3 and 4, Planche I, of this author, Balfour was of the opinion that the primitive cumulus becomes lost in the caudal thickening. What is called the primitive cumulus by Locy is undoubtedly the primary thickening above described, while his " caudal thickening " is the secondary thickening. Morin admitted
* Claparede — Recherches sur I'Kvolutiou des Araignées, Naturk. Verhandel. I.
62
K. KISHINOUTE.
the existence of a blastodermic thickening giving rise to germinal layers, but denied the identity of it with the primitive cumulus. He says that the primitive cuniolus is formed after the formation of the germinal layers and is composed of mesoderm cells. My observations on Lycosa show that the secondary thickening, or the primitive cumulus of Claparède, is formed after the formation of the primary thickening and that both are formed before the distinction of ger- minal layers is possible. lîoth are accumulations of indifferent cells, not yet referable to any germinal layer (PI. XII, figs. 11-14). I can not tell whether the position of the secondary thickening corresponds to the anterior or to the posterior (.)f the future ventral plate. This much is certain, that it entirely disappears at the time when the germinal layers are established.
These two thickenings, the primary and secondary, are of a great significance, as the germinal layers are established from them, the primary thickening contributing the largest part in their forma- tion. In a longitudinal section, these two thickenings are as in figs. 12 and 14, while in a cross section they appear as in fig. 11. From these figures it is evident that they together form along the median ventral line of the future embryo a ridge-like thickening which sticks out into the cavity of the yolk. Cells from the top of this ridge (the lowest part of the ridge in the figures) proliferate into th*e yolk and become scattered without any definite arrangement through the entire yolk. These are the endoderm cells. They become large by takiijg nourishment from the yolk as they pass through it. The cell-layer of the ridge nearest the external face of the egg becomes established as the definite ectoderm. The cells of the ridge which are left close under the ectoderm form the mesoderm (PL XIII, fig. 17). They soon spread horizontally below the ecto- derm. The mesoderm is at first in a single median mass on the
ON THE DEVELOPMENT OE ARANEINA. 63
ventral face and does not extend to the dorsum of the embryo which is composed of the ectoderm only.
As to the nature of these two thickenings, the primary and secondary, it is difficuU to state anything definite. The stage in which the one-cell layered blastoderm is established on the surface of the egg is to be looked upon as the blastosphere stage. When the ridge appears in this Ijlastosphere along the line which becomes the median ventral line of the future embryo and sends otf cells into the yolk cavity, the whole process must be regarded as a modified form of invagination and the ridge is to be looked upon as the b]asto[)ore. Why there should arise two thickenings instead of one remains inex- plicable to me. The primary thickening is without doubt the remnant of the blastopore. Whether the secondary is to be looked upon as a part of the same, I cannot decide.
From the Formation of the Germinal Layers to the Reversion of the Embryo.
After the establishment of the ventral plate, its anterior part becomes marked off as the cephalic, and its posterior part as the caudal lobe, and the middle region between the two lobes is divided by trans- verse rido'es into seo-ments. The least number of se^'ments observed between the cephalic and caudal lobes was five. The foremost of these corresponds to the segment which bears the pedipalpi and the four following are the thoracic segments, each of which subsequently produces a pair of ambulatory appendages. The segment which is to bear the chelicerœ is soon after cut off from the cephalic lobe and the abdominal segments are gradually cut off from the caudal lobe, the process proceeding posteriorly, until there are formed eight abdominal segments (Lycosa).
64 K. KISHINOUYE.
In this process of segmenting the mesoderm of the ventral plate shares (PL XIII, fig. 16), and is divided into as many parts as there are segments in the body (jf the embryo. Moreover it divides itself into two longitudinal bands at the median line except at the cephalic and caudal lobes. Thus there is formed in each segment a pair of mesodermic plates. After a while, eacli of these paired mesodermic plates produces a cavity — the cœlom — apparently by its splitting into two layers (PI. XIII, fig. 18). The outer of the two layers is the somatopleure, and the inner the splanchnopleure. The cœlom there- fore consists at this time of a number of paired cavities (PI. XIA , fig. 22), which are separated from one another. Cœlomic cavities in the cephalic and caudal lobes appear only later on.
Shortly after the formation of the cœlom, a pair of protuberances appear on each segment. They are the first traces of the appendages (PI. XIV, fig, 23, th. app). The order of their appearance cor- responds to the order of appearance of the segments to which thej- belong. The appendages are formed on segments of the chelicera^ and pedipalpi in all the thoracic and the second, third, fourth, and fifth abdominal segments (PL XIII, fig. 20, PL XIV, fig. 22). The cephalothoracic appendages are formed at the lateral ends of the segments, while the abdominal appendages are formed nearer the median line (PL XIII, fig. 20). Tlie abdominal appendages are little round protuberances, and do not elongate as rapidly as other appendages. The first abdominal segment bears no appendages, as Schimkewitch* has correctly observed. This segment is gradually aborted, and is not distinctly visible at tlie time of the reversion of the embryo. The cœlomic cavities of each segment extend into the appendages.
The foundations of the nervous system are laid soon after the
* Schimkewitcli — Etude sui- le Development des Araignées, Arch, de Biolog. VI.
ON THE DEVELOPMENT OP ARANEINA. 65
establishment of the ventral plate during this period. The ectoderm of the cephalic lobe is very mach thickened as shewn in figs. 22 and 23. This process of thickening proceeds backwards as two longitudinal bands, one on each side of the body, along the inner side of the attach- ment of the appendages in the thoracic and abdominal segments, finally meetino" each other in the caudal lobe. These two l^ands are the first rudiments of the ventral nerve chain. Thus it is continuous from the first with the cephalic thickening above mentioned which becomes the brain, as in the case of scorpions observed by Kowalevsky and Schulofin.* This is not in accordance with the view of some authors
a
who maintain that the brain and the ventral nerve cords are formed independently of each other. The cells composing the ventral cords aggregate in each segment and give rise to the ganglia.
The cephalic thickening of the ectoderm is now divided into two semicircular lobes (PL XIII, figs. 20, 21). Near the front edge of these lobes, there is formed on each side a semicircular groove (sem. gr.). This paired groove which is cut ofi' from tlie ectoderm is the chief origin of the brain. I'riice** compares it with the amniotic f )ld of insects ; but the comparison is certainly not justifiable. Kowalevsky and »Schulgin found that in Scorpions the ectodermic invagination comparable to the amniotic fold of insects is distinct from and formed earlier than the semicircular groove, which is no doubt homologous with the similar groove of the spider, as it also gives rise to the brain. Sections of the semicircular groove are represented in fig. 23, PI. XIY.
Besides the semicircular grooves, there is a pair of small ecto- dermic invaginations in the posterior part of the head near the outer bor.ler (PI. XIII, fig. 20, PL XIV, fig. 23, lat. v). So far as I
* Kow.ilevsky and Sohulgin — Zur Entwicklungsgeschichte des Scorpions, Biolog, Cen- tralbl. VI.
** Bruce — On Insects and Arachnids.
ee
K. KISHTNOUYE.
know these invaginations have been till now entirely overlooked. Til fig. 19, PI. XXI, of Balfoar's work, I find one of these in- vaginati(jns represented ; but he gives no informati(3n about it. It is globular in form ; henceforward I shall call it the lateral vesicle. The lateral vesicles, which are also gradually constricted off frc^m the ectoderm, go to form a part of the brain (PL XV, figs. 44-46).
The stomodœum is formed as an ectodermic invnirination at the anterior margin of the cephalic region (PI. XIII, fig. 20, PI. XIV, figs. 24, 25). At this stage it is easy to see that all the appendages are postoral in origin.
Late in this stage a number of large cells appear at the dorsal part of the embryo. They are never found in the ventral plate. They are very easily recognised by their large size and the peri- pherally situated nuclei, their central porti<3n being filled with fat (PI. XV, figs. 40, 41,/. c). Undoubtedly they are nourishing cells, wandering everywhere, and some of them are changed into blood corpuscles. They were called by Balfour the secondary mesoderm, l)y Schimke witch the secondary endoderm, and by Locy the endo- derm cells. These three authors ascribed the oriu'in of tliese fit cells to the cells in the yolk, whereas according to Morin they are formed in Pholcus from dispersed mesoderm cells originally composing the so-called primitive cumulus,* and in Theridion which wants the cumulus probably from cells of the mesodermal somites. Schimke- witch, Locy, and Morin observed that these cells become blood corpuscles. For my own part, I am inclined to agree with Balfour, Schimkewitch, and Locy and to derive them from the endoderm. For in the first place, they are found immediately above the yolk, arid in some cases between yolk granules presenting the appearance as
* Morin states, what I have before referred to, that the primitive cumulus is formed after tlio foruiation of germinal layers, and consists of mesoderm cells.
ON THE DEVELOPMENT OP ARANEINA. 67
if they have just emcrg'cd from the yolk. In the second place, their nuclei ao;ree in their loroe size with those found in the yolk.
At the end of this stage the mesoderm in the caudal lobe is faintly divided into two layers, between which an unpaired cavity makes its appearance (PI. XIV, û^. 24). In the cephalic lobe also the mesoderm is faintly divided into two layers on each side (PI. XIV, fig-. 23), enclosing the rudiments of the cœlomic cavities. It is still undivided in the median line. The cœlomic cavities in the thorax secondarily fuse together into a single cavity. They remain, however, quite distinct in the abdominal region.
The Period of the Reversion of the Embryo.
The stage in which the reversion of the embryo occurs is as difficult to study as it is important, since many organs arise at the same time. At the end of the last stage, the ventral plate had reached the maximum limit of dorsal flexure, the cephalic and the anal lobes almost toucl.dng each other (PI. XIV, figs. 24, 25). As Balfour states, the reversion of the embryo is due to the expansion of the dorsum ; and the expansion of the dorsum is due to the horizontal increase of cells which compose that part. The head and the tail are pushed away from one another further and further. As the dorsum is very rapidly expanding and the cells are pressed for room, a groove is produced immediately behind the tail lobe to increase the surface of the dorsum, and the tail lobe then stands out as a conical process (ri. XIV, figs. 26-29). The cœlomic cavities belonging to the segment in front of the tail lobe being pressed from the dorsal side by the increase of cells in the dorsum are compressed horizontally and pushed into the conical tail process, enveloping the unpaired cœlomic cavity of that process from the dorsal side. The caudal lobe stands
68
K. KISHTNOUYE.
out gradually more and more prominent, until the stage represented in fig. 27 (surface view, fig. 21) is reached. After this, the tail process gradually shortens (figs. 28, 29) until after a while there is no tail projecting from the general body surface (fig. 32).
At about the same time with the increase of cells of the dorsum, the two nerve cords begin to diverge from each other. They are most widely separated from each other at the anterior part of the abdomen and gradually approach each other anteriorly and posteriorly until they meet in the cephalic and tail lobes (fig. 21). Their divergence together with the expansion of the dorsum makes the embryo assume the ventral flexure.
The cœlomic cavity of the caudal lobe now becomes gradually conspicuous. This unpaired cavity is transformed into the so-called stercoral pocket (Rectalblase, Kloake) of the adult spider. Hence the stercoral pocket does not arise from the swelling of the internal end of the proctodaßum, as has been supposed by other authors. This organ is purely mesodermic in origin and nothing more than a remnant of cœlomic cavities. This may be understood by examining figs. 24-32, PI. XIV. From these figures it will be seen that the proctodseum is formed in the caudal lobe later than the stercoral pocket.
The fact that any part of the adult alimentary canal should be derived from the cœlom seemed to me so remarkable that I have repeatedly examined my series of sections and am convinced of the correctness of the observation. I do not know how to interpret this fact unless it be that the stercoral pocket is a part of the primitive excretory system — a supposition which is strengthened by its peculiar relation to the remaining part of the digestive tube (PI. XVf, fig. 55) and by the fact that the Malpighian tubes open into it.
At this period the mesodermic somites and the ganglia of the
ON THE DEVELOPMENT OF ARANEINA. 69
anal lobe and of the four appendage-bearing abdominal segments have attained their utmost development. The first abdominal seg- ment and those between the fifth and the last abdominal segments are aborted.
The mesodermic somites which are produced at first in the ventral plate now grow on dorsalwards and meet at the dorsal median line (PL XV, figs. 40-43). They first meet at their dorsal part, enclosing some of the large fat cells and their derivatives be- tween them. The ventral part fuses later. Thus the dorsal circulatory tube is formed, the wall of which is produced from the mesoderm, while the blood corpuscles are produced from large fat cells (endo- dermic in origin). I am inclined to believe that both the aorta and the so-called heart are formed as stated above and not separately as many authors believe. The fusion of the mesodermic somites to form the dorsal vessel does not take place throughout the entire length, as there are left paired lateral slits between each two consecu- tive somites. The blood aerated at the lung-book returns to the heart through these lateral slits. These slits shut and open as the heart beats. They are found in the abdomen only.
In the basal part of the first abdominal appendage of each side, there arises an ectodermic invagination whose opening faces away from the median line. It is neither deep nor spacious but is a little pocket-like invagination. This is the beginning of the lung-book. The development of this organ, briefly stated, is as follows : Of the wall of the invaginated pocket, that which faces the distal end of the appendage is much thicker than the opposite wall, filling the interior of the appendage. The cells composing it become after a while arranged in parallel rows (figs. 34 and 47). Each two of these parallel rows adhering together produce the lamellae of the lung- book. The external epithelium of the appendage which cover these
^0 K. KISHIXOUYË.
■
lîimellaî becomes the operculum of the kmg-book after it is depressed in height. Judging from figures (figs. LXXIX and LXXIX') given in " On Insects and Arachnids," Bruce seems to have mistaken the caudal prominence of the early period of this stage (see my figs. 24-28) as the operculum of the lung-book. According to him tlie abdominal nppendage is invaginated to form the lung-book, but as we have seen, it is not so. Locy has correctly described the forma- tion of the lung-book lamella3. He says that the lungs arise from infoldings ; but he is silent about the place where these infoldings arise.
In the basal |)art of the second abdominal a[)[)endage on the interior side, another ectodermic invagination is produced. It as- sumes the shape of a deeply invaginated tube and remains in this condition till after the time of hatching. The appendage itself is not invaginated and becomes from this time gradually shorter.
It is very probable that the lung-books were derived from the gills of some aquatic arthropodous animals such as Limulus ; for the lunof-books are nothinsf more than the lamellar branchia3 of
O a
Limulus sunk beneath the body surface. The tubular trachea may afterwards have been derived from the lunsr-books. The branchin 1 lamella} of Limulus are formed as outgrowths <jf the ectoderm at the lower (posterior) surface of abdominal appendages, and those of spiders are also produced really in the lower surface of the fii'st abdominal appendage (in the dipneumonous spider). Hence I tliink that the spider with two pairs of lung-books is the most primitive one, and the one with one pair of lung-books and the other pair transformed into the tubular tracheai is more primitive than the spider with only one pair of lung-books. I cannot agree with the view of some authors who maintain that the luno'-book is derived from a chister ol tracheœ.
ON THE DEVELOPMENT OF ARANEINÂ. 7l
The third and fourth pairs of the ahdoiniual appendage are modified into spinning niammillœ (PL XV, fig. 34). At the distal end of each of tliese appendages a solid proliferation (sp. gl) of ecto- derniic cells is for?ned. This becomes the spinning gland. Spiders have generally three pairs of spinning mammillas ; two of which are modified abdominal appendages, while the remaining one is added very late, after the hatching of the embryo. The primitive spider must have had only two pairs of spinning mammiilœ. Some tetrap- neumonous spiders have only two pairs.
The two semicircular halves of the cephalic lobe, between which there is at first a deep median notch (PI. XIII, fig. 20), now fuse with each other at the median line above the stomoda^um, so that tlie notch becomes much shallower (fig. 21). The grooves formed along their anterior margin during the preceding stage separate from the ectoderm beginning from their external end and sink down beneath the body surface. They are cut off from the ectoderm latest at the hindermost j)ai'ts of their inner limbs (PL XVI, fio-. 48). The lumina in the two separated semicircular grooves come to com- municate with each other at the anterior median part (PL XV, fio-. 45).
At the last point of separation there is left a shallow in\a<'ina- tion or rather sac on the sui-face. The invagination is ])aired. The openings of these sacs are directed towards the mouth of the embryi^, and the invaginations are directed anteriorly. They are the first traces of the posterior median eyes f^ee below) or the 'Hauptaugen' of Bertkau* (PL XV, figs. 41-46, 48, P. M. E.). The anterior wall of the sac is thicker than the posterior, the former being two t(j several cells deep, the latter only one cell deep. The formation of
* Bertlvau— Beiträge zur Kenatniss der Siuuesoi'y;iue dur Spiuneu. Arch. f. Mik. Anat XXVII.
72
K. KISHINOUYE.
the posterior median eyes in connection with the brain in .spiders is quite analogous to the simihir process in scorpions as observed by Kowalevsky and Schulgin. This interesting relation was not observ- ed by Locy who studied the spider, or by Parker* who studied the scorpion.
Hitherto these eyes were called the anterior median eyes ; but morphologically speaking, this nomenclature is not correct. For all the eyes of spiders are formed in reality in the Neutral jjhite, never in the dorsum, and gain their apparently dorsal position in later stages only by the bending upward of the ventral plate. Hence, in this last position the eyes that composed the ])osteri(jr row in the ventral position come to occupy the anterior position, while those that formed the anterior row in the ventral position are thrust further backward by the curving upw\ard of the ventral plate and thus become the apparent posterior row. Hence those I called the posterior median eyes are in the apparent anterior row of the adult.
The three remaining pairs of eyes are formed later than the posterior median pair and in a different manner. Their first traces are the local thickenings of the ectoderm of the cephalic region Anterior lateral eyes (A. L. E.) ai)pear above the lateral vesicle (PI. XV, fig. 46).
At this time the lateral vesicles are c<jnipletely cut off from the general ectoderm (PI. XV, figs. 44, 46). Their walls are thick and their lumen is cons[)iGuous. In development and position they ^'ery much resemble the eyes of Peripatus.
The chelicera3 are now two-segmented. They have shifted their
position a little anteriorly and have approached toward the median
line (PI. XIII, fig. 21). Their ganglia are placed at the sides of
the stomodteum and form tlie commissural part between the supra-
* Parker— The Eyes in Scorpions, Bull. Mus. Comp. Zool. XIII.
ON THE DEVELOPMENT OF ARANEINA. 73
and infrfi-œsophageal ganglia. They are in contact with each other at the anterior part. The basal joint of the pedipalpi is very broad, the maxillary part being- easily distinguished. The ganglia of the pedipalpi and of the succeeding four thoracic segments are well deve- loped and are in close contact with each other, thus forming the large snb-œsophageal ganglion. The ganglia belonging to the abdo- minal segments are also well developed. . :
The stomodœum elongates itself obliquely upwards and is sur- rounded externally by the well developed upper and lower lips (PI. XIII, figs. 19-21 ; PI. XIV, figs. 24-26). The ectoderm forming the wall of the stomodieal invagination is thick.
The ectoderm of the ventral part of the anal lobe is conspicuous- ly thicker than that of the dorsal part, being continuous with the two ventral l3ands. At the beginning of the reversion, it is uniformly two or three cells deep (PL XIV, fig. 27); but when the reversion is fairlv advanced, so that the elono-ated anal lobe beo'ins to become short again, the cells in the middle part of it are elongated and thei'e they are only one cell deep (fig. 28). At this part an in- vagination takes place (fig. 29). Fnjm this stage the ectoderm of the ventruni of the anal lobe, placed anterior to the invagination be- comes two or three times thicker than the posterior part, and is dif- ferentiated to form the anal ganglia (figs. 29-32, (r). The invagination is the protodaeum. It is very shallow and small, aud its bottom is in direct C(3ntact with the wall of the stercoral pocket. The wall of the prootodasimi is thinner than that of the stomodsenm. It is remarkable that the proctodîeum is not formed at the extreme hind end of the ventral plate but somewhat in front of it directly behind the- anal- ganglia, and that both the stomodœum and the proctodaemn are produced at the two extremities of the nervous system simulta- neously with the development of the latter near them. The portion
74 IC. KTSHINOÜTE.
of the ventrnm, posterior to the pi-octoda?iim, gradmilly thins oif, and after the process of reversion is completed it can not he dis- tinguished from the dorsum (PI. XIV, figs. 31, 31).
The posterior part of the mesenteron is formed hy an accumla- tion of endoderm cells at the anterior ventral part of the stercoral pocket. It is a wide open funnel-shaped tuhe, resting ahove the mesoderm (fig. 32, Post, mrsent).
The stercoral pocket produces paired diverticuhi fr(^m its lateral sides (fig. 33). At first, I was inclined to think that these diverti- cula become the Malpighian tubes, as these tubes were formerly th<mght to arise as a pair of outgrowths from the stercoral pocket. But I found that these diverticula give rise to no definite structure in the adult, and that the Malpighian tubes arise in a ditferent way, as will be explained further on.
At this stage a very important organ is produced, which has been almost entirely neglected by embryologists. I mean the coxal gland, Avhich is f)rmed from an ectodermic invagination at the in- ternal posterior base of the coxal joint of the first ambulatory appendage (PI. XV, fig. 38, Co. gl). The invagination opens into the cœlomic cavity (figs. 35, 36). Its development is traced farther in the next stage.
After the formation of the circulatory system the cœlomic cavities atrophy, except the one of the anal lobe forming the stercoral pocket, and some part of the thoracic ones in connection with the coxal gland. The so-called body cavity of the adult is not the remnant of the cœlomic cavity ; but it is a secondarily produced blood-space. T'he mesodermic cells which formed the wall of these cavities form The covering of the nervous system, the alimentary canal and other organs.
Some mesodermic cells at the base of the cephalothoracic appen-
ON THE DEVELOPMENT OF ARANEINA. 75
dages become rounded in outline (PI. XV. figs. 35, 36). They are easily distinguished from the fat eells by their centrally located nuclei, and from other cells by their well-defined spherical form and slightly stninable protoplasm. They appear first in the chelicenv, then in the pedipalpi, nnd so on gradually backwards. These cells liave no relation whatever with the coxal gland uov with the poison gland. Their function is unknown. It seems to me that Locy has mistaken these cells at the base of the chelicera^ for the first rudi- ments of the ])oison gland. He says that these cells are probably derived from an infolding of the ectoderm.
From the End of the Reversion to the Hatching of the Embryo.
This stage is characterized by the api)earance of a constriction separatiiig the céphalothorax from the abdomen. The yolk in the ventral part of the abdomen is absorbed, so that the abdominal appendages of both sides appr("»ach each other at the median line.
The senncircular grooves of the cephalic lobes formed in the preceeding stage are no longer grooves, nor semicircular in form. Now they are completely constricted oif from the general ectoderm, and are consequently tubes. Their inner Yunhs approach each other in the median line and they form as a whole a T-shaped body (PI. XV, fig. 45). The lumina of the two tubes communicate with one another at the anterior median part. They as well as the lumen of the lateral vesicle begin to atrophy by the thickening of their walls and finally disappear. At the same time the transverse bar of the T-shaped mass becomes curved on each side to a peculiar shape shewn in profile in fig. 45 a. This and the disappearance of the lumen change the brain into a compactly packed mass, instead of having its various
76
K. KTSHINOYUE.
parts stanrling apart as heretofore. The transverse bar (fiof. 44, a) of the T-shaped brain is separated from the median stem just behind the point where the Inmina of the two sides communicate with each other, while the median stem is in its turn transversely divided into two segments (Fig. 44. b, e). Thus the spider's brain consists of three segments, as l^ntten* claims. These three segments may be called the transverse dorsal (Fig. 44, a), the anterior ver.tical (Fig. 44, />), and the posterior ventral section (Fig. 44, c). The lateral vesicles arein the level ofthe third segment. From his description. Patten seems to mean that in scorpions and spiders the three segments (^f the brain are formed from three separate invaginations ; but I cannot cor- rol)ornte this statement. Moreo^er he says that the anterior median eyes (my posterior median eyes) belong to the second segment, while the three remaining pairs belong to the third segment. Supposing tlint his second segment is anterior to the third segment, 1 cannot corroborate this statement either, as accoixling to my own ol)servati<^ns all the eyes belong to the third segment. It seems to me impossible tliat the posterior eyes should arise in a segment anterior to that in whicli the anterior eyes are produced.
The opening of the sacs of the posterior median eyes becc^mes gradually smaller and is finally closed (PI. XYI, fig. 49). The anterior wall ofthe sac becomes enormously thick and obliterates its lumen. The ectodermic cells which lie ii])on the sac elongate and form the vitreous body (tigs. 49, 54, ivV). The anterior wall of the sac forms the retinal part (fig. 49, PC). The retinal cells elongate anteriorly. The anterior surface of the anterior wall of the posterior median eyes, is morphologically the inner side of the ectoderm though it faces externally. The lens is formed by a local thickening of rhe cuticula, which is secreted from the epithelium at this stage
* Patten — Segmental Sense-organs of Arthropods, Journ. of Morph. II. ^
ox THE DEVELOPMENT 01" ARANEIXA. 77
(PJ. XVI, fig. 49. L). The nerve cLjes not enter the p<jstenor median eyes even a few days attei' the hatching of the embryo. Probably the nerve is sent out from tlie retina from the anterior (morphoJooi- calJy inner) surface of it, as this is the case in the aduU. The deve- lopment of the posterior median e^'es is comparatively slow. They are homologous with the median eyes of scor|)ions, as the develop- ment is quite the same.
The three remaining pairs of the eyes or ' Xebenaugen ' of Bertkau* are formed later than the posterior metlian eyes ; but their development is completed earlier. They arise from ring- like depres- sions of the ectoderm (fig. 50). The walls surrounding these depressions grow over them and finally meet (fig. 51). The spot where the walls meet is one-cell layered. This spot gi-adually ex- tends to a certain extent and forms the vitreous body which is characterized by elongated cells (figs. 51, 54, vit). The growth of the walls of the depressions is not uniform in every direction and there- fore the point of closure may not correspond with the centre of de- pression. Thus the ' Nebenaugen ' are also formed from ectodermic sacs ; but these sacs are diiferent from the sacs of the posterior median eyes. While it is the anterior wall of the sac that becomes the retina in the posterior median eyes, it is in the case of the " Nebenaiigen' the posterior wall of the sac, which, forming a central elevated })ortion thicker than the anterior wall and siu'rounded by a ring-like depres- sion, gives rise to the retina (figs. 50-54, R). Also retinal cells elongate posteriorly instead of anteriurlij, as in the posterior median eyes, and form nerve fibres (figs. 50, 51, A^). These nerve fibres are subsequently connected with the fibrous portion of the brain. The retinal portion is cut ofi:' from the general ectoderm at about tlie time
* Burtkau, lue. cit.
78 K. KISHINOUYE.
of hatching, mid at the same, time becomes concave (tig. 54), instead of being convex as heretofore (ûg. 51).
In the ' Nebenaugen ' — but not in the posterior median eyes — there are f(n-med transverse liars and a circumferential ling (^g'i. 51- 54, tai)) of chitinous natiu-e, posterior to the retinal cells and secreted by these cells. These chitinous bodies (the tapetum) are transparent and lightly yellowish by transmitted light and silvery olitterinsf bv reflected liuht. Tlie lens is formed in a similar manner as in the case of the posterior median eyes. The tapetum and the lens are eqntdly secretion products of the ectoderm and both of them are chitinous in nature, liut they are not homologous. The former is produced at the proximal end of the ectoderm cells, while the latter is formed at the distal end. : .
I know of only two authors who have studied the development of the spider's eyes b)^ recent modes of investigation. They are Locy and Schimkewitch. The results obtained by these authors are not entirely satisfactory. Locy could not find the diHerence in the mode of development between the 1 wo différent types of eye. He says that the 'Nebenaugen' originate in substantially the same way as the anterior median eyes (my posterior median eyes). Moreover he states that the development of the eyes begins by a local thickening of the hypodermis and a backward directed infolding which inverts the thickened region. Schimkewitch says only that the retinal part of the eyes originate from a pyriform eidargement from the brain, upon which the ectoderm invaginates in the form of a ring.
Patten recently gave a short account of the spider's eyes in an article entitled the " Segmental Sense-organ of Arthropods " in the Journal of Morphology, Vol. IT. ; but his account differs from mine in many jioints, as I have already mentioned. He says that there are segmental sense-organs, homolog(jus with the eyes, at the base
ON THE DEVELOPMENT OF AKANEIXA. 7i)
of the legs. Unfortunately I could not find any trace of such an organ, though I carefully searched after it.
The development of the pigment begins from the cephalic region backwards, after the ditferentiation of the vitreous Ijody (fig. 51). In the case of the ' Nebenaiigen ' the pigment is first priKluced in those cells which form a kind of a cup around the retinal portion (figs. 51-53), and it seems to me most probable that these cells wander in to the retinal portion, first jtmong the nerve fibres beneath the ta[)etimi (fig. 53), then among those above thetapetum (fig. 54). In the case of the posterior median eyes, however, the pigment is pro- duced from the beginning in retinal cells, below the vitrecnis body.
As we have already seen, all the eyes of the spider are formed in the ventral plate and near its anterior margin.
The concentration of the nervous system towards the céphalo- thorax goes on further in this stage than in the previous stage. In the thoracic region the two lateral oanplionic chains are united into one and form the subœsophagcal ganglion. The inner portion of the ganglion becomes finely fibrous. The abdominal ganglia gradually atrophy and attach themselves to the posterior end of the subœso- phageal ganglion. At this stage the whole nervous system is com- pletely cut off from the ectoderm.
The stonioda'uni has devchjpcd very mucli. After chjiigating itself obliquely upwards, it takes the horizontal backward direction and reaches to about the segment of the fourth ambulatory a[)pendage. It is lined with a cuticular covering which is continuous with the cuticula <jf the general body surface. In the pliarynx, the cuticular lining is tliick and transversely ridged. The ridges rim parallel with each other and appear in the sagittal section like teeth, the pointed edge turning dorsalwards. The wall of the stomodieum is very thick. The stomo- dieum gives rise to the pharynx, the œsophagiis, and the st<jmach.
80
K. KISHINOUTE.
Early in this stage some endoderm cells ucciimiihite at the posterior end of the stomach and form the anterior part of the me- senteron. These cells are arranged as a funnel-shaped tiihe \vid(; open posteriorly. The posterior funnel hîis united with tlic wall of the stercoral pocket at its hind end (tig. 55). The anterior and the posterior funnels of the mesenteron do not at this stage unite with each other.
Locy says that on each side of the stomach are given off ca^ca, which extend into the hases of the liml)s. lie adds that the cellular elements comp(3sing the walls of these tubes are flattened ; hut he gives no account concerning the time of their appearance Though I have carefully examined embrycjs of all the stages, I could not And such tubes.
The proctodajum is lined with a cuticular covering as the stomo- daäum ; but the stercoral pocket has no such covering. This fact confirms my observation that the stercoral [)ocket is not a portion of the proctodœum. The communication between them is formed at this stage. The communicating canal is very narrow. In the last stage, the stercoral pocket was somewhat globular in shape (PI. XIV, fig. 32), now it is elongated anteriorly and is oblong (PI. XVI. fig. 55). Its lateral diverticula have disappeared.
I could not make out the development of the Malpighian tubes satisfactorily ; but I am certain that they do not originate from the ectoderm. Also it is certain that they are not outgrowths from the stercoral pocket. It seems to me probal)le that they originate from mesodermic cells belonging to the abdominal S(jmites in front of the anal lobe. At this stage they are solid jjaired cords of cells (iig. 55, ' j\[alp. t) extending from the anterior end of tlie second abdominal segment to the sides of the confluent point of the posterior mesenteron with the stercoral pocket.
ox THE DEVELOPMENT OF ARANETXA. 81
The mesodermic cells of the coxal gland, which was formed in the preceeding stage, are very much differentiaied from the ecto- dermic cells of it. They are the glandulär cells, their size becoming- large and their protoplasm granular and unstainal)le (PI. XV, tig. 37). The ectodermic cells form the duct.
At the distal end of the chelicera^ a solid growth inward of ectodermi<* cells takes place. These cells are surrounded by meso- d(H'mic cells. The distal half of the former becomes the s^landular portion, and its proximal half the duct, of the poison gland, while the mesodermic cells torm the muscular wall of the gland (hg. 39).
In this stage four paii'ed transverse septa are formed between the four appendage-bearing segments of the abdomen by the sinking of the mesoderm into the yolk. A median unpaired se|)tum, similarly formed, also stretches forward fro]n the posterior end. These septa are foi'med after the disappearance of the cœlomic cavités in the al)domen. In fi,<r. 34, PI, XV., two anterior septa are represented. The first pair of septa probably give rise to the generative organ, and all or some of the others to the so-called liver.
After undergoing one or two moults, the embryo hatches. The body of the embryo is covered with cuticular hairs. At the end of the pedepalpi and the foui* ambulatory appendages, the claws are pro- duced, and at the end of the chelicerœ the poison fangs, by thickenings of the cuticula.
Summary.
(1) The polygonal areas are on the periplasm, and are pro- bably formed when the eggs pass through the oviduct.
(2) In the process of segmentation the yolk and the nucleus are divided at the same time. The segmentation is syncytial.
82
K. KISHINOUYE.
(3) The yolk nucleus is found in segmenting eggs on to the four-cell stnoe.
(4) After the segmentation all the nuclei are found only at tlic surface of the egg, and none of them remain in (he volk.
(5) The primary blastodermic' thickening may he considered as a modified gastrean mouth, the formation of whir-h was obstructed by the abundance of yolk.
(6) The secondary blastodermic thickening or 'primitive cumulus ' of Claparede plays a secondary part in the formation of the germi n al 1 ay er s .
(7) The brain and the ventral nerve cords are formed as a continuous ectodermic thickening.
(8) All the appendages are postoral in origin.
(9) The first abdominal segment bears no appendages.
(10) The large fat cells are derived from the endoderm. They ff^rni blood corpuscles.
(1 1) Ati invagination at the posterior l)ase of the first abdominrd appendage gives rise to the lung-book. A similar invagination at the base of the second gives I'ise to a tube — abortive trachea.
(12) The unpaired cœlomic cavity, belonging to the anal lobe, changes to the so-called stercoral pocket. Prolwbly it is excretory in function, not a part of the alimentary canal.
(13) The dorsal circulatory vessel is formed by the fusion of the mesoblastic somites at the dorsal median line.
(14) The so-called body cavity of the adult animal is not the descendant of the cœlomic cavity, but it is a secondarily formed
space.
(15) The brain is composed of the semicircular grooves and the lateral vesicles cut off from the ectoderm. Later it is divided into three segments.
ox 'I'PTE DEVELOPMENT OF ARANEINA. 88
(16) The development of the posterior median eyes is connected with that of the hrain. Their development is quite different from that of the other eyes ; but all the eyes are dermal in origin, not neural. And the nerves of the eyes enter always from the inner ends of the ectoderm cells.
(17) A pnii- of coxal glands opens at the base of the third appendage. The glandulai- portion of it is formed from a portion of the cœlom, while its duct is formed frc^m an ectodermic invagination.
(18) The alimentary canal of the spider is formed from the ectoderm and the endoderm. The pharynx, the œsophagns, the stomach, and the anus ai-e produced from the former, and the intes- tine from the la t fer.
(19) Tlie Malpighian tubes are produced neither from the ecto- derm nor from the stercoral pocket. They are mesodermic in origin.
<.
84
K. KTSHTNOUYE.
Explanation of Plates.
The figures are all exact representations of preparations, the outlines, the nuclei, and other details being drawn faithfully by my- self with the use of the camera lucida, and they are not diagramatic, except in the case of a few figures expressly so stated.
List of References.
(t, first segment of brain.
((hd. app., abdominal a]i]iendao-o.
a. I., anal lobe.
A. L. E., anterior lateral eye.
ant. mesent., anterior portion of me
senteron. fe, second segment of brain,
c, third »» >' >> ceph. /., cephalic lobe. eh., chelicerae.
ch. g., cheliceral gano-lion. eo. gl., coxal gland. cut., cuticula.
d, dorsal side. dor., dorsum. ect., ectoderm. end., endoderm.
/. c, fat cell. G, ganglion.
inv,, invagination of lung-book. L, lens. lat. v., lateral vesicle.
Malp. t., Malpio'hian tulto.
mes., mesoderm.
N, nerve.
pedip., pedipalpi.
P. M. E., ])osterior mediaii eye.
post, mesent., posterior portion of
mesent eron. prim, th., primary thickening. proct., proctodasum. B, retina.
sec. th., secondary thickening-. seg. cav., segmentation cavity. sein, gr., semicircular groove. sp. gl., spinning gland. sterc. p., stercoral pocket. stom., stomodaeum. tci])., tapetum.
th. app., thoracic appendage. V, ventral side. vit., vitreous body. y. n., yolk nucleus.
ox THE DEVELOPMENT OF AKANEINA. 85
Explanation of Figures.
Fiu'. 1. All iiiiseuiiieiited eyi»-, sliowiriü' the polvofoiîil nreas above yolk graimle.s. (^Liictisa). 2 B (Zei>^s).
Fig. '2. A segnientatioii egg oï the four-cell stage, showiiio- the rosette-like yolk pyramids, {hijcosa^. 2 B.
Fig. o. A segmentation <^'g^^, shewing the union of tlie poly- gonal areas with tlie segmentation nuclei. (^Ltjcosa). 2 B.
F^ig. 4. The same as above, Ijut of a little later stage. This shows that the yolk pyramids become very small and that the poly- gonal areas do not correspond in p(jsition with the yolk granules. (Lijcosa). 2 B.
Fig. 5. An tgg shewing the primary thickening of the blasto- derm. (^Lycusa). 2 A..
Fig. 6. An eiig- ha^'in"; the secondary thickeniusf of the blasto- derm, produced at the margin of the primary thickening. (Liicoaa). 2 A.
Fig. 7. An egg in which the primary thickening has extended enormously, and the secondary thickening is at the margin of the [)rimary one as before. (Lijcosa). 2 A.
Fig. 8. A section of an egg of the two-cell stage, shewing the division of the yolk, and also y<j'k columns, the segmentation cavity, and the yolk nucleus. (^Jjijcosii). 2 C.
F^ig. \). A section of an egg (jf the sixteen cell stage. {Lijcosli). 2C.
Fio-, 10. A section of a se^'mentation eg-u' in the stag^e of Fig. 3, containing twenty two nuclei. {Liicasa). 2 C.
Fig. 11, A portion «jf a section of an egg in the stage of Fig. 5. (Lijcosa). 2 C. .
SQ K. KISHINOUYË.
Fig. 12. A portion of a section of an egg in the stage of Fig. 6. {Lycosa). 2 C.
Fig. 13. A section of the secondary thickening. (Lncosa). 2D.
Fig. 14. A portion of an section of an egg, a little more ad- vanced than the egg in the stage of Fig. 12. (Lijcosa). 2 C.
Fig. 15. A section of an egg after segmentation showing the absence of the nucleus in the yolk and a number of small yolk balls. (Liicosa). 2 B.
Fig. 16. A longitudinal section of an egg of the protozonite .stage. {Agalrita). 2 B.
Fig. 17. A ))ortion of a cross section of an egg of the proto- zonite stage. (^Agak'Nu). 2 1).
Fig. 18. A cross section of an egg showing the separation of the mesoderjn into two lateral halves, the formation of the cœlomic cavity, and the appearance of the appendage, in the thoracic region. The mesoderm of the cephalic region is not yet divided. (Ai/alcfia). 2 B.
Fig. 19. The median longitudinal section of the embryo in the reversion stage. ÇAgalenci). 2 B.
Fig. 20. A diagram of the ventral [)late (imagined as unrolled) of an embryo in the stage of the maximum dorsal tiexare.
Fig. 21. A diagram of the ventral [»late (imagined as unrolled) of an embryo in the stage of reversion.
Fiof. 22. A lonofitudinaJ section of an e^s^ in the staue of Fiy-. 20, showing the appendages and cœlomic cavities. (Agalenay 2 B.
Fio;. 28. A cross section of an eora- in the same stage as of the previous figure, showing the semicircular groove, the lateral vesick', the continuous mesoderm of the head, and the cœlomic cavities and thoracic ganglia. (Agalena). 2 B.
Figs. 24, 2t5. Fortions of median longitudinal sections, showing
0\ THE DEVELOPMEN'T OF Ah'.ANh:iXA. ö(
clo.seiies.s of the ceplialif and anal lobes, and the formation of the «toniodaïum (Agalcua'). 2 B. . ^ .
Fig. 2(). A portion of the median longitudinal section of an eg<^ in the reversi(jn stage, showing tlie expansion of the dorsum. {A(jalena). 2 B.
Figs. 27-o2. Longitudinal sections of tiie anal lobe in succes- sive stages, showing the formation of the proctod^eum and the change of the cœlomic cavity of the anal lobe to the stercoral pocket. {Aijakna). 2 D.
Fig. 33. A cross section of the anal lobe, sh(_)wing its unpaired cœlomic cavity and gangli(jn, and its two lateral diverticula. (^Agalena). 2 D.
Fig. 34. A sagittal secticjn of the alxlornen of an embryo after the reversion stage. Two anterior abdominal septa are represented. {Agalenci). 2 C.
Figs. 35. 36. Sagittal sections of the coxal joint of the tirst thoracic appendage, showing the communication of the cœlomic cavity with the exterior by an ectodermic invagination. (^Agah'na). 2 D.
Fig. 37. The glandular portion and the outlet of the coxal gland. (Agaleua). 2 D.
Fig. 38. A cross section of the céphalothorax, showing the position of the coxal gland. (Agalena). 2 B.
Fig. 39. A cross section of the poison gland of an embryo, a little before hatching. (A galena). 2 D.
Fio-s. 40-43. Portions of cross sections of the abdomen, show- ing the formation of the dorsal circulatory organ. (^Agalcna). 2 D.
Fig. 44. A porti(jn of a frontal section of an embryo in the reversion stage, showing the three segments of the brain. (Agalena). 2 B.
88 K. KISHINOUYE.
Fig. 45. A diagram of the brain and the cheliceral ganglia.
Fig. 45a. A diagram of the profile view of the brain and the cheliceral ganglia of an embryo in the reversion stage.
Fief 45. A frontal section of the 1)rain of an embrvo \u tlie reversion stage, showing the formation of the eye. (Agaleiiay 2 G.
Fig. 47. A porticm of a cross section of the alxlomeii in the reversion stao-e, showino- the formation of tlie hino-l)ook lamella'. {Agalena). 2 F.
Fig. 48. A sagittal section of the brain of an embryo in the reversion stage, showing the formation of the posterior median eye. (Agalena). 2 D.
Fig. 49. A sagittal section of the posterior median eye of a hatched embryo. {Agalenci). 2 D.
Figs. 50, 51. Portions of frontal sections of the céphalothorax in different stages of growth after the reversion of tlie embryo, show- ing the development of the anterior eyes and the formati(jn of nerve fibres, the tapetum, and the vitreons body. (Lycosa). Fig. 50. 2 F. Fig. 51. 2 D.
Fig. 52. An oblique frontal section of the anterior lateral eye of an embryo about the time of hatching. (^Lijcosa). 2 F.
Fig. 53. A longitudinal section of the anterior median eye about the time of hatching. (Lijcosa). 2 F.
Fig. 54. A frontal section of the anterior median eyes of a hatched embryo. {Lycosa). 2 D.
Fig. 55. A sagittal section of the abdomen about the time of hatching. (Lycosa). 2 B.
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Pjst. mesent. Malp. t.
Observations on Fresh-water Polyzoa.
(Pectinatella gelatinosa, nov. sp.)
by
A. Oka.
Iiuperia] University, Tokyo, with Plates XVII— XX.
The pi'csent paper emborlies the results of my investigations on a new species of Fresli-water Polyzoa that lives in a large pond in the grounds of the Imperial University, Tokyo, and is published with the hope that it may throw some light on certain points in the structure and development of the order Phylactolaemata, which have hith('rf(^ remained ol)scure in spite of many efforts of former investi- gators. The researches were begun, in the spring of 1888, at the suggestion of Prof, [, Ijima, and I am indebted both to him and to Prof. K. Mitsukuri for useful advice. My thanks are also due to Mr. S. Watase, now of the flohns Hopkins University, who, while here some years ago, studied the same species, for kindly sending me his drawings showing the formation of the statoblast.
Altliough the species which I have studied does not agree in some points with the generic description of Pectinatella in Hyatt's Observa- tions (5), it can belong to no other genus. The statements given there were made when only one species, viz Pect, magnifica, was known, and must certainly be modified to receive the new one. The
90 A. OKA.
diagnostic cliaracters of the present species to which I give the name of Pect. geJatinosa, are as follows :
Colony oval, hyaline; branches of cœnœciuni di- chotoinous ; no septa between the eel 1 s ; ec tocys t gel ati - nous, fills ap the space; between the branches, forms a common base for many colonies; invaginated fold obsolete; alimentary canal straight when retracted; tentacles 90-98; statohlast saddle- shaped , curved in two axes; marginal spines minute, only seen under a moderate power of microscope.
The colonies grow among aqueous plants and on the underside of floating logs just below the surface of water, and seem to flourish in direct sunshine as well as in shadow. They are found together in a large number forming a luxuriant mass of gelatine, sometimes two metres in length. The outline of each cohjny is irregularly hexagonal on account of mutual pressure. The gelatinous ectocyst of neighboring colonies coalesce, and form a common base 2-3 cm. thick.
This species furnishes very favorable materials for the student of this group of animals, the transparency of its gelatinous ectocyst, the unequalled large size of the polypide and the promptness with which they evaginate, giving great faciUty for investigation.
The general a{)pearance of a group of colonies is represented in natural size in fig. 1, PL XVII. The color of the cœnœcium and tlie lopliopiiore is sligiitly yellowish, the œsophagus and the stomach are brown, and the rectum usually contains dark grayish refuse matter, otherwise of light brown color.
The largest colony that I have seen me.isured 7 cm. in diameter . The polypides are most crowded and in fullest vigor along the margin of a colony, aiid much less crowded in the middle portion^
OBSERVATIONS OX FßE.-jH-WAl'EK POLYZOA. 91
&ay about one in ei'.cli four «(^uure millimetres. The more centrally situated polypides being older are the tirst to die, so that in old colonies, th.', polypides are f(3und only on the outer part, leaving the inner part bare and only marked with dark spots, the remains of dead polypides. When agitated the polypides retract only for a short time, and soon expand their tentacular crown again. Even in being transferred from one vessel to another, some of the ])olypides of a colony do not reti'act at all. In confinement, however, they seem to become more timid and, once retracted, remain in that state for a longer time than when free.
Each colony originates from a single individual that comes out of the statoblast in the first weeks of July, becomes larger and larger by successive budding, attains its full growth in October, and C(mtinues to live until the end of December. Compared with a species of Plumatella living in the same pond, the times of the first appearance and of the total disappearance are each about two months later. As I have not found this species anywhere else, I can say nothing about its geographical distribution.
Methods of Investigation.
Before proceeding further, I may here give a brief account of the methods of investigation employed. To kill the animal in a fully expanded condition was in this case very easy, although it is the princij)al difficidty met with in the preservation of all other genera. When 70% ^dcohol is gradually [)Oured into a vessel contain- ing the colonies, more than half the ])olypides die protruded. If we use such stupefying reagents as chloral hydrate or ccjcain chlorhydrate, every one of the polypides dies in a fully ex[)aiKled condition.
The colonies after being killed were put into alcohol to be hard- ened. S(jme of them were fixed with a saturated solution of c<jrros-
92
A. OKA.
sive sublimate or a weak «olation (0.1%) of cliromic acid, previous to hardening. For staining-, borax-carmin and picro-carmin were chiefly used. In cutting sections, I imbedded sometimes a whole colony, sometimes separate polypides, in celloidin and paraffin.
In studying the development of the polypide within the stato- blast, I proceeded in the following way. First, a statoblast was put into alcohol to harden its contents which in tlie fresh state consist of a thick milky fluid. Then it was held between two pieces of elder pith, and the edge was cut with a sharp razor so as to make an open- ing in the chitinous shell. Next, it was stained and kept in alcohol until it was to be cut. In cutting tlie statoblast, celloidin v/as in- dispensable, for, the shell being too hard, it was impossible to get good sections with paraffin only.
For examining fresh specimens, the only thing I had to do was to put a colony (stupefied with Cocain) or a part of it on a slide,' and cover it, putting a wire ring under the cover-glass to prevent over- pressure. In this condition, the polypides had no power to retract, and the ciliae were in vi^'orous motion.
To study their habits, I kept colonies alive in a glass vessel. I kept also the statoblast in a vessel, in which a contrivance was made to have water always flowing. At last the shells burst, and the little polypides peeped out of the sutures, carrying about the shells like a tiny bivalve. Each of them floats about for a very short time, and then attaches itself by means of the gelatinous ectocyst to any object it may meet with, and gives rise to a new colony.
A. Anatomy.
The branched membranaceous tube (cœnœcial endocyst) forming the greater part of the mass of a colony, together with the gelatinous covering (ectocyst) over it, constitutes the cœnœcium. The terminal
OBtJEHVATlOXS OX FRESH-WATEE POLYZOA. 93
portion of each branch is turned nearJy vertical to the plane of the colony and is capped by another short tube (polypidal endoeyst\ through tlie pellucid wall of which is seen the alimentary canal con- tained within. This terminal tube, with the tentaculate lophophore at its free end, and several delicate organs in its cavity, is called the polypide (fig. 2, PI. XYIL).
Besides this division of the colony into the cœnœcinm and the polypides, we may divide it into a number of equal parts, each consisting of a polypide and a portion of the cœnœcium. For the sake of convenience I shall call such a part ^' pulijzouid" and the portion of the cœnœcium belonging to it ^^ cystid.'' AVe thus consider a colony as being made up of as many polyzoöids, all structurally alike, as there are polypides.
In all genera with chitinous ectocyst. the ca'nœ^ciuni is dixided by more or less de\eloped septa into a number c)f compartments or cells, each destined to receive a polypide when the latter is retracted. Such septa are not found in forms wdth gelatinous ectocyst, and the cystidal cavities stand in open connection with one another.
When a polypide is retracted by the contraction of the muscles that connect it with the bottom of the cystid, its tubular wall invaginates and 1)6 G(3mes a sort of sheath for the tentacles, known as the tentacular sheatli. In the process of evagination, the tentacular sheath begins to reflect upon itself from the lower end. The evagination generally stops when the lower end of the polypide is still within the cystid. In other words, the evagination is incomplete, thus leaving a permanent fold at the boundary between the cystidal and the polypidal endocyst. In this genus, howevei-, the polypides are often stretched out their whole lengtli, and then no such fold is to be seen.
The shape of the polyzoan colony is ditterent in dilferent genera and species, but it is characteristic for each species. The manner of
94 A. OKA.
braucliiijo- of the cœuœciuni iu Vaci. iie]atirio.s;i is .shown in lii"-. 3. PJ. XVII.. It is (lichotomouä with a sh(;/rt branch at each axiL The branches are no bent that all the poJypides stand npright and as the phnnous tentacles cover the whole surface of the coh)ny, their regular symmetrical arrangement cannot be discerned without chjse examination.
The general plan of the structure of a [xdypide and its relation to ihe cystid are shown in tig. 4, I'l. XVII. The alimentary canal is bent in the sliape of the letter V, and hangs freely in the perigastiic cavity. The mouth guarded by a tongue-like epistome (Epist.) is surrounded by a number of tentacles (Tent.) arranged along the entire margin of a horse-shoe shaped Jophophore (Loj)Jt.). The anus opens outside the tentacular area near the mouth, on that side of the body on which the arms of the lophophore stretch out. A nervous ganglion (X. Gang.) is seen on the anal side (jf the oesophagus. A thin hollow tube, called funiculus, in which the statoblasts are developed, joins the angle of the alimentary canal with the cystidal wall. An ovarv (Orr.) is seen inside the tip of the cœnœcial branch. The length of a polypide from the tip of the tentacles of the angle of flexure of the alimentary canal is about 4 mm.
Although the term " individual " as applied to such foi'uis as polyzoa is very diihcult to detine, yet homulogously with its nearest relative, the Ijrachiopods, each polyzooid might be regarded as an individual in the (ordinary sense of the word. Polyzoan individuals show a close analog}' to " phytons " of plants.
The polypide and the cystid that constitute a pol\zoüid, are respectively vegetative and reproductive in function. As will be seen further on, all the functions for the preservation of the species are performed by the latter, the funiculus being regarded as a part of it, while the former serves to procure nourishment to the cystid.
OBSERVATIONS OX FRESH-WATEK POLYZOA. 95
All fresh-water Polyzoa are annuals, tlie vegetative and the reproduc- tive portions undergoing entire decomposition every year, while in marine forms, several generations of the vegetative portion, i.e., the polypides, form and decompose themselves on the perennial cystid, like leaves on thelmniches of a. tree. This singular phenomenon led many naturalists (Allmnn nud others) to regard the polypide nnd the cystid as two distinct individuals. In the present species also, the duration of vitality of the two portions is by no means the same. The poly- j)ides invarial)ly die after a certain period of existence, usually after the formatioii of younger polyzooids of the fourth or the fifth order, but the cystids remain until the colony itself disintegrates in winter. In the central porticin of a large colony, therefore, we often see only hare cystids, each with o dark grayish mass, the remains of the dead polypide, banging in its cavitv, ;nid yet with statoblasts continuing their development in tiie funiculus.
About the application of the terms " antei-ior,'' "posterior," "dorsal," "ventral," Ac, there is much diversity of opinion. For in- stance Allman calls the free end of the polypide "anterior," and the fixed end "posterior"; while Hyatt, following E. S. Morse, calls the fixed end " anterior," and the free end " posterior." Huxley homologizes Polyzoa with Tunicata, and names that side on wliich the anus opens " neural," and the side opposite to it " haemal," although there exists no heart. Again, if we were to compare this animal witli Phoronis, we should have to call the narrow spare between the mouth and the anus "dorsal," and nil other parts " ventral." In fact, every one mioht «five different sets of names in orienting the animal, according to his conception ( f the homology which exists between Polyzoa and other nnimals in which the an- terior and posterior, or the dorsal and ventral ])oles are universally recognized. In the following pages, I shall call the fixed end
96 A. OKA.
" linvor," and the free end " upper," the side on which the anas opens "nnal,' and the side opposite the anus "oral."
The organs that constitute the Polyzoan hody may he classified in the folio wi no- way.
A. Organs for the preservation of the polyzobids or the colony.
1. Dermal System, consisting of the ectocyst and the endocyst.
2. Digestive System, consisting of the epistome, the oesophagus,
the stomach, and the intestine.
3. Tentacles.
4. Excretory Organs (?), consisting of two short ciliated tiihes.
5. Muscular System, consisting of five groups of muscles.
6. Nervous System, consistino- of a o-anoflion with two arms
f >r the lophophore.
B. Organs for the Preservation of the species.
7. Ovary and Testis.
8. Funiculus, in which the statoblasts are developed.
9. The part of the endocyst that prc^duces buds.
1. Dermal System.
The integinnent of Polyzoa consists of two layers, quite different in their nature, the outer "ectocyst" and the inner "endocyst" (see fig. 4). The latter is not everywhere covered by the f n'mer, but is exposed on the polypides.
The ectocyst is gelatinous in this species. It fills up the space between the branches of the cœnœcial endocyst, whereas in Pect, magnifica, Leidy, there is no ectocyst between them. In this respect
OBSERVATIONS ON FRESH-WATER POLYZOA. y<
as well as in the erect position of polypides. this species comes nearer the genus Lophopus. The oelatinons substance is formed Ly the secretion of cells of the outer layer of the endocyst. Numerous cells, some oval, others irregidar in their shape, are scattered in it (fig. 6, PI. XVIII.). Their nucleus and nucleolus are distinctly visible. These cells seem to have wandered out of the outer layer of the endocyst, and may have helped in producing the gelatinous substance, remindin-T us of the cells in the test of the Tunicates. 'i'he gelatinous substance is adhesive and without taste ; it ser\ es apparently to protect the coh^ny. On drying, it shrinks almost to nothing.
The endocyst consists of four layers (fig. 7, PI. XYIII.)
a. Outer cell layer (OiU. Icuj.).
h. Basement membrane (^Bas. vianhr.).
c. Muscular layer (L. mus. and Tr. nuis.)
d. Inner lining epithelium (Lin. cpith.).
All of these layers are not present everywhere, nor is each ol them of the same structure throuHiout its distribution.
The cells of the outer layer, which represents the ectoderm, are everywhere distinctly bounded, columnar on the cœnœcium, tiat and h<)riz(jntally elongated on the polypide, except on the tentach^s and the upper surface of the lophophore. In the former, they are culjical, in the latter hexagonally prismatic, and distinctly ciliated in either case. Many of the cells on the cœnœcium contain a vacuole (fig. 7, vac.) filled with a very refractile fiuid. The numi)er of these vacuolated cells increases as we ap[)roach the tip of cœnœcial branches, where every cell shows a large vacuole, almost filling up the whole cell (fig. 33, PI. XIX. Out. huj.).
In preserved specimens, the cells are more or less shrunk, often leaving' spaces between them. The nuclei are oval, and have a dis- tinct, well-staining nucleolus. The cells on the cœnœciiun are
98
A. OKA.
0.02-0.04 mm. liiuh. The nucleus measures about 0.007 x 0.00 i mm.
The basemeiit membraiïe situated directly Ijeneath the outer celldayer is secreted either by this, or by the internal lining epithe- lium, or by both. In the gretiter part of the cœnœcium where this ]nembrane is separated from the inner epithelium l)y the muscular laver, it would be natnral to refer its origin to the outer cell-layer alone, but where the muscular layer is deficient, it is difhcult to decide. On the other hand, in the wall of the funiculus into which this membrane and the inner epithelium, but not the outer cell- hiver, are continued, it cannot but be the jn'oduct of the inner epithelium only. Generally, the l)asement membrane and the mus- cular Go;it are treated as one layer under the name of Tunica nuis- cularis, but as they are in reality quite distinct from each other, it will ]je better to regard them as two distinct layers. AVlien a colony is treated with a weak solution of acetic acid, the basement membrane separates from the rest of layers. It is thin, tough., transparent, and homoii'eneous.
Next to the basement membrane conies the nuiscular layer, con- sisting' of transverse and lomjitudinal fibres. The f3rmer run external to the latter. They are not very densely set, so that in a surface view they cross one another as in coarse linen. On the main ]>art of the polypide, only the longitudinal fibres are present. In such genus as Cristatella, the muscidar layer gives the colony the power of slow locomotion, but what function it has to discharge in fixed Pectinatella, I am not prepared to say. In the cœnœcium where this layer is best developed, it is 0.005 mm. thick. It is not found in that part of the endocyst wh.ere buds^ are formed, and is also absent in the walls of the lophophore and the tentacles.
The internal epithelial Inyer lines the endocyst everywdiere. It is thickest in the cœnœcium, especially at those points where budding
OBSERVATIONS OX FRESH-WATER POLYZOA. 99
takes |)]:ice, and is thinnest in the tentacles with nuclei scattered widely apart (%s. 16 and 17, PI. XVIIL). The cells of this layer are fused, hence cell boundaries cannot he distinguished. The nucleus is oval, but I am unable to detect distinct nucleoli. The size of the nucleus is nearly the same everywhere, and is about 0.00(S X 0.004 mm. This layer is furnished with short cilia, which set the perigastic fluid in motion. Average thickness of the layei" in the cœnœcium is 0.008 mm.
2. Digestive Sj^stem.
Minute algae and infusoria that pass by are caught in the whirl- pool caused by the vibrating cilia of the tentacles, and sent into the œsophagus. The e[)isti)me that guards the mouth is ftu'ni.shed with special muscles which enable it to shut the oral aperture now and then. Perhaps the entrance of non-nutritive matters is prevented by this contrivance. The food, after staying ibr a short time in the oesophagus, pushes open ihe funneldike valve (fig. 4, PI. XVI I. fniuicl-like v.) that intercepts free conununication between the oeso- phagus and the stomach, and enters the gastric cavity where it is moved about by the peristaltic contraction of the wall of that organ. After l)eing fully digested, the residue mainly composed of the cell- wall of diatoms and other algae, passes through the pyloric valve little by little, and accumulates in the intestine. Here, the refuse matter, usually of a dark-grayish color, is cemented together into a mass by a transparent gelatinous secretion of the intestinal wall. AYhen the intestine is full, the contents are pushed out of the anus by the agency of the muscles of that part. The form of the excremental mass, characteristic of each genus, is the same in form as the lumen of the intestine which in our species is an elongated oval tapering toward the anus.
100 A. OKA.
There ni-e often certain amœboid cells to be found in the intestinal cavity. The}^ stain very well, nnd are on that account vei'y con- spicuous among a mass of unstained matter. Judging- fcom their shape and size, it is very probable that they are parasitic Protozoa.
The process of digestion is carried on very rapidly. When fresh colonies are brought from the ])ond and kept alive, all the polypides dischnrge their dark intestinal contents in a few hours, rirndually, new refuse niatters ])egin to accumulate in that organ, i)nt thev are always i\ go;()d deal lighter in cohn'. These are again excreted iii the next three or four hours. As the amount of food that these animals con- sume is considerable, it was impossible to keep them alive more than a week without furnishing them very often with water from the pond, which C'.mtained minute organisms.
The layers that constitute the walls of the alimentary canal are the same as those of the endocyst. In fact, they are direct continua- tions of the latter only slightly modified to serve special piu-p(^ses.
The epistome is a tongue-like prolongation of the disc of the lophophore on the anal side of the mouth. Its cavity (see fig. 8, PL XVIII.) communicates with the general perigastric cavity by a com- paratively narrow passage on the anal side of the cerel)ral ganglion. The cells of the outer layer of its wall are similar in appearance to those of tlie lophophore. They are prismatic, and the height increases nearer the mouth. The oval nucleus with distinct nucleolus lies near the base. The whole external surfiice is furnished with cilia. This organ has no muscular layer in the wall, l)ut is furnished with special muscular fibres which traverse its internal cavity. These fibres are simply elongated cells with the uncleus at about the middle of their length. They are separate and never form bundles. The length of the epistome is about ^mm.
The oesophagus is that portion of the alimentary canal that lies
OBSERVATIONS ON FRESH-WATER POLYZOA. 101
hotween tlie month and the fiiunel-hke vnlve nt the cardia] opeiiino- of the stoiiiaeh. Its upper aud lower sections are lined by epithe- lia of quite different appearance. The cells of the nipper section (fis:. 9, PI. XVIIl) have cilin, and their nncleiis lies near the base. Yerworn says that the cells of this section do not come in to any contact with one another throughout their whole length, being separated l3y a narrow intervening space but I cannot find any such space in Pect, gelatinosa, except such as is in all prob^ibility due to the post-mortem contraction of cells. In the lower section, the lining cells have no cilia, and the nuclei lie irregularly near the middle (fig. 10, PI. XVIII). In the upper section, the free end of cells is -flat ; in the lower, it is rounded. In both the nucleus has a distinct nucleolus. The cells of the lower section do not stain Avell, and seem to contain a secretive sul)stance, which may be comparable with the saliva of higher animals.
The length of the œsophagus is about 1mm. and its diameter 0.3 mm. The lumen of the œsophagus when expanded is round in sec- tion throughout its entire length, but in its upper section contraction changes it into a stellate sliape. The inuscular layer is but scantily developed in the œso'phageal wall. The outer covering is the con- tinuation of the lining epithelium of the endocyst with which it agrees in all respects.
The œsophagus in its downward course occupies an excentric position in the tubular body of the polypide, and where the latter is externally marked off from the lophophore l)y a slight constric- tion it actually comes in contact with the body-wall on the oral side. At this point, the lining epithelium of the polypidai wall is continuous with the outer covering of the œsophagus, and fwrns a sort of mesenterv (fig. 15, PI. X^'IIL). This mesentery extends horizontal- ly on both side for a short distance, and prevents over-invagination
102 A. OKA.
of the body-wall when tlie polypide is retracted. Thus the ahmen - tary canal is attached to the body- wall at four points, viz. the mouth, the anus, the fnniculus nnd tlie above mentioned mesentery.
At the entrance of the stomach there is as already mentioned a funnel shaped valve, with the free end pointing into the cavity of the stomach (tig. 11, PI. XVIIL). It consists of a fnnnol-like pro- longation of the basement memljrane, on the oesophageal side of which are arranged the characteristic cells of the œsopliagus, and on the gastric side, the pyramidal cells of the stomach. This valve, whose length is about 0.2 mm., prevents the passage of food from the stomach back into the œsophagus.
The stomach is a spacious saccular orgnn whose long axis is bent in the sha[)e of V. bi'inging the pyloric opening nenr the cardiac. It measures 2 mm. in length, and 0.6 mm. in breadth at the widest part. The inequality of the length of the arms of Y brings the cardiac opening about 0.5 mm. nearer the free end of the polypide than the pyloric.
The inner layer of the stomach has two kinds of cells ; the long club-like cells (fig. 13, I'l. XVIII. cL c.) and the short pyramidal cells (pill'. ('.). As they are arranged in gr(3Ups forming alternate longitudinal rows, the lumen of tlie stomnch is stellate in cross- section. The number of the rows of each kind is generally twelve or more (hg. 12, PI. XVIIL). In both, the nuclei lie at the base and the nncK'oli are distinctly visible. The l<:>ng club-like cells do not shiin well, while the short pyramidal cells freely take up the coloring- matter. In the fresh state, the longer cells contain a yellowish brown fluid and the shorter cells are of a light yellowish color, so tliat the stomach appears longitudinally striped with yellow and brown bands. As the alimentary canal has no distinct glandular appendage, the brown fluid contained in the longer cells probably performs the
OBSERVATIONS ON FRESH-WATEK POLYZOA. lOo
function of the dig-estive fluid. Hence tliey huve been called hepatic cells by Alluum. Tlie function of absorption seems to be pei-fornied by the shorter cells. The length of the longer cells is various, the longest measuring 0.06 mm., while the shorter [)yramidal cells mea- sure approximately 0.02 mm. On the gastric side of the cardiac valve, and at the blind end where the stomach is continuous with the funiculus, the rows of the longer cells stop short, and only the short pyramidal cells are })resent.
The muscular layer of the gastric wall, composed only of the transverse fibres, is w^ell developed, especially below. At the thickest part this layer is 0.007 mm. in thickness. At the l)lind end of the stomach, however, tliere is no muscle, and here the inner cell-layer comes in direct contact with the fluid contents of the funicular cavity (fig. 32, PL XIX.). At this point, the wall is generally pushed inward in the form of a shallow pit.
The outer epithelium does not diiter from the corresponding la^er of the œsophagus and the endocyst.
The pyhjric valve is represented by a simple constriction of the entire wall of tlie alimentary canal. Its opening is very narrow, allowing the passage of only a small quantity of indigestible matter at a time.
The intestime is a tul)ular organ tapering tow^ard the anus. It is about 1.2 nnn. in length, and 0.3 mm. in width. The inner layer is composed of only one kind of cells, which are much shorter but somewhat broader tlian the longer cells of the stomach. The height of these cells is about 0.025-0.03 mm. The nucleus is at the base and the nucleolus is distinct (fig. 14, PI. XA'IIL). These cells do nut stain well ; the gelatinous fluid they contain is probably the medium by which the excrement is cemented into a C(jmpact mass. The mus- cular layer of this part, in which onl}- ring fibres are present, is weakly
104 A. OKA.
developed except near the aiiu.-^, where it f(3nns a sort of si)hincter. The anus when expanded is us wide as the widest part of tlie in- testine, but when contracted it closes altogether. The outer cell- Inyer is similar in all respect with that of other parts of the alhnentary canal. At the point where the intestine is tightly pressed against the oesophagus, the outer layer of the former ])asses directly into that of the latter, bringing the cells of the inner layers of both organs in C(3ntact.
3. Tentacles.
The tentacles are arranged in one continuous series along the outer and the inner margin of a horse-shoe shaped lophophore, as mentioned before. They are hollow cylindrical organs measuring 1 mm. in length, and 0.03 mm. in breadtli. They are t(3 be con- sidered as prolongatioiis drawn out, as it were, from the endocyst. In the living state, they are freely movable in every direction at the will of the animal, but I have never seen them coil or contract. Generally, they stand nearly parallel to one another in graceful curves (fig. 2, PI. XVIL).
The cross section of a luphophoral arm (tig. 30, PI. XIX.) is almost semicircular in outline, slightly convex above and rounded below, measuring 0.3 mm. in breadth, and nearly as much in depth. The ciliati(3n on the upper surface is distinctly visible on sections.
The cells of the outer layer of the tentacular wall have all the essential characters of those of the endocyst. They rest on a fine base- ment membrane and are furnished each with a long cilium (fig. 16, PI. XVIII. (Jut. lay.), constantly vibrating in a certain fixed direc- tion. The ciliation ofthat side of the tentacles turned away from the mouth drives the water upward, while that on the opposite side tends to drive it toward the mouth below. The iiiner layer of the tentacles
OBSERVATIONS OX PRESH-WATEli POLYZOA.
105
(fig. 16, PL XVIEI. Lin. ej)itli.) is very thin and has the nuch-i scat- tered at great intervals. I was not aljle to detect any trace of cih'a on the lining epithehiim, but the rapid motion 'of the [)erigastric "fliud, a'oins" toward the tii) alono- one side and coming' back ak^n«' the other in the narrow tentacular cavity, indicates their existence. The lumen is a little more than 0.01 mm. in diameter.
The account, given by Yerworn, oi' the manner of junction of tlie tentacles with the Io[)hophore and the tentacular membrane in CrUtatella applies equally well to the species investigated by me. In fig. 18, PL XVIII, I have endeavored to show diagrammatically the relation of several parts at the bases of tentacles.
Externally io the row of tentacles there is a thin membrane, the tentacular membrane, 0.3-0.4 mm. in Ijreadth, formed by a, duplicature of the outer layer of the lophophoral wall along its outer edge. It consists of a basement membrane covered on both sides by a layer of flat cells, tlie direct continuation of the outer layer. The basal portion of each tentacle is joined to the tentacular membrane by another narrow triangular membrane.
Alternating with the bases of the tentacles, a series of duplicatures (jn each side of the lophophoral cavity is produced in the inner layer, so that if Tve were to cut across the arm and look into it, we should see a series of vault-like arches. The tentacular cavity opens »nto that of the lophoph(3re l^etween each two of such folds of the inner layer. These folds descend almost to the floor of the lophophoral cavity, and have been reckoned as part of the muscular system by Hyatt, under the name of" brachial contractors," but I see no ground for regard- ing them as such, since they consists simply of flat cells.
The bases of the tentacles are not in one plane. Those on the anal side near the e[)istoine are the most elevated. Tlie numl)er of the tentacles is generally even, but in some individuals there is a
106 A. OKA.
median tentacle on the anal tside, making the total num1)er «xld.
There can be uo d(juLt that the function of the tentacle« is three- fold, äer\ing for respiration, for collecting food and for feeling. Of these, however, the first seems to l)e their principal office, when we consider the large extent of their surface exposed to water, and the constant current kept np in the latter hy a special contrivance, as well as the perigastric fluid that circulates within their lumen. The Tentacles thus bear a close resemblance to the fringed arms of ßrachiopods.
Circulation. The perigastric fluid contained in the general body- cavitv may justly be regarded as representing the blood. Of its nature and the mechanism of circulation, little was known before. There are no special orgarjs, such as heart and blood vessels, and the only means of driving the perigastric fluid is the supposed ciliation on the lining epithelium of the general body-cavity. The nutritive part of the food taken up by the alimentary canal is conveyed to all parts of the body by this fluid. It is transparent, colorless, and has no taste. Water seems to constitute the greater part of its con- stituents.
The fluid contains, floating in it, numerous round cells, each with a large vacuole almost filling up its body and filled with a refi-actile fluid (fig. 20, PI. XYIII). The nucleus is pushed against the wall by the vacuole. The study of the development of polypides in the statoblast shows that these free cells are derived directly from the iiianular mass that constitutes the main contents of the statoblast, and in young stages they contain similar granules instead of the vacuole. It is therefore plain that they are, at any rate, nutriment carrying cells, which might be regarded as blood corpuscles.
OBSERVATIOXS ON FRESH-WATER POLYZOA. 107
Besides these, there are o'onerally present a g'reater or smaller number of cells or fragments of cells of a c|nite différent appearance, which have prc)hably detached themselves from some part of the body.
The floating elements were observed by previous investigators (Allman, Hyatt, Verworn), but no great im])ortance was attributed to what were brobably either parasitic organisms or detached cells. Hyatt, for instance, observed "numerous organisms, many of which probably parasitic, which float in the flnid, sometimes in such "a number as to interfere with the examination of tlie internal structure." It is prolmble that at least some of these " organisms '' were what I regard as tiie blood corpuscles.
The direction of the blood currents as (feerved in the natural state is show^i in fig. 21. On the anal side of the body cavity the fluid is driven toward the free end of the polypide, evidently by ciliary action, whicli however could never be actually Ijrought to view^ In the lophophoral arms, tlie corpuscles travel ;dong the floor to their ends, and either returii directly along the ceiling, or enter the tentacles, in which they ascend on the side nearer the tip of the loph(^phore, and descend along the opposite side. In the cavity of the epistome, the fluid streams along the ceiling to its tip and com- ing back ah:)ng the floor of that (^rgan, either enters the epistome again, or goes to the tip of the lophophoral arm along its lower side. On the oral side of the polypide, the fluid is always seen flowing do ^vn ward.
Allman and Hyatt deny the presence of cilia on the external wall of the alimentary canal, but Yerworn (saw them at the end of the stomach in Gristatclla. My observations in living specimens of Pectlnatella confirms tlie statements of tiie last author.
Both Allman and Hyatt observed that the cœnœcia of Lophopiis, Cn^fatella, and Phnuatdla vitrea, readily emptied themselves of
I(l8 A. OKA.
their peri<^n><!fri(j fluid when taken out of the water. They assumed that the fluid passed ont through pores in the endocyst, 1)nt they searched in vain f(3r such communications.
It is certain tliat when a polyj)ide retracts, a portion of the fluid contained must of necessity pass ont at some place, since the cœnœcial wall does not expand heyond a very limited extent. Notwithstand- ing my s[)ecial attention to this point, Feet, (jelatinosa also gave no resnlt, and I should ])refer to go no further than to assnme the presence of external openings in connection with the excretory organs.
4. Excretory Organ (P)
Joliet (6), in a paper entitled " Organe segmentaire des Bryo- zoaires Endoproctes," gives a pretty full description of two short funnel-shaped tubes in PedicelUna and Loxosoina, first noticed by Ilatschek. In the division Ectoprocta, however, our knowledge on lhis sul)ject is vei-y limited. As far as I know, the two ngures given In' Fai're, ;uid the remarks by Uincks and Smitt, both of whom do not go beyond conforming the observation of the first, constitute the wliole ])i])liography on this subject. Tliey all noticed a ciliated pipe that opens between the mouth and the anns in AUijonidiiuii and Mem- hranipora, hotli of which are gymnoliematous. In regard to the order Phylactolcematn. if we except the short account given by Yerworn, illustrated with two semi-diasframmatic fig-ures. there exists no litera- ture known to me. Yerworn left the terminations of that organ nudetermined, confining his attention t«^ <^iily ^^hc middle portion where it is most conspicuous. Braem touches on this subject in his note in the Zoologischer Anzeiger, but he too could not deter- mine how the tubes terminate. Such beins: the case, I have investigated this organ with s[)ecial attention.
OBSERVATIONS ON FRESH-WATER POLYZOA. 109
There are two ciliiited tnhes just l^enentli the outer layer, on tlie anal side of the body, l-jetween the aims and the bases of the median tentacles of the inner row. The walls of these tubes are continuations of the epithelial lining- of the invaginable portion of the endoeyst. They open below into the body-cavity by fnnnel-shaped opening's. They measure 0.15-0.19 mm. in length, though the portion where the wall is entire is much shorter (fig. 26 bis. PI. XVIII). The shape of the funnel-like openings may be compared most appropriately with the obliquely cut end of a hollow tube.
The exact form of these tubes and their relation with other organs will be best undestood by referring to figs. 21-26, PI. XVIII, which show their cross sections with the neighboring parts at various levels.
In a cross section passing through the middle part of the tubes, we see them as two oval sections lying side by side (figs. 24 and 2-1 A). The ciliated epithelial wall consists of cells which are cul)ical near the median plane of the polypide and flat on the opposite side. Consequently both the nuclei and cilia are densely set in the portion nearest the median plane of the polypide and scattered at some distance from one another on the outer side. The tubes are closely enveloped on the anal side by the outer layer of the invagina- ble tube (Out. ki)/.), and on the oral side by the lining epithelium (^Liii. cpit]!.) of the body-cavity. The diameter of the tubes measures about 0.03 mm.
Tracirig these tubes downward, that part of the wall farther removed from the median line soon disapjtears, i, e., the tubes open into the body-cavity on that side (fig. 26). As the two tubes deviate from each other below, a part of the perigastric s})ace appears between them (fig. 26, rpistom. car.) This is the passage by which the cavity of the epistome commu.nicates with the perigastric.
110 A.OKA.
The inodinn side of the wall ends abruptly on the anal side of the o;anglioii ; below this point cross sections show only one conti- nuous body-cavity. Thus, the body cavity is divided into three brandies on the upper part of the polypide. The middle one (fig. 26, (■r>i>ilom. cav.), passing along the anal side of the ganglion, extends into the epistonie, while the lateral ones are prolonged into the lophophoral cavity. The inner walls of these lateral branches pass gradually into the ciliated tubes.
If we now trace the tubes upwards, they are found gradually to approach each other, and their walls soon coalesce. A little higher the cavities of both open into each other, and there is seen a single flattened tube (figs. 23, Ncplir. & 23 A). The whole inner surface of this part as well as that of the two deviating tubes below, show distinct ciliation in sections, the cilia being always directed toward the perigastric opening. If we trace this flat tube still further upwards, it again becomes divided in most individuals into two, in some into three tiil)es (tigs 22 t' & 22 A), each of which is continous with tentacu- lar lumen. In this part, the ciliation is no longer visible, but compared with the inner layer of the tentacles, there are more nuclei. But, further upwards, the nuclei are fewer in number and the lining epithelium presents similar appearance as that of ordinary tentacles (figs. 21 ^' & 21 A). What can be the function of these ciliated tubes ? The fact that they open int(^ the perigastric cavity by ciliated funnel- shaped openings naturally reminds us of the segmental organs of certain worms. And thus many observers have been induced to regard the function of these tubes as being of an excretory nature. If such is re:dl V th(î case, there should be some orifice by which they open outwards, for the high degree of development they attain prove that they are not useless remnants. This makes me venture to assume the existence of minute apertures, at least on the two or three innermost
OBSERVATIONS OX FEßÖH- WATER TOLYZOA. HI
tentacles of tlie una! side, presumably at their tips, althonah I ;im imaljle to prodnce any positive proof. The pores, if ever present, must be of very minute size, indiscernible by ordinary methods in a manner analogous to the pores at the tip of Actininu tentacles,
5. Muscular System,
The mnscnlar system consists of live groups of muscles. They are :
a. Muscles of the funiculus.
h. Pariet<i-vaoinal muscles.
f. Retractor of the polypide.
(L Muscular layer of the alimentary canal.
e. Muscular layer of the endocysl. T(^ these may be added the muscles of the e[)istonie.
Tlie first three are, as development shows, moditications of the last two, which in turn may be regarded as only locally differentiated forms of one and the same layer.
In the develo})ment of the polypide in the statoblast, the muscidar fibres are formed from certain cells of the granular mass, and, in the process of budding, from the lining epithelium. In either case, the cells elongate, and become spindle shaped, with the nucleus at the middle. They lengthen more and more and the nuclei become indis- cernible, although these can often be made visible l;)y the aid of acetic acid. Excepting some fibres of the parieto- vaginal muscles, which remain in this state to the end, the muscular fibres are ex- tremely thin, and do not sliow nuclei in tlieir interior. It seems that these fine fibres arise by the longitudinal splitting of tlie original muscle-cells, as is known to take place in many other animals.
The muscles are never striated. Even in the retractor of the
112 A. OKA.
polypide, which is obviously of grentest physiological iiiiport;iiice, the fibres are smooth. In marine Polyzoa, however, I have observed that the muscles of the avicularia and the vibracula are striated.
The muscular fibres belonging to the funiculus run longitu- dinally on the inner surface of the basement membrane, on which the cellular wall of the funiculus rests (fig. ol, PL XIX). They run separately without forming bundles, and present the same appearance as those of other parts. Their extreme fineness as well as their small number agrees with the fact that the funiculus contracts, if ever, in a very limited degree.
The muscles running between the cystidal wall and the bottom of the invaginated fold (at the junction of the cystidal and the poly- pidal endocyst) are called the Parieto- vaginal muscles (fig. -1, PI. XVII, M"). Their fibres run either solitary or in bundles, forming on an average 13-14 sets arranged somewhat radiall}'. Their points of attachment to the cystidal Avail is irregular. These sets of muscles cause the presence of the invaginated fold of the body-wall. In i'6'c'f. (jdatinosa when the polypides fully expand, this fold, which is otherwise distinctly present, disappears, the muscles relax- in o' to their full extent.
The great retractors of the [)olypide consist of a pair of well developed muscular bundles, right and left in the perigastric cavity (fig. -1, PI. XVII, Jl/^^^). The fibres are modifications of the muscular layer of the endocyst, extraordinarily developed to serve their special purpose. The point of attachment of each bundle to the bottom (^f the cystid is siiigle, but the upper portion is split into a large number of smaller bundles which are inserted into the walls of the œsophagus and the stomach at various places, but most numerously at the upper part of the former. The bundle is ensheathed in a sort of fine sarcolemma, which could distinctly be demonstrated at such places
OBSERVATIONS OX FERSH-WATER POLYZOA. 113
where the fibres were mechaiii<'a11y torn away leaviii^i!,- the shealh uninjared.
In the nuisciilar layer oî tlie alimentary canal, (jiily transverse fibres are well developed, and the longitudinal fibres, if ever there be any, are very scanty. The layer becomes thicker as we approach the blind end of the stomach. The musculature in (juestion [)erfjrms peristaltic movements, periodically on the (esophageal and fairly constantly on the gastric wall. The ])lii]d end of the latter is subject to strono-er constrictii-ns in accui-dance with the thickened muscle- layer cf this part. The peristaltic movement of the gastric wall helps not only to move about the contents ofthat organ, but also to setid the residue into the intestine. The muscular fibres of the intestinad wall are especially well developed near the anal opening ; they serve to discharge the excrements out of the l)ody and to keep the anus tightly closed. At the point v\diere the blind end of the stomacli joins the funiculus, there is no muscular layer (fig. oo, PI, XIX).
The muscular laver of the endocyst has already been treated under the body-wall. The outer ring fibres are especially well developed around the orifice oî the cœnœcial branches and f)rm a sort of sphincter to close the opening produced when the polypides re- tract. When the polyjâde is extended, the cœnœcial branch becomes slender by the contraction of the ring fibres, but apparently it is not by their agency that the polypides are pushed out, for tiiis pr(jcess takes place even in a cœnœcial branch witii its wall cut open, so that the fiuid contained can transmit no pressure upon the in\'aginated polypide.
The muscles that move the epistome remain in a very primitive state of development, coiisisting of hjosely distributed fibres which, as already mentioned, are mere elongated cells with t lie nucleus at the ufiddle. They tra\erse the cavity of the epistome, joining its
114 A. OKA.
underside with the ceiliu^^. As seen in cross sections, they are more closely set nenr the edg-e and abnost entirely wanting in the central part of the epistouie.
6. Nervous System.
This system has been described more or less fally in all works on Polyzoa, but the accounts given are very difterent from my own observations. Xearly all investigators describe the cerebral ganglion ns a solid cellular mass. Nitsche, studying the process of gemma- tion, states that the ganglion has at first a ventricle, which, however, obliterates with the growth of the animal. Contrary to this state- ment, Saetftigen (10) recently discovered that in Gristatdla and Pliuiiatclla, the cavity of the ganglion persists throughout life, and further that the ganglionic wall is not everywhere of the same thickness, being at some parts as thin as the lining epithelium of the body- walk I have observed that in rcctinatdla also the cavity exists in the mature state ; it is so very large that at first sight it might be mistaken in sections for a part of the body-cavity.
In tig. 28, PI. XrX, I have represented the form of the ganglion in Pedinalella (jclatiiwsa. It may be compared with a spindle bent somewhat in the fjrm of U, and fitted with its concavity to the anal side of the œsophagus, in rather an oblique position with the arms turned slightly upward. The end of each arm again makes a sharp bend in the anal direction and is continuous with a large ner^•e trunk which proceeds into each hjphophoral arm. The ganglion is in direct contact with the inner cell-layer of the œsophagus, the outer layer of that tube enveloping it on all other sides ; the ganglion is in fact situated between the two layers of the œs(.)})hagus (fig. 29, PI. XIX). The lophophoral nerve trunks are likewise located between
OBSERVATIOX OX FRESH-WATER POLYZOA. 115
the outer and flic iiinei- cell-layers of the bod 3^- wall ; they run, namely, immediately beneath the outer layer of the lophophoral ceil- ino-. covered below by the lining epithelium.
As mentioned above, the ({anodion is not a solid cell-mass as has been described by nearly all investigators. On the contrary, it contains a spacious ventricle, extending to the end of the arms, or horns, as is diau^rammatically shown in fig. 30 a, h, c. PI. XIX. The wall of the ventri(de is very thin and of an epithelial nature on all sides except at the bottom somewhat on the anal side, ^vhere it is verv thick, forming the ganglion sensu strict a, — a condition which reminds us of the ïeleostian cerebrum.
This thick portion is distinctly bounded from the thin epithelial pai-t of the wall, and is well seen in the fre.sh state as a somewhat reddish mass, with a slight constriction in the median plane of the polypide. It is this part that Hyatt took for the ganglion which he describes as comp(^sed of two lateral masses united by a verv tliick commissure. It is no wonder that he overlooked the thin epithelial portion, since this is hardly recognizable in surface views. As can readily be imaodned by combininçf the three sections i>dven in fio-. 30, passino- through the brain in different directions, the thick portion is a transversely elongate rounded mass, with a transverse slit-like de- pression, looking orally and upward. The whole mass is not of the same structure throughout, but shows a differentiation into peripheral and central portions. In the former, the nuclei (of ganglion-cells) are densely crowded, while in the latter we see a faintly stained granular mass (Punktsubstanz) containing only a few or no nuclei. Tlie cell outline to each nucleus is not to be seen.
The thin part of the wall of the ventricle differs in nothing from ail ordinär}'' epithelium, being composed of a layer of flattened cells. It is c«intiniious with the peri[)heral portion of the proper ganglionic
IIG A. OKA.
part. ITow the nerve fibres, if there he any, pass ont from the latter into the nerve-trunhs, I have 1)een unal)le to ehicidate.
Tlic cross-section of the lophoplioral nerve trunk is kidney- sh;ip('(h with the concavity tnrned above (fig. 31, PI. XIX. nrrr('). In it tlie nuclei of nerve-cells are seen mnch crowded. Longitudinnl sections show that the nerve-cells in cpiestion are spindle-shajx^i (bipolar) with the nucleus at the middle, and closely packed tog-ether. A few fil)rcs run amongst them ; these are probably to be regarded as nerve-fibres. The trunks themselves are very thick and large in companson wifh the mass of the central ganglion, and their structnre gives the impression of an elongated ganglionic mass rather than of a nerve. The trunk gives off on each side a branch into each tentacle. Such a branch is of fibrous appearance and could be traced onlv for a very short distance after its de])arture fi-oui the trunk.
The presence of a circumcesophageal nervous commissure in fresh-water Polyzoa is a matter of obscurit}^ having been accepted by a few and denied by many. My observations on Pect, gdathinsa convinced me of its absence.
T'he colonial nervous system present in many marine Polyzoa, wliich keeps the action of the members of a colony in har- mony, seems to be altogether wanting in this species, as is probably the case in all other fresh-water Polyzoa. Special attention to tliis point showed no trace of nervous connections between the polypides in ])reparations of sectioned colonies. The fvct agrees with the behavior of the p(^lypides in a living colony, in which only directly disturbed polypides retract, while all the rest remain pro- truded as if nothing had liappened.
OBSEP.VATION OX FRESH WATER, POLYZOA. 117
7. Ovary and Testis.
Pcct'niafdhi qchitinn^a has a distinct ovary, although it devolopes only in verv rare instances. AV'hen present, it is situn,te<l inside the cystid near its tip on the oi-al side. It is a solid clnh-shaped ontoTowth of the internal lining epithelium, and nsnally contains ten or more ova in different stages of development (fig. 33, PI. XIX), the space between them being filled with connective tissue stroma. Ripe eggs can fall into the perigastric cavity only by the rapture of the ovarian wall. The largest ovarian (ninn measured 0.35 mm. The length of the ovary is about 0.9 mm., and the breadth 0.5 mm. Xo doubt can ever be entertained about the ovarian nature of the b(jdy in question. Tiiat the funiculus has nothing to do with the production of eggs has also been ascertained by Braem f)r Crisfafella and PlumateUa.
As to the testis, my investigations gave no result. I searched fu- it in hundreds of polypides, but in vain. I once saw son^.ething like spermatozoa within the tip of a cystidal branch, l)ut I filled to make it sure. At any rate, true sexual organs are very imperfectly deve- h^ped in accordance with their secondary importance in the reproduc- tion of this species.
8. Funiculus.
The funiculus is a hollow tubular organ, about 5-6 mm. long, whieh Connects the blind end of the stomach with an o))posite })oint of the cystidal wall. Its wall is composed of three layers, but the innermost one, consisting of a few longitudinal muscular fibres, hardly deserves to be called a layer (fig. 32, PI. XIX). The outer- most layer is the continuation of the outer lining of the alimentary canal or the lining epithelium of the endocyst, from either of which
118 A. OKA.
it rliffer.s in nothing. The cells of this layer rest on the outside of a tiil)e of basement niem1)rane, which forms the middle layer, and are rather thickly set, every cross section of the tube showing from nine to twelve nuclei. Thus my observations on this organ are identical with and only confirm Nitsche's. Verworn denies the existence of muscular fibres in Cristatdla. In FectinatcUa they are decidedly present, although few in number and isolated, so that tliey are liable t<.) be overlooked if not specially searched for. The outer- most layer is the only cell-layer in the wall of this organ. I cannot l)ut assume that Kra?pelin had fallen into error in describing the funiculus as made up of two cell -layers, the ecpiivalents of the outer ln\er and the lining epithelium of the endocyst respectively.
The diameter of the lumen is about 0.02 mm., and the thickness of the wall about half as much.
The narrow lumen of this tubular organ, whose wall must be ivgarded as entirely mesodermal, is bounded at its upper end by the inner cell-layer (entoderm) of the stomach, and at the lower end, by the (Miter layer (ectoderm) of the endocyst (figs. 33 and 34, PI. XIX). It is in this organ that the statoblasts are developed. That the funiculus should not be reg^u'ded as tlie ovary, as was done l)v some former investigators, is self-evident, at least in the present species as well as in those in which a distinct ovary has been demonstrated in quite another region of the.liody.
9. The part of the Endocyst that produces buds.
Budding takes place at a, certain fixed position as Braem asserts, namely, at a definite area on the oral side of the cystidal endocyst. Here the endocyst is somewhat thicker than other parts of the same
OBSERVATION OX FKESH-WATEK I'OLYZOA.
119
wall, and the outer cell-layer and the lining epithelium are clciirly distinguishable from each other, a.s at (jther places, although no muscular layer intervenes between them. At this place, the cells uf the outer layer are wanting in vacuoles and both layers stain more deeply than anywhere else. The area is comparable to the growing point in plants. How the buds arise, shall be treated under a s[)ecial chapter later on.
B. Reproduction.
In fresh- water Polyzcja, reproduction may take place sexually or asexually in three ditferent ways, as tabulated below :
[Reproduction by
Xature : Function
iSTevv individual originates from :
The number of body-layers that enter into the formation of the new individual :
1 Ovum sexual
2 I 3
Statobhist BuddinjT
asexual
to form primary poly_ zooid irivinii' rise to a new colony.
to form a nundjer of new polyzooids, thus increasing the extent of a colony.
one cell
one
many cells
two.
13y the first nuxle, an ovum should undergo segmentation, and passing through a series of metamor[)hosis give rise to a new primary
120
A. OKA.
polyzoöid. This mode, however, heems t(j take place Nerv rare]y, if ever, in the present species.
By the second mode, germs enchjsed in hard chilinous cases (statoblasts) are produced in the funicuhir cavity of polyzoöids. They are set fi-ee by the decay of the parent cohjny, and float on the surface of water during" winter, sometimes packed in ice. Next sum- mer a primary polyzoöid is developed in each, serving as a foundation for a new colony. Thus, this and tlie first mode perform tlie same pur- pose, in so far as both serve to establish new colonies, and the with- drawal of the latter is supplanted l)y the great activity of the foriner.
By the third mode, a certain part of the endocyst adds, by growth in a certain definite manner, new polyzcjüids to the primary polyzoöid. This mode of reproduction increases the size and de- termines the form of the colony.
In certain cases the colony may propagate itself by simple divi- sion. For instance, Allman and Hyatt observed that in old colonies of such genera as CV/6'f((f6'//(/, Lophopus iiuû FectiiiatcU't, all of which have gelatinous ectocyst, the branches separate themselves from the cœnœcial trunk by constriction. In Feet, (lelafinosa, however, I have never met with the same phenomena. On the contrary, all the ("olunies collected by me shc^wed no sign of such fissiparity, all of them being entire and of the form characteristic to this species. In most of them, the shell-halves of the statoblast in which the primary polyzoöid has developed were seen sticking to the underside some- where about the centre.
With regard to the first mode of reproduction, I had no chance of making observations any further than determining the j)resence of ovaries in certain polyzoöids. The phenomena of reproduction by the remaining two modes shall be treated, for sake of convenience, under the followini»' four heads:
OBSEKVATIOXS OX PKESH-WATER POLYZOA. 121
1, StatobJiist,
2, Development of the Statobla.sl in the Funieulus,
3, Devel(.)pnieiit of the Polypide in the K^Slatohlast, und
4, ]j Lidding.
1. Statoblast.
The general strueture of this seed-like body, dilfei'iug in shape and size in different species, is now well-known and the following description refers specially to the statoblast of I'cct. gdatiiiusa. In winter the dead colony is soon decomposed and the statoblasts con- tained in it are set free. Dm'ing winter and spring months, they may 1je found on the surface of the water in large numbers, clinging to float- ing logs, Ijamboo sticks or trunks of aquatic plants. They are of a dark brownish color with a wide marginal zone of a lighter tinge.
Let us take one of them and examine it more minutely. Its s]i:i[)e is, properly speaking, like a flat lens. The (jutline, as it lies flat, is quadrate-oblong, about 1.5 x 1.3 mm., and about U.3 mm. in thickness. I may here mention that this s[)ecies has the largest statoblast among all known Phylactolcomatous Polyzoa. It presents double curvature after the manner of a saddle (fig. 5, PI. XA^II). For conveniences sake, we may call that side on which the longer axis is convex as the "conv^ex surface," and the opposite side as the ''con- cave surface," although tliese terms do not hold good with regard to the shorter axis. On both sides, the whole surface is beautifully marked into hexao'onal areas, more distinct in the marginal zone than in the central portion. The extent of the central darker area is various in different statoblasts, and it may also differ on different sides of the same statoblast. Generally it ranges from 0.5 mm. to 0.6 mm. in diameter.
122 = A. OKA.
Closer examination shows that what appeared as a distinctly reticuinted marginal area is a sort of broad rim around a cliitinous body of compact nature. This rim consists of a nundoer of prismatic caskets filled with gas, the diameter of the caskets increasing as we approach the margin. The hollow caskets have their axis vertical to the plane of tlie statoblast and are arranged in two horizontal lasers. They serve as a buoy to float the central body, which is the most important part of the statoblast.
If the free edge of this rim, or the annulus as it is called, be examined under a strong power, we see a great number of minnte hooks projecting from it (fig, 35, VI. XIX). They are found most abundantly where the margin is somewhat angular. Soine of them are complex, while others are simpler, but all are fijrmed by the combination of simple hooks in various ways. They are mere out- li'rowths of the ed^'e of the annulus, and have no direct connection with the central body, as is the case in Cristatdla and Pect, magnißcd. They are short and stout, and the tips are rounded. They measure about 0.02-0.03 mm. in length and are too minute to be of much functional importance. When the annulus splits hori- zontally, as it does of itself when the polypide begins to develope within, these, spine.5 are found onl}' on the margin of the concave side.
The curvature <jf the annulus and the presence of hooks on the free edge seem to be worth carefid consideration. In :dl statoblasts, tlie annulus serving as buoy p)erforms an eiiectual service in dis- tributing the species as well as in enabling the establishment of colonies near the surface of water. Where the annulus shows curvature, the distributive power is evidently enhanced, ex- posing its curved surface to the influence of the motion of water, or, if dried up, of wind. As to the hooks I have no doubt thîit, as Kraepelin has said, they serve as anchors to secure attachment for
OBSERVATIONS OX FJiESH-WATER POLYZOA.
123
the colony that is to grow. At the same time they must be looked upon as assisting- (listril)ution to a great extent. B}^ their means, foT instance, the statohhists have a chance of clinging to the feathers of some water-birds or to floatmg logs or weeds and of being carried away to distant localities. The strongly developed hooks on tlie statoblasts of Cristntdla or of Pect, magnißca, in which the annulas is but weaklv developed and cannot serve more than as a mere buoy, may perhaps have in this respect a great importance. In the present species, the extreme insignificance of the hooks as distributing organs is probably sufficiently counterbalanced by the extensively developed an- nuhis with its double curvature, so marked a feature of this as compared with all other species. Braem regards the hooks as protective organs, but as such they can have no great value in the cnse of Feci, fiel atinosa.
The annul us, as studied on sections (fig. 46, PI. XIX), is made up as usual of two h(^rizontal strata, each consisting of a single layer of upright hollow prisms which -remind us of cells in a honey- comb. The central part shov^dng indistinct reticulation in sur- face-yiews proves to be the exposed surface of a thick chitinous capsule of spheroidal shape (centr. caps.^ This central capsule is made up of two watch-glass like valves tightly apposed with rims, the demarcation between them being visible as a faint line. The wall is composed of two distinct layers of chitin, which maybe called the outer and the inner stratum respectively. The outer is darker in color, and by far the thinner of the two. This stratum is the continuation of the chitinous wall of the annulas, and its exposed surface is raised into l<nv ridges that form a network with hexagonal meshes.
The thick inner stratum of the chitinous capsule looks bright yellow on sections. Directly beneath this capsule, there is a mem- branous envelope (r//ü. /^?^'//;/;y.) distinctly composed of flat hexagonal
124 A.OKA.
cells with centrally situated small nuclei. This cellnlar envelope completely encloses a granular mass of protoplasm Qpyin. mass.) in which are scattered minute nuclei. These nuclei measure only 0.001x0.003 mm. in average, and are thus several times smaller than the nuclei of body tissues. They are very flat witli their plane parallel to that of the statoblast.
The granular contents and the cellular envelope form the essential part of the statohlast, while the chitinous cnpsnle, the an- nul iis and the marginal spines nre all accessory organs for its preservation and distribution.
2, Development of the Statoblast.
The knowledge of the origin of statoblast is certainly of vital importance in determining the true nature of this gennnule-like body, but in the rather scanty literature on this subject the state- ments given are widely different from one another. As to my own observations, I have seen in tlie lumen of the funiculus sometimes a single cell and at other times a loose group of two or more cells, representing the earliest st;!ges of development of statoblasts. They are refund in outline, and each supplied with an oval nucleus, j^either in size nor in general appearance do they perceptibly differ among tliemselves, ov from those of neighboring tissues. This circumstance deprives me of all grounds to share Verworn's view that the increase of cells is (hie to continued division of an originally single cell. This author sums up the earliest steps in the development of a statoblast in the following words : An einer bestimmten Stelle des Funiculus vermehren sich die Epithelzellen desselben zu einer kleinen Auf- schwellung and drängen dadurch gegen das Lumen. Eine Zelle davon tritt in das Lumen hinein and wird zur Eizelle, während die anderen
OBSERVATrOXS ON FRESH-WATER POLYZOA. 125
sich ZU einen Follikel formiren. Die Eizelle maclit einen reo-elimiss- igen Fui-clinng8proces.s durch, dessen Resultate eine solide M(^ruhi ist. Wie man sieht, wird also auch durch diesen F urchungs Vorgang die Knospennatur der Statoblast widerlegt." Hence he concludes : "Die Statohlasten sind als parthenogenetische Wintereier aufzufjis- sen welciie sich im Gegensatze zu befruchteten Eiern am Funiculus entwickeln." I did not find this view corroborated l)v facts. Neither the thickening of the funicular epithelium nor aii "Eizelle," which to judge from his figures must have beeii several times lare'er than any ordinary cell of the funiculus, couhi be found.
On the contrary, what I have seen in PectinateUa fidatinom leads me to the conclusion that each statoblast originates from at least eight cells of separate derivation. Where the}' come from is a qiiestion which I cannot answer from direct observation. However, that it receives no element from the entoderm is evident from the fact that where there are many statoblasts in the same funiculus, the older ones always lie nearer the stomach, completely shutting np the ]iassage. The question then reduces itself to whether the original cells are derived from either the funicular wall (mesoblast) or the (mter layer of the endocyst (ectoblast) at the point where it bounds the funicular cavity below, or from both. As will be seen later on, the intrastato- blastic development of a polyzooid essentially agrees with the process of development liy budding, differing only in such points as are necessitated by the mechanical conditions of each case. Wes hindd then expect similar elements in the " anläge" of a statoblast as in a bud. that is. both the funicular wall and the outer layer of the endocyst should a priori give their contingents to form a statoblast. The correctness of this assumption is proved by the observations of Braein (Zool. Anz. 1889.). According to this author, the primitive statoblast consists of two kinds of cells, which are genetically different, one deriving
126 A. OKA.
itself from the fiiniciilas and the other from the ectoderm. It is needles,^ to say that in the aho\e light, a statoblast cannot he a?)y thing else than a specially modified form of hud, in other words, a t)ortion of both layers of the endocyst protected against severe climate by special contrivances for the preservation of the species.
But to return to the process of development, a certain nnmber of cells, probably from tlie two sources referred above to, assemble in the funicular lumen and arrange themselves into a group at first loose and irregular. During this early stage, the funicular wall nowhere shows thickening, contrary to Verworn's observations. Very soon the group becomes compact and assumes a morula-like form. It can now be safely asserted that new additions of cells no longer take place, but that the morula henceforth increases in size l)y multjplic^a- tion of its own cells. The mass bulges out the funicular wall as it e id arges.
Arrived at a stage when the morula measures about 0.05 mm. in diameter, a certain nnml)er of cells (8-12 as seen in equatorial sections) on one side of it form a special group (fig. 38, PI. XIX), at first very indistinctlv distinguishable from the rest of the cells. Graduallv, a small cavity appears in the rentre of that 8[)herica! group of cells which are steadily increasing, changing it into a hollow, rather flattened sphere with distinct epithelial wall. This hollow sphere is the " cystogene Hälfte" of German authors, so called on account of its giving rise to the chitinous covering of the stato- blast, and the remaining mass of cells constitutes the " Bildungs- masse." x\ccording to my observations, these two portions are not morphologically distinguishable from each, other at a very early stage, but become secondarily distinct. This is also the view held by Kitsche and Yerworn, while Braem saw them originate sharply separated from the outset in Cristatella. According to the last-mentioned
OBSERVATIONS OX FKESH- WATER i'OLYZOA. 127
author the cystogenous sphere, which consists solely of cells of ectodermiil origin, is the first to form and to this is added the Bildungsniasse by proliferation of (mesodermal) cells of the funi- cular wall. Provided that in either case the two [x^rtions are respec- tively ectodermal and mesodermal products, it would be of but secondary importance whether they are distinct from the beginning or become outwardly indistinguishable for a time. More study of this point is exceedingly desirable.
Further history of tlie development corresponds in the main with what is already known. The cells of the two portions are con- si'antly increasing in number and the entire mass in size. Meanwhile, the cystogenous cells attain the character of columnar epithelium ; the whole cystogenous sphere flattens, and s(-on takes the form of a shallow watch-glass, the internal cavity disappearing (hg. 40, PI. XIX. ajst. c.) We may speak of it as the cystogenous cu|). The C(jncavity of the cu[) grows deeper, always closely clasping the mass of the remaining cells, i.e., the " Bildungsmasse." The cells of the latter begin to présenta granular a[)pearance by the deposition of refractile «pherules in the protoplasm, comparable in nature to the deutoplasm of eggs or of 3olk-cells in Plathelminthes. Braem could not convince him- self of the truth of Nitsche's and Verworn's opinion that the granules are direct products of the nuclei ; nor cou.ld I lind any sup[)ort to this view. x\1jout this stage, the cells in cjuestion assume a spindle-;?hape, the axis standing vertical to the cavity of the cystogenous cu)) (tig. o'J, PI. XIX, gr. m.). This state was also noticed by Braem in Cris- tatella. H<3wever, as the granulation advances, they become rounder again, until each cell is represented by a globular mass oi' granules with a nucleus at the centre (fig. -il, PI. XIX, gr. in.).
As the cystogenous cup grows in size, its rim begins to close around the granular cell mass. This occurs after the latter has
128 A. OKA.
almost attained its maxiuuun size. In the nieaiitime, a tliiu sheet of chitin is secreted ])e(\veen tlie two layers of the cystt)geiiOUs cup; it is difficult to say whether it is the product of one or of both layers. This chitinoLis slieet subsequently attains considerable tliickness. We may speak (jf it as the chitinous cup, as it has that shape along with the cystogenous cup. As the latter expands, its mouth narrows and the whole body of the youiig statoblast somewhat flattens, taking the form of a spheroid, the axis of whicli corre^|)onds with tliat (jf the cystogenous cup. The two layers of the cystogenous cup were at first of the same thickness, but now the outer begins to thicken by the increase in heiglit of its cells while the inner undergoes a contrary change. The cells of the latter begin io flatten tirst at the bottom-portion of the cystogenous cup.
Along the equatorial hue of the spheroidal mass, the outer layer of the cystogenous cup is thrown into a fold, whicli encircles the young statoblast belt-like all around. The belt becomes more and more extensive, and consists, as seen in sections, of two closely opposed strata of cylindrical cells.
Meanwhile, a second chitinous layer is formed over the chitinous Clip already present. Thus, the chitinous cup c<jmes to consist of two layers ; the outer of which is by flir the thinner. Simultaneously and directly continuous with this outer chitinous layer a thin plate of the same nature is also deposited between the two e[)ithelial strata of the belt. It may conveniently be designated the belt plate.
The elongated prismatic cells of the outer cystogenous layer, secrete around their basal ends thin chitinous wall continuous with the belt plate or the outer chitinous cup, on which they all sit. I'hey thus bring forth hexagonal caskets open at one end, into which every one of them abuts with their bases. But the wall of these cells does not develope everywhere to the same extent. It keeps very low on
OBSERVATIOXS OX FRESH- WATER POLYZOA. 1^9
the exterior <jf tlic bottom of the cy.stogenou.s cup, aiid when the cup closes into ÎI complete capsule, tis it does later, the same condition is also seen on the opposite side, so that on a mature statoblast the polar surfaces show only a network of very low ridges. However, on both sides of the belt plate and of the capsular surface immediately adjoining them, the chitinous wall of cells attains considerable height, but never reaches the surface of the cell-layer. The open ends of chitinous tubes thus formed are finally closed by the formation »jf what is called the lid-plates. This process proceeds on the one hand centrifugally from the outer layer of the chitinous cup, at a line which circumscribes the reticulated polar area, and on the other in the opposite direction starting from the marginal edge of the belt-plate, so that the tubes on the midway are closed last. A glance on tigs. 48-J:6 will make the matter clear at once. j\Ioreover, the lid-plates divide the prisniîitic cells on either side of the belt-plate into an outer and an inner \)uv- tion. The latter is completely enclosed in chitinous caskets, while tiie former conjointly with the epithelium covering the polar area invests the entire outer surface of the young statoblast. This invest- ment is to be seen as long as the statoblast remains at the place of its development, but decays when the latter is set free by the dissolu- tion of mother-polypides. As the lid-plates are developing, the marginal spines appear. Also at about this stage, the closure of the mouth of the cystogenous cup takes place. It thus completely encloses the granular cell-mass, followed by closure of the two layers of the chitinous cu^), which then is turned into a perfect capsule. After this, the two polar areas present no point of structural difference.
The portion of the prismatic cells that are enclosed within the chitinous wall soon undergoes decomp(jsition and gives place to a gas filling up the caskets. Thus the formation of the swimming- belt is
130
A. OKA.
complete. Nitsche'.s statement that the cells evacuate the caskets before their closure is probably an error.
As already said, the inner cystogenous layer thins out by the flattening of its cells, and when the chitinous plates completely inclose the granular mass it forms a thin epithelial covering to the latter directly within the central capsule (figs. 42-46, PI. XIX, Enü. m.'). The size of the nuclei becomes smaller as the height of cells decreases, and reaches at last the dimensions given before wdien the niatiu-e statoblast w-as described. The cells of this membrane are distinctly bounded and hexagonal in sha})e.
Keturning to the stage represented in fig. 41, the granular spheres, composing the mass contained within the cystogenous cup, have each a centrally placed nucleus, and growing larger (fig, 42, PI. XIX.) press upon one another so that they assume a polyhedral form. P'lie}- remain distinctly bounded as long as the rim of the chitinous cup remains open, but fuse together after the latter closes. It is a singular fact, that in some statoblasts, either the granular mass is produced in over-quantity, or the capsule formed is too small, so that a portion of the mass is left outside the statoblast as the cap- sule closes, afterwards disappearing.
The nuclei of the granular mass become smaller as the develop- ment of the statoblast advances. Arrived at a stage represented in tig. 42, PI. XIX, the nuclei almost lose their peculiar chromatin reac- tion, and stain very faintly, so that in some preparations it is very ditiicidt to detect them. This condition, however, lasts for a very short interval, and in all the later stages the nuclei are again distinct- ly visible. This [)eculiar behavior of the nuclei may have lead Verworn to assume that the granules are the product of the splitting of nuclei and that the latter as such are not found after the com- plete development of the granules.
^ OBSERVATIONS OX FRESH-WATER POLYZOA. 131
The statoblast at the earliest stage of its (levelopniont is of a milky- white color. The chitinoiis parts as they form tliemselves at first present hght 3'ellow color, which, as the development advances, darkens to the characteristic hue of the mature stato1)last.
On attaining a certain size, the statoblast bulges out the fimicidnr wall chiefly on one side, with its plane always parallel to tlie axis of the funicidas. When many statoblasts develope in the same fanicuhis, tliey generally lie alternately disposed, by wliich means econoni}- of space is effected. It is on that side of the statoblast with whicli it joins the funicular tube that the cystogenous cup closes.
The number of statoblasts that develope in a single polyzooid is usually five or six, in some cases as much as eight. Of these, the uppermost one is the oldest and the lowest the latest formed, so tliat at a certain period statoblasts in various stages of development in serial order may be seen in the same funiculus. In those old poly- pides that occupy the central part of a colony all the statoblasts usu- ally attain maturity, while in the peripherally situated younger poly- pides the latest formed statoblast is generally still in c|uite an early stage of development at the time when the colony begins to dissolve away. These immature statoblasts undoubtedly suffer common decom- position with the mother-colony. As every polyzooid produces statoblasts, their number in the entire colony is really very great. Once I counted no less than 870 statoblasts in a very small colony of about 1.5 cm. in diameter.
132 A. OKA.
3. Development of the Polyzoöid in the Statoblast. *
As the mature statoljlast floats on the surface of water, the belt- plate of the annuhis splits horizontally, so that tlie shell may now l)e said as being composed of two valves. These however remain tight- ly apposed during winter. On the arrival of warm temperature, they separate from each other, l)ut holding the whitish contents between. The two valves have then very much the a[)pearance of a pair of cymbals. The separation takes place at a stage when no change is yet percejitible in the contents ; hence I am inclined to ascribe its cause to some external influence rather than to internal pressure.
The contents of the statoblast, i, e., the granular mass with its enveloping epithelium, form a spheroidal mass. All along the outer marö-in or the equator of the spheroid, where the separation of the sliell-valves has brought it in direct contact with water, the enveloj)- ing epithelium becomes thicker (figs. 48, Out. lay. and 48 A, PI. XX.), owing to increase in height of cells, accompanied by great increase in size of tlie nuclei, which are now as large as those of grown-up polypides. The process of thickening thus begun at the equator proceeds gradually toward the two poles of the spheroidal mass, so that the membrane (hickens latest at these places.
Meanwhile, the cells at two opposite areas on the equator become especially taller, so that the enveloping membrane acquires a marked thickness at these places. The areas in question are oblong
* Aftoi- finishing the manuscript of this paper, I received No. 324 (1889) of the Zoolo- gischer Anzeiger containing Braem's preliminary report entitled " Die Entwick]. d. Urj-ozoen- colonie im keimenden Statobl." His statements differ in many fundamental points from mine. There is sufKcient ground to assume that very considerable variation of development obtains among different speci« s of Poljzoa.
OBSERVATIONS ON FRESH-WATER POLYZOA. 138
in shape, lying with tlicir long axes along the equator, ahhoiio-h no sliarp hoiindary can be fixed. From an earlv stage, tliev show difFer- iMicv.s in tlie apj)eai'an<3e of theii" cells and lake quite diiterent dii'ec- tions in their future develo|)nient. The axis jc^ining the centres of these areas corresponds, as Avill be seen later on, with the longitudinal axis of the future polyzooid. With regard to the relation of this axis with tlie longer or shorter axis of the statoblast, there seems to be no constant rule, although in the majority of cases the former cor- responded with the shorter axis of the statoblast.
In one of the two areas, the cells acquire distinctly cylindrical form, and vacuoles are formed in some of them. In f ict. they soon take the form and character of the cells of the outer layer of tlie endocyst. They liegin to secrete gelatinous ectocyst of a sticky nature, by which means the germinaling statoblast attaches itself to anything it may meet with, be it the wall of an aquarium, floating wood, or shells of other statcjblasts.
The either area gives rise to the polyzooid. Its cells are of less height and vacuoles develope in them later than in the other area. At alx^ut the middle point of the area, the cells nuilti[»ly, and a group of them sinks into the granular mass below, forming a solid club- shaped b(Mly, which a little later on becomes Ik^IIow by the retreat of its cell« toward the periphery. We have now a hollow closed sac bounded by an epithelial layer of cells and connected with the super- ficial thickened area by means of a very short solid stalk (fig. 40, PI. XX). Soon after, the latter also acquires a limien, and the cavity (fig. 49, PI. XX. prim. /.) of the hitherto closed sac comes to com- municate with the exterior. Some cells of the granular mass lose a part of their gi-anules, and arrange themselves hito a sort of layer on the outside of the sac (fig. 49. PI. XX. Lin. I'pifliy Tlie nuclei of these cells Imtotiic lai'g(M' as the granules lessen in (juantitv. and
134 A. OKA.
appronrh those of , ordinavy cells in size and appearance. The outer limit of this layer is by no means definite, gradually losing itself in the granular mass.
As the sac elongates, it becomes constricted at the middle, divi- ding into an outer and an inner chamber. The constriction be- tween the two chambers is the future mouth, and the inner chamber represents the future oesophagus and the stomach. The outer cham- ber soon ac<|uires the form of a hollow cone, at the base of which the mouth opens and which tapers towards the outer opening. At the base of this conical chamber the epithelium is especially thickened and eventually gives rise to the lophophore and the tentacles, the chamber itself being the tentacular sheath. The investing layer derived from the o'ranular cells (lin. epitli.') become more and more conspicuous, and lines the entire outer surface of both chambers.
The lophophore is at first a semicircular ridge, clasjông the mouth on that side which corresponds to the original bottom of ihe cystogenous c ip (convex side). The ridge arises by the folding of the wall, in which process both layers arc concerned. The ends oi" this semicircular ridge are prolonged in the form of free finger-like processes, the rudiments (^f lophophoral arms. The interior of the h>phophoral rudiment is occupied by the granular mass as soon as it is formed. The developing polypide lies on its anal side when the statoblast is placed on its concave side.
Another constriction divides the lower chamber into the oeso- phagus and stomach. The stomach begins to send a hollow process upward to form the intestine (fig. 51, PL XX. Intest.).
The free edge of the lophophoral rudiment is divided into a series of knobs, which are conspicuous nearer the median line, becoming gradually smaller towards the tips of the arms. These knobs are the origin of the outer row of tentacles. In the meanwhile, a second
OBSERVATIONS OX FKESH-WATEK i'OLYZOA. 135
ridge runniDg parallel with, but less extensive than, the first one, developes on the anal side of the mouth. Its extremities soon meet and fuse together with the limbs of the first-formed semicircular ridge. Tentacles are formed on the new ridge in the same way as described above ; the range of their row extending on either side to tips of lophophoral processes. Thus the inner row of tentacles is established on the lophophore.
The hollow process sent up by the stomach grows larger, and finally its cavity opens into the u]>per clinmber or the tentacular slieath, Avhich, when evaginated, forms the tubular body of the polypide.
The account given above may suffice to show how the general shape of a polypide is formed in the contents of a stntoblast. In the meantime rudiments of many other organs, of which the brnin, the muscles, and the funiculus are the most important, have begun their development.
The cerebral "anolion arises as a pit-like invaoination of the inner
CO i. ~
layer of the oesophageal wall, which is continuous with tlie outer layer of the body- wall. The process begins to take place at a stage when the stomach sends up the process that afterwards becoines the intestine, on the anal side of the oesophagus, just inside the mouth. The invnjjfination is soon constricted off, turning" it into a closed sac, wliich as it is being formed, carries with it the outer layer of the oesophageal wall, so that the latter invests it externally, at the same time connecting it with the oesophagus. The cavity of the sac per- sists as a sort of ventricle. The lower portion of the wall of the ^ac early begins to thicken, which process does not of course concern the investing layer, and finally developes itself into that portion which constitutes the main ganglionic mass (vide p. 115). The remaining portion of the sac- wall, except at two points, becomes thinner and
136 A. OKA.
tliiiiiier a.s tlic entire j^anglion iiicieiise« iu size. The two exceplional points just referretl to, are wliere the sae-wall produces a pair of solid liorn-like processes, each of which gradually elongates towards tlie ti[) of the lophophoral arms, passing between the two layers of their ceil- ing. The position of the lophophoral nerve-trunks directly beneath the outer layer led me at first to assume their origin from the latter, in a way anrdogoiis to the development of the central nervous system in \ertebrates. A careful study, howevei-, convinced me that such is not the case.
At the time when the intestinal cavit)' becomes continuous with the exterior at the anus, the whole body-cavity is still tilled up with the ü'ranular mass. Some of the cells of the latter are seen to ditfe- rentiate themselves from the rest, at two regions as seen in a median sagittal section (fig. 51, PI. XX.), the one extendiug between the involuted tentacular sheath and the cystidnl wall, and the other be- tween the lower part of the oral side of the oesophagus and the part of the cystidal wall opposite to it. At these places, the cells lose their granules, elongate, and become spindle-shaped joining the two pointas between which they lie. Their further development has been already treated under the muscular system. The muscles that develope in the above mentioned regions are the pariet(j- vaginal and the retractors of the adult polypide respectively. The muscular layer of the endo- cyst and the alimentary canal developes itself later, prob:djiy from the cells of the lining e[>ithelium in a similar way.
Almost sinuiltaneously with the first appearance of nuiscles, the cells of the granular mass lying between the blind end of the stomach and the coenoecial wall opposite to it, lose a porticjn of their granides, and aggregate into a solid rod, which is, in sections of stained speci- mens, readily recognizable on account of the deeper coloring of its cells in contrast with the surrounding faintly colored granules.
OBÖKUVATIOXS OX FUE«H-WATEU POLÏZOA.
137
Aftcrvvai'cls, what remains oî the granules in these eells is entirely absorljed, and a linnen is formed inside the rod, converting it into a tube, the rudiment of the funiculus. Thus, it will be noticed that both the muscles and the funiculus are produced in sita from the granular m;iss in the statoblast.
When the devehjpment (jf the polypide is C(jmplete, two buds are idreudy j)resent on the oral side of the cystid;d wall, one on each side of the median plane. These buds are first seen in the stiige when the intestine is still blind. The manner of their development will be treated under the buddini;'.
As noticed Ijefore, the granulnr cell mass compactly tills u|» the entire body-cavity until after the formation of all the important organs of the polypide. The cells then loosen themselves, as the conse- quence of the decrease of granules, which are being constantly used up, while the enhanced growth of the cystidal wall makes the body-cavity more and more spacious. When the young pijlypide begins to evaginate and expand their tentacular crown, naked conglomerates of granules, each with a nucleus at the centre, are seen scattered in the body- cavity. Mixed with these conglomerates, we see some <jthers which have obtained a distinct wall, with the nucleus pressed against it. In a somewhat later stage, the granules are no longer visible in those cells with peripherally situated nuclei ; irjstead of them we see a large vacuole in each cell, which has thus acquired the characters of wdiat 1 have proposed to call blood-corpuscles.
It is perhaps worth nijticing th-.it the developing polypide carries the shell halves on the anal and the oral side of its body, presenting an appearance comparable to the condition of shells in Brachiopods.
138 _ A. OKA.
4. Budding.
Tliis mode of reproduction in Polyzoa has been studied by numer- ous investigators, but their opinions ure more or less divided, especially us to the origin from which the bud receiv^es its h^^poblastic elements, and consequently, with regnrd to the relations of the germinal layers. Most of them derive tlie hy[)oblast from the outer layer of the enclocyst, while a few are inclined to believe that the bud receives it from the gastric organ of the mother polypide.
According to Allman (1), who describes the process of budding in Lop]iopm and Alcijonella, the outer la3'er of the end(jcyst gives rise to all the lining cells of the alimentary canal, while the lining epithelium of the mother polypide becomes also the lining epithelium of the Ijud.
Metschnikoif (7) gives an account of Ijudding in the embryo of Alcijonella. He found that after continued segmentation of the egg, the cells arrange themselves into a two layered hollow sphere, both layers of which enter into the constitution of the bud, the outer giving rise to the outer layer of the tentacles, the inner lining of the alimentary canal and probably also to the nervous ganglion, and the inner, to the lining epithelium and all the muscles.
Nitsche (<S) studied the process of gemmation in AlctjoneUa fimgom and Cristatella mucedo. In both species, the wall of the alimeiittu-y canal is formed from a part of the endocystic invagination of the mother polyzoiiid. In other words, the lining layer of the alimentary canal is deri\ed from the outer layer of the body-wall. Both Metschnikoif and Nitsche regard the outer layer of the endocyst as the ectoderm and the inner as the entoderm.
Hatschek's (4) acccjunt of l)udding in Cristatella is as follows. A hollow sac lies directly beneath tlie outer layer, invested by
OBSERVATIONS ON FRESH-WATER POLYZOA. 139
the inner layer of the body-wall on its inner side, at the position in which the buds are constantly developing. When a bnd is to be produced, a portion of this sac is constricted off and gives rise to the inner layer of the alimentary canal, while nil other parts of the young polypide are formed by an invagination of the body wall. Thus, the sac is being constantly constricted off, as long as new buds are added to the coh)ny.
Reinhard (9) studied the first budding in the embryo of Aleyondla fungom and Cristatella mucedo. The cells formed by the segmontn- tion of the ovum produce a true gastrula by invagination. Tlic blastopore, however, soon closes. The gastrula is comparable in all respects to the type of some other animals, and, therefore, he regards the inner layer as the entoderm. In the development of tlie bud, the entodermal cells seem to push into a certain thickened portion of the ectoderm, and form a part at least of the wall of the alimentary canal.
Salensky (11) also states that the outer layer of the zoœcium (cystid) gives rise to the lophophore and to the internal cells of the digestive tract, while the inner layer becomes the lining epithelium of the new polypide. He believes that the entoderm of the alimentary canal originates from the ectoderm of the zoœcium.
Haddon (3) who studied the gemmation of some marine Polyzoa, came to the conclusion, on theoretical grounds rather than from actual observation, that the alimentary canal is derived from the entodermic tissue of mother polypides.
To the position and the order of budding, the previous workers seem to have paid but little attention, except Bra^m who dwells on the matter at some length. To this author we owe much of the exact knowledge of the process of budding. As will directly be seen, the process of budding takes place at certain definite poly- zoöids and in a certain definite manner, thus determining the shape
140 A. OKA.
of the colony so characteristic for each species. What Er?em de- scribes for Cristatella on this point does not apply in all its details to the present species.
At the plnce where buds appear, there is no muscular layer, as already observed by Nitsche, and the endocyst may here be repre- sented as consisting- of only two layers, viz. the outer cell layer and the inner lining epithelium. The latter, in direct contact with the former, passively follows all the changes in form undergone l)y the outer layer of the endocyst. So, it must be borne in mind, that when in desci-il)ino- different stao^es of budding", the changes of the outer layer (which is the inner layer of the bud as will be seen fur- ther on) alone are mentioned, similar chang'es are repeated by the lining epithelium (the outer layer of the bud).
At first, some cells of the outer layer push their way inward in the form of a solid knol) covered by the lining epithelium (fig. 57. Ph XX). At a certain observed stage in which the knob consisted of eighteen cells, many more were on their way of entering.
A cavity ultimately appears in the centre of the knob (fig. 58, PI. XX.) and the cells arrange themselves regularly around it in epithelial order. The cavity soon comes to communicate with the exterior by means of a cajial formed by the gradual retreat of cells at that part (fig. 5Î), PI. XX.). The bud now represents a double- walled sac whose inner and oiitei- layers are respectively eontinuations of the outer and inner la3^ers of the endocyst. Thus it is plain, that tlie. bud originates not by direct invagination of the two layers of the endocyst, but by the formation of a closed sac which secondarily opens outward.
As the bud grows in size, it inclines dowji wards and its oral side is connected to the crenœcial wall along its wh(^le length by a me- seiitary-like membrane whi<'h is the continuati<^n of the lining epi-
OBSERVATIONS ON FRESH-WATER POLYZOA.
141
thelinm. A glance at fig. 56, PL XX. will make this clear. The middle portion of this mesentery-like membrane becomes thinner, and is finally perforated as shown in fig. 57, PI. XX. The sac is then joined to the cystidal endocyst at two points, viz. at its opening and at the bottom. Rndiments of new buds are produced in the region lying between these two points, which separate more and more from each other.
The solid rod-like part of the lining epithelium whirh now joins the bottom of the sac-shaped bad witli the cystidal wall, is the rudi- ment of the funiculus. It gradually lengthens, and a lumen is secondarily formed in it, turning it into a tubular organ. It grows in size, and with the eai'ly appearance of scanty muscular fibres inside its cavity the development of the funiculus is complete. Thus the result of my observations on the formation of this organ seems to agree essentially with tliat of Bra^m (2) wIkj describes the process in the following w^n-ds : " In der Mediane erheben sich die Zellen des äusseren Blattes in Gestalt einer an der Oralseite der Primärknos])e herablaufenden Längsleiste, welche seitlich von den Fortsetzungen der Magenfalten begrenzt erscheint. Indem sich die Zellen des Knospenhalses dann nacli vorn umschlagen und an der Bildung des Integuments betheiligen, löst diese Leiste sich von dem Mutter- gewebe, welclies hintei- ihn zusammenfliesst, als selbstständige Strang los und verdindet einen oral und median vor dem Primärknospe gelegenen Pimct der Leil)eswand mit dem Grunde des Knospen- Sackes.
A constricti<^n is formed in the middle part of the sac-like bud, dividing it into two chambers. The constricted opening is the mouth of the future ])«>ly|>id(', and the lower chamber developes into the alimentarv canal. The upper (-hamber becomes somewhat conical in shape tapering toward the orifice of the bud. At the basal disc of
142 A. OKA.
this chamber, where the mouth is situated, the cells of the inner wall are prismatic while elsewhere they are flat.
We now recognize all the parts that we have seen at a certain stao-e of intrastatoblastic development. The lophophore with its tentacles, the nervous system and the intestine, all develope just in the same way as described in the previous chapter. One im- portant difference exists in this, that in the one case the lining epithelium is produced from cells of granular mass, while in the other it is the result of the increase in extent of the same layer of the mother cystid. It will be noticed from above statements, that the entire inner layer of the alimentary tract is derived from the solid knob sunk in from the outer layer of the endoeyst. The hollow process (the intestine) sent up from the stomach meets with and opens into a pit sent in from above outside the tentacular area, on the side turned toward the centre of the colony. The lophophornl arms of every individual always project toward the anal side of the poly- pide ; consequently they are nil directed toward the centre of the
colony.
While new polypides are thus being developed, their cystids are also growing in size, and some cells of its lining epithelium gradually o-ive rise to the muscular layer. At tirst, when the young polypide is still represented by a simple sac, the portion of the mother cœnœ- cium arouud its orifice is only slightly elevated above the rest of the wall, but as the growth of the polypide advances, it becomes more and more prominent, growing in such a manner as to form at last a cell for the young polypide.
The retractor muscles of the polypide begin t(^ appear when the bud is still a simple sac, shortly after the formation of the rudimentary funiculus. At the point of junction of the rudimentary polypide and the cœnœcium, some cells of the lining epithelium becomes difteren-
OBSERVATIONS ON FKESH-WATEK I'OLYZOA.
143
tinted from the re.st by assuming a spindle-sliape. These cells gradual- ly separate from their mother-layer and form two loose bundles which join the cœnœcium with the middle portions of the now two- chambered bud. The parieto-vaginal muscles also originate in a similar way, but at a considerably later stage, when the lophopliore already shows a certain number of knob-like tentacles at its median portion. Thus, in the process of budding, both the funiculus and tlie muscles are de\ eloped as ditferentiations of the lining epithelium. The young polypide. as it first evaginates, is a very pretty little animal with less than thirty tentacles. The more medianly situated tentacles are best developed, while they are yet knob-like nearer the tip of the Icjpliophoral arms, where new tentacles are being added by degrees.
The buds arise ou the marginal cœnœcial branch alone, on the side facing away from the centre of the colony, i.e., on the oral side when we take the [)olypide into consideration. I'hey always develope in pairs, one on each side of the median plane. Hence the dichotomy of the cœnœcium, with a polypide-beariiig branchlet at each axil. The colony as a whole is consequently fan-shaped at first. With continued budding, it grows toward the periphery, its radius leng- thening in arithmetical, and the marginal line in geometrical ratio. The two extremities of the latter soon touch each other in a complete circle ; after this the growth of the colony throws its marginal line as well as its hitherto fiatly expanded surface into folds, which make the regular arrangement of polypides unrecognizable at a glance.
The upper series of diagrams in fig. 62. 1*1. XX, show early stages in the development of a colony, each circle indicating an individual. These figures represent for sake of simplicity each in- dividual as giving off only two buds at a time, and each of these buds again performing gemmation after some time. In reality, however,
144 A. OKA.
such is iKjt tlie ca«e. On the contrary, we usually see in an actively budding individual at the margin of a colony, not (jnly buds of the iirst order but also tlKJse of second and third order already formed, lîuds of the first order are present, as already stated, in a single pair, while those of the second occur in two pairs, and the next order, the most rudimentary, in four pairs. AVhen the buds of the first order have grown sufiiciently to be regarded as new individuals, those of the second and the third order occupy the grade of the first and the second order, while those of the third order arise anew. A comparis(3n of the lower series of diagrams in fig. 62. with the upper series will help to make the matter clear. The blackened spots in the lower diagrams slnnv the gemmiparous porti«jn of the endocyst. This spot might appropriately be compared with the growing point of plants. With the growth of the colony, it advances centrifugal ly, splitting dichotomously at regular intervals. In this way, the colony oTows as long: as the condition is favorable.
It need scarcely be pointed (jut that the development of the first polyzoiUd in a statoblast essentially agrees in process and conditicjn with that of hiter polyzooids l)y means of budding. In fact the first polvzoöid is similarlv budded oft" from the statoblastic contents, the whtjle of which is to be seen in the light of a piimary cystid derived (jf and containing all the essential elements of cystids of the previous year. Whereas in marine forms the cystids winter as such, those of fresh-water forms persist only in the form of statoblasts to germinate in the following year as do the perennial cystids of the former. In the budding of fresh- water Polyzoa, a cystid and a polypide are formed simultaneously and an intrastatoblastic primary cystid is to
OBSERVATIONS ON FRESH-WATER POLTZOA. 145
be considered as a particular sort of bnd in which the formation of a polypide remains latent until the next year.
With regard to relations ef germinal layers in a primary C3'stid, all the granular cells of the " Bildungsmasse " might with propriety be called the mesoblast on grounds of their geneyis and of their future history. For the same reasons, the enveloping epithelium might be looked upon as the ectoblast except at the growing point, i.e. where the buds are formed. At this point the cells are still in undifferen- tiated embryonal condition comparable to cells of a blastula which differentiates into Ectoblast and Entoblast for the first time at its invagination. As the colony grows, the growing point of the pri- mary cystid is split and transmitted into each succeeding bud, very much like the growing point of a plant ; in other words all the growing points seen in marginal polyzooids of a polyzoan colony have started. I believe Bra?m is of the same opinion. Considering, on the contrary, the outer layer of the ectocyst at the growing point as strictly epiblastic, the conclusions, to which jSTitsche, Joliet, Salensky, • &c. were led, that no hypoblast enters into the bud and that it is formed as a secondary product of the epiblast, are certainly unavoid- able. But such a conclusion does not accord, as was pointed out by Haddon, with the generally accepted nature of budding in the animal kingdom. In my opinion the budding in Polyzoa is only so far ex- ceptional as the Epiblast and hypoblast take part in an undifferentiated embryonal condition.
Hn A OKA.
Works referred to.
1. G. J. Allman. — A Monograph of the Freshwater Polyzoa. 1856.
2. Fr. Brœni. — Untersuchungen über die Ijryozoen des süssen
Wassers. Zoo]. Anz. XI. 1888.
3. A. C. Haddon. — On budding in Polyzoa, Quart. Journ. Mic.
Sc. XXITI. 188P).
4. ]j, Hatschek. — Embryonalentwick. u. Knospung d. PedicelHna
echinata. Zeit. f. w. Zool. XXIX. 1877.
5. A. Hyatt. — Observations on Polyzoa, Suborder Phylactola^niata.
1865.
6. L. Joliet. — Organe segmentaire des Bryozoaires endoproctes.
Arch, de Z(^ol. exjM'r. et gén. VIII. 1880.
1 O
7. E. Metschnikotf.— P>ull. de l'Acad. de St. Pétersbourg. XX.
1871.
8. H. Nitsche. — Beiträge zur kenntniss der Bryozœn. Zeit. f. w.
Zool. XXV. Suppl. 1875.
9. W. Reinhard. — Zur kenntins der Siisswasser-Bryozoen. Zool.
Anz. IIT. 1880.
10. A. Sa?fftigeii. — Das Nervensystem der Phylactol.iînien siisswassei'
Bryozoeu. Zool. Anz. XI. 1888.
11. M. Salensky. — Etudes sur les Bryozoaires endoproctes. Ann.
des Sc. Nat. 6 sér. Zool. V. 1877.
12. M. Verworn. — Beitrage zur Kenntniss der Süsswasser Broyzoen,
Zeit. f. w. Zool. XLVI. 1888.
OBöEltVA'l'lONS OX FKESU-WATEK PoLYZOA. l^'^
Explanation of Plates. Plate XVII.
t'ig. , 1. A «mall group of colonies', nat. size. Fig. 2. A polypide. x 10. Fig. S. vShape of the cœnœcial endocyst.
Fig. :/. Diagrammatic representation of a [)olypide and a portion of the cœnœcial endocyst.
Tent. Tentacles. Epist. Epistome.
N. Gang-. ISTervons g-ano^lion.
Oesoph. Oesophagus.
Tnvafif. tube. Invai^inable tiil^e.
Over. Ovary. Stato. Statoblast.
M. I. Muscles of the funiculus.
M. II. Parieto-vaginal nuiscles.
M. III. Retractor of the polypide.
M. lY. Muscles of the gastric wall.
M. V. Muscular layer of the endocyst.
M. VI. ^luscular fibres of the epistome.
Nephr. Nephridia. Loph. Lophophore.
Tent, membr. Tentacular membrane. Fig. 5. Statoblast. a. Front view. h. View in profile.
Plate XVIII.
Fig. 6'. Cells in the ectocyst. F x 2.* Fig. 7. Section of the endocyst. F x 2. Out. lay. Outer layer.
* Zeiss' powers.
148 A. OKA.
Bas. iiiembr. Basement membrane. Tr. mu.s. Transverse muscular fibres. L. mus. Longitudinal muscular fibres. Lin. epitli. Lining epitbelium. A'^ac. Vacuole.
.F((j. 8. Longitudinal section of the epistome, with the ganglion and the excretory organs. B x 4. Gang. cav. Ganglion cavity.
Fig. 0. Cells of the upper half of the œsophagus. F x 2.
Fig. 10. Cells of the lower half of the œsophagus. F x 2.
Fig. 11. Section of the cardiac valve. B x 4.
Fig. 12. Cross section of stomach.
Fig. 13. Cells of the inner layer of the gastric wall. F x ::^.
pyr. c. pyramidal cells.
cl. c. club-shaped cells. Fig. U. Cells (jf the rectum. F x 2. Fig. 15. a. Diagram showing the extent of the mesentery. h. Section of the mesentery. D x 2.
Fig. 16. Cross section of a tentacle. F x 2.
Fig. 17. Longitudinal section of the tentacle. F x 2.
Fig. 18. Diagram showing the base of tentacles.
Fig. 19. Diagram showing the direction of the currents of the
perigastric fiuid. Fig. 20. Cells floating in the perigastric fluid. F x 2.
Figs. 21, 22, 23, 24, 25, 26. Sections at various levels of the upper portion of a polypide. B x 4.
Figs. 21 A, 22 A, 23 A, 24A. Sections of the excretory organs. F x 2.
Fig. 26 his. Entire form of the excretory organs.
OBSERVATION'S OX FliKSH-VVA'l'ËK FoLYZOA. l'lî>
Plate XIX.
Fig. 27. Nervous ganglion.
Fig. 28. Saggittal section of the gatiglion. E x 2.
Fig. 29, a, h, c. Diagrammatic Sections of the ganglion, showing the extent of the ganglion caA'ity. <T, sagittal, b, horizontal, c, frontal, sections.
Fig. 30. Cross section of a lophophoral arm. D x 2.
Fig. 31. Cross section of the fimiciiliis. F x 2.
Fig. 32. Longitudinal section of the upper extremity of the funi- culus. D x2.
Fig. 33. Longitudinal section of the lower extremity of the funi- culus. D X 2.
Fig. 31. Section of Ovary. F x 2.
Fig. 35. Marginal spines of statoblast. F x 2. •
Fig. 36. The Envelopingcell-layer of thestatoblastic content. F x 2.
Figs. 37-15. Various «tages in the development of the sttitoblast. 37-39. Fx2. 40. I) x 2. 41-45. B x 4. Fun. Funicular wall. Cyst. c. Cystogenous cells. Gr. m. Granular cell-mass. Caps, chitinous capsule. Env. m. Envelojung cellular membrane.
Fig. 16. Section of a mature statoblast. B X 4.
Fig. 16 A. A portion of the statoblastic content. F x -j.
Plate XX.
Figs. 17-52. ^'arious stages in the development of Polypide in the statoblast. B x 4. Prim. 1. Primitive lumen. Bl. c. Floating cells.
150 A. oitx
tigs. 47 A, J^8A. Portions of the .stutobJnstic content in the stages corresponding to Figs. 47 and 48. ¥ x 2.
Fig. 52. FJoating cells. F x ii.
Figs. 53-60. Stages in Budding. 53, F x '1. 54-56, D x !>. 57-60, Bx 4.
Fig. öl. Diagrams showing tlie manner of budding. The lloman numerals slnnv the order of the individuals.
'«^'^'•Vii
Jour. Sc. Coll. Vol. IV PI. XV H.
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Jour. Sc. Cell. Vol. IV PI. XVIII.
ZropSnphmtii.e^viij
Jour. Sc. Coll. Vol. IV PI, XIX.
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Jour. Sc. Coll. Vol. IV PI. XX.
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'tj i'iy jtto- pMik- pr"
On Diplozoon nipponicum, n. sp.^^
by
Seitaro Goto, Rigakushi,
Post-graduate Student in Zoology, Imp. Univ.
With Plates XXT— XXriI.
Since Diplozoon paradoxum was first discovered and described by V. jS[ordmann,"Mt has been made the object of special investigations by many eminent naturahsts. But our knowledge of the anatomy and especially the histology of this interesting genus, hitherto with but a single species, is, notwithstanding the publications of Paulson, Zeller, and others, by no means as complete as could be desired. I have, therefore, undertaken, at the suggestion of Prof. Ijima, to subject it to a renewed investigation. I at first believed that the Japanese species was identical with the European ; but as I went on with my work, many points came to view, that made me doubt this identity ; and a close comparison with some preparations of the Euro- pean species taken from Leuciscus rutilus, and brought back fr(3m Germany by Prof. Ijima, has led me to erect it into a new species, for which I propose the name of
Diplozoon nipponicum.
Before proceeding any farther, I must here discharge the pleasant duty of acknowledging my deepest obligations to
1) This paper was originally presented as a graduating dissertation.
2) Nordmaan— Mikrographische Beiträge. I. Heft, 1832. p. 56.
152 s. GOTO.
Professor Ijima, already named, not only for constant supervision of my work, but also for lending me his books and preparations pertain- ing to the subject at hand. He has also handed over to me his un- finished manuscript, in which the anatomy and external features of many ectoparasitic Trematodes have been made out to a great extent — a circumstance f)r which I here express my warmest thanks.
Dipl. nifponicum is very common on the gill of Carassius vulgaris. Its differential characters as compared with Dipl. paradoxum are 1) the smallness of the posterior suckers, 2) the greater length of the posterior half of the body, 3) the shortness of the " connecting canal " between the intestine and the oviduct, 4) the presence of a pair of glands at the entrance of the mouth, and 5) the fact that the intestin, does not present lateral branches in the posterior portion of the body.
"Comment la reunion des Vers, a-t-elle lieu? sont-ils réunis comme les frères Siamois, ou bien sont-ils ci'oisés comme les deux jambes d'un X?" Hy the investigations of v. Siebold^' and Zeller,^^ it has been established beyond doubt that the double animal results by the union of two Diporpac in the form of a cross — a fact which had already been anticipated 1)v Dujardin^^ their discoverer. The manner in which the two individuals are united, and the details thereof have already been made out by Zeller, who has also discussed the various opinions of his predecessors, and corrected their errors. I shall however, add a few remarks on some points not noticed by him, some of which are perhaps peculiar to the new species. For examining the external features of the worm, as well as for other purposes, it is best to kill it with boihng sublimate, in a, watch-glass in which just sufficient water has been placed to cover its body. The worm which
1) V. Siebold — Ueber die Conjugation des Dipl. paradoxum. Ztschr. f. wiss. Zool. Bd. III. 1851. p. 62.
2) Zeller — Untersuch, ii. d. Entwicklung d. Dipl. paradoxum. Ztschr. f. wiss. Zool. Bd. XXII. 1872. p. 168.
3) Dujardin — Histoire naturelle des helminthes. 1845. p. 316.
ox DIPLOZOON XIPPONICUM, N*. SP. 153
has been killed in this way, preserves a natural {xjsition corresponding to its condition of rest, and can be examined when convenietit.
Each individual, if considered separately, is elongated and lan- ceolate in form, with a deep notch on one side a little posterior to the middle of its winde length, by means of which it is united with the other individual ; so that we may hereafter speak of the anterior and posterior halves of the body. The anterit)r lialf is widest near the place of union, and becomes narrower anteriorly, where it ends with a rounded outline, and where the mouth is situated on the ventral side. In cross-section it presents an oval outline, which gradually becomes more circular as we proceed anteriorly. If the worm has died in a contracted state, the siu'face of the body is thrown into numerous transverse folds ; otherwise the surface is entirely smo<jth, except where little conical elevations, hereafter to be described, exist. The posterior half may briefly be described as an elliptic cylinder in the anterior portion, which, posteriorly, passes irregularly into a rect- angular prism. [t is also much slenderer than the anterior half. Seen in profile, the surface of the posterior portion is always, in specimens killed with hot sublimate, thrown into a number of strong folds, due no doubt to the powerful development of the diagonal muscular libres in this region ; so that here the margin is deeply crenate or even zig-zag (PI. XXI, Fig. I). A cross-section through one of the posterior zig-zag folds presents nearly a rectangular out- line. The folds suddenly come to a close at a short distance before the beginning of the posterior suckers. In this portion the crcjss- section presents a flattened ellipse ; and this part is, on surface view, distinctly marked off from the sucker-bearing portion which directly follows it, and still more so from the strongly folded more atiterior portion, by a sudden change of level (Fig. 1). The lateral margins of this sucker-bearing portion are suddenly thickened on the ventral
154 s. GOTO.
side, so that a cross-section through it is somewhat cbo- shaped. Under the pressure of a cover-glass, this portion asstunes a somewhat oval form — a circnmstance which probably induced v. Nordmann^^ and Paulsom' to indicate it as an oval "Scheibe." Van Beneden^-* further speaks of" un pédicule " by which the " deux organes ", which carry the suckers, are attached to the body ; but I have not observed any such structure in my species, and it is probably due to a deformation cause<l by pressure and the extreme mobility of this part. The pos- terior margin of the body shows either a nearly straight line or, more commonly, a slight concavity (Fig. 2).^^ Toward this concavity, the body again becomes thicker, the thickening begin- ning this time in the median line, and thence spreading toward the sides, as indicated in Fig. 2, where the shading is made as if this portion were seen from the ventral side, on a longitudinal section, therefore, which does not pass through the hiteral suckers, the bcjdy is seen to present posteriorly a club-like thickening, and end suddenly as if it were cut off. Van Beneden speaks of an "excavation plus ou moins profonde," by which he no dcndjt means the hollow, just spoken of, between the suckers.
The peculiar sudden bend (Knickung) towards the ventral side, which the body of the worm suff'ers at the place of crossing, has already been noticed by Zeller. There is, however, another feature not observed by him. If the worm, ijamely, is viewed from the p(^sterior end, or if sections of this part are cut, it will easily be noticed that the bodies of the two individuals do not stand exactly opposite each
1) Xorduiaun — 1. c. p. 60.
2) Paulson — Zur Anatomie v. Dipl. paradoxum. Mém. d. I'acad. St. Petersbour>^. VIT. Sér. T. IV. 1862. p. 4. I have not been able to gain, access to this work, and am indebted for its account to Prof. Ijiuia's notes.
3) P. J. V. Beneden — Mémoire sur les vers intestinaux, p. 41.
4) The European species shows a decided convexity.
ON ÜIPLOZOON NIPPOXICUM, N. SP. 155
otlier, but that one is always a little either to the left or to the rio-ht side of the other, according as the worms are united by the corres- pondiiiiT sides of their bodies. This feature is usually less noticeable in the anterior hah es, l)ut it can easily he brought to view by bring- ing them close to each other. It is caused, no doubt, by the flict that the bodies of the two individuals are closely united onkj at the point of crossing ; as may be seen, if one phices two pie(^es of straw against each other in the form of a «-ross, and presses l^heni together between two hngers at the point of rrossing. Beside this imperfect apposition of the corresponding halves ()f the two individuals, must also be noticed the twist, to which each is subjected at the place of crossing, in consequence of the fict that one grasps with its ventral sucker the dorsal papilla of the other. To this twist, though very small in degree owing to the presence of the notch already men- tioned, must be attributed the common occurrence that, when the ^vorni is killed under the pressure of a cover-glass, tlie anterior and posterior halves (jf tlie same individual present to view opposite sides of the b()dy — the anterior half presenting the dorsal if the other half presents the ventral side, and vice versa. I'he two individuals are united with each other by their sides, so that here a deep indentation arises — the notch already spoken of. Here the epidermis is absent, and the muscular layers of the two individuals are directly applied to each other. Zeller describes a direct connection between the vas deferens and " Laurer's canal" of the two individuals ; but a careful ex- amination has ctuivinced me that this view is erroneous. I lind Laurer's canal to open distinctly into the intestine, and the vas deferens of one in- di\ idual into the yolk-duct of the other, as will be {)roved later on. In this connection, it may be mentioned that the same writer thinks the Diporpa incapable of "eine noch weiter gehende Entwicklung ohne dass zuvor die Copulation mit einer zweiten Diporpa zu Stande gekommen
i5é s. GOTO.
wäre."'* But last «iimmer I met with two Diporpae which were ah'eady producing eg'g«, but which were not united. They were attached to the «ame gill very near to each other. They were quite a« large as any average Dipluzuuu, and measured about 6 mm. in length in a completely outstretched condition.-* They were provided with four pairs of posterior suckers, but there was no trace either of the ventral sucker or of the dorsal papilla. In place of the ventral sucker, the longitudinal muscular layer was very strongly developed in the corresponding part ; and the body shewed a sudden increase of breadth just anterior to the anterior end of the ovary, looking as if this part were bandaged. I have used the utmost care in detaching the worms from the gill, inasmuch as I carefully scraped off the gill- slime with a s[)atula, avoiding as nuich as possible any direct contact with the worms. The Dq^orpae in question were observed to be quite independent of each other from the moment they were detached from the gill ; nor have I been able to detect any mechanical injury, or the notch by wliich they might have been united to each other ; so that the chance of their being detached Diphzoon is, I believe, almost entirely excluded. Such a case of isolation is of course exceptional ; but it shews that the Diporpa can, under certain conditions, become mature without uniting with another Diporpa.
It would have been interesting and instructive could I have determined where, in this abnormal case, the vas deferens opened. But unfortunately, owing to my inexperience then, I killed both the Diporpae under the pressure of a cover-glass and prepared them for oTobs mountinu" ; and when I afterward cut one of them into sections,
1) Zeller— 1. c. p. 17G.
2) The size of the common Dipori^a varies according to its stage of development. Dujardin o-ives it as 0.26 — 0.56 mm. in length and 0.18 — 0.35 mm. in breadth (1. c. p. 317). A specimen of the Diporpa of Dipl. parapoxum lent me by Prof. Ijiuia and possessing three pairs of suckers measured about 0.6 mm. iu length. That of Dipl. nipponicum vi the same stage is of about the same size.
ON DIPLOZOON NIPPONICUM, N. SP. 157
I could no longer trace the course of such a delicate canal as the vas
deferens.
Remark : — In Prof. Ijima's manuscript I find the following passage which I have his permission to puhlish.
" Ich will mir endlich noch eine Bemerkung über die von Heller^^ beschriebene Monstrosität erlauben. Dieser Forscher lässt, obschon ihm das Verhältniss des CopiiJafio lateralis decussata (Siebold) nicht fremd blieb, sein interessantes Exemplar sich dadurch erklären, dass die Verwachsung der beiden Diporpen sich über die ganze vordere Kck-jjerhälfte ausgedehnt bätte. Paidson, der sieb übrigens mit die. Ansicht Leuckart's fheilt, dass die Diporpen einfach mit Bauchfläche zusammenhängen, hebt die Unmöglichkeit des Zustandekommens jener Monstrosität durch Cojndatio lateralis decussata hervor, und nimmt an. es handele sich um eine Missbildung per defectum eines Diplozoons, bei welchem sich einer der Vorderleiber gar nicht entwickelt hätte. Dabei kam er sein- nah an die richtige Inter[)retation der Heller' sehen Monstrosität, die meiner Ueberzeugung nach, nichts anderes sein kann, als eine Diporpa, nicht Diplozoon, mit in doppelter Anzahl angelegtem Schwanzende, also eine Misslnidung per adjectwn. Dies darf man nicht W luidei* nehmen, denn wir wissen zahlreiche Fälle ähnlicher Missbildungen unter den l'lanarien. Ich keniie selbst einen Fall von ganz jungen, eben ausgeschlüpftem Dendro- cœlum lacteum, mit zwei hinteren Hälften, deren je eine einen Mund und einen Pharynx besitzt."
I shall now proceed to the consideration of the various parts.
1) Heller — Merkwürdiger Fall vorderer Verwachsung an Dipl. paradoxum. Sitzungsber. d. k. Akad. d. Wiss. Wien. 1857. p. 109.
158 :^. GOJO.
I. The Epidermis.
The nature of the integument of the Trematodes has been variously represented by various authors. This subject I hope to discuss more fully in a later work which shall treat of our ecto- parasitic Trematodes in general. Zeller'^ tells us that if no occa- sion is offered the embryos to attach themselves to the gill, " schon nach Verfluss von 5 Stunden (^ after the embryos have left the e^^g) einzelne der Wimperzellen reissen sich los, bald mehrere und schliess- lich alle, ilinmiern aber auch abgetrennt noch eine Zeit lang fort." The embryos finally die. It is not clear from his statements whether this throwing off of the " Wimperzellen " is a normal process or not. In Polijstomum he merely says that they " schrumpfen," but does not describe their exact fate. In the case of Distomum, how- ever, it has been proved by Schwarze^^ and Biehringer^^ that the so-called " cuticula '" consists originally of cells which undergo one by one a peculiar transformation, and which do not at any time possess the typical ej)ithelial arrangement. After the first rough manuscript of these pages had been finished, I received the article of Braun''* in " Centrbl. für Bakteriologie u. Parasitenkande," in which the writer brino-s forward some strong and interesting evidences as to the epidermal nature of the integument. In view of these facts estab- lished by the preceding investigators, I believe I may regard the inteo-ument of the monogenetic Trematodes as a modified epidermis, — the more so from the consideration that it has a distinct cuticle and
1) Zeller— 1. c. p. 173.
2) Schwarze — Die posi^embryouale Entwiekhmo- <lei- Treinntoden. Ztschr. f. w. Zool. Bd. XLII. 188G. p. 49.
3) Bielu'inoer — Beitrüge zur Anatomie n. Entwickl.-gesciiichte d. Trematoden. Arljeiten a. d. zool.-zoot. Inst, in Würzbnrg. Bd. VIT. 18S5. p. 4.
4) Braun, Max — Einige Bemerkungen ü. d. Körperbedeckung ectoparasiti scher Tremato- çlen. Centralbl, f. Bakteriol. u. Parasitenkunde. Bd. VII. 1890. p. 594 (Nr. 19.)
ON DtPLOZOON NIPPON ICUM, N. SP. 159
sits on a basement membrane An embryolog-ical stncl}', however, of the transformations which the original epidermis undergoes is. as Braun maintains, very desirable.
The integument of Dipl, nippouicum is comj)Osed of two layers, the cuticula and the underlying matrix. The cuticuLi, when examined in a living worm, is a very thin, structureless, refractive membrane. In sections of hardened specimens it appears as an insignificant line bonnding the subcuticular (= epidermal) layer against the external world. It is very well seen in a living specimen wliich has been nllowed to macerate in water for some time under the cover-glass. Numerous watery blisters then form in the epider- mis, and separate the cuticula from the underlying layer. The former cnn then be examined as a separate structure. Transverse canals have been described in the cuticula of many Trematodes, but I have not observed any in the new species. The cuticula is reflected inward for some distance into the mouth.
Directly luider the cuticula lies the epidermal layer, a uniform, granular matrix in which no nuclei are to be observed. I believe I have observed indistinct dark Hues traversing the breadth of this Liyer but not quite reaching the cuticula. The epidermal layer, like the cuticula, is continued into the cavity of the mouth, and the sticky glands hereafter to be described (p. 166) are but local modifications of it. Wierzejski'^ describes the "Haut" of Calicotyle Kroyeri as consisting of " einer feinen Cuticularschicht mit den darunter liegenden kleinen, runden Matrixzellen "; but judging from his figure, I beheve he has mistaken the imclei of the connective tissue for his " Matrix- zellen." The epidermal layer rests on a basement membrane, which eagerly takes up coloring matter, and is very conspicuous in cross-
1) VVierzejski— Zur Keantaiss des Baues von Calicotyle Kroyeri. Ztschr. f. wiss. Zool. Bd. XXIX. 1877. p. 552.
160 s. GOTO.
sections as a dark line with indistinct l/orders, sepai'ating the epider- mal from the muscular layer. It is also much thicker than the cuticula. The total thickness of the integument, with the cuticula and hasement membrane taken together, is about 0.004 mm.
-, It has already been mentioned that little conical elevations exist here and there on the surface of the body. These are more abundant on the ventral than on the dorsal side, and are entirely absent in the posterior half of the body. They are simple elevations of the epider- mis with an almost homogeneous mass of connective tissue under it. Here the nuiscular layers do not touch the basement membrane, but p:!ss straight on ; so that these elevations are somewhat subject to changes of form. I have represented one of them in section in Fig. 7 (PI. XXII). As will be seen, they are pointed at the end. A very similar structure has been described in Sphijranura Osleri,^^ where it seems to act as a sense organ. But although I directed my special attention to the point, and applied the highest magnifying power at my disposal (Zeiss Imm. L.), I could not discover any canal opening at the apex, or any hair-like projection, or any fibrils such as have been observed in the above-mentioned species to supply these conical bodies.
II. The Muscular System.
The muscular svstem is const inued bv the muscular wall of the body, the dorso-ventral muscles, and the muscles pertaining to the various organs.
The muscular layer of the body consists of three layers. These are, counted from outside inwards, the circular, the diagonal, and the longitudinal muscles. The circular fibres run everywhere immediately
1) R. Wriglit and Macallum — Sphyrauura Osleri : a Coutribuiiou to American Hclmin- thology- Journ. of Morph. Vol. I. 1887. p. 9.
ON DIPLOZOON NIPPOXICUM, N. SP. 161
beneath the basement membrane. They run isolated without form- ing bundles. This layer is most strongly developed at the anterior extremity of the body in the region of the anterior suckers, and im- mediately anterior to them, especially on the ventral side (Fig. 9), where its thickness amounts at some places to 0.01 mm. In the posterior part of the body it is very weakly developed, and in the region of the posterior suckers the fibres ai*e very difficult to detect.
Closely applied to the circular layer of muscles run fhe second or diagonal fibre« (Fig. 10). In the anterior half of the body these, like the transverse fibres, run isolated without forming bundles ; and those coming from opposite sides of the body cross each other at an angle of nearly 120°. In the posterior half of the body, this layer is strongly developed in the region of the folds already men- tioned, where the fibres run in flat bundles and close to one another. According to Taschenberg,^-" the diagonal fibres are situated inner- most in Tristomum ; but in all the species of ectoparasitic Trematodes I have hitherto examined, viz., in Microcotyle, Axine, Octohothrmm,-^ Dactylogyi'us, and a new genus not yet named, the diagonal fibres are situated between the transverse and longitudinal muscular layers. Lorenz, ^^ who includes the transverse and diagonal muscles under one head, also places the "zarteren Fasern " (by which he means the two sets of muscles just mentioned) outward ; and an examination of the sections of Tr. molae, kindly placed at uiy disposal b}' Prof. Ijiuia, has convinced me of the error of Taschenberg, occasioned perhaps by the circumstance that in Tristomum the longitudinal fibres describe a
1) Taschenberi;- — Beiträge zur ICenntniss ectoporasit iseher mariner Trematoden. Halle, 1879. p. 11.
2) In a species of this genus wliich I have examined, there are in addition isolated longi- tudinal fibres between the diagonal and circular uiuscles.
3) Lorenz — Ueber die Organisation der Gattungen Axine u. Microcotyle. Arbeit, a. d. zool.-zoot. Inst. d. Univ. Wien etc. Bd. I. 1878. 3. Heft.
162
s. GOTO.
curve in the lateral portions, corresponding to the circular or oval outline of the worm. The same writer did not observe the diag-onal fibres in OnchocoUjle appendiculata and Pseudocotyle squatinae ^'; but since they are present in all the species 1 have examined, they were probably overlooked by him.
Internal to the diagonal muscle, and separated from it by a greater or less amount of connective tissue, run the longitudinal muscular fibres in parallel bundles of greater or less strength. They are more strongly developed on the ventral than on the dorsal side of the body, as is usual in most Trematodes, and cause a slight curve of the body on the ventral side when the worm is killed with hot sublimate. The fibres that constitute the bundles are but loosely united together by connective tissue, and form by no means such compact muscular bundles as we see in some other Trematodes. Tliey appear in cross-section as dots, separated from one another by a greater or less amount of connective tissue between. Some of the fibres of a bundle often diverge from their previous course, and enter into the formation of a neio^hborino^ bundle. Most of the lono;itudinal fibres combine toward the posterior part of the body to form a certain number of strong bundles, which proceed posteriorly, and are inserted one to each sucker on the median chitinous piece of the posterior wall (Fig. 5).
The dorso-ventral muscles (dvm in Figs. 11, 13, 16. !24) are well developed. Each muscle generally breaks up into a few branches dorsally and ventrally before being inserted into the base- ment membrane. They traverse the brain, vitelline body, and other internal organs. In longitudinal (sagittal) sections of a specimen, in which the vitelline body has not yet well developed, the dorso- ventral muscles are seen to be placed at pretty regular intervals. In
I) Tascheaberg — Weitere Beitrüge zur Keautaiss ectopar. mar. Treinatoclen. Halle, 1879.
ON DIPLOZOON XIPPONICUM, X. SP. 163
specimens with fully develojjed vitelline body, these muscles are obscured to a g^reat extent.
III. The Organs of Attachment.
The organs of attachment are constituted, posteriorly by the four pairs of suckers already mentioned and a pair of hooks, and anteriorly by a pair of suckers and sticky glands. Each posterior sucker (Figs. 3, 4, 5) may Ijrieüy be described as a short-ovate, flat bag with its wide mouth directed ventrally, its walls very thick, and the line of its greatest breadth directed transversel}^ to the long axis of the body ; so that we may speak of the anterior (aw), posterior (pw), and lateral walls. The first two walls are very thick, and are directly continuous with each other at the bottom of the bag (Figs. 4, 5). The lateral walls are very thin, and seem to consist of a cuticula-like refractive membrane only. The entire structure is sup- ported by a framework of chitinous rods, which are by no means so numerous or complicated as Nordmann has represented them. They are five in number : a U-shaped median piece (pm), a pair of curved pieces (ppa), (resemliling in form certain fishing-hooks), to support the anterior wall, and a pair of simihu- pieces (ppp), with a large process ([)p) at the base, to support the p(rsterior wall. Having thus given a general idea, I shall now proceed to the explanation of the three figures already referred to, by which I hope to make clear the structure of the suckers. Fig. 3 represents the chitinous rods as very commonly seen in a specimen observed under the pressure of a cover-glass, with the mouth of the sucker directed below in the figiu'e and the rods belonging to the anterior wall shaded more deeply. Fig. 4 represents a section made in the direction indicated by the line ab in Fig. 3, whereby it is to be remarked that the median
164 s. GOTO.
piece has been cat nearer the fundus of the sucker. This section shews the thickness of the anterior and posterior walls, as well as their fibrous structure. The prismatic fibres, of which these walls are com- posed, are strongly refractive, and are scarcely colored by haem- atoxylin. They seem, therefore, not to be of the same nature as the muscles of the body ; these being well stained by the same coloring fluid. In fact, they seem to be not contractile but elastic fibres. The supporting rods are all of them hollow, with, the inner surface, however, not quite smooth, but with irregular projections, which sometimes unite with those of the opposite side, and form septa-like partitions (Fig. 3). The paired rods are some\vhat triangular in section, and are imbedded in their respec- tive walls along the margins. The rods of the posterior wall are articulated at their bases each with another piece (pp), which is im- bedded in the substance of the wall, and imparts greater strength to it — a flict well in accordance with the circumstance already mentioned that the main bundle of muscle is attached to this wall. Fig. 5 repre- sents a section made in the direction indicated by xy in Fig. 3, i. e., in an antero-posterior direction. In this section, the direct continuity of the anterior and posterior walls is clearly seen ; the U-shaped median piece has been cut but in part, as also the extremities of the paired pieces at the entrance of the sucker. The median piece exhibits, in the posterior wall, a deep cut, where the main bundle of muscle is attached for controlling the varied movements of the sucker. Beside this bundle, weaker (jnes are attached to the paired pieces. The fibrous substance of the wall is Ijounded by a cuticula both against the external world and the surrounding inesenchyma. The support- ins; rods are v^er\- easily broken into fi-aa'ments when the animal is subjected to too much [,>ressure ; and tliis takes place pretty regularly in the manner represented by Nordmann, who, however, describes the
ON DIPLOZOON NIPPOXrCUM, N. SP. 165
fragmentary pieces ii>* " Bügel, zahnfönnige Vorspriingf. Ki}ipen, u. s. w." All the |)«)steri<^r suckers are of the same build ; but they vary somewhat in size, the last pair being always smaller than the anterior ones,^^ and the first pair very often smaller than the following two pairs. Measurements on five individuals gave the average breadth of the suckers as 0.093 mm.''
Besides the suckers just described, there is, on the dorsal side, a pair of solid chitinous pieces (Fig. 6). Each piece consists of two parts. The basal portion, to which a small bundle of muscle is attached, is straight, and acts as a handle. To this is articulated a hook-like piece, whose end alone sticks out fr(mi the surface of the cuticula ; the handle as well as the other part of the hook lying in the integument. The straight handle-like portion and the liook con- stitute a single piece, and not two pieces as v. l^eneden'^' thinks. The total average length of the piece is 0.072 mm.
The anterior suckers are either round or egg-shaped, according to the different states of contraction, and are situated right and left at the entrance of the mouth. Like the posterior suckers, the walls (Fig. 9) are composed of prismatic fibres placed at right angles to the investing membrane, which lines the whole internal cavity, and bounds the wall from the surrfMuiding mesenchyma. In cross-section, the sucker is generally circular in outline. Each is provided with a numlier of special muscles for the control of its uKnements in suction. These muscles I have represented in Fig. 12, where there will be seen three bundles coming from the dorsal side, two of which are attached to the anterior border of the sucker, and the remaining one to the
1) This faet must not be taken as proving that the hindermost pair is formed last.
'J,i A corresponding- measurement on tlie European species «f about the same size gave the average result as 0.144 mm. fort lie sucker, and 0.084 mm. for the tot;il length of the handle and hook.
3) P. J. V. Beneden— 1. c. p. 42.
166 s. GOTO.
posterior ventral border. A biuidle, which soon divides itself into two smaller bundles, proceeds from the ventral side, and is attached, one of the branches to the same point as the posterior dorsal bundle, the other branch a little more ventrally and anteriorly. Two weaker bundles start, in addition to the above, from the upper and lower lips of the mouth, and are attached to the corresponding borders of the sucker. I have observed some of the fibres of these various bimdles directly continued through the substance of the wall, and inserted on the cuticula that lines the cavity of the sucker. By the combined action of these muscles, the worm can exercise a strong suction on the gill of the host, and. extract its blood.
Besides these suckers, there is a pair of glands at the entrance of the mouth, just anterior to the suckers, which seem to be pecnHar to Dipl. nipponicum. They can be seen well in a living specimen under the cover glass, or in preparations of the entire worm, as a round, paired body. One of them is seen in section in Fig. 8, which shews it to be a gland formed bv the invagination and local modiiicarion of the epidermis. It has generally a reniform cavity, which opens into the mouth by a canal, just anteriorly and close to where the sucker opens into the mouth. The epidermis is continued into the canal for a certain distance, and then changes its character, becoming firmer and refractive like the cuticula. The cavity of the gland is destitute of any distinct epithelium, but is generally filled with a granular mass, which stains very well. This mass is densest near the wall, and gra- dunlly becomes thinner towards the centre, where there is generally an empty space. I have often observed the exit canal filled with a deeply stained granular mass, very similar in appearance to the con- tents of the sticky glands of DacNilogi/riis and other allied forms, and which is doubtless the sticky secretion of the gland. Next the gran- ular content is a basement membrane. The wall is exceedingly
ox DIPLOZOOX NIPPOXrCUM, X. !SP. 167
thick and niu.sriihir. The luiisciiJar übres are mostly arranged meri- dionally, i. e. if we suppose the ventral and dorsal pole of the gland to correspond to the two poles of the earth, the muscular libres are arranged nearly in the plane of the meridians. Fibres also come from the dorsal side of the animal, and enter the wall. ]>et\veen the muscular fibres, I have sometimes observed nuclei, which are to all in- tents and purpose exactly similar to those of th^ general mesenchyma of the body, and probably belong to it.
IV. The lYIesenchyma.
Ut" the mesenchyuiatous connective tissue of the Trematodes, Leuckart^' distinguishes two forms. In the Hrst torm, the mesen- chyma consists of a "fast homogene helle und feinkcirnige Substanz mit zahlreich eingelagerten kleinen Kernen '" ; in tlie second ioviu oi the mesenchyma, \ve see "' Zellen von mehr oder minder ansehnlicher • rrösse, die îuit einer meist wasserhellen Masse gefüllt sind ' and generally of a polyhedral form, with a tibroiis net- work between. Taschenberg"' regards the mesenchyma " als ein Bindegewebe, wel- ches zu einem Maschenweike entwickelt ist, in welchem die urs})riing- lichen Bildunuszeilen iheilsnoch \'orhanden sind, tlieils aljei' nur an dein Proto[)lasnia mit darin eingelagerten Kernen sich erkennen lassen." All these forms of the mesenchyma, however different they may seem U) be with one another, can. in m\ (ipini(jn, l)e deri\'ed from the dilferentiation in different- directions of a single primiti\e fjrm. fhe strong resemblance of the mesenchyma of the Trematodes to the chorda dorsalis of the \ ertebrates lias already been observed by i.euckart ; and I 1)elieve the former is formed jn.st in the same manner as the latter. But first the mesenchyma oî Dlplozoon.
]) Leuckart — Die Parasiten des Meuschen. It. Auflaj^e. I. Bd. 3. Liefg. p. 13 et seq. 3) Tasehenberg — 1. c. p. 13.
168
s. GOTO.
In this tissue are imbedded all the organs hereafter to be des- cribed, as also some of the organs already described. Owing to the presence of the vitelline body, the mesenchyma in the anterior half of the body is mainly confined to the peripheral portion, but is also present in a scanty quantity between the lobes of the vitelline body and the cells of which they are composed. When one takes it up for study, he finds great perplexity and difficulty in making out the true nature of the elements that compose it, until he compares it with the mesenchyma of other allied species. In Diplozoon, it consists of a fibrous substance, in which are seen nuclei each with a distinct mem- brane of its own. These nuclei always enclose one or more deeply stained nucleoli. The nuclei are of various size and shape. In the anterior portion and generally in the anterior half of the body, they are gener- ally of a comparatively small size (Figs. 7, 8, 9, 25) ; in the posterior half of the body, however, they are generally of a larger size (some- times having the diameter of about 0.01 mm.) and have a circular or oval outline (Fig. 13). In the vicinity of the internal organs, where the connective tissue is generally more or less compressed, the nuclei are smaller and often fusiform in shape. Around the pharynx, the fibres form a fine close net- work (Fig. H).
Beside these elements, we see here and there, scattered apparently without any regularity in the parenchyma, large vesicular bodies of a circular or oval outline (Fig. 13), with a large conspicuous nucleus in the centre surrounded by a mass of granular protoplasm, which on close inspection betrays a fibrous structure, and which gradually thins out peripherally, and leaves an empty space between it and the wall. These vesicular bodies are sometimes drawn out towards one end, and are very abundant in the posterior half of the body, posterior to the testis. In the region situated between the ovary and the testis, the mesenchyma consists of distinct cells with a granular, generally
ON DTPLOZOON XIPPONICUM, X. SP. 160
well-stained protoplasm, of a polyhedral form, and leavino- irregular intercellular spaces between (Fig. 14).
In Axme, the mesenchyma is distinctly seen to consist of laro-e, vesicular cells, each with a nucleus generally in the centre, but some- times attached to the wall, and filled with a hyaline fluid containing numerous almost uncolored granules. The nucleus as in Diplozoon, has a distinct membrane, and encloses a deeply stained nucleolus, but is considerably smaller. Beside these cells, there are, as Lorenz^' has already observed, in the neighbourhood of the vagina, cells whose con- tents take up the staining finid very eagerly and appear like ganglion cells. In MicroGOtyle, the mesenchyma presents somewhat different aspects in ditferent parts of the body — a statement that holds good to a greater or less extent in all other allied forms. Around and outside the vitelline body, the mesenchyma presents an appearance very similar to that of Diplozoon. Nearer the median line, it consists of large cells with tlie nuclei in tlie centre, from which protoplasmic fibres radiate to the wall, whose cavity is filled with a clear fluid without any granule. Along the median line, finally, the mesenchyma consists of cells with a granular somewhat fibrous protoplasm which deeply stains with haematoxylin.-* Here in Microcotijle, I believe, are manifested the transitional steps tlirough which the mesenchymatous connective tissue such as that of Diplozoon has been differentiated from the primitive parenchyma cells. These primitive cells are, I believe, very nearly represented by the cells of the median portion of Microcotijle. The next step onward toward the differentiation of connective tissue is, according to my view, represented by such a form of mesenchyma as that of Axine, or that portion of the same in Microcotylc situated just inside the vitelline body — composed of cells of a vesicular appearance
1) Loreaz — 1. c. p. 7.
2) In appearance, these cells are very similar to the yolk-cells of Diplozoon during the wiutor season. Vide. Fig. 20, PI. XXTl.
170
s. GOTO.
and filled witli a hyaline fluid. A step further onward in the same direction would result in the formation of abundant fibres, and the boiindai-ies of tlie oriji'inal cells would be partly absorbed and entirely obliterated ; so that we should then have a ground-mass of irregular fibrous substance, with miclei scattered therein — in fact just such a form of mesenchyma as we really see in most parts of the b(xly of Diplozoon. The lai-ge, round, vesicular ))odies above mentioned (Fig. 13) arc in fact the remnant cells of the original parenchyma, and the poi'tion, already referred to. situated between the ovary and the testis, seems to ha\(' tuulei'gonc ])ut little transf >rmati(^n. and to have pre- served tlic original cclhdar structure. According to the view here stated, the so-called j)seudocoel of tlie Trematodes would he not spaces formed by the departing of the cells from one another leaving inter- celhilar spaces between them, l)ut spaces which were before triil v infra- cellular. I do not, indeed, entirely deny the presence of truly rnfer- cellular spaces, but these ;u-e, 1 believe, comparatively insignificant.
Similarly, of the two t\pical forms of Leuckart, the first results apparently l)y a simple oblitei-ation of the boundaries of the original cells. The second f >rm can be (lci'i\ed by a process similar to that Avhich we have seen to ha\-e taken phice in Microcoli/le, in which some of the cells (the larger vesicular ones) have maintained their cellular natiu-e moj'e com])letelv, while others have been moi'e or less com- pletely transformed into conne(;tive tissue, and j)ressed in, forming the " Maschengewebe," between the former ; as already |)roved embry- ologically by Schwarze. ^^ The two forms above mentioned, are con- nected by numerous intermediate forms, and an actual transition between them has been observed in some species."^
1) Schwarze — 1. c. p. 59.
2) Looss — Beiträge zvir Kenntniss der Trematoden. Ztschr. f. \v. Zool. Bd. XLI. 1885. p. 432.
ON DTPLOZOON NIPPONICUM, X. SP.
171
Beside the various elements hitherto described, there nre, in the neighborhood of the brain nnd pliarynx, lari^'e cells of a roundish or polyg'oiial outline, easily distinguishable from the surrounding elements of the parenchyma (Fig. 25). They are of a gigantir- size, and in some sections they seemed as if they were drawn out into fibres in more than one direction. They have conspicuous \esic(dar nuclei enclosing each a (U^eply stained nucleolus, which again gt-ncr- allv encloses a vacuole. They are entire! v destitut<' of cell-walls, and have a finely gramdar protoplasm. Their very appearance suggests their nervous nature. i)ut more than that, oareftd examinations have convinced me tliat these large cells are very constant in their position and number. Thev are f~)und. namely, laterally and behind ihe pharynx, and ran be seen in living specimens under the cover-glass, especiallv well after the water has evaporated to a cei'tain extent. As will be seen from the figure, they are situated symmetrically, right and left, on ))oth sides of the pharynx. Ijesides the four cells on each side and a median ventral one. drawn in the figure, I ha\'e counted anotlier pair and a median unpaired one more posteriorly. T'here are also similar <'ells. which are scattered aj)parently without symmetry, around the brain, but always outside it in the mesen(-hyma. Two of these are shewji in Fig. 17.
Considering the form and appearance of these (^ells, the constancy and symmetry of their position and luunber (at least in the more anterior <Mies), together Avith the circiunstance that there are no nervous cells m the brain or nerves, I am sti-ongjy inclined to ntti-i- bute nervous functions to these gigantic cells ; but I have not been able to trace anv direct connection with the nervous system. I have tried methyl-violet and c()Ghineal stain. By the latter, they are but slightly colored, and neither of these stains affords any better clue into their exact natiu'e. They seem to l)e ditt'ereni from the remnant
172 s. GOTO.
cells of the parenchyma ah*eady described (Fi,o-. 13); hut I must leave the exact nature and function of these cells undetermined.
Y. The Digestive System.
The digestive system consists of the mouth (Fisr. 2, mo), the prephnrynx (p[>h), the pharynx (ph), the oesophagus (oe). and the intestine (int).
The mouth is a funnel-shaped opening situated on the ventral side of the anterior extremity of the body, at the entrance of which are placed the glands and suckers already described. Its cavity is lined hv the continuation of the cuticula of the general surface of the bodv. The fundus of the fiumel leads directly into an expanded cavity, the prepharynx, into which the anterior half of the pharynx protrudes. This latter is an ellipsoidal body which has a narrow tubular cavity passing through the centre, and whose major axis is directed antero-posteriorly. In cross-section (Fig. 11) it is circular. The internal tubular cavity is lined by a comparatively thick struc- tureless juembrane. The thick wall is composed of muscular fibres arranged in regular grou|)S, and of connective tissue, in which nuclei, very similar to those of the general mesenchyma, are to be observed. Most internally, and separated from the structureless membrane lining the internal cavity by a sort of basement membrane, is a thin layer of circular fibres (mci). Most externally, and directly internal to the cuticidn-like membrane that envelopes the whole pharynx and sepa- rates it froia the surrounding mesenchyma, is another layer of circidar fibres, about double as thick as the first. Besides these, there are radi- al fil)res extending between the internal basement membrane and the external cnticula of the pharyngeal wall. These radial fibres are weakly developed, and do not riui in bundles, as they have been observ-
ox DIPLOZOON NIPPON ICUM, N. SP. 173
eel to do in some other Trematodes. Between these fibres is found a muss of connective tissue with conspicuous nuclei. These nuclei are doubtless the remnants of the cells that produced the muscular fibres and the connective tissue of the pharynx. Strong dorso- ventral muscular bundles (Fig. 11, dvm) are closely applied to the wall of tlie |;harynx, and no doubt assist in its action. The total thickness of the pharyngeal wall, the internal membrane inclusive, is about 0.02 mm.
The cavity of the pharynx leads directly into the oesophagus, a simjjle, slender, tubular portion, which is directly continued into the meilian trunk of the intestine. This median trunk sends out in the anterior half of the body, right and left, lateral branches, which rami- fy dichotomously once or twice. Some of these lateral branches are distinctly paired, but I have also observed others which are as dis- tinctly unpaired. Posterior to the place of crossing of the two in- dividuals the lateral branches are absent. Here the median trunk divides into two, one of which retains nearly the median position, while the other proceeds more laterally towards the ovary. Posterior to the testis these two branches unite, and thenceforth the intestine proceeds towards the suckers as a simple unbranched tube, and ends between and a little anterior to the first pair of suckers, where it generally presents a rounded enlargement. '• A l'endroit ou les deux corps s'unissent, les coecums digestifs semblent atrophiés, mais en dessous de l'appareil générateur, dans le bout postérieur du corps, chacpie tube présente de nouveau ses ramifications régulières et com- plètement séparées, comme dans la partie antérieure," says v. Bene- den,^* and I can confirm his observation with my own on the Euro- pean species ; but in 7iipponicum I have found this part of the intestine always sim[)le. The wall of the intestine is destitute of an epitheliinn
1) P. J. V. Beneden— 1, c. p. 40.
174
s. GOTO.
such HS we. niv wont to see in the Distoines. In its .stead, we find large cells (Figs. 14, 16. 19, de) separatee] from one another by a considerable interval, and filJed with duvk-I)rown or sometimes even black gra- nnies. I have not (Jl)ser^•ed any wall or nncleus in these (.-ells, al- though Zeller'' points to the presence oi" the latter in J'o/ystonium. and I could distinctly oljserve it in OrtohotJiriiün. These black {»igment- containin"' cells I hold, m agreement with Taschenbero','^ to be dio^estive cells, and the pigment-grannies to be tood-particles taken in from the ca\itv of the intestirje. Digestion, therefore, takes place in the allied forms intracellulary, as in the Turljellarians. The intervals between these cells are usually destitute of any distinct meud.u'ane in the anterior half of the body, so that here the digestive svsteni consists of mere hollows in the mesenchyma ; but in the p<.)sterior part, where the intestine is simple, 1 could usually distinguish a more or less dis- tinct memlirane of compact connective tissue.
VI. The Excretory System.
The excretor}'' system (jf the Plathelminthes has been minute- ly examined by Fraipont,"' Lang," l-*intner''' R. AVright and ^lacallum,''' and some others. ]>y these investigations two [)oints seem to have been lirndy established : 1) That the excretory system
1) Zeller — Untersuch, ü. d. Entwiek. n. d. Bau. d. Polystomum integerrimum. Ztschr. f. w. Zool. Bd. XXir. 1872. p. 19.
2) Taschenber;;- — Weitere Beiträi^e. [> 11.
S) Fraipunt— itecherches sur l'appareil excréteur des 'l'réujatodt s. Archiv, d. Biologie. T. I. I have not been able to gain access to this work, aud_ am indebted for its account to J. V Carus's " Zoologischer Jahresbericht" (1880. 1. p. 277) and to Looss (1. c).
4) Lang— Der Bau von Gunda segmentata u. d. Verwandtschaft etc. Mittheil. a. d. zool. Station z. Xeapel. Bd. III. 1882. p. 187.
5) Pintner -Untersuch, ü. d. Bau. d. Bandwurmkörpers, mit bes. Berücksichtigung etc. Arb-it. a. d. zool.-zoot. Inst. d. Univ. Wien, etc. Bd. III. 1880. 2. Heft.
C) R. Wright and Macallum— 1. c. p. 20.
ON DIPLOZOOX NIFPONICUM, N. SP.
17n
of this class consists of vessels with :i distiiK-t wall, 2) that these vessels are of two kiln Is, tlie larger oiies serving iii:iiiily f<jr leading out the contained fluid, and the cnpillarÎL's which end in fnnnel-sluiped little bodies shewing the so-called " Wimperflannne " in the interior, and which are the most important part of the system.
In DipL nipponiciun^ as in Dipl. panidoxum^ two main canals (an always be distinguished on each side of the body, one of which is larger than the other and opens to the exterior by means of a circnhir o])ening on the dorsal side^', close to the lateral mai'gin, a short dis- tance posterior to the pharynx (Fig. 2, eo). Immediately at the entrance of the o])eniiig, the vessel presents an enlargement (the so- called " vSammelrohr "), then proceeds anteriorly to about the level of the pharynx, whei-e it bends backward and proceeds posteriorly, winding more or less on the w^ay, and giving off but a few branches. On reaching the posterior suckers, it bends inward to them and reaches nearly the posterior margin of the body. Here it turns on itself and proceeds anteriorly, following closely its former course, but this time liberally sending ont branches which anastonnjse with one another and with those from the opposite side of the body. Anteriorly this main vessel reaches the upper lip of the mouth, where it divides itself into numerous branches, having also become smaller during its course. These two main vessels follow closely in their course that of the ventral nerves, on whose dorsal side they are situat- ed except where they make windings towards one side or the other. I have sometimes observed a direct connecting vessel between the two main ones. Within these vessels as w^ell as the branches that proceed from them are seen, in a living specimen, active vibratory movements, which generally come to view only after the animal has been left f)r
1) Cf. Brauu — Uebur (.lie Lage d. Excaetiouspori bui d. ectupar. Trematudeu. Zool. Auz. Jahrg. XII. 1889. p. 620.
176
s. GOTO.
sometime under the cover-glass, and which are executed in such a way as to drive the contained fluid towards the excretory pores. These movements are probahly due to the presence of vil)rati]e flaps in the wall, but I have not been able to observe them in sections. The wall is seen, in section, to be f(jrmed by a compact refractive mem- brane with douljle contour, which does not stain with haematoxylin (Fig. 16, as). Evidences have been advanced by Lang^* and Ijinia'^ that the excretory vessels of the Turbellarians are " nichts Anderes als durchbohrte Zellen." In the Cestodes, Pintner^' has observed a well- developed epithelium on the wall of the main vessels, "das zweifels- oline als Matrix ihrer glashellen, homogenen Membran aufzufassen ist." According to Schw^arze*\ the central excretory vessel of the Distomes is ut first a solid string of cells, which afterward acquires a lumen. He also supposes that the finer branches originate in the same way, and that the structureless condition of their walls in the adult worm may be explained by supposing " dass nach der Resorption des Inhaltes der primären Zellen keine äussere, muskulöse Zellenlage gel)ildet wird, somlerti die Wandung sicli, al lein, aus der äusseren ZeUmein- hraiini der ursprüngliclieu Aidagc zusaunneiisctztr Whether the walls of the excretory vessels oi Diplozoot is to be regarded as similar to those of the Turbellarians, with the difference that the protoplasmic remnants of the original cells have been transformed into a structureless mem- brane, or whether they had been produced by a distinct epithelium which afterwards underwent degeneration and finally disappeared, or whether they were formed by such a process as Schwarze^- supposes
1) Lang— 1. c. p. 212.
2) Ijima — Untersuch, ü. d. Bau u. d. Entwickl. d. Siisswasser-Dendrocoelea. Ztschr. f. w. Zool. Ed. XL. 1884. p. 397.
3) Pintnei— 1. c. p. 21.
4) Schwarze — 1. c. p. 58. The italics are mine.
5) In the extreme case, viz. wliere the cells are arranged in a si agio row, the view of Schwarze reduces itself to that of Lang and Ijima.
ON DIPLOZOON NIPPONICUM, N. SP. 177
to have taken place in the smaller excretory vessels of the Distomes, I must leave entirely undecided, with the single remai'k, however, that in Diplozoon I have observed no trace of nuclei in the wall.
The capillaries, furnished like the larger vessels with a distinct wall of compact refractive membrane, proceed from tlie smaller branches of the main vessels, and continue throughout their whole course without undergoing any perceptible diminution of their calibre. They are especially abundant in the layer of the mesenchyma just under the muscular wall of the b()dy. The}' do not, like the branch- es of the larger vessels, anastomose with one another, and no vibratory movement is to he observed within. They branch freely, and each of the branches ends with a minute funnel-shaped enlargement (Fig. 15), within which is to be seen an active vibratile flap, the so-called " Wimperflamme." Various structures have been described in con- nection with these funnels, but, although I directed my utmost atten- tion to the point and applied the best lenses at my disposal (Seibert apochr. syst., 4inmx8),I could not observe any of them. The majority of the writers wdio have specially investigated this subject seem to agree in excluding any direct communication between the cavities of the funnels and those of the surrounding mesenchyma. In this respect, however, Fraipont makes an exception. He observed "fenêtre ovale" in the wall of the funnel, by which its cavity was put in direct connection w^ith the surrounding pseudocoel. I had at first supposed the end of the fiumel completely closed ; but on repeated observations with the apochromatic system of Seibert, it seemed to me very probably open, and to communicate with the cavities of the mesenchyma. I have not observed any of those peculiar cells described by preceeding writers.^'
1) On reading Wright and Macallum's description, the question naturally arises if the writers have not mistaken the ciliated portions of the capillaries, such as have been described
178 s. GOTO.
^ vil. The Nervous System.
With the excellent investi ligation of Lang" on the nervous system of the Trematodes before nie, I directed my special attention to this svstem, and can confirm his statement in its general aspect, though it seems to me to require modification when the writer ex- tends it to the Trematodes in general. Let us begin with the brain.
As to its position, Lang says, "Ich glaube überhaupt, dass bei allen Trematoden das Gehirn diese Lage hat, dass es nämlich bogen- föi-mig über den vorderen Theil des Pharynx verläuft und ich zweifle, ob sich die abweichenden Angaben bei erneuter, genauer Untersuchung bestätigen würden." Leuckart-' is inclined to explain those cases where the brain has been observed behind the pharynx "durch eine Lagen- veranderuns" " of the latter, " die um so leichter eintreten kann, als das Nervenband nirgends ringförmig geschlossen ist, obwohl das für einzelnen Arten behauptet wurde." T find, however, after careful and repeated observations, with these statements full in view, that in Diplo- zoon and also in Axhie, Microcotijle, and Oclohothnum^ the brain is a band-shaped nervous body arching over the oesophagus on the dorsal aide and heJiind the pharynx. In a fresh specimen, it is seen to be composed of very thin fibres ; but sections shew that in addition to these fibres the brain contains a finely granular substance doubtless identical with the " Punktsubstanz " of the Turbellarians (Fig. 17). The fibres in the brain are seen to run mainly in two groups, one on
by Looss, for the funnels, and overlooked these latter. I also belive that they go too far when they endeavor to attribute excretory nature to the large cells observed by Looss and others in the pharynx of many Tiematodes.
1) Lang — Untersuch, z. vergleich. Anatomie u. Histologie d. Nervensystems d. Plathel- minthen. Mitth. a. d. zool. Station z. Neapel. Bd. II. 1881. p. 28.
2) Leuckart— I.e. p. 22.
ON DIPLOZOON NIPPONICUM, N. SP. 179
its dorsal side, the other more on the ventral side, close to the dorsal side of the oesophanfus. These 1 have marked in the figure with a lightei' shade. They unite at the two ends of the brain where the nerves take their rise. The l)rain is traversed by numerous dorso-ven- tral bundles as already inentiiuied.
From the brani are given off nerves both anteriorly and posteri- orly. One pair (Fig. 2. nai) yn'oceeds anteriorly near the median line embracing the pharynx, near the nnterior ])art of which it is lost in the mesenchyma. A second p;nr (nnc) ]^r(U'eeds more laterally, and can be followed as far as the suckers, externally to which it proceeds and there withdraws itself from view. These internal and external anterior nerves are connected with each other by a commissure at a little distance from their origin in the brain.
Two pairs of nerves also proceed posteriorly, one of which may be called the ventral pair and is by far the stronger ]iair. The other pair (nvl) may be called tiie ventro-lateral nerves and proceeds ])osteriorly just at the angle between the ventral and lateral borders of the body, and can be followed as far as where the two individuals cr(~>ss each other. The ventral nerves (nv) take their rise in the brain at its ])ostero-lateral corner, and ran be followed to near the posterior bor- der of the body, rhey become, liowever, more and more indistinct as tliey proceed ])osteriorly, and finally become invisible at about tlie level of the hinderniost pair of suckers. They closely follow in their course the main excretory vessels, (^n whose ventral side they are situated at a little distance from the muscular layers. At tlie place where the two individuals cross each other and where the ventro- lateral nerves withdraw themselves from view, the ventral nerves take a more lateral position, and this position they keep throughout the remainder of their course. The ventral nerves are connected with each other and with the ventro-lateral nerves by a number of com-
180 :.': S- <5oto.
missures occurring nearly at regular intervals ; and in such a way that each commissure between the ventral nerves lies in a line with that between them and the ventro-lateral nerves. The ventro- lateral nerves, atrain, sends ont branches towards the lateral margin of the body, just at those points where they receive the commissures from the ventral nerves ; so that all the nerves form a regular I'ect- angular net-work, and divide the whole ventral surface of the body into a number of distinct areas. At the points where the commis- sures cross the main nerves, the course of the fibres is interesting. From any main nerve, namely, which we may be considering, fibres are given otf on both sides to the neighl^oring nerves. Beside these, there are also fibres coming from the latter and proceeding directly past the main nerve without mingling with its fibres, so that the four main nerves are probably ])ut in direct connection with one an- other. I ha\e counted as manv as thirteen commissures in the an- terior half of the body, in addition to the pair of commissures between the anterior nerves. In the posterior half the commissures seem to be less numerous. I have l^een able to count only a few ; but this is perhaps due to the presence of the strong fields already mentioned and the special development of the diagonal muscle in this region, which greatly increases the difficulty of following the course of the nerves. I have not been able to make out the ])lexus whicli the nerves probably f )rm on the dorsal side.
As to their histological character, tlie nerves present typical "Balkenstränge" (Fig- 16)- In some of the meshes are to be seen sections of nervous fibrils as exceedingl}^ miiuite dots, which are visible only in the most favorable cases. Pintner'* maintains that the " Biilkchen selbst" which form ilie mesh-work are the sections of the fibrils which are probably arranged "reihenweise, nebeneinand-
1) Pintner — I.e. p. 71.
ox DIPLOZOON NIPPOXICUM, N. SP. 181
erstehend." Poirier^ ^ describes the nervous fibres oi' D slnnnm clavatum as filling up tlie entire cavity of the meshes. But an examination of the nerves in a fi-esh state shews very distinctly the exceedingly fine fibrils. They do not seem to be so regularly arranged as Pintner supposes, and are not at all large enough to fill up the entire cavities of the meshes. Without doubting the correctness of Poirier's obser- vation, I am convinced that in Diplozoon the nerves consist of a frame- work of connective tissue, in the meshes of which i"un tlie true nervous fibrils. I liave not observed any of the nervous cells describ- ed by Larig and others in the ner\es. This set me to a careful searcli after ganglion cells, as these were not also to be found in the brain, where in other species they make such a conspicuous figure especially in the peripheral portion. But I have ncjt been able to find out any to which 1 could decidedly pinnt as nervous cells {Vide supra p. 171).
VII. The Reproductive System.
We now C(jîne to the consideration of the most complicated system, the reproductive organs. Of these the female portion consists of the vitelline body, the ovary, the oviduct, and rhe uterus, with a "connecting canal" the natiu'e of which is not at all clearly known. The male portion consists of the testis with a single vas deferens. I shall beo-in with the latter.
The Male Organs — The testis is a nearly globrdar or ovoid body situated about midway between the point of crossing of the two in- dividuals and the posterior niargiji of the body, and is composed of many lobes. Each hjbe is separated from its neighbour and from
^) Poirier — Coatribution h l'histoire naturelle des Tréiuatodes. Arch. d. zool. expérimen- tale 2e. Série. T. III. 1885. p. 603.
182 s. GOTO.
tlie .surrounding- niesendn-niM by a layer of dense connective tissue (Fig. 2, t& Fig. 18). During the winter season, it is a solid mass of vesicular cells that have assiuned a polyhedral form by their mutual pressure. Each cell encloses a conspicuous round nucleus, which seems to be provided with a wall of its own, and in which numerous chromatin particles are to be observed. The cytoplasma is a hyaline fluid which scarcely takes up any color. The nuclei are of various sizes in the same lobe, some being very small, leaving abundant space for the cytoplasma, while others are of such a size as nearly to h II up the entire cavity of the cell.
From the anterior end of the testis proceeds a single vas deferens, which passes anteriorly in a straight coiu'se dorsal to the oviduct and ventral to the yolk-duct. Daring the first part of its course, it lies ventrally to the uterus ; but at al)out the level (^f the anterior end of the ovary, it turns dorsal to it and opens info the vitel- line duct of the other indiridaal a little more anteriorly than the an- terior end of the ovary. Zeller" represents the vas deferens of one individual as standing iu direct connection with the " Laurer's canal" of the other. But my observations contradict this view entirely. 1 have traced the course of the vas deferens in more than one series of the sao'ittal sections of the worm. One of these series is reproduced with- out interruption on PI. XXIIT. The opening of the vas deferens of one individual into the yolk-duct of the other is seen in Figs. XI. & XIII. By the same series of sections, the opening of the connecting- canal of the oviduct into the intestine is distinctly seen (Figs. V & XIX). The vas deferens is destitute of any distinct wall of its own. It seems to be merely a continuous tube-like cavity in the general mesenchyma., and to collapse entirely during the winter season.
^1 Zeller — Ueber deu Géschlechtsapparat des D/pZ. 'parado.vuni. Ztschr. f. w. Zool. Bd. XLVI. 1888. p. 233.
ON DIPLOZOON XIPPONICUM, N. SP. 183
The Female Organs — The ovary (Fig. 2, ov) is a long conico- cjdindrical body which is doubled on itself by its middle portion, so that the two ends come close to each (jther, and placed on the dorsal side of the body just anterior to the testis, to which its smaller end is closely applied ; the anterior end where it is doubled on itself reaching as far as where the dorsal jjapilla formerly was. From its larger end, wdiere ripe ova are found, proceeds the oviduct. As we approach the other end, the ova become smaller and smaller until finally we see a mere assemblage of round nuclei imbedded in a com- mon mass of protoplasm. The whole ovary lies in a mere cavity of the mesenchyma without any distinct wall of its own. A section through the larger end (Fig. 21) shews the ovary to be a solid body consisting of large ova which are either polygonal or wedge- shaped according to the direction of the section. Each ovum is des- titute of any membrane, and consists of a mass of homogeneous deeply stained protoplasm, in which lies a large vesicular nucleus provided with a distinct wall and containing a hyaline fluid in which float numerous deeply stained dots, the chromatin {)articles. Each nucleus again encloses a large deeply stained nucleolus in which are again to be observed one large or a few smaller vacuoles. Zeller^' mentions and figures in the ovum of Pokjstomum and Diplozoon a thick, elastic " Hiille " ; but I have no doubt that the ovarian ova of Diplozoon are destitute of any membrane. This is also the case in Axine, Micro- cotijle. Octohothrium, Dactylocjijrus^ in fact in all the species of ectopara- sitic Trematodes I have hitherto examined. Willemoes- Suhm^' men- tions no '' Dotterhaut " in I'ohjstomuin occllatam, ; Taschenberg"^* asserts
1) Zeller— Ztschr. f. w. Z. Bd. XX 11. p. 5 & 169 foot-note; Bd. XLVI. p. 235. Is not the elastic membrane the result of fertilisntion?
-) Wiilemoes-Sahui — Zur Naturgescn. d. Polyst. integerrimvim u. Polyst. ocellatum. Ztschr. f. w. Z. Bd. XZII. 1872. p. 33.
^) Taschenberg — Beiträge, p. 36.
184 s. GOTO.
the absence of any membrane in the ovum of Tristomum ; so also Wierzejski'' in that of Calicofiße Kroijcri ; and I believe the same is true of the ova of all ectoparasitic Trematodes. As we proceed nearer the smaller end of the ovary, the ova and their nuclei become smaller and smaller, the vacuoles within the nucleolns disappear and finally the nucleolns itself, until we see only spherical nuclei crowded to- gether and surrounded by a common mass of uniform protophi>;m. Fig. 22 shews a section through this part.
The oviduct proceeds from the larger end of the ovary and takes its course posteriorly and to the right, ventral to the vas deferens and the testis. At a short distance from its origin, it receives a canal (Fig. 2, cc) which proceeds anteriorly and, after making a slight wind- ing or two, opens into the intestine (Figs. V & XIX). This is the " Laurer's canal" of Zeller which he represents as standing in direct connection with the vas deferens of the other individual. In Poljisto- inuni integer rimuur^ he asserts a direct connection between the ovary and the testis ; and in proof of this he alleges his observation of the ova passing through the oviduct and Lanrer's caiial and entering the cavity of the testis. But it has been pointed out by Ijima'"' that the canal in question distinctly opens into the intestine, and that a similar canal is present in many other species of the group ; and I can con- fidently state from my own study that the ''dritte Dottergang" of Lorenz in Axineixwà Microcotyle distinctly opens into the intestine. A similar connecting canal is also present in a species of Octohothrinm which I have examined."*' The fact cited by Zeller can be explained
1) Wierzejski— 1. c. p. 558.
2) Zeller— Weiterer Beitrag z. Kenutniss d. Poljstomeen. Ztschr. f. w. Z. Bd. XXVII. 1876. p. 245.
3) Ijima — Über den Zusammenhang d. Eileiters mit d. Verdauungscanal bei gewissen Polystomeen. Zool. Anz. Jahrg. VII. 188i. p. 635.
4) Voeltzkorw (Arb. a. d. zool.-zoot. Inst, in Würzburg. Bd. VIIT. 1888. p. 267) describes an evidently homologous canal in Aspidogaster conchicola. According to him it ends blindly near the dorsal surface of the worm. He calls it Receptaculum vitelli.
ON DIPLOZOON NIPPOXICUM, N. SP. 185
if we consider that the intestine is destitute of nny distinct wall, and that when the testis is nearly empty there is ahnost nothing that would prevent the entrance of the ova into the cavity of the testis by way of the intestine. I therefore believe, notwith- standing his positive statement to the contrary, that the canal in question opens also in Polystomum into the intestine at the point where he represents it as arising from the testis. In Dactijlogijrus a similar canal opens externally on the dorsal side, at a short distance from the right lateral margin of the body. In Dipl. paradoxum this canal is very long and undergoes numerous convolutions, but in nipponicum it is shorter and nearly straight, and the internal surface is clothed with cilia. Its nature and function, if it has any, I hope to be able to treat of later. At a little distance from the point where it receives this canal, the oviduct receives also the yolk-duct (yd). After this it continues its former course, and then, making a sudden turn anteriorly, opens into the uterus.
The uterus, under which I include both the " Ootyp "' and the " Eiergang " of the German writers, is a cylindrical tube with a dis- tinct wall which is thickly beset for the greater part of its length with long cilia on its internal surface. It shews an ovoidal enlargement at its origin, the " Ootyp," then diminishing in diameter proceeds an- teriorly, following the same course as the vas deferens, and opens ex- ternally by a small aperture on the ventral side just at the angle formed by the ventral side of one individual with the dorsal side of the other, at the top of a conical elevation which is sometimes very small, sometimes larger and very conspicuous. Just before opening, it presents a second enlargement in which a single egg is usually found during the period of reproductive activity. "II y a à l'origine de ce conduit (i. e., of the uterus) une sorte de pylore," says v. Beneden.^'
1) V. Beneden — 1. c. p. 43.
186
s. GOTO.
This is caused by the. opening at this point of numerous flask-shaped unicellular glands (shg), fjie shell-glands. The wall of the uterus proper (Ootyp, Fig. 24) is lined by a distinct epithelium, whose cells contain each a round nucleus projecting into the internal cavity. The protoplasm is granular and no cell-boundaries are to be seen. The epithelium sits on a distinct basement membrane and is destitute of cilia. The remainder of the uterus (Eiergang) is provided with a similar wall (Fig. 23), with the nuclei, however, more separated from one another. Here, as already stated, the wall is beset with long cilia.
The vitelline body is an extensive lobed body (Fig. 2, vb) situat- ed exclusively in the anterior half of the body, all around the intestine both on its dorsal and ventral sides. In specimens in wdiich reproduction is going on, each lobe is seen, when fresh, to contain a dark granular mass. Sections (Fig. 19) shew that each lobe consists of a number of cells containing numerous yellowish granules, each with a nucleus and a nucleolus in the centre, and a thin cell- wall. These are the ripe yolk-cells, îmd when freed take up a globular form. In the peri|)heral portion iu*e seen smaller cells wdth a deeply stained protoplasm, a nucleus and a nucleolus. The protoplasm is homogeneous, finely or coarsely granular according to their different stages of development. They are the young yolk-cells ; and there are also to be observed cells intermediate between these two kinds — cells one half of whose content has already been changed into yellowish yolk-granules while the other half still consists of granular protoplasm. During the winter months, the yolk-cells present a quite different appearance (Fig. 20). Tliey are then scarcely to be distinguished from the cells of the mesenchyma of certain species of Microcotyle. They are then of a polygonal form, with a distinct cell- wall, a round nucleus and nucleolus, and a granular protoplasm which stains very
ON DIPLOZOON NIPPONICUM X. SP. 187
well. In this granular protoplasm there are fibrons structures radiating from the central nucleus to the cell- wall and more or less forminsr a net-work. The steps hy which these cells are changed into ripe yolk- cells and the origin of the deeply stained young yolk-cells I must leave at present unexplained.
As will he immediately seen from the above investigation, the union of Diplozoon is, as Zeller maintains, a permanent copulation. But the relation in which he has represented the parts of the two individuals to stand to each other reqaii-es correction. We have seen that the vas deferens of one individual opens into the yolk-duct of the other. This is well in accordance with the probable mode of copulation in some allied forms. In ]\[icrocotiile, which seems to be very closely allied to Diplozoon, there is a dorsal vagina which leads into a canal opening into the yolk-duct. In this canal I have often observed spermatozoa, and as during the period of reproductive activi- ty yolk-cells are constantly going down the yolk-duct and push down before them anything that might come u}) from below, it is very prob- able that these spermatozoa had found their way here from the dorsal vagina. Hence the supposition is very natural that in copulation the penis of one worm is directly applied to the dorsal vaginal opening of the other. Now if this very probable supposition be true, and if we further imagine such a relation to persist permanently, we should have j List the case that we actually see in Diplozoon, with the only difference that the copulation is not cross-wise. Whether in Micro- cotijle also, as in Poliistoniiun, the copulation is normally cross-wnse and mutual is well worthy of our attentive observation, since if this be the case, the copuhition of Diplozoon would l)e nothing more or less than the regular mode of copulation in. allied forms made per- manent.
188
s. GOTO
In conclu sien I wish to express my best thanks to Prof. K. Mitsakiiri and Prof. C. G. Knott for kindly looking through my paper and making suggestions. Tohjo, October 1890.
ON DIPLOZOOX NIPPONICUM, N. SP. 189
Explanation of Figures.
Abbreviations common to all the figures.
as ascending stem of the excretory vessel (according to the
direction in which the contained fluid moves).
hv brain.
cc connecting canal between the oviduct and the intestine.
dem dorso- ventral muscle.
ds descending stem of the excretory vessel.
dc digestive cell.
eo excretory opening.
int intestine.
mce external circular muscle ]
, [ of the phai-yiif'-eal wall.
mci internal ,, ,, i
mo mouth.
nae external anterior nerve.
nai internal anterior nerve.
nv ventral nerve.
nvl ventro- lateral nerve.
ov ovary.
ovd oviduct.
oe oesophagus.
ph pharynx.
pph prepharynx.
of the posterior suckers.
19Ö S. GOTO.
pm median piece
ppa paired anterior piece
ppp „ posterior ,, ,
pp process of the posterior piece j
sa anterior sucker.
sp posterior sucker.
sg sticky gland.
shg shell gland.
t testis.
ut uterus.
vd vas deferens.
vh vitelline body.
yd yolk-duct.
All the figures, if not otherwise stated, were drawn with cam. lue, Zeiss Ex 2.
PI. XXI.
Fig. 1. — Dipl. nipponiciuu killed with boiling sublimate; free-hand, surface view, x about 14. The black dots represent the digestive cells seen throuo'h the tissues.
Fig. 2. — The same, free-hand, from a specimen killed under the cover-glass, shewing the internal organs, half-diagramatic. The right antérieur half [)resents the ventral, and the corresptjnding posterior half the dorsal aspect ; and vice versa with the other individual. The nerves are colored yellow ; the excretory ves- sels indigo- blue.
Fig. 3. — Chiti nous frame- work of the posterior sucker as seen in a specimen under the cover-glass.
Fig. 4. — Section of the postericn' sucker in the direction indicated by ab in Fig. 3.
By inadvertciicc of tlie printers, the micle(ili in Fi^'s. 8, 9, 11, lo, Iß, 17, 18, 19, 20, 23, and 24 are represented either as lyino- outside the nuclei or quite eccentrically in Tliem, whereas they ou<i'ht to occupy more central positions. Their true positions are indicated in most of the fi<,aires hy weakly shaded dots.
ON DIPLOZOON NIPPONICÜM, N. SP. 191
Fig. 5. — Section of the same in the direction indicated by xy in
Fig. 3. Fig. 6. — Hooks between the posterior suckers.
PI. XXII.
Fig. 7. — A part of a cross-section of the worm passing through one of the conical elevations of the epidermis. It also passes throug-h one of the transverse folds into which the surface of the body is thrown when the animal contracts ; hence the longitudinal muscles are separated from the circular by a rather thick layer of connective tissue.
Fig. 8. — Section of the sticky gland, from a cross-section of the worm.
Fig. 9. — Section of the anterior sucker, from a cross-section of the worm.
Fig. 10. — To shew the direction of the diagonal muscular fibres, from a horizontal section of the worm.
Fig. 11. — Cross-section of the pharynx.
Fig. 12. — Diagram shewing the muscles accessory to the pharynx.
Fig. 13. — A part of a cross-section of the worm, from the posterior half of the body, a little posterior to the testis ; to shew the character of the mesenchyma.
Fig. 14. — The portion of the mesenchyma situated between the ovary and the testis, from a sagittal section of the worm.
Fig. 15. — Excretory funnel, Seibert apochr. sys. 4 mm. x8.
Fig. 16. — Cross-section of the ventral nerve.
Fig. 17. — The brain, from a cross-section of the worm.
Fig. 18. — The testis, from a longitudinal section of the worm.
192 s. GOTO.
Fig. 19. — The vitelline body, from a longitudinal section of a worm
collected in September. Fig. 20. — The same, from a cross-section of a worm collected in May;
the yolk-cells not ripe. Fig. 21. — Section of the ovary near its larger end. Fig. 22. — The same near its smaller end. Fig. 23. — Longitudinal section of the uterus (Eiergang). Fig. 24. — Cross-section of the uterus proper (Ootyp). Fig. 25. — A cross-section of the worm through the region of the
pharynx ; to shew the peculiar gigantic cells. Zeiss Dx2.
PI. XXIII.
An uninterrupted series of sagittal sections of the worm. To the respective abl)revnations is subjoined the letter r or I according as the parts belong to one or the other individual. Zeiss Bx2.
Jour. Sc. Coll. Vol. IV. PI. XXI.
Fig. 1
m "
Piih
Ph
S. Goto del.
Fi;,
«V
Jniir Sc. Cntl. Vnl IV. PI ïyi.
;?s
A New Species of Hymenomycetous
Fungus Injurious to the
Mulberry Tree.
by
Nobujirö Tanaka.
With Plates XXIV— XXVII,
In Japan the mulberry tree has been widely cultivated, from time immemorial, for rearing: silkworms. Althouo'Ii the methods of its culture have much improved, yet its diseases, especially those caused by fungus parasites, have been overlooked even by skilful cultivators. The chief reason f )r general neglect ivgarding these points is the want of accurate knowledge of the nature and biology of fungi. One of the most serious diseases of this kind is that which is known under the name of " Mompa-byö."* This disease has produced much distress at various intervids for about eight years, in the experimental farm of the Agricultural College at Komaba, Tokyo. Some dis- tin^fuished biologists and au'riculturists have investifrated its nature, and stated that it was due to the ravages of a sterile mycelial stage of a fungus of some other form, but its true nature has never yet been fully explained. I have lately had the good opportunity to study this disease under the direction of Prof. R. Yatabe. The object of this paper is to deal with one or two of the unsettled questions regarding it, namely, the morphology of the perfect condition of the fungus which causes the disease, and its systematic position.
* Mompa, a kind of nappy cotton-cloth ; byö, disease.
194 N. TAN AK A.
Towards the end of last year, I obtained specimens of mul- berry trees attacked by the disease, but unfortunately the speci- mens were so far advanced in decomposition that the course of the mycelium of the fungus in its relation to the internal tissues of its host was not clearly definable, and also the fructification of the fungus could not be found. Since then I have examined many other speci- mens, up to the beginning of April of this year, and at length found the perfectly developed condition of the fungus. Its specific characters
are as follows : Pi lens sessile, resupinate, somewhat orbicular
or oblong, often iircgnlarly lobecl, 5-10 cm. across, 2-4 mm. thick, at first velvety and membranaceous, then subcoriaceous, some- what convex, incrustate, purplish brown, at length albo-pruinose ; hymenium wdiite ; basidia curv( d, 1-o-septate, tetraspored ; sterig- mata elongated ; spores ovoid, curved, hyaline, 10-12 n. long, 5-7 U. broad.
By the above characters, especially ])y its peculiar form of b.asidia and by its nature, I consider that this fnngus belongs to the genus Helicohasidium in the fiimily Thelephoreœ of the Hiimenomifcetes. It has much resemblance in its characters and hal^it to many species of its allied genera ; but it can be distinguished from Thelephora and Gorticeum chiefly by having an intermediate stratum in the pileus, and from Stereumhy hny'ing a usually superior hymenium. Of the s[)ecies of the genus Hclicobasidiuni liut few are known ; in Saccardo's Sylloye Fungonim * only two species, H. purpureum (Tul.) Pat. and H. cirratum Pat. et Gail.^ ru-e given. By comparing my description oî the fungus with that of the above named species, it can be distin- guished from the forniei- chiefly by the colour of the pileus and the number of spores borne on a basidium, and, from the latter, by the diameter of the pileus, the number of spores borne on a basidinm,
* Vol. VI. p. 666.
A NEW SPECIES OF MULBERRY FUNGUS. 195
and their size. An allied fungus on the mulberry tree in South Carolina, North America, was described by Prof. Berkely under the name of Stereum moricolum ; and two other species of Sterevm^ viz. S. suhcruentatum, B. et C. and .S'. contvariiim Berlc, are given in Saccardo's Sylloge* These are Japanese species, but unfortunately I have never yet found them. They must, however, be very distinct from my species. For these reasons i venture to call it Helicohasidium Mompaf from the well known Japanese name of the disease.
The fungus at first attacks the root of a living tree, and the diseased tree shows external symptoms of the disease on portions above ground : usually the growth of shoots is arrested, the newly develop- ed leaves become gradually smaller and at length die otf ; then the lower part of the shoots begins to die, though the bark higher up may preserve its normal appearance. It takes a tree one or two months to reach this state, after it has first shown the external symp- toms of the disease.
On uprooting a young mulberry tree badly attacked by the fungus, the roots are found to be killed from below upwards, and present the appearance represented in Plate XXIV, Fig. I. The tree figured there is three years old ; the roots marked a have grown three years, and those marked h and c are of this year. The portions marked a' are dead roots, whose bark was already severely injured and so loose that it was separated by the act of uprooting. As these dead roots were of no use to the tree, it produced the new roots h to absorb nourishment from the soil. But the newly formed roots were also injured as the disease advanced, and became unfit to per- form their function ,• and at length another crop of newer roots c was produced higher up, by means of which the tree was enabled to
* Vol. IV. pp. 507 and 579. t See p. 193.
196 N. TAX AK A.
-sustain its life. In the state just described no fructification of the fungus is yet observable, although its subterraneous vegetative mycelia are actively growing.
After the fungus has Ijeen growing in this manner for some time, flat irregular disks of mycelia begin to form under certain circum- stances on the aerial portion of the tree at the bases of the shoots. These disks are the first stages of the |)ileus. The successive stages -of growth of the pileus are shown in Plate XXIV, Figs. 2, 3, and 4. It first appears as a thin etfused mass of mycelia of a dark purplish brown colour, haviug a paler margin of definite outline, and present- ing a smooth velvety appearance (PL. XXIV, Fig. 2, a). It surrounds the basal [)art of the shoots of the diseased tree to a height of 15 cm. or more, sometimes leaving here and there small narrow portions unG<wered. It often encloses in its embrace some extraneous matter, such as decayed leaves, branches, and the like, together with particles of soil. As it gradually develops, it forms generally an irregular r(3undish flat disk, one part of which stands out at right angles from the surftce of the shoot, while the other remaining part is firmly attached to it. The projecting part of the [)ileus then expands laterally either on one side of the shoot or on both sides ; and as the shoot is usually bent horizontally at the base, the pileus becomes also horizontally expanded. The hymenium is produced on the free sur- face of the pileus, on the u{)per and lower sides of the projecting parts, as well as on the exposed side of the part fastened to the shoot. The fully developed pileus is of a whitish colour tinged with violet ; the projecting part is about 5 mm. thick, and its upper surface is more uneven than its lower surface (PL. XXV, Figs, 1, 2).
By carefully detaching the young pileus from the substratum, numerous mycelial strands of unequal thickness may be observed on its lower margin (PL. XXV, Fig. 3). These strands are found on
A NEW 8PECLES OF MULBERRY FUNGUS. 197
almost every portion of the diseased roots, forming irregnlnr networks of various complexity (PL. XXV, Fig. 4). They are ;^-l mm. thick and of a purplish brown colour like the young pileus ; and as to tlieir mode of ramification there seems to be no regularity. Without des- troying even their finest brandies, they can be very easily detached, with a needle, from the roots upon which they grow, t() a length of several centimetres (PL. XXV, Fig. 5). They are often found free, either forming large groups in spaces left between the partly detached cork layers of old diseased roots, or solitarilv in the soil.
The microscopical structure (jf the mycelial sti-and is ditferent from that of Agaricus iiielleus, whose minute details are now well known from the excellent description given by the late Prof. De ßary.* Li the ])resent species the axial portion of the mycelial strand consists of thick-walled hyplue, 3 U. in diameter, mixed with a few finer ones ; and the peripheral portion consists entirely of finer hyplue (VL, XXVI, Fig. 1). Ill the transverse section of the strand this is more clearly seen (PL. XXVI, Fig. '2). In the mycelial strand of Agaricat) vielleiis the hyjiliœ are so compactly arranged as to form a tissue as is clearly seen in the cross section ; + but in the present species the hyphas composing the strand are so loosely put together that they easily separate from one another, and in the cross section they present a circular and not angular form, since they are not pressed together so as to assume the latter form. Moreover the form of the cross section of the strand in Agaricus inellcas is round, but in this species it is flattened. The thickening of the strand is ett'ected either by the copious branching of a single hypha (.)r by the coales- cence of two or more strands. In the group of hypha; formed by the first method, there is always an axial or original thick hy[)lia
* De Bary, Vergl. Morphol. u. Biol. d. Pilze ; Eng. traus. p. 2H-29 t See Fig. 11, p. 2t, of the baiue book.
19S
N. TANA K A.
surrounded by finer ones wliich liave been produced by its ramifica- tion (PL. XXVI, Fig. 3). As the strand grows, the branches of the original hypha also ramify ; and the secondary branches thus produced surround the primary branches, just as the latter surround the original hypha. In this way branches of higher orders are succes- sively produced, and surround the branches of the next lower order. Ordinarily the branches of the liyjiha^ grow in one direction, but occasionally there are found those that grow in two opposite directions from the point of origination (PL. XX\^I, Fig. 4). The older hyphai or those lying towards tlie center of the strand are much more darkly coloured than the younger or those of the periphery. The mycelial strand of the fungus is found only on the surface of the host. When it makes its way into the tissues of the latter it usually forms longitudinally elongated masses, such as are seen in the interstices be- tween the cork layers of the host (PL. XXVI, Fig. 9). Similar mass- es are also found on the surface. These masses of the hypha3 spread widely in the cambium zone and in the yourjg bast, forming membrane- like expanded networks of wliitish mvceli:i. These mycelia send out single colourless hypha*, L5-1 U. in dinmcter (PL. XXVI, Fig. 5), into the rind and wood, and especially into the dotted vessels. They also send out masses of coloured hypha3 to the surface of the host, from which are again developed ordinary external mycelial strands.
Crystalline spheres of calcium oxalate, ^-\ mm. in diameter (PL. XXVI, Fig. 6), are found in great numbers on those places where the white mycehal membranes abound. They consist of an enormous numher of somewhat radially arranged wedge-shaped crystals (PL. XXVI, Figs. 7, 8), ench of which is 20-30 u. long and 10-15 n. broad. If we examine one of these crj'stalline spheres under the microscope, taking care not to crush it, we see only the sides and broader ends of the wedge-sha[)ed crystals ; and by crnsliing
A NEW SPECFES OP MULBERRY FUNGUS. 199
it we can recognize the radial arrangement of tiio crystals. Prof. De l>ary has described crystalline spheres of a similar nature found in the narrow cylindrical hyphaä of the mycelium of Fhallus caniims.* Crystals of calcium oxalate of other forms, such as regular quadrate octohedra, rod-shape, &c., are also found in great abundance in the same place where the crystalline spheres are found.
The mycelia of the fungus form an em^rmous nnmber of sclerotia in all parts of the diseased portion of the roots (PL. XXVII, Fig. 1, (t). The sclerotia are irregularly roundisli bodies 1-4 mm. in diameter, and are dark purplish brown in colour. If tlie nourish- ment in the sap-containing layers of the host plant becomes scanty by the parasitic action of the fungus, and also when the vegetative activity of the host plant is diminished in autumn, the interior of the lenticels and the interstices between the cork layers become filled with the sclerotia of the fungus, while the mycelial strands which remain outside spread widely on the surface of the roots. By carefully detaching the mycelial strands we can ascertain that they have no direct communication with the sclerotia. The number of sclerotia is different in different parts of the roots, according to the degree of the injury done by the fungus ; and the greater the degree of the injury, the greater the number of the sclerotia. The formation of sclerotia does not take place on the outside of the host plant, but always in the inside or in the spaces partly exposed by the formation of fissures (PL. XXYII, Fig. 2). The sclerotia have a dark l)rown rind (PL. XXVII, Fig. 3, i), and a medulla of white soft tissue (Fig. 3, (i) with a few air-conducting passages. The hyplia? of the medidla are cylindrical and septate, anastomosing with one another in a rather loose manner (Fig. 4, ci), and are 4-5 U. in diameter. Towards the surface of the sclerotia, the medulla passes gradual I v into the rind,
* De Bary, Vergl. Morphol. u. Biol. d. Pilze, Eng. traas. p, 11.
200
N. TANAKA.
which consists of thicker- walled nnd shorter-celled hyphœ, forming a compact tissue without interstices (Fig. 4, b). In its younger stage the surface of the rind is felted over wnth the remains of dead hyphae (Fig. 4, c). A series of five ditferent colours — white, yellow hrown, dark brown, rose violet, and dark violet hrown — may he seen in the ordei- stated, from the centre outwards in the section of the Sclerotium. As the mycelial strands gradually grow upwards, they aggregate into a few flat thick strands, more than 1 mm. broad. These strands spread themselves from the a|)ices and unite into a thin broad layer, consisting of reticulated hyphal filaments and covering the base of the shoots of the host plant. As the development of this layer proceeds, the pi lens is formed from it. The pileus is an irregularly roundish flat disk witli a smooth velvety surface, and takes a purplish brown colour, leaving its margin whitish (PL. XXIV, Fig. 2, a). Thin radial sections of a ftdly developed pileus, show that its medullary stratum is composed of loosely anastomosing branclied hyphœ, dark violet brown in colour, and 3-4 u. in diameter (PL. XXYII, Fig. 5). Towards the outer surface of the pileus these hyphte take a vertical position, and produce short and blunt branches (PL. XXVII, Figs. 6, 7). These branches of hyphœ are colourless and shortly septate, and form the hymenial layer. Some of them elongate here and there, and form the basidia, which are curved and 5-8 u. in diameter. From the convex surface of the basidium are produced four sterigmata, which are pointed, slightly curved and 6-10 U. in length (PL. XXVII, Figs. 8, 9, 10). The spores are formed singly on the apices of the sterigmata ; they are ovoid, curved, 10-12 u. long and 5-7 u. broad (PL. XXVII, Fig. 11). The portion of the pileus attached to the substratum produces hairs or rhizoids on its inner surface, which penetrate into the substratum. But the horizontally projecting part of the pileus produces the hvmenium on both surfaces, when it does
A NEW SPECIES OF MULBERRY FUNGUS. ^^01
ii«)t lie uni on the üronnd. The internal .structure of these two ]VM-ti(^ns is, however, essentially the same.
In the merlullary stratum of the pileus which lies on the an^i'ud, an iiumense number of minute algae, belonging to the genera Conferva and Profococrus (PL. XXVII, Fig. Iß) are found in groups, very much like the gonidia of Lichens. On the higher parts of the stems and branches of old mulberry trees, are frequently found orbicular and lirownish purple patches, from 1-10 cm. in diameter ; they are com- monly called " Köyaku-byö " * of the mulberry tree. They resemble very much in their structure the young ])ileus of the speciees of Helicohafiidium in question, except that the hyphfe in the pileus of the foriuer are more slender than those of the latter, being only 2-8 U. in diameter (PL. XXVII, Fig. 12). The sterigmata of the former are also very minute; and I hv.\e not been able clearly to determine their number on a basidinm (PL. XXA'II, Figs. 13, 14). Besides the ordinary slender basidia. 3 u. in diameter, much thicker and segmented basidium-like extremities of hyphîe bearing no sterigmata are often seen in the hymeninm (IM.. XX VII, Fig. 15 h Whether the orbicular patches just described simply represent a form of tlw present species or not can only be determined after further investiga- tion. But I venture to say that it is probably a poorly nourished form of the latter.
In conclusion, I wish to express my thanks to Prof. K. Yatabe who has helped me throughout my work with valuable suggestions.
* The Japanese word kaijaku means a medical plaster; byô, disease.
202 X. TAXAKA.
Explanation of Figures in Plates XXIV — XXVII.
Plate XXIV.
Fiq. 1. Sketch of tlie base of a young mulberry tree, injured by the disease at the roots a, }>. The upper portion a' and the roots c are free from the disease ; the lower portion a of the roots a is completely disorganized. Beduced.
Fig. 2. Portion of the base of a shoot, showing the young pileus a of the fungus. Natural size.
Fig. 3. More advanced stage of a similar pileus with its pro- jecting parts a. Natural size.
B'ig. 4. Mature form of a similar pileus ; a its projecting part; b its basal ])art. Natural size.
Plate XXV.
Fig. 1. Mîiture form of the pileus of the fungus, showing its
upper surface. Natural size.
Fig 2. Lower surface of the same. Natural size.
Fig. 3. Young stage of the pileus carefully detached from its
substratum. Natural size.
■/'':: Fig. 4. Portion of a diseased root, with mycelial strands of the
iiTDgus. Natural size.
- - Fig. Ô. Portion of the mycelial strands detached. Natural size.
Fig. 6. Group of mycelial strands. Natural size.
Plate XXVI.
Fig. 1. Hyphee of mycelial strands. x 440.
F'ig. 2. Cross section of the same. x440.
A NEW SPECIES OF MULBHRRY FUNGUS. 203
Fiff. 3. Hypha3 of mycelial strands, showing the mode of ramification. X440.
Fig. 4. A kind of branching in a similar hyphn. x 440.
Fig. 5. White hypha3 in the tissues of the host plant.
X 440.
Fig. 6. Crystalline spheres of calcium oxalate. xö.
Fig. 7. A similar sphere much magnified. x240.
Fig. 8. Wedge-shaped crystals B of the same ; A showino- their radiating structure. x240.
Fig. 9. Ma.sses of coloured mycelia a in the interstices of cork layers b. x 10.
Plate XXVII.
Fig. 1. Portion of a diseased root, with numerous sclerotia a of the fungus. Natural size.
Fig. 2. Longitudinal section (jf the bark of a root, showing the formation of sclerotia. x 5.
Fig. 3. Vertical section of a Sclerotium; a, medulla; ^, rind ; c, remains of hyphas. x50.
Big. 4. Portion of the same, showing its tissues ; the letters correispond to those in Fig. 3. x440.
B'ig. 0. Hyphas in the medullary stratum of the pileus.
x440. Figs. 6', 7. Hypha^ in the hymenial layer of the pileus.
x440. Figs. 8, 9, 10. Basidia with sterigmata and young spores.
X440. Fi(j. 11. Mature spores. x440.
Fig. 12. Hypha' in the medullary stratum of the orbicular
204 N. TANAKA.
p<atcheH on the higher parta of the stem aud branche« of an old mulberry, tree. x440.
Figs. 13, lé. Basidia of a similar patch. x 440.
Fig. 15. Basidium-like hypha of a similar patch. x440.
Fig. 16. Alga3 in the medullary stratum of the pileus ; A, Con- ferva; B, Protococcus.
Jour. Sc. Coll. VoJ. IV. PI, XXIV.
N. Tanaka del.
Jour. Sc, Coll. Vol. IV. PI. XXV.
X. Tiiiinka do
Jour. Sc. Coll. Vol. IV. PI. XXVI.
Fig. -5.
N Tanaka .1h|
Jour. Sc. Coll. Vol. IV. Pi, XXVII.
N. Tniiaka <lel.
Notes on the Irritability of the Stigma.
by M. lYliyoshi, Rigakiishi.
Witli Plates XXVIII— XXIX.
It is filready known l)y the researches of Meckel* and others that the hifid stigmas of certain plants, such as Martijnia, Biguonia, and especially of some Scrophularinece, e.g. Miinuhis, Torenia, Gratiola, are irritable to touch. But as our knowledge on the subject is still scanty, it will not be superfluous here to state some of my observa- tions on this subject. The plants I studied were 3[azus rvgosus, Lour., var. macrantlia, Fr. et Sav., Miimdus iiepalensis, Benth.. M. sessifolms, Maxim., M. 'mnschatiis, Dong. I shall give in detail only the case of
* • Mazus rugosns, Lour., var. macrantha, Fr. et Sav. (PI. XXVIIl, Fig. 1.)
The plant belongs to Scrophnlarinfce, and may be briefly de- scribed as follows : —
A low annual. Branches prostrate, 5-40 cm. long, often r(^(^ted at the nodes. Leaves exstipulate, sparingly hairy, coarsely and irregularly dentate ; the radical sessile, cuneate-spathulate, 1-4 cm. long, 0.5-1 cm. broad ; those of the branches opposite, some- times alternate, obovate, narrowed int<3 the cuneate base, smaller than the radical leaves. Flowering stems, erect, more or less
* E. Hecke] :— Du mouvement dans les stigmates bilobiés des Scrophularinéps, des Bigno- niacées et des Sésamées. (Comptes rendus, t. LXXIX. 187-4. No. 12, P. 702-704) ** The Japanese name of this plant is Sagigolie.
206
M. MIYOSHI.
]'ube>Gent. 5-25 cm. hiii'h. Flowers distant ; ])edicel8 bracteate, minutely piil;escent, 1-2.5 cm. long- ; bracts minute, scaly, acute. Calyx (Fil!-. H) 5-lobed, cainpanniate, persistent, 0.7 cm. Ioii<>- ; lobes ovate, acute, at length spreading. Corolla (Fig. 2) bilabiate, light blue or often deeper-coloured, sometimes snowy white. Upper lip erect, or curved upward, bifid at the apex. Lower lip deflexed, o-lobed, 1-1.5 cm. l)road and long; the two lateral lobes broader than the mi<ldle ; its palate convex, beset with delicate hairs, whitish or yellowish, with yellowish brown or deep brown S|)ots. Stamens (Fig. 2) 4, didynamons, inserted in the tube of the corolla, distinct at hrst, eacli pair connivent and adher- ing by the anthers at maturity ; anthers wliitish, 2-celled. PolJen- grains (Fig. 6) whitish yellow, elliptical, with 3 longitudinal grooves. Style (Fig. 3) longer than the stamens, ascending under the upper lip of the corolla. Stigma (Fig. 3) 2-lobed, lobes semicircular, 1 mm. long. Ovary superior, globose, 2-celled, Capsule compressed, loddicidal. Seeds numerous, minute, brown. The plant is common everywhere, especially on sunny lawns, and bears flowers from early spring to mid-summer. When I hap- pened to notice* the irritable property of the stigma and began my observations early in April, I visited daily certain spots in the Uni- versity grounds where I found the plant in profusion, some growing in positions \ery convenient for examination.
To observe the phenomenon, take the flower of this plant, and touch the lower lobe of the stigma with the point of a needle or the like ; we shall then see the affected lobe move steadily upwards with uniform speed until it comes in close contact with the upper lobe (IM. XXIX, Figs. 7, 8, 9). We may cause the same action with the least
* A few weeks after, I was iuformed by Mr. T. Yoshiuaga of Tosa, of the same fact whieli be had himself observed.
NOTES OX THE IRRlTABltlTY OF THE STIGMA. 207
possible toucli as, for example, witli the tip of a l)ri.st]e or hair. On the other hand, plaeing a small drop of water on the stiginatie lobes or blowino- upon them does not iiidiiee the motion. Again, mere rub- bing on the style or on the (joter surface of the hjlies does not show even the least sign of motion, though a slight touch on the inner sur- face is very effective. Moreover, this curious property is not contined to the lower lobe only, as may at first sight appear, but it is possessed by the upper lobe as w^ell. Since the lower lobe is widely reflexed, the motion there is very manifest ; but the upper one being nearly in the same line with the style shows no decided motion other than a slight bending down.
I made these experiments on the natural position of the flowers, and measured the time required for the closing and reopening of the lobes. The results varied not only in the flowers of different stocks, but in diff'erent flowers of the same stock, even in the same flower in different stages of development, in different hours of the day, and also in different states of temperature and weather. Generally speak- ing, the closing and reopening in a given flower are more rapid at the middle of a clear warm day than at other times and in other states of weather. Complete closing is performed usually in 3-6 seconds, but may sometimes take 7, even 10, seconds. Com- plete reopening takes place usually after 7-12 minutes, but some- times sooner, sometimes later. Some flowers which I examined on a very warm day, reopened only after 5 minutes. I also found that in young flowers, the closing is more rapid, while the reopening is much slower, requiring about 13-15 minutes. But in mature flowers, chasing takes place in the usual interval of time, while reopening is quicker (7-10 minutes). In all cases the movement of closing may easily be observed, but that of reopening is so gradual that we cannot recognise it without careful observation. The experiments may be
208 M. MIYOSHI.
repeated several times in a given flower apparently without any sign of decrease in irritability. The experiments may also be made on the plants kept in the house with just as good results as on those in their natural habitats. Of the flowers detached from the shoot, the same holds good as long as they are prevented fi-om withering.
*The stigmatic lobes, when magnified are seen to be made up of bundles of filaments (^Pl. XXIX, Fig. 10, 11, loos, tiss.) composed oi cells full of granular protoplasm. The filaments are very loosely acro-regated, passing below to the closer conducting tissue (cond. tiss.) of the style. The inner sui-face (Tig. 10) of the lobe is quite naked but studded with many papillœ (pap.) or the clavate apices (clav. ap.) of the above-mentioned filaments, among which the pollen-grains (pol. gr.) take lodgement. The outer surface (Fig. 11), on the contrary, is loosely covered with a very thin layer of epidermis (directly con- tinuous with that of the style), the cell-walls of which are more or less cuticularized and marked with minute longitudinal wrinkles (Fig. 11). Besides, there may be seen differences in the outlines of the component cells of the epidermis, as we pass from the lobes of the stigma (stig.) to the stylar portion (styl.) below — those of the former being irregular and sinuate, while those of the latter are almost rectangular.
As has been pointed out by Pfeffer. Sachs, and others, cells form- ino" irritable parts of plants, when acted on by external stimulus, allow water to pass out of their protoplasm, thereby suffering diminution of volume ; and this contraction affecting the exten- sive and elastic cell-walls makes the motion visible to the naked eye. This, I believe, may also explain the irritability in the present case,
* The sfcruetares o£ the style and stigma have been studied by J. Behrens. (Untersuchungen über den anatomischen Bau des Griffels und der Xarben. Göttiugen, 1875 )
XOTES OX THE IRRITABILITY OF THE STIGMA.
209
althoLio-li I am as yet unable to detect any decided structural pecLiliarity.
The folli^wiiig observations were mnde to ascertain the signifi- cance of the movement and to know in what relations, if any, it stands with respect to the visits of insects.
April 16, 17. Rainy. I visited certain spots wliere the plants were abundant. Many flowers were open. I saw no single insect near, and the stigmatic lobes of almost all the flowers were deflexed.
April 18. Clear warm day ; 22°C. at noon. At one o'clock p. M. I went to the same places and found that many of the flowers had their stigmas closed. Soon I saw two or three bees come with a buzzing note. They alighted on some of the flowers, thrusted their mouth-parts deep into the throat of the corolla which had honey stored in the basal part of the lower lip. In so doing the heads of the insects unavoidably struck against the open lobes of the stigma wdiich at once closed. The heads were then thrust in deeper and came in contact with the anthers. In a few minutes thev visited no less than a liundred flowers and then flew away.
At 3 p. M. On the same day I revisited the same places and found a similar occurrence.
At 6 p. M. Comparatively small number of flowers (about one-third) had their stigmas closed ; no insects were flying about.
At 9 p. M. Dark night. The flowers did not close, and the stigmas were wide open.
April 19. Foggy morning. At 7 a. m. I saw the stigmatic lobes cpiite re flexed.
At 9 A. M. A few insects were found entering the flowers. April 20. Clear but very windy day. At noon I visited
210 M. MIYOSÖI.
the same place without noticing a single insect, and most stigmas were o|)en.
During these days I likewise examined tlie same species in the Botanic Garden of the University at Koishikawa. and found almost the same state of things.
In all cases I observed that those growing in shady places and those kept in the house had their stigmas always open, while those on open sunny lawns had the parts mostly closed, — the differences seeming to be due to the relative frequency or total absence of the in sect -vi si tors.
These insect-visit(3rs belong almost exclusively to the Hymeno- ptera, a species of Eucera (PI. XXVIII. Figs. 4, 5) of Apidœ, identified for me by Dr. C. Isliikawa, being the chief visitor. The visit of this bee, however, is not confined to the flower of Mazus, for I often noticed that the insect burdened with yellow pollen dusts of other flowers, probably of Taraxacum, thrust its body into the lips of the flower smearing the stigma as well as the corolla with the golden yellow powder.
So far as my observation extends, I may conclude that the iri-italjility of the stigma of this plant is not for the pm-pose of protection against wind and rain, of which the stigma may be tolerably well kept out by the overhanging n[)per lip of the corolla, but — as has been suggested by Hermann Müller* in the case of Miinulm liiteus — for a more important purpose, i.e. ïov cross-fertiliza- tion, which no doubt takes place in the following manner.
A bee laden with the [)olleu of one flower enters another flower of the same species for honey, and thus comes with its liead in contact Avith the lower lobe of the stigma which just overhangs the
* Die Befruchtung der Blumen druch Tnsecton und die ireoenseitig-eu Anpassungen beider. Leipzig, 187:î.
NOTES OX THE IRRITABILITY OF THE STIGMA. 211
stamens. Soon after the contact (hy which the stigma receives the pollen), the lower lobe folds up, opening' the way for the bee which tlien enters deeper and becomes dusted with a new sii])ply of pollen. That reopening of the lobe takes place in abcnit 10 minutes after the closing seems to be well adapted to the reqnirement of the rase, when we consider the intci-Nal of time which usually elapses before the bee revisits the same ünwer. Tlie nsual deep bhiish purple, or rarer snowy wliite, colour of the corolhi serves no doubt to attract the insects, while tlie hairs on the floor of the lower lip seem to assist the visiting insects in aHgliting.
In 3Ii)}nihts tirixilciisis, Benrh.. M. sessifolius ]\faxim.. and M. moschatiis, Doug., all of wiiicli I liaNe observed, the mechanism is precisely similar and adapted for the same purpose as Mazus, so that it is hardly necessary to enter into details.
212
M. MIYOSHI.
Explanations of Plates XXVIII and XXIX.
Indications of Reference Letters.
il. I., upper lobe of the stigma ; /. /., lower lobe of the stigma ; sty., style; stig., stigma; loos, tis., loose tissue of the stigma ; cowl, tis., conducting tisssue of the style ; pap., papillœ ; pol, gr., pollen-grains.
Plate XXVIII.
Fig. 1. Mazus rugosus, Lour., var. niacrantlnis, Fr. et Sav. (natural size).
Fig. 2. Coi'olla cut open along the middle line of the central lobe of the lower lip. showing 4 didynamous stamens (magni- fied 3 times).
Fig. 3. Calyx cut open showing the pistil and its bilobed stigma (magnified 3 times).
Fig. 4. Euccra sp, whicii visits the flower of Mazus. (magnified 1.5 times).
Fig. 5. Upper and lower wings of the same, showing the veins (magnified 3 times).
Plate XXIX.
Fig. 6. Pollen-grains in different positions (magnified 540 times).
Fig. 7, 8, 9. Stigmatic lobes in the successive stages of closing (magnified 22 times). Fig. 7, at the moment of a shock given. Fig. 8, after 3 seconds. Fig. 9, after 5 seconds.
XOTE.S ÜX THE IKRITABILITY 0¥ THE STIGMA.
218
Fig. 10. I*i)i'li()ii of the inner .surfaccof Hie .stigmatie lobe showing- i\iv papilltc or eiavate apices of the loose filameîits togethei- with .some pollen-graius develojiing j)ollen-tii])es. The Illimité globules in the cells represent the granular asj)ect of the proto[)lasm (magnitii'd 540 times).
Fi(i. 11. Outer surliice of the stigmalic lobe togetlier with a portion of the style; the epidermis is shown as broken along the îniddle h'ne so as to sliow tlie loose tissue inside. The cells of the e])idermis on the stigiiiatic portion are sinuous, those on the stylar portion nearly rectangular (iiiagnitied •!?){) times).
Jour. Sc, Coll. Vol, IV. PI. XXVIII.
Fig. 4
Fig. 5
Fig. 2
W
Jour. Sc. Coll. Vol. IV. PI. XXIX,
lOOis
Fig. 10
Fig. 11 7oo«. tu.
'^Wiiid tis
i1 i ^ty
Cond tis
i^'ig- 7
Fig. 8
u. l.
Fig. 6
Notes on the Development of the Suprarenal Bodies in the Mouse.
By Masamaro înaba, Rié^kushi,
With Plates XXX-XXXI.
It hns long lieon known that the suprarenal bodies of the ver- tebrata consist of two substances, the medulla and the cortex. As to Innv these two substances arise and in what relations they stand to each other the o])inions of previous investigators are divided. During the academic year, 1888-89, I studied the development of the organ in the common dimiesticated mouse, a variety of ^lus musculus, and came to the conclusion that the cortical cells are derived, as Janosik stated, from the peritoneal epithelium, and the medullary substance arises, as described by Mits uk uri, from the sympathetic elements. The following is a brief account of my investigation. I nmst here express my sincere thanks to Profs. Mitsukuri and Tjima, f)r tlieir constant encouragement and valuable suggestions, without which I could not have finished the work.
As to the method of investigation I preserved after Selenka the specimens, young and adult, in Kleinenberg's picro-sulphuric acid mixed with chromic acid in the ratio 8 : 1. Some of tlie adult speci- mens were also preserved in bichromate of potash, but as Gottschau justly remarked, it is n<)t necessary to use the chromic acid, at least in
216
M. IX AB A.
tlie case of tlio monso, to demonstrate tlie distinction hotween tlie medul- lîiry and (-(^rtical elements. In the preparations of the chromo-picro- sidphnrie acid the mediilJa i« not coloured Ijrown ; this seems to he due partly to the shortness of the interval during" which the emhryos were exps^sed to the action of the reagent (1'/^ liours) and partly to the presence of the [)icro-sul[)huric acid. To stain emhryos, I used a weak solution of Kieinerdjerg's hematoxylin, as it gives the clearest and most ditferentiated figures. With picrocarmine I also ohtained good preparations of the suprarenal Ijodies of the young mouse. The objects were stained in foto before imbedding in the celloidin paraffin. In all cases I took pains to stain (h^eply and to cut sections as lliin as possible.
I am not C(uite snre of the age of the embryo, since I could not observe any actual c<^-]inlation. After the method of Selenka, I separat- ed the individuals of two sexes for from ten to fifteen days, then put a ]inir together f >r a night, and separated them again the next morn- ing. I connt(M:l the day of separation as the first day of gestation, the next the second day. and so fu'th. Frcnn a number of preserved embryos I determined the approximate size (from the tip of the head to the root, of the tail) of the embryo in each stage as follows :
nth day 3-4.5 mm.
12th day 4.5-6 mm.
13th day 6-8 mm.
14th day 8-10 mm.
15th day 10-12 mm.
In cases of embryos older than this stage, I opened their ab- domen as (piickly as possible before immersing them into the killing fluid, and could not make any relialile measurement.
Suprarenal ])odies of the Mouse, from the new- born to the adult. — I commenced my study with the young mouse about
ox SUPRAKEXAL BODIES IX THE MOUSE, 217
one month old. In thtse specimens, the two substances of the suprarenal bodies are already well marked. In cross sections, the organ is elliptical, consisting of two concentric zones (PI. XXXI. tig. 21); the inner central zone (med.) stnins somewhat less than the outer zone (cor.). Under a high power, the central zone is found to be composed of irreü;ular cord-like cell-a^'o-reo-ates. each of which is
i O Co o
bounded by strong connective tissue fibres. The cell-protoplasm is faintly stained ; the nuclei are large (6 U- on an average) and slightly granular. The nuclei of the cells of the outer zone are smaller in size (5 /z.) and highly granular. Their cells are smaller than those of the central z(3ne ; this is especially the case in the middle portion of the outer zone where the cell-protoplasm is stained deeper than in any other part, so that the outer zone is subdivided into these minor concentric zones. But these three zones gradually merge one into another without presenting any distinct limit. The transition from the <3uter (cor.) to the central zone (med.), on the other hand, is very sudden ; the limiting line is distinct and tolerably even, forming an elli[)tical outline. Evidently the central zone is the medulla, and the outer the cortex.
Turning now to the mouse ten days old (PI. XXXI. fig, IS), a considerable difierence is observed in the structure of the medulla. The medullary substance (med.) projects irregularly into the cortex (cor.), and the boundary is not yet even, though its elliptictd outline can already be made out. The cells and nuclei of the medulla are stained deeper than befjre, so that the distinction of it from the c(.)rtex is obscure in some parts where the farmer projects int(j the latter. The difficulty is further increased by the fact that the cord-like arrangement of the medulla is as yet very weakly developed, and the respective sizes of the nuclei in the two substances are approximately equal. Put tracing carefidly the nnirgin of the medulla, we can tind here and
218 M. IXABA.
there the distinct groupiiigs of its cells into cords (tig. 19), where the nuclei are larger and the protoplasm is less stained, than in the adj(jining cortical cells. This stage seems to be the formation of the medullary cords. The three minor zones of the cortex are already to he found, thouoh less distinct than in the staii'e described before.
In the mouse three da^^s old (hg. 1(5). the medulla is very irregular in its outline. Alon£>' its maro-in the cells are "'reatlv minüded with the cortical cells, luit the distinction is cleai-, the cells and nuclei of the medulla being stained more deeply and packed more closely, than in the cortex. The three minor cortical zones are not yet distinguishable.
In the newly-born nKjuse (wood-cut 1 and PI. XXXI. hg. 15), the medulla no hunger forms any compact mass, but has cortical cells, intermixed throughout its substance. The distinctions between the two substances can however be easily made out as before.
The relative size of the nuclei in the two substances is interesting. In hgs. 15 and 16 (PI. XXXL), the nuclei of the medullary cells are evidently smaller than those of the cortical cells, while in tig. 21, the case is reversed. I measured the nuclei of cells in the two sub- stances near their boundary line at various stages. The following gives the average size (in u) of those nuclei.
1 day old. 3 days. 10 days. 29 days. adult.
Medulla 5.2— 5.6— :^.Q+ (5— 6 —
Cortex G.5 — 6. — 5.4— 5 — 5 -f-
It will be seen from the tal)le that for about a month after birth, the cortical nuclei are gradually decreasing in size ; at the same time the medullary nuclei are growing though very slightly. This is, I believe, due to the formation of the cord-like arrangement on the part of the medulla, and of the z<_)iia reticulata <_)n the part of the cortex.
ÜX SÜPRAKENA BODIES IX THE MOUSE.
219
Woodcut 1.
From a mouse one day old. The left .suprarenal body is represented. Ao=Aorta, B v. = Veins, Cor.=cortex, Med. = Medulla, Mes.=Mesentery, s. s. = Maiu mass of Sympathetic ijanglia, sy. <j:.— gang-lion of sympathetic origin. 2xBB.
So far US trart'd, the niediilla i.s always di.stiiK-t fVum the cortex, and its origin cannot be decided. lUit some interesting (and evident- ly a little ahnornial) cases were met with. In one mouse jast born (woodcut 1), the roughly eliiptictil medulhi (med.) .situated in the centre of the organ sends otf an (jifslxjot at one place toward the medial side, actually reaching the C(jmiective tissue capsule. Outride the organ hes a large ganglion (sy. g.), which is found on tracing- sections to Ije continuous with the main sympallietic system (s. s.). The medullary cells of the suprarenal body and the true ganglion cells are very similar in their size and colouration. This condition was observed only on the left suprarenal.
In a three-day (jid mouse (woodcut 2), again on the left side, I obser\'ed an actual ctjnnection of the medidhi with the gangli(jn. In tig. 17 (PI. XXXI.), which is a more magnified tigure of the wootl- cut 2 I), a mass (jf cells with small and deeply stained nuclei (med.) eads out of the organ, and directly joins the ganglion cell mass (sy. g.)
22Ö
M. IX ABA.
lyiii«^ close to it. In another mouse at the same stage, a simihir condi- tion Avas observed; the gan<^lion besides Ijeing joined Ijy a nerve com- ing from tlie neighbourhood of the kidney.
Woodcut 2.
■i snccessiTL- sections (not cunsccutivu) fiom the posteriui' cud of the left suprarenal, a :3-<lay old mouse. Horizontally sliadrd part— Cortex. Vertically shaded part- Medulla.
riuided by these facts, I examined again tlie ten-da^^s old mouse, and found in one case the medulla projecting on its medial side and actually t(3U(-hing the connective tissue capsule (PL XXX f. fig. 1^0.) but it Avas not traced to the sympathetic ganglion. These facts plainly show that the medulla is derived from the ganglion colls. When and how the ners'ous elements enter the organ, will be describ- ed below.
ON SUPRA-REN'AL BODIES IN THE MOUSE. 221
In passing, it may be remarked tliat in wciodcut 2, a small portion of the rortical substance is projecting far posteriorly and is separated from the main mass h\ the sympathetic g'angli(Mi. In fig. 17, the part (ac. ror.) is distinctly separated from tlie main mass hy strong connective tissne cells. This is the so-called accessory suprarenal body. From the mode of the entrance of the nerve into the organ, as seen in this and other rases, I am inclined to be- lieve that the introduction of the nervous elements into the organ greatly influences the formation of the accessory suprarenal body, though it may not lie the sole canse.
Uf the adult suprarenal body (PL XXX. hg. 22). I have little to say, as it does not differ much from that of the ono month old monse (hg. "21). One feature interesting from the embryologienl point of view is the occasional ]jresence of the ganglionie remnants. In one specimen (hg. 23), T f>und at the murgin of the medidla on its medial side, a mass (sv. g.) of indistinct cells, highly granular and deejdv stained. Their nuclei are smaller than those of the mc(bdla or cortex cells but decidedly larger ihan those of the connective tissue cells. P)V tracing sections, [ fonnd the mass t(^ project pyramidally into the cortex and finally reach the capsule. In comparis(^n with the ten-days old suprarenal l)ody (tig. 2»») this mass may be considered as a part of the nei-vons elements, wliich has not been transformed into the true medulla. Of the laro-e ganulion cells such as seen outside the adult suprarenal body. \ could find none pressent within the adnlt organ.
I)(Melopment of the HeduUary Substan<'c, in the 1 3 t h - 1 8 t h day E m b r v o s . — lîalf )ur ' remarked i n his mono - graph on elasmobranch fishes that the suprarenal bodies of
1. Olilei* erature I had not access to.
■ 222 M. IN ABA.
Vertel)rate,s consist of two substances distinct in tlieir ovig-in. This Braun " hns confirmed in Reptiles, and Mitsiikiiri ' in Mammalia. Mitsukuri says that in the 16th day embryo ral)bit the medullary substance is already distinct ; sympathetic nerve cells closely applied to the inner side of the suprarenal blastema send in a process partly composed of nerve fibres into the ventral end of the suprarenal ; the cells thus carried in become gradually transformed into the medulla, (iottschau* and Janosik'' dispute this statement. TlnMigh these authors do not deny the entrance of the nerve fibres into the suprarenal, they state that the two jiarts of the suprarenal substance cannot be distinguished at the time of the entrance, and the medullary substance is gradually ditterentiated from the cortical substance at a considerably later stage, Gottschau even states that in some mam- mals the medulla is developed only after birth. Yet fivMn the descrip- tions of the two authors, the exact nnxle of the formation of the medulla is not yet clear, and it is also necessary to trace the ultimate fate of the nervous fibres sent into the suprarenal Idastema.
The suprarenal blastema is already distinct in the 13th day embryo. It is a somewhat elongated mass of cells lying between the 16th and 17th l)ody-segnients, just behind the lobes of the lun^'s. The anterior end of the l)lastema lies on about the same level as the 2nd tubule of the mesonephros, while the 3i'd segmental tul)ule lies on ab(out tl>e middle portion of the suprarenal. In cross sections ( wooden r 3 and V\. XXX. fig-. 8), the blastema
2. F>au und Entwicklung der Nebennieren bei Reptilien. Arb. aus dem Zoo]. Zoot. Inst, in Wurzburg. Bd. V. 1882.
;î. On the Development of the Suprarenal Bodies in Mammalia. Quart. Journ. of Mic- roscop. Science, XXII. 1882.
4. Structur uad embryonale Entwiclclung der Xe))ennieren bei Silugethieren. Arch. f. Anat. u. Physiol. 18S3.
5. Bemerkungen libn- die Entwicklung der Xe})enniere. Arch. f. Mikr. Anat. XXII. 1883.
ox SUPRARENAL BODIES TN THE MOUSE
223
(s. r.) is seen ns n rounded mass (al)out ^ mm. tliiek) of cells lying between the aorfa(Ao.) and the mesonepliros (st.), immediately below the cardinal veins (v. car.). Already at this staL>,"e, a blood vessel (e. V.) is seen in the posterior portion of the blastema, coming from the cardinal vein ; this vein is ultimately transformed into the central vein of the adult suprarenal. The suprarenal blastema (s. r.) is distinguished from all neighl)ouring tissue cells by the densely packed state of its large and faintly granular cells. Cell boundaries within the blastema are only faintly indicnted, but a careful observation sliows that relis are collected into irregular groups, separated by scanty connective tissue cells. The cell nuclei are slightly granular and their size varies between 5-7 u. These characters of the cortical cells are retained during the subsecpient developmental phases and aie useful in distinguishing them from the medullary cells.
Woodcut 3.
UigJit
A cross section taken near the posterior end of the suprarenal bodies. — 13th day embryo. Ao.=aorta, c. v.=eentral vein of the suprarenal, Gr. 0.=generatiye organ, s. r. = suprarenal blastema, sy. g. ^sympathetic ganglia, v. c =vena cava, v. car ;= cat'dinal vein. 2xaa.
The sympathetic ganglia (woodcut 3 sy. g.) are well developed on the upper lateral corner of the aorta, ami a strong branch from
224
M. TNABA.
the spinal nerve enters each ganglion. The ganglia send out branches downwards between the aorta and the cardinal vein, but they are ver^' tine, often consisting of a single row of cells and cannot be clearly traced. Yet on the medial side of the suprarenal blnsteinn, closely applied to it, there is seen a small irregular grou]) of deeply stained cells (fig. 8, sy'. g'.), whose nuclei are a little smaller and more granular than those of the suprarenal, and similar to the cells of the sympathetic ganglia. Probably these cells are of the nervous nature.
Woodcut 4.
Migli <- —
A cross section taken near the posterior end of the suprarenal 1)odi»js.— Later stage of the 13th day. Ao.— aorta, Bv.=veins, G. O.^geuerative organ, s. r.=suprarenal blastema, s. t.=segmental tubiilus, sy. g. = symi)athetie ganglia, v. o.-- vena cava, v. car.— cardinal veins, "W. D.=WolfRan dnct. 2xaa.
Towards the close of the 13th day (woodout 4), the cardinal veins greatly retrograde, on the right side almost completely. Thus the central vein of the right suprarenal becomes now the direct continuation of the vena cava, and the left central vein becomes a side branch from the great vein. The suprarenal blastemas of the tw^o sides are now placed not ventrally, but laterally to the aorta. The mesonephros is pushed laterally and Miiller's duct is distinct. In
ON SUPllAREXAL BODIES IX THE MOUSE. 225
the 14th day embryo, the blastemas have a considerable size, a little projecting into the coelom cavity. The kidneys appear at the post- erior and dorsal side of the suprarenaL By dissecting the embryo, the suprarenals are seen as a pair of oval shaped bodies, flattened antero- posteriorly as if pressed by tlie developing kidney. The inner end of each su])rarenal is attenuated and thus overlaps the anterior inner corner of each kidney, — a state of things retained and more distinctly seen in later stages. In the 15th day embryo (woodcut 8), the suprarenal bodies liave shifted their ])osition, farther dorsalward, being now placed just laterally t(j the ^'ertebral body and dorsally to the aorta. Thus at no stage, are the suprarenals of the two sides con- nected together as some writers state. As Mitsukuri and Gottschau well remarked, it is the ganglion placed inside of each suprarenal, which is posteriorly joined to its fellow by a cross bar.
The nerves sent out from the sympathetic ganglia are distinct in the later stage of the loth day (woodcut 4). Two or three branches are successively given out from the ganglia and all are united into the splanchnic plexus lying inside of, and closely applied to, each suprarenal. A Ijranch is further sent downwards from the plexus to the front <jf the aorta, where it is connected (in the next day) with its fellow of the other side. From the 14th day onward (woodcut 5), we can distinguish in each splanchnic plexus at least two ganglia, the larger anterior and the smaller p(3sterior ones. The posterior <j;ano^lion on the ri^'ht side is elono-ated and becomes con- tinuous with the cieliac ganglion, no that the latter may be said to be the direct continuation of the right splanchnic plexus. From the ganglion closely applied to each suprarenal (that is the second ganglion of the plexus), some fibres enter th(3 organ. Though very fine, these fibres can be traced for a certain distance within the organ. Woodcut () and tig. 9, taken from the 14t,h day embryo, repre-
226
M. IXABÀ.
sent the state of things, when the nervous elements are just entérina- the organ. It is seen only for one section.
Woodcut 5.
^'2')lanchnic GinujUa VenaCara Aorta Siilanchnic Gaii/jlia Left Siqirarriiitl
Eight Su2:>rctreiiai
Central Vein
J?. Siiprai'. Artery Ren. Art.
Ren. Vein
L. Siqn-ar. Artery
Central Vein
Ren. Art.
Ren. Vein
Ureter Vena Cava Aorta Ureter
Semi-diagramatio figure, showing relations of suprarenals to ganglia and bloodvessels.
Woodcut 6.
From a 14th day embryo, representing the right suprarenal. The place marked x is more magnified iufig. 9. (PI. XXX ). Ao.=aorta, Bv. —veins, G. 0.=generative organ, s. r. = suprarenal blastema, s. s. — main mass of sympathetic ganglia, sy. g. = ganglion of the sympathetic origin.
In I he loth dav enibrvo, the nerve fibres within the oriran are
stronii'er and more easilv to be ascertained. Tiiest; branches are
ox SUPHAKEXAL IJüDIEö IN THE .MOUSE.
1^27
tolerably constant in iiuin1)er. tJcucrally into tlie left snprarena] (woodcut 8), one ^'el•y .strijng Ijumlle enters at about the middle and ventral portion of its inner margin. At the corresponding point of the right suprarenal (woodcuts 7 and 9 A) a strong bundle (but nnjre slender than that of the left side) is seen ; on the same level and S(Hnewhat dorsal to the one just mentioned anotlier smaller Ijundle runs in from the same ganglion. Besides these, a small bundle may S(jme- times be seen entering the organ at its p(jsterior end (woodcut 9 B). All these bundles are very delicate, and can be seen only for three (jr four consecutive sections.
It will be necessary here to describe the characters of the ner\ous cells to distinguish them from the cortical cells. The protoplasm in these cells is not so rich as in the cortical cells, and is very granular ; their nuclei are comparatively small (4.5 u on an average), thickly packed, and deeply stained due to the presence of many granules.
Woodcut 7.
•5'y. 9.
A cross section takeu from a loth daj embryo, right suprareual. S. r. = suprarenal blastema, Sy. g-. = <>-aug-lion of sympathetic origin. 2 X B.
The place marked ^ is uiDre uiagnified iu fig. 10. A. (PI. t.) The jilace marked * is more magnified iu fig. 10. B.
In tig. 10 A (which rei)resents a portion of tlie woodcut 7 under a higher ))ower) taken frc^m a 15th day embryo, a mass of
228
M. IN ABA.
nervou« cells is seen insinuutini^' itself intcj the cortex. The other smaller bundle (marked in the woodcut witli a *) is interesting. It is very delicate and scarcely visible, running deeply into the cortex, and iinally ending in a small cluster of cells, which are distinctly of nervous nature (Pi. XXX. tig. 10 B).
Woodcut 8.
A cross section of a IGth day embryo, left side. Ao.= aorta, cor. = cortical substance, med = medullary substance, Sy. g. = ganglion of symijathetic origin. 2xBB.
In the 16th day embryo, the nervous elements carried in the organ are consideral)le (woodcuts 8 and 9). They form now a reticulated network imbedded between the cortical cells, appearing in sections as small scattered groups of cells. Though the main mass of the nerve cells is clustered in the centre, some cell groups (PI. XXXI. tig. 11) are fjund in the peripliery of the organ at its medial side and send out their tibres, which actually piercing tlirough the con- nective capsule become continuous with the ganglion near the organ. In others (tig. 12), altlnjugh the tibres pierce through the capsule.
ON SUPRAKEXAL BODIES IN THE MOUSE.
229
they can not be traced to tlie ganglion, but are lost on the way ; iti otliers again, they are lost in the connective tissue capsule of the organ. rro7n this stage onward we can call the nervons elements within tlie suprai-enal more appr(^i)riately the medulla. I l)elieve this and tlie previ(Mis stage are snfticient to show the nature of the medullary substance. Probal)ly these two stages were not observed by (rottscliau and Janosik. who thus concluded that the medulla is differentiated gradually from the cortical substance.
Woodcut 9.
Cross soction takon from a Itltli day embryo, rif^lit side suprarenal,
A, at the mid<llo of the or^-au. P.. near the posterior end.
c. v. = central vein. oor. = cortex, med. = medulla, sy. "•. = o-ano'lion of sympathetic
origin. 2xBB.
As to the further growth of the medulla, I have little to describe. It consists merely in the increase oi' the medullary cells which gradually form a compact mass in the centre of the organ, the cortical substance becoming in consequence scanty in the centre and pushed to the; ])eriphery. (PI. XXXI. 14)
The severance of the nervous connection commenced in the previous stage is usually complete in the 18th day embryo, which
230 M. IXABA.
wns t'iie oldest one I investigated. The process takes place simply by the growth of the connective tissue capsule around the piercing rierve whicli is consequently reduced to a narrow neck and hnady cut ott' (fig. 13). Still the direct connection of the niedulhi witli the syni{>athetic ganglion is retained in some cases, especially on tlic left side, fn all such cases observed, the connective link which persists is enorinc^uslv strong, so much so that sometimes the ganglion itself may be iimnersed in the organ. This is one reason why the connection j)crsists longer. Fiu'ther ns before stated, on the left side the nervous fibres entca- the organ mostly as a single conspicuous bundle, whih^ on the right side they are usually divided into several smaller clusters, which will more easily be cut off. Hence the connection when it persists in tlie newly born mouse is always found on the left suprarenal as before described.
As to the general aj)pearance of the Idstological elements of the suprarenal bodies in this stage, it does not much differ from those of tlic newly born animal.
Development of the Cortical Substance in the 11th- 1 :^ th day Embryos. — As regards the (n-igin of the cortical sul)stance the attention of earlier writers has been principally directed to the in- ditferent mesoblast. Kiilliker''' stated that the siipi-arenal bodies in the rabbit first ap|)ear in the 12tli or 13th day embryo as masses of some- what large round cells on each side of, and ventral to the aorta, on the inner side of the Wolffian bodies and doi-sal to the mesentery. Mi- tsukuri continued this and added that dors;dlv tliis mass is tolerably distinct from the <)ther mesoblastic cells, but \entrallv its termination is indetiiiite. Ihaimi', 13raun, and more i-ecentlv Gottschau derived
f). Entwieklmio-sovscliiehte des Menschen uml der li('>lieren Thieve. 1S79. 7. Eiu Beitrage 7.nr Kentniss des feineren Baues und der Entwiclduno'sgeschichte der Nebennieren. Arch. f. Mikros. Auat. VI IT. 1S72.
ON' SUPIiAREXAL P.ODIES I\ THE MOUSE. 231
the cortical cells from the mesolilast, l)nt in connection with the walls of the blood vessels (atn-ta, cardinal veins, vena cava, or vena renalis). Recently for the hrst time Janosik stated that the suprarenal body takes its origin from the peritoneal epithelinm, and it is in fact in tlu' ch^sest connection witli tiie beo-inniiiL»- of the sexual oro-an : this connection pt-'rsists i'nv a tolerably long time nntil it is cnt otF by the entrance of b]o(-)d vessels, especiall}' the vena vertebralis |)osteriori and other veins emptying into the same from the Wolffian liodies. Weldon,"" on the other hand, derived the blastema from the Wolffian 1)odies. According to his statement, a cell-mass proliferates from tlie walls of the glonieriilus and separates into two masses : the one travellirjg liackwards becomes the suprarenal Ijody, the other growing downwards and entering the sexual organ becomes the tubuli semirjiferi (in the male). Mihalcovics" also affirmed like Weldon the connecti(Mi of the suprarenal Ijlastema with the sexual " strano* " (=:segmental " sträng" of Jîraun), wdiidi he dci-ives, however, from the germinal epithelium. At this point he agrees with JaiK^sik, but ditfers in the statement that the suprarenal b(xly is only tlie undiiferentiated anterior continuation of the sexual or(^an. In front of the anterior end of the generative ridge the suprarenal cells are said to be directly proliferated from the peritoneal epithelium, and posteriorly they are said to he continuous with the sexual sträng but not in direct connecti(^n with tlie peritoneal e[>ithelium. In Ijirds and mammals, the direct proliferation of the peritoneal epithelium to firm the suprarenal blastema is said to be confined to a very small tract, so that it might be overlooked if series of sections were not studied.
8. Suprarenal Bodies of Vertebrates. Quart. Jour, of Micros. Scieneo XXV. 1885.
9. Untersuchuuo-en über die Entwicklung des Harn- und CJe.selileehts-apparates der -imnioten. Inter. Monatschr. f, Anat. u. Hist. II. 1885.
-•">- M. IXAKA.
To trnoo the on'o-in of the cortical snhstanco is in far-t extroniel}^ difficult, as its cells are faintly distinguished from the other tissue cells. The cortical hlastema in the mouse is tolerably v:e]] seen in the early stage of the 12th day of gestation. The mesonephros in the monse is very weakly developed. Only the aiiterior two or three segmental tuhiiles actna]l3M-)pen to the Wolffian duct ; iolh^.wing these ran be traced five or six blind tubules, vhicli lessen in size one after another, until finally no tul)ular structure is seen beyond tlie 8th or 9th one, the cells being merely clustered in ])r(^per ])laces. The supi'arenal blastema extends from about the middle of the anterior two segmental tuljules to about tlie 6th or 7tli tubule. In ci'oss section, it is large anteriorly and gradually lessens in size posteriorlv. It is placed just at the angle of the mesentery (PI. XXX. figs. .") and n\ occupying the space enclosed by the aorta and the cardinal vein on the medial and dorsal side, and liy the mesonephrc^s and the genera- tive organ on the lateral size. ^Fediallv the [blastema is distinctly liounded by connective tissue cells. Where the S-shaped segmental tul)ules are projected in medial direction, they approach the dorsal end of the suprarenal blastema ; in other cases they are far removed from the suprarenal. In no cases do the tubules send out cells medially. The walls of the cardinal vein show no signs of proliferation. ]>ranches of the vein to the suprarenal are not yet developed.
The relation of the suprarenal blastema with the beginning of the generative organ is interesting. These two blastemas are ]il;iced side bv side, their anierioi- extremities reaching about the same level, but posteriorly the generative blastema extends far beyond the end of the suprarenal. The cell elements of the two are very similar, consisting of large cells with large round nuclei, which are stained slightlv deeper than those of the connective tissue cells. Ihit the two blastemas are separated from each other in all places, except at
ox SUPRAKENAL BODIES IX THE MOUSE. 233
the anterior parts, bv an intervening tliiu septum of connective tissue cells. Tliis septum, consisting of the two or three rows of cells, runs from the peritoneal epitheHum in dorsal direction, and finally separates itself into two branches, tlie one bending laterally and covering the generati\e (jrgan, the other bending medially and cover- ing the dorsal end of the suprarenal.
The cells of tlie peritoneal epithelium which touches the supra- renal blastema are arranged in a single row (fig. 6). But as we proceed anteriorly (fig. 5) the epithelium cells are evidently proliferating 5 they are actually pushed upwards and are even con- tinuous with the suprarenal blastema. Tracing sections still anterior- ly, the connection becomes more intimate, till near the anterior end of the suprarenal (TL XXX. fig. 4) the |)eritonea] epithelium cannot be distinguished from the suprarenal blastema itself. Here the septum no longer exists between the suprarenal and generative organs. The cells of the two blastema are laterally continuous with each other, the two being indicated only Ijy the two rounded eminences projected dorsal ward; ventrally they are both seen to be the proliferation of the peritoneal epithelium.
In a stage somewhat earlier than that above described, the sup- rarenal blastema is not yet so distinct. Figs. 1-3 were taken from an endjiyo in the later stage of the 11th day of gestation. Fig. 2 taken frcjin near the anterior end of the left suprarenal blastema corresponds with fig. 4, and figs. 1 and 3 taken on both sides at the middle ot the organs corres[)ond with fig. 5. From the somewhat detailed description of the previous stage, any further remarks will not be needed. Only it may be added that the proliferating cells are xevy indistinctly bounded dorsally, but a carefid study shows that they are proliferated from the e[)itheliuni. Why I do not consider these ])roliferatinL!; cells as the sole bei^'inniiiL;- of the u'enerative oru'an
234 M. IX AB A.
is simply that tlie position <jf (hat oro^an is always in the following stages a little removed fr<jni the angle of the mesentery. Further in figs. 1 and 3 the proliferation of the peritoneal epithelium can be roughly se[)arated into two parts, the medial and lateral.
From the above description, I think that Janosik's statement as to the origin of the cortical cells is quite correct. My figure 1 corres- ponds with his figure 1. The only ditference is that the mesonephros in the mouse is not so well developed as in the case of the pig. Thus Junosik stated that the cells proliferate in the medial direction to the aorta, ^vhich condition is observed in the mouse only on the right side. The mesentery in the mouse being shifted from the medial line a little to the right side, its angle on the left side is carried far to the medial line, so that on this side the suprarenal blastema is projected upwards and a little lateralwards in the direction of the mesonephros (compare figs. 1 and 3). I camiot determine whether the suprarenal body is really the anterior continuation «jf the fj-enerative ridge or not. The state of things as seen in the tigure given by Mihalkovics from a sheep embryo (his fig. 1(37) I could not find at the corresponding point of the mouse. Dut from the fact that the peritoneum is proliferated and tlie su[)rarenal blastema is placed side by side with the generative organ in its entire length, it is more likely to be the lateral separation, and not the anterior continuation of the generative organ.
Further growth of the suprarenal blastema consists simply in its separation from the peritoneum and clustering into a more compact round mass, as will be seen in fig. 12. The pr<diferation of the peritoneum, though slight, is still observed towards the close of the 12th day. Beyond the anterior end of the suprarenal bodies, a slight proliferation of the peritoneum w.is sometimes observed (Fl. XXX. fi^r. 7). I think that the com[)act suprarenal blastema is formed
ox SUPRARENAL BODIE« IX THE MOÜSIv 1^35
rom the main mass of the proliferated cell«, while a small portion may be left behind, which .seems linally to disappear without eDterin<i- into the formation of the suprarenal bodies.
T o b u m u p :
1 . T h e M e d u 1 1 a a n d t h e cortex are distinct in their o r i g i n .
2. T he CO r t i c al b 1 a s t e m a a p p e a r s in t li e later stage o f the 11th day of gestation, as a proliferation of the perito- n e u m at t h e angle o f t h e m e s e n t e r y a n d laterally continu- ous with the beginning of tlie generative organ. The separation from this connection is complete on the 13th day.
o. The medulla is derived from the sympathetic t! 1 e m e n t s , w h i c li enter the o r g a n in t h e 1 4 1 h d a y e m Ij r y o . They i n crease a n d f o r m a reticulate d mass at the n entre, from which the cortical cells are gradually pushed aside. The connection with the sy nipathe t ic sy s tem is usually cut toward the close of gestation, but in some may be re t a i n e d until a f t e r birth.
2S6 M. IX AB A.
Explanation of Figures.
tic. cor. = accessory suprarenal. A()= Aorta. Art. c.=cœliac artery. Bv.=N'ciiis. cor.=cortical cells, c. Y.=central vein of Suprarenal l)0(]ics. l)iai;'.=Dia[)liragni. <i. o.=Generative organ. Kid.= kichu'v. Med.=Me(lulhu"y cells. Mes.=Mesentery. S. r.=Supra- renal body. IS. t.= Segmental tuljules. Sy. f.=Synipatliedc nerve fibres. Sy. g.=Synip;ithetic ganglion cells, v. car.=cardinal veins. V. c.= \ ena ca\ a. \V. D. = Wolffian duct.
Fig. 1. From the 11th day embryo. Right side. Taken from
the level of the ind segmental tubule. 2 x E.
Fig. rJ. From the 11th day endjryo. Left side. Taken from
near the 1st segmental tubule. 2 x E.
Fig. 3. From the 11th day embryo. Leftside. Near the 2nd
seirmental tubule. 2xE.
CT
Fig. i. From the 12th day embryo, early stage. Left side. Near the anterior ends of the suprarenal and generative organs.
2xE.
Fig. Ô. From the 12th day embryo, early stage. 10 sections behind. 2 x E.
Fig. (J. From the 12th day embryo, early stage. About the level of anterior one third of the left suprarenal. 2xE.
Fig. 7. From the 12th day embryo, late stage. Left side. l>eyond the anterior end of the suprarenal bodies 2xF,
Fig. (S'. From the loth day embr^^o, early stage. Right side.
2xE.
Fig. L>. From the 1-lth day embryo. Right side. Tlie [)lace marked x in woodcut G. 2xF.
ON SUPHiVTIEXAL P.ODIES IX THE MOUSE.
287
Fig. 10. From the loth day embryo, llioht side. A. tlie place marked ^ in the woodcuf 7. 2 x E. P». tlie pl.ice marked ^^
2xF.
i'Vy/. ii. From the IGtli (hiy embryo. Left side. More maonitied tii^nre of woodcut 8. oxJ)D.
t'ig. 12. From the Killi (biy embryo. Rio-ht side. M..re magnified fionre of woodcut Î) A. 3 x J^D.
I'ig. IP). From tlie 18th day em1)i-yo. Fi-om the posterior part of the left .suprarenal. 2xE.
Fig. 11. From tlie IStli day embryo. Fi'om another em1)rvo. Central portion oi a .section, taken near tlie j^ostci-ior end of the right suprarenal. ox])D.
Fig. IT). From the 1 day old mouse. Right su])rarenal.
3xD.
Fig. IC). From the o days old mon.se. 2xF].
Fig. 17. From the o day.s oM mouse. Another speeimen. Rosterior end of the lefi suprarenal. Move magnified fioufe of woodcut 2. R).
Fig. IS. From a mouse about 10 days old. 2 x E.
Fig. 19. From a mouse about 10 days old. Medulla is
weakly developed. 2 x F.
Fig. 20. From a mouse aliout 10 days old, another specimen. The remnant of the connection with the sympathetic.
2 X E.
Fig. 21. From a mouse about 1 month old. 2 x E.
Fig. 22. From an old wild mouse. 2xE.
Fig. 2S. A p;u't of the right su[)rareiial from an old mouse.
2xE.
Jour. Sc. Coll. Vol. IV. PI. XXX.
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Page 245, line 10, for Prof. Schenk read Schimper. „ 246, „ 20, „ I). Kochihe read B. Kochihei. „ 300, ,, 5, from end, for " nickel " read " bisrüuth."
On some Fossil Plants from the Coal-bearing Series of Nagato.
By
Matajiro Yokoyama.
With Plates XXXri— XXXIV.
Fii tlic :'])i-iii£i' of 1S90, aIc. l\i,('liilM> oi' tlie (k'oloo-icnl .airvev (lir'ooYcred soihc ])]:iiit i'ciiiüiiis in the cw.'il-lK'nn'n^' icrie.s of Xm^'uIo :it •A ])]:!(•(' f:i]I('(l V:iin:!iioi, some .']() kiloineters en;'t of the city (jf Ak:un;iLi-:is(-ki/' Tliese ])]:nits lie ren^o-iiize«! :is ^[c.'ozoic, and sulj^e- (pieiitlv sent tlieni to nie ior exruninatioii. ()n lookiii^'at tliese ])lant>!, I was at (^nce struek 1)v the oetanTenee of form.: whieli are (jnite foreio-n to onr ^riddle dnrassie flora, lately worke(l ont"-' 1)\' myself, and wliidi arc liirlua'to knoAvn oid\' a,' ocrni'rinL;" in tlie IHuptie. Tiiterested in this disco^■ery, I visited the locality myself in tlie ninmci' ()f tlie same year, in ordi'r to ohtain. ii" ])ossil).lc, :i laiycr mnnhcr of species, which, as T thonu'ht, Avould l)e (jnite indispensahle for the determination of tlieir exact a_u"e. Soi'ry to ::av, ho\ve\ei', T did ni)t succeed in makino- :inv LjTeat additions to tlie iiiimher i-f s])ecies, nearly all tlie jilants whicli I found ha\i:iLi- Ijeen already represented in tlie Ci,IIection of ^Ii-. i\ochihe. Still my collection ])ro\'ed to l)e \ery useful, f )r I had tlius a laru'er numhia* of in(h'\ idual.- for comparison.
The coal-heariiii^' série.; of Xag'ato occupie,; a limited area in tlie .southern ])ortion of that ])rovince bordering' the Iidaiid sea, and con-
1) 'I'liis city is better Icnowu nuilpr the old uauie of SluiiioiKischi.
■1) Yokoyama, Jurassic Phmts from Katja, ITidn, mul Kchi~i')i, -Inininl of the College of Science. Imperiid University, Jajxin, vol. Ill, part I, ISS'.l.
240 M. YOKOYAMA.
.si;st.^ of :i thif'k oom])lox of sandstone-!, cltiy-sl'itcs iind shnles, witli subordinate layers of sclmlstciii and autlirncite in it.s lower ])art :ind of brownco:d in its u])])er p'U't. These strata wliieli form a low hilly country surrounded 1)\' niount-nns of u'ranite and of l^alaeozoic formation strike generalh' from east to west, and show steeper dips in the northern than in the southern part of the district, where they gently .slope towards the sea. Owing to the repeated foldings to whicli these strata luive heen subjected, their geoL^gicid structure is complicated, and hns not yet been clearly mnde out. It will be onlv added here th:it our fossils were discovered in the lower or ^•cha]stein-l)enriijg ])ai't of this formati(^/n.
The fossil locality lies on one side of a rond wliich lends from the village of Yamanoi to the town of Habu, in a valley surrounded l)y liills. Here in a space of al)out 4 meters, I observed four fossil horizons. The loAvest of them is a yellowish o-rey aru'illnceous sandstone vieldins" ini]y Dietyopliyllum japom'cum, ])ut in great numljers. The plants of tliis horizon are easily (hstiuguishal)le from those of the others, being coloured dark green as if the veget:d)le matter were still remaining (^n tliem. Tlie next horizon is that of a light greyish argillaceous sand- stone wliich on weathering also assumes a yellowish colour. In this horizon all the species below described were found, ]\Ir. K<!cliii)e's plants ha\ ing been probably taken also from this layer. Tlie two iij)per horizons have yielded only some fragments of DiclyopJiylhim japonicwn. I>esides tliese two lu^'izons there is, I ])resume, another, as I ibund some jnnniv of the snme species in a black slate situated more to tlie nortli and occupying |)r(jl)ablv a higlier ])osition than the yaridstorjes. From this, we can see tliat there are several fossiliferous zones in tlie coal-liearing series of Xagato. Uut at present as the iiumber of species found in them is very small, it is not possible to fiiake any palaeontological distinctions in them.
FOSSIL PLANTS FE.OM NAGATO. ^41
Fos.sils, where there they are found in alnindiince, are generally very well preserved. Owing, hcnvever, to the l)ritt]e nature of the rock containing them, it i,s very ditticidt to oljtain any large .specimen.
After these brief preliminary remtirks I shall first p:iss to the description of the species, and then to the conclusions which can be drawn from them.
Description of the Species.
1. Asplenium Roesserti Fresl sp. VI. XXXII, Fig. 1-5, Pi. XXXIV, Fig. 2.
Asplen'niin Roesserti Schenk, Fossile Pflanzen aus der Albourskettc gesammelt von E. Tietze, p. 2, pL I, fig. 2-1, II, 8-10, IV, 19, VI, 33, VII, 3G.
Ayilcnitea llnesscrti Schenk, Foss. Flora d. Grenzschichten d. Keupers u. Lias Frankens, p. 49, pl. VII, fig. O-Ta, X, 1-4. Zeiller, Examen de la Flore foss. des Couches de Charbon du Tongking, p. 302, pl. X, fig. 3, 3a.
Chlailtijilt/clii.s itvhliL'Jt.se rar. lloesserti Nathorst, Floran vid Höganas och Helsinrr- borg p. 42, Helsingborg pl. II, fig. 1-3.
All of our specimens excepting fig. 3, 4, pl. XXXII agree so well with the figures of Aspleniuiii Eocsseiii given by Schenk and Nathorst, tliat I have not the slightest douljt about their identity with this well known species. Tlie pinnules are more or less falcate and inclined forward, witli secondary veins only once forked. As to the form of the pinnules, I must say that they are very varialjle, bein"- sometimes long and fino-er-like, sometimes short and triangular, as may be sufficiently seen from the spechnens here figured. The arrangement of pinna' along tlie |)i-inci[)al rhachis is in our specimens o[)posite or suljoppositc which according to Schenk is said to be the case in the l(jwer part of the fr(jnd.
242 M. YOKOHAMA.
Specimens represented in li^\ 3, 4, ]>]. XXXH, difler fmm others in liaving' twice forked secondary veins in s[)ite of the smaller size of the pinnnJes, nuifli as in fiuiires coinmonly ,u'iven of tlie typical forms of Asplcnntiii irliitbicnsc^ l>>''jf- (<-'• \X- in J leer's ]]eitr. z. rinraflora Ostsili, u. d. Amurl. 1876, pi. T, III. and in Schenk's Jurassische l^flanzen in Ivichthofen's China, vol, J\', pi. LI I.), jhit as it has been ah-eady sliown by eminent autliorities, that Aspkiiitivi n-ldthicnsc is synonymous with Alcthopteris indicuin Old. et Morv.^'^) whicli in turn exhiljits no difference from our Aspltniiiui Bœsscrti,'^^ so it would be n(3w (phte objectionaljJe to separate tlie abo\'e specimens into dis- tinct species. StiJl however, as I (obtained no transitional forms be- tween tlie two, I sh(_)uld prefer to descriljc forms with bifurcate second- ary veins as Asplcniiun llœsscrtl vav. irltithiciisis.
Asplcniimi Uœs^crli occurs in tlie L ]>per and Lower Gondwjina System of India, in the Kha3tic of Europe, Persia and Ton<iking, and in the Lower Oolite of various countries.
This fern is very comiiKjn at Yamanoi. l)eing' the most abundant fossil next to DictiiopluiUum jupoiiiciiiii.
2. Dictyophyllum ef. acutilobum Bymiit sp. V\. XXX 11, Fiu-. 6.
J >icti/(ijilii/(hnii. aciitilulniiii Schenk, Fuss. Ptlanzcii a. d. Albouvskctte, p. o, pi. II, fig. 7. Foss. Flora d. Grenzschichten, p. 77, ph XIX fig. 3-5, XX, 1. Nathorst, Ftoran vid liuganas och He'singborg, p. ]4, Hngunas aldre p]. I, fig. 8, p. 44, Hüganäs yngrc, pi. I fig. 10-18, Heisingborg pi. I fig. (J-lO. Zeil]er, Exam, de la flore foss. da Tongking, p. 311, pi. X, fig. 11.
1) Feistuiantel, Fossil iïlora of tlie Soiilli. Hcirali. OiDuhcana Basin, p. 21», 1S82, Calcutta. Heer, Bcitr. z'tr Jurajhra Ostsib. u. d. Aiiiiiii. 187G, p. 38.
2) yaporta considers in his '' Piautes Jurassiques " (Palcunt. franc. Terr. Jurass., Végét- aux) p. 301) C7«l(((io^)/(/c'>/.s ('yi.'./'ic/;/«»;^ Iiöj.<crli Prcsl as ideutlcal with Pecoiilcris ( Asijlcniuia) whithiensis Br^t.
FOSSIL PLANTS FROM NAGATO. ^43
A fragment of ;i coar.sely toothed pinna, with teeth triangular, ohtusely pointed at apex and slightly inclined forward, and with reticulate venation, is undoubtedly a species of Dlctyophylluiii which is at least very closely akin to DicfijopliiiUniii acntllohuin of the lihcL^tic of Europe. In our only specimen tlie teeth are closer together than in most of the figures given of this species, and the secondary veins slightly zigzag.
Besides occurring in the R luetic of Eiu'ope, this species has been also described as occurring in that of the Albours Chain in I'ersia and of Tongking.
3. Dictyophyllum japonicum //. sp. VI XXXIIL
Although this is the most aJjundant of all the plants found at Yamanoi, vet not a specimen was oljrained representing a complete frond, all being isolated ])inna', which may l)e characterized as follows :
Pinnie linear-lanceolate, ljroade:;t near the middle, slightly tai)er- ing towards both ends, lobed exce[>t near the base where they are simply wavy (jr entire; lobes more or less inclined forward, triangular in shape, with the aiiterior margin straiglit or c(jncaAe, with the posterior margin usually convex, and the apex obtusely pointed. Ivhachis very stn^ng, straiglit or S(3mewdiat curved, running to the apex of the pinnae ; secondary veins, coarse, slightly cr(j(jked or zigzag-, directed forwai'd and going up to the apex of each lobe, thus forming its median vein ; tertiary veins distinct, somewhat inclined anteriorly and dichotomizing, the branches forming by their union with those of the neighb(jurring ones coarse pentag(jnal or hexag(jnal nets, which are usuallv drawn out in the direction of the median \'ein ; (piaternary veins very fine, forming secondary nets within the primary ones.
244 M. YOKOYAMA.
A glance at the plate with show th;it a great resemblance exists Ijetween this species and Thaumatopicris M'dnstcri vav. ahhreviata Gopp. (Scliimper, Traité de Paléont ^éget, vol. I, pi. XL, tig. 7) from the Ivhaîtic (3f Franconia. kS(j great is tlxis resemblance, that I was at tirst inchned to treat the two species as identi'-il ; but a careful comparison between Schimper's figure and many tens of specimens at hand seems to show that the secondary veins in (jur plant are not so strong and rigid as in the European. J^esides, none of our specimens had the lol^es linear and tinger-like as in the figure of Schimper, 1)ut always had tliem m(3re or less triangular. Under these circumstances, I deem it more advisable to treat it as a new species.
DictijophijUum japouicuiii is also not indike Camptoptcrts serrata Kurr (Xathorst, Floran vid Bjuf, pi. A', fig. o) in the general appearance of its pinna?. Ihit the latter is said to have very indistinct sec(jndary veins.
A Spiropteris shown in fig. 5, pi. XX XH', I believe to belong to DictijnplniUum japuiiicmii^ as it was found in the lowest fossil horizon, where no other species occur.
4. Dictyophyllum Koehibei //. sp. VI XXXIX, lig. 1, la.
Pinnœ elongated, deeply pinnatifid ; pinnules ovate or ovately lanceolate, crenate at margin, obtusely pointed at apex, passing off either at ri^dit angles from the rluichis, or sliglitly inclined forward. Khachis moderatelv strong ; secondary veins (piite distinct, somewhat zio-za"', one in each lobe ; tertiarv veins also distinct, forming- by their union two to three rows of irregularly polygonal nets ; (piaternary veins very fine, forming secondary nets within the [)rimary ones.
fJudii'ing from the size of the rhachis and the weaker impression
FOSSIL PLANTS FROM NAGATO. 245
m:i(lo 1)V fliololio:^ on -tone, tliis fern -eeni.- to liave been more delieute tlinn the ])ref'e(liiio- oiie.
Tlie i»nl\- Jurr<,]'t':in s])ecies whicli ran l)e compared witli it is Thaniuatdjdcrix Scln'iild Xatli. (= T. Jlraunidna Sdieiik) from the Hha^tic of Sweden (Xatliorst. Flora \ id 1 [(in-aniis och ?Ielsinf;'h(^r[i', ]). 46 }I()!4-anäs ynu're, ]>I. I, hi;-. 1, 1 h']siiii>-l)()i-o-, p]. fj, fio'. 4) and Francoin'a (Scluadc, Fli-ra dei- < irenz.-chichten. |). 73, ])]. XA Tld, firr. 1-3,])]. XTX, fii!-. 1.). It lias also erenate ])innn]es; Init these are U'erierallv linear a.nd inneh lorii^'er, and the erenations finer.
As to Tlie u'eneric deiiomiiiation of our species, I follow Vrof. Sclienk, wlio considers Thanmatoptcris ^»öpp, :is identical witli Dicfi/o- pliißluiii Findf ct Iliitt. (liandliiicli dec Falaeontolcio-ie, TI. Ahtlieil.
p. US).
Tlie fiü'mvd s])ecimen is tlie onh' one found.
3. Podozaniites lanceolatus LlnflJ, .s/?. V\. XXXIV, Fiu-. 3, 4.
I'odnzcDiiitc.s htiiceo'.ntiis Niitlioi'st, Floran vitl Bjuf p. 73, pi. XVI, fig. 2-lOa, Heer, JavaHora Ostsibiriens, 187(; p. 45, 10(3, pi. I, fig. 3a, pi. XXIII, Ic, 4abc, XXVI, 2-10, XXVII, 1-8. Beitr. 1878, p. G, 20, pi. V, fig. Ml. Foss. FJora Spitzbergens, p. 35, pi. 'VII, fig. l-7c,(l. Schmalliunseu, Jtu-aflora Paisslands, p. 2!) pi. V, fig. 3-5c. Schenk, Javassisclie Pflanzen, in Iliclithofen's China, vol. IV, p, 248, pi. XLIX, fig. 4, 5, p. 255, LI, 3. LII, 8, p. 258. LI, 7, p. 2G1, LIV, 2c. Yokoyama, Jurassic Plants from Kaga, Hida and Echizen, p. 45, pi. IV, V, VI, 1, VII, 8b, XII, 18, XV, 12b.
Podozaniites distaiis Zeiller, Exam, flore foss. du Tongking, p. 320, Pi. XL, fig. 2. Nathorst, Beitr. z. foss. Flora Schwedens p. 23, pi. XIII. fig. 0-lG, XV, 20.
ZaDiites distaiifiSGhQuk, Flora d. Grenzscliicliten p. 158, pi. XXXV, fig. 10, XXXVI.
Xow aiid tlien occur leaflets of n Vodozainiir^i wliicli are to he
identified witli tlie \S('I1 known cosmo{)olitan sjiecies ahove name(l.
Our specimens are all in frag-ments, that rejiresented in fio-, 3 heino" the
246 M. YOKOYAMA.
liest, but wnritiiii^' the ti]). Jiidgino- I'roiii its rreneral outline, it seems to l)e]oi\"- to the vnriety (ffuii'mti ol' lleer in wliidi tlie le-iflets are drawn out into an acnininate a])ex. Fia'. 4 a])])enrs to liave been nuidi shorter, and I am not quite sure wliether it really hclono-s liere.
6. Baiera ? sp. PI. XXXTV. Fio-. 6.
Fra^'ments of loni>', ])'n'allel-sided leaves, ajiparently representing; lobes of a I'aiera or of a (iinkn'O/. oerau' in some eases tliiekly seattered on f ices of stone. In one case they were observed arising' from a commori base, as sliown in the ficaire, each ha\in<i- 8-4 ])arallel veins. It is much to be regretted that tlie specimens are so im])erfect as not to allow any ])recise determination.
As to the results to be drawii from tlie study of tlie al)i)ve jilarits, I must sav that the number of species is yet too limited to allow us to form any very definite conclusions. Some of them however seem to lie tolérai )1 y characteristic. DiclijoplinUnvi aciitlloJuiiii, has hitherto been restricted to the Kluptic of Euro])e and tlie similar formations of Persia arid Tongking. DicfiicplniUiuii japunicinii, altliough new, ex- liil)its a great relationship to D. Miuiskri rar. ahhreviaf t (MJp])., Avhich occurs only in the Rha^tic. A tliird IHctiioplniUmn, 1). Kuchihc^ is (piite new, showing only a (bstant relation to the Pluetic form V. Srliniîîi Xath. .sp.. It cannot tlierefore, strictly s])ea.king, lie em- ])loyed in the determination ol' the age. Tlie two other well deter- minable s])ecies, A^plciiniiii lloa^i^erti and l'oilozaiiiitcs laiicenlatus, are widely diffused in the Phtpfic as well as in the dnrassic. Thus we have here two species ])ointing to the Pha'tic, and two species pointing
FOSSIL PLANTS FROM XAGATO. 247
to the liha^tic or to the JurassiV. From these facts, I aiii inch'ned to believe, at present, that this little flora is somewhat older than that of the Middle Jurassic of Central Ja]ia]i, r'orres])oiidiiiu- either to the Liassic or, as it seems more probable, to the ii])])ermost Trias or Rha^ic of Europe. Ordy the discovery of a o-i-eatei- înmdK'r of species ran decide the question. Ft is here interesting- to note that a similar fl(^ra is already known to exist in Ton_o'kin,£i', (Zeiller I. c.) and perhaps also in China, ^'Xathorst having- recently nieAit'ioncd Dictijophyllum Nihsonl Brfft. up. and Podo.zamitr.^ lancrolafus (Jisfmis Prest. as occnrrino- in the " U])pf'i" Yan^-tszi." Anotlier point to be noted in onr flora is the C(^m])arative impiciicy of sjiecies of Diet ijopluiJl urn ^ a n-enns whicli had its maximal develojnnent in Europe durinii' tlie bMia^tic time.
1) Xathorst, Om fôreVnnuiten af Dictyophylhim NiUsoni llrtjt. xp. i /v'/ha.^ Kol/nramle Bild- niufjar. Oefversigt. af Kono-l. V^teuskaps-Akademiens Fnrhaiiillinoar, ISOO. Xo. S.
PLATE XXXII.
Plate XXXII.
Fig. 1, 2, 5. — A.spleiiium lÂœs.serti Fresl. sp. ,, 3, Sa, 1. — Asplenium Kœsserti rrcsl. \nv. wliitbicnsis Bnjt. 5, 6'. — JJictyophyllum ci' aciitilobum Braun sp.
Yokoycnna, Fossil riants.
Jour. Sc. Coll. Vol. IV. PI. XXXII.
Aue tor m lapidejn. ih.l.
PLATE XXXIII.
Plate XXXIII.
Fi(j. 1-7. — Dictyoplivlkini japoiiiciiui //. sp. ; 2 left repreoeuta the l)asal part aiid 5 the a[>iea] ])ai'( of a piinia.
Yokoyama, Fossil Plants.
Jour. Sc. Coll. Vol. IV. PI. XXXIII.
Au.ctorirtla'pide'm, dd.
PLATE XXXIV.
Plate XXXIV.
Fi (J. 1, la. — I)ictyo]ihylliii!i T\(x-lii1)ei //. sp.
,, 2. — Ayplciiinm Roc:<^erti PresL ftp.
,, 5. 4. — rodoznmites Innceolntns L. el IT. ^p.
,5 Ô. — Spiroptcn'is.
,, 6'. — l);iitT:i ? s]).
Yokoyainciy Fossil Plants,
Jour. So. Coll. Vol. IV. PI. XXXIV.
Auct^T in lap II] Cm V-cl .
Comparison of Earthquake Measurements made in a Pit and on the Surface Ground.
By
S. Sekiya, Professor,
and F. Omori, Ri'éakushi.
Imperial University, Japan.
In certain earthquake report« it is stated that there has been com- paratively Httle or no movement felt at the bottom of a deep pit or excavation, while 2:reat damasse was done on the surface of the o^round* and it seems to be generally believed that shocks are felt less intensely in mines. It is not easy to make instrumental measurements in a mine, and, in fiict, we have very little exact knowledge of underground shakings. From a practical point of view, however, with reference t(j the Imildin"- of houses, it is more interesting' to investio'ate the shakinirs in pits or excavations such as might be made for foundations. The only instance of such actual measurements as yet published, as far as we are aware, is that described by Prof. John Milne in a paper entitled "On a Seismic Survey made in Tokio in 1884 and 1885 " (Trans. Seis. Soc. Vol. X.) He made observations in a pit 10 feet in depth, whose bott(3m was dry and consisted of hard natural earth. Comparing the maximum amplitudes, maximum velocities and maximum accelera- tions obtained in the pit during tlie tolerably severe earthquake of
* For iustauce, see Trans Seis. Soc. Vol. VIII. page 98. "The Earthquakes of Ischia."
250
SEKIYA AND OMORT.
March 20th, 1885, with those obtained on the surface ground about 30 feet distant he found that they were in the ratios of 1 : 34, 1:52 and 1 : 82 respectively. But for small disturbances, tlie records in the pit did not differ much from those on the surface. The observations we have made are really a continuation of Prof. Milne's, the same method being adopted in both cases. The results con- tained in the present paper also show in certain cases some difference of movement on the free surface and in the pit.
The observations were made in the Imperial University at Hongo, Tokyo, where the soil is hardened alluvium. The pit is 4 feet square and 18 feet deep, and is situated only a few yards distant from the instruments in the Seismological Observatory. Its bottom is ]iaved with bricks to a thickness of about 2 feet. The soil appears here to be very homogeneous, so that there will be little difference in earth-shakings arising from the heterogeneity of ground between the surftice and the bottom of the pit.
Comparison of the Instruments used on the Surface and in the Pit.
The comparison in tlie present paper is restricted to the horizontal components of earth movements. The instruments employed were Prof. 'I. A. Ewing's Horizontal Pendulum Seismographs. For earthquakes which are not too great these instruments give diagrams which represent practically absolute motions of the ground.*
The instruments used in the pit and on the surface were made as much alike as possible. To compare their action, they were placed on a shaky table, and their diagrams for the same motion were
• See Memoirs of the Science Dep., Univ., Tokyo : No. 9, and the Jour. Science Coll., Imp. University, Vol. I.
EARTHQUAKE MEASUREMENTS IN PIT AND ON SURFACE.
251
taken. Specimentj of such comparison diagrams are given in PJ. XXXV. The multiplying ratio of both sets of instruments was intended to be five. If we go through the diagrams, we see that for moderate motions both give waves of almost exactly the same amplitudes and periods. Even small ar^^d irregular ripples are faithfully recorded. Fig. 1 is for the East-AVest component instruments, and Fig. 2 is for the North- South component instruments. In the following tables is given the numerical comparison of the amplitudes of some of the corresponding waves as recorded by the pit and surfice seisujographs.
For E.W. Component Instruments.
Amplitudes in mm. GIVEN BT |
Ratio. |
Amplitudes in mm. GIVEN BY |
Ratio. |
||
The Surface |
The Pit |
The Surface |
The Pit |
||
Instrument |
Instrument |
s |
Instrument |
Instrument |
s |
s. |
P- |
p |
s. |
P- |
P |
1.3 |
1.4 |
.9 |
1.3 |
1.45 |
.9 |
.92 |
.92 |
1.0 |
.9 |
.9 |
l.u |
.6 |
.75 |
.8 |
1.2 |
1.2 |
1.0 |
.85 |
.9 |
.9 |
2.5 |
2.45 |
1.0 |
1.2 |
1.2 |
1.0 |
2.1 |
2.6 |
.8 |
l.(j5 |
1.55 |
1.1 |
.67 |
.67 |
1.0 |
.4 |
.4 |
1.0 |
1.3 |
1.3 |
1.0 |
.3 |
.O |
1.0 |
1.05 |
1.2 |
.9 |
.15 |
.15 |
1.0 |
.9 |
.9 |
].0 |
.4 |
.35 |
1.1 |
1.45 |
1.45 |
1.0 |
1.4 |
1.4 |
1.0 |
1.5 |
1.55 |
1.0 |
2.1 |
2.3 |
.9 |
1.45 |
1.6 |
.9 |
2.9 |
2.6 |
1.1 |
1.5 |
1.5 |
1.0 |
1.2 |
1.05 |
1.1 |
.26 |
.26 |
1.0 |
.23 |
.20 |
1.2 |
1.3 |
1.25 |
1.0 |
.15 |
.15 |
1.0 |
1.03 |
1.2 |
.9 |
252. SEKIYA AND OMOUI.
For E.AV. Component Instruments. (Continued.)
Amplitudes in mm. GIVEN BY |
llATIO. |
Amplitudes in mm. GIVEN BY |
Ratio. |
||
The Surface |
The Pit |
The Surface |
The Pit |
||
Instrument s. |
Instrument |
P |
Instrument s. |
Instrument |
P |
.1 |
.1 |
1.0 |
l.l |
1.05 |
1.0 |
2 |
.22 |
.9 |
A |
.48 |
.8 |
2.65 |
2.85 |
.9 |
.1 |
.1 |
1.0 |
2.5 |
2.35 |
1.1 |
.25 |
.13 |
1.9 |
2.2 |
2.0 |
1.1 |
.12 |
.10 |
1.2 |
.65 |
.85 |
.8 |
.2 |
2 |
1.0 |
.82 |
.7 |
1.2 |
.27 |
.30 |
.9 |
2.7 |
2.55 |
1.1 |
.36 |
.4 |
.9 |
3.05 |
2.8 |
1.1 |
.4 |
.4 |
1.0 |
1.75 |
1.6 |
1.1 |
.55 |
.55 |
1.0 |
1.85 |
2.0 |
.9 |
1.9 |
1.8 |
1.1 |
1.1 |
1.1 |
1.0 |
.9 |
1.0 |
.9 |
.18 |
.17 |
1.1 |
1.8 |
1.8 |
1.0 |
1.4 |
1.35 |
1.0 |
2.1 |
2.0 |
1.1 |
1.55 |
1.55 |
1.0 |
1.82 |
1.9 |
1.0 |
1.9 |
1.9 |
1.0 |
.9 |
.9 |
1.0 |
Averag |
e of all the ] |
L'atios |
1.01 |
For N.S. Component Instruments.
Amplitudes in mm. GIVEN BY |
Ratio. |
Amplitudes in mm. GIVEN BY |
Ratio. |
||
The Surface Instrument s. |
The Pit Instrument P- |
s P |
The Surface Instrument s. |
The Pit Instrument P- |
P |
1.9 2.1 1.8 |
1.7 1.9 1.7 |
1.1 1.1 1.1 |
2.9 1.35 1.3 |
2.75 1.4 1.25 |
1.1 1.0 1.0 |
EARTHQUAKE MEASUREMENTS IN PIT AND ON SURFACE. 253
For X.S. Component Instrument«. (Continued.)
Amplitudes in mbi. GIVEN BY |
Ratio. |
Amplitudes in mm, ÜIVEN BY |
Ratio. |
||
The Surface Instrument |
The Pit Instrument |
1' |
The Surface Instrument s. |
The Pit Instrument P- |
1} |
I A |
1.3 |
1.1 |
1.1 |
1.15 |
1.0 |
1.15 |
1.15 |
1.0 |
.58 |
.55 |
1.1 |
\A |
1.45 |
1.0 |
.7 |
M |
1.1 |
1.15 |
1.2 |
1.0 |
.92 |
.89 |
1.0 |
1.2 |
]A |
.9 |
.9 |
.8 |
1.1 |
2.5 |
2.4. |
1.1 |
.2 |
.2 |
1.0 |
1.7 |
2.0 |
.9 |
.65 |
.61 |
1.1 |
2.1 |
2.4 |
.9 |
.18 |
.13 |
1.4 |
1.2 |
1.0 |
.8 |
.74 |
.74 |
1.0 |
1.5 |
1.4 |
1.1 |
.71 |
.69 |
1.0 |
1.8 |
2 2 |
.8 |
.3 |
.3 |
1.0 |
2.15 |
1.G5 |
l.o |
.65 |
.65 |
1.0 |
1.3 |
1.15 |
1.1 |
.42 |
.42 |
1.0 |
2.1 |
1.8 |
1.2 |
.4 |
.4 |
1.0 |
1.5 |
1.7 |
.9 |
.31 |
.31 |
1 .0 |
2.0 |
2.1 |
1.0 |
.21 |
.20 |
1.1 |
1.9 |
1.8 |
1.1 |
.16 |
.15 |
1.1 |
1.7 |
1.7 |
1.0 |
.1 |
.08 |
1.3 |
1.9 |
1.9 |
1.0 |
.76 |
.76 |
1.« |
2.85 |
2.(3 |
1.1 |
|||
Ayerag |
<-Q of all the 1 |
atios |
|
1.04 |
In the above tables, the numbers are the actual semi-ranges of motion as recorded by the instruments each divided by 5. These shew that the two .sets of instruments give on the whole results which are practically identical, so that their records are at once comparable.
254 SEKIYA AND OMORl.
It should bo «tated tliat the «urface-grouud and the ])it instriunent« were interchanged with each otlier in June, 1888.
The (j nanti ties calcuJated lor the different earthquakes are : —
(1). The number of waves in 10 seconds, marked n. (2). Amplitude, (r), or semi-range of motion in mm. (3). Complete Period, (T), or the time taken to make a complete for-and-back moticjn of the u'round in sec.
2 TT r
(4). Maximum ^ elocity in mm. per sec, (V), or — ™ — .
V- (5). Maximum Acceleration in mm. per sec. per sec, ÇA) or — ^.
In (4) and (5), it is assumed as usual that the motion of the ground is simple-harmonic It is rare, however, that any complete Avave presents a very good simple-harmonic character during the whole of its course, but usually differs in extent of motion and in the corresponding time of describing it in the first and second semi-])hases of the motion, and so in some cases we have calculated V and A for the two diffèrent semi-phases oï a wa\'e. Sometimes also we give the maximum period during the 10 seconds interval.
The East-West and Xorth-South components of the horizontal motion are not compounded, but the same components in the pit and on the siu'face are compared separately. It is a well known fact tbat motions of very quick periods and of small amplitudes generally occur at the beginning of earthquakes, and in the diagrams appear superposed on the principal imdulations. In severe earthquakes, such as those of January 15th, 1887, and of Feln-uary 18th, 1889, these ripples are very prominent ; and, being very (juick in period, though small in am- plitude, they have maxinuun accelerations very much greater than those of the principal waves, which are longer in period though greater in amplitude. We have also made calculations on some of these ripples, which can sometimes be identified in the two sets of diagrams. As
EARTHQUAKE MEASUREMENTS IN PIT AND ON SURFACE.
255
may he iningined their calculation is very difficult, especially in the estimation of their periods, so that any great exactness is not to he ohtained. The calculation will, however, give some approximate idea as to the state of things. Hence, for some of the earthquakes, "large waves " and " ripples " are separately calculated. " Large waves " are those principal undulations for which calculation is usually made in earthquake reports, ;and " ripples " are the irregular wavelets superimposed on them. In douhtful cases the amplitudes only are given. With respect to n, the numher of waves in 10 seconds, there is no difference to he found hetween the large waves of earthquakes observed on the surface and those observed in the pit ; l)ut, for ripples, the number is often very much less in the pit diagram, because of the reduction of amplitude and the consequent unification of some of them amongst themselves. The quantity n is therefore given only for ripples and not for large waves. The distinction between large waves and ripples is often very doubtful and does not exist for small earthquakes.
We may here remark that the maximum acceleration, A, is a quantity which approximately measures the overturning and fractur- ing effect of the shocks. In the case of a ripple, whose period is very short, this effect might probably be also measured by the total amount of impulse communicated to a body during a semi-phase of the wave, which is found to be proportional to the maximum velocity.
Records.
For the materials of the present paper we examined the records of thirty actual earthquakes. Of these, tliree interesting shocks have their diagrams shewn in PI. XXXVI. and IM. XXX\'II., and their peculiarities are discussed. The other twenty-seven shocks were com- paratively small and the different quantities, measured and deduced
256 SEKIYA AND OMORI.
from the actual diagrams, are arranged in tabular form. Notwith- standing tlie frequent occurrence of earthquakes in Tokyo, simul- taneous records of the pit and the surface instruments have been obtained for a comparatively small number of earthquakes. This was owing to the difficulty of managing the underground instrument.
(1.) — January 15th, 1887. — This was an earthquake of unusual severity a full account of which has already l^een given.* The beginning portions of the surface and pit diagrams are given in PI. XXXVI. j^j" and these for the convenience of comparison are placed side ]\y side. Fig. 3 is for the E.AY. component, and Fig. 4 is for the N.S. component. The glass plate whicli received the record of the surface instrument made one revolution in 128 sec, and that of the pit instrument in 68 sec, so that the latter moved nearly twice as quick as the former. Such 11 difference of the rate of revolution w<juld however cause no material difference in the diagram. In these, as well as in the follow- ing diagrams, the corresponding parts are marked with the same alphabets, and the short radial lines mark the successive seconds counted from the beginnings of shocks.
The earthquake begins as usual with tremors. After a few seconds, the motion liecomes suddenly great. The character of the motion is striking. The ripples are very prominerit, and these are superimp<^sed on slower undulations, whose period is alxjut 2 sec. in the E.W. component, and about 3 sec in the N.8. component. After a short time the ripples become less evident but the amplitude of the motion continues to be great, and the maximum displacement occurs at a point marked o in tlie E.W. component. Comparing now the surface and pit diagrams, we see that the latter is much smoother
* See the Journal of the College of Science, Imperial University, Japan, Vol. I., Part Til. or Transactions of the Seismological Society of Jajoan, Vol. XI.
t The complet ' diagram of the surface instrument is given in the same volumf s as cited a bove.
ÈAliTUQlIAKE MEASÜKEMEX'J'Ö IN PIT AND ON «UKFACE.
257
than ihc lonncr, cspcciallv licar tlicir ])cgiiiiiiiii^s. The iiumhci-s. 1, 2, 3, etc., in the first cohnnn in this and (Jther tahJes are niereJy uiven for convenience.
(I.) Large Waves. E.W, (component.
No. |
Amplitoue. |
Pkkiod. |
u |
AX. VeL. |
Max. Acc. |
|||||||
Surf. |
Pit |
Suvf. Pit |
Surf. |
Pit |
Surf. Pit |
Surf. |
Pit |
Surf Pit |
Surf. |
Pit |
Surf. Pit |
|
1 |
nun. l.(J |
1 .35 |
1.2 |
... |
||||||||
2 |
1.1 |
1.26 |
0.9 |
• •• |
||||||||
3 |
1.58 |
1.45 |
1.1 |
|||||||||
4 |
2.05 |
1.93 |
1.1 |
|
, , , |
|||||||
5 |
1.75 |
1.54 |
1.1 |
... |
||||||||
() |
1.7 |
1.25 |
1.4 |
. . . |
||||||||
7 |
.95 |
.93 |
1.0 |
.86 |
1.1 |
0.8 |
7.0 |
5.3 |
1.3 |
50. |
30. |
1.7 |
8 |
1.05 |
.8 |
1.3 |
.89 |
.93 |
1.0 |
7.4 |
5.4 |
1.4 |
52. |
36. |
1.4 |
9 |
2.4 |
1.75 |
1.4 |
2.0 |
2.2 |
0.9 |
7.6 |
5. |
1.5 |
24. |
14. |
1.7 |
10 |
3.53 |
2.65 |
1.4 |
2.8 |
2.0 |
1.4 |
7.9 |
8.3 |
0.9 |
o-y |
26. |
0.9 |
n |
2.2 |
1.25 |
1.8 |
1.3 |
1.7 |
0.8 |
IJ. |
4.6 |
2.4 |
52. |
17. |
3.0 |
12 |
1.35 |
.95 |
1.4 |
1.5 |
1.1' |
1.1 |
5.7 |
■i.3 |
1.3 |
24. |
19. |
1.3 |
18 |
2.75 |
2.55 |
1.1 |
1.8 |
1.7 |
1.1 |
9.6 |
9.4 |
I.O |
34. |
35. |
1.0 |
11 |
1.8 |
1 .65 |
1.1 |
1.6 |
1.2 |
1.3 |
7.1 |
8.6 |
0.8 |
28. |
45. |
0.6 |
10 |
1.4 |
.65 |
2.2 |
.93 |
1.1' |
0.7 |
9.5 |
2.9 |
'5.5 |
65. |
13. |
5.0 |
IG |
2.15 |
1.8 |
1.2 |
2.8 |
l.*^> |
1.5 |
1.8 |
6. |
0.8 |
11. |
20. |
0.6 |
17 |
.71 |
.1 |
7.4 |
1.1 |
.6 |
1.9 |
4.2 |
1.0 |
1.2 |
21. |
10. |
2.4 |
18 |
1.7 |
_ . _ • J |
0.8 |
.97 |
2.7 |
U.4 |
11. |
5.0 |
2.1 |
72. |
12. |
6.0 |
19 |
1.8 |
1.8 |
1.0 |
3.2 |
2.7 |
1.2 |
3.5 |
4.2 |
0.8 |
7. |
9.8 |
0.7 |
2Ü |
1.3 |
. 5 5 |
2.4 |
2.5 |
1.1 |
1.8 |
3.3 |
2.5 |
1.3 |
8. |
11. |
0.7 |
21 |
.7 |
.1 |
7.0 |
1.3 |
.9 |
1.4 |
3.4 |
0.7 |
5.0 |
17. |
5. |
3.5 |
22 |
1.6 |
.38 |
4.2 |
1.0 |
1.0 |
1.0 |
10. |
2.4 |
4.1 |
63. |
15. |
4.2 |
23 |
1.3 |
.14 |
9.0 |
1.8 |
.9 |
2.0 |
4.6 |
1.0 |
4.7 |
16. |
7. |
2.4 |
24 |
1.65 |
.44 |
3.7 |
2.1 |
1.3 |
1.6 |
5. |
2.1 |
2.1 |
15. |
10. |
1.5 |
25 |
l.G |
1.5 |
1.1 |
1.9 |
1.5 |
1.3 |
5.3 |
6.3 |
0.9 |
18. |
26. |
0.7 |
26 |
1.83 |
.9 |
2.0 |
1.7 |
1 .3 |
1.3 |
6.8 |
|..|. |
1.6| |
25. |
22. |
1.1 |
27 |
1.65 |
.85 |
1.9 |
3.1 |
3.2 |
1.0 |
3.1 |
1.7 |
2.0 |
/ . |
3.4 |
2.0 |
28 |
1.7 |
.55 |
3.1 |
1.5 |
1.5 |
1.0 1.2 |
7.1 |
2.3 |
3.1 2.1 |
30. |
10. |
3.0 |
A^ |
'erao'i |
J. |
2.3 |
2.1 |
258
SEKIYA AND ÔMOKI.
(II.) Large AVuve?^. IST.S. Component,
No. |
Amplitude. |
Period. |
Max. Vel. |
Max. Acc. |
||||||||
Surf. |
Pit |
Surf. Pit |
Surf. |
Pit |
Surf. Pit |
Surf. |
Pit |
Surf. Pit |
Surf. |
Pit |
Surf. Pit |
|
1 2 o 1. 5 6 |
1.12 1.G5 1.65 1.85 1.8.5 1.5 |
.85 1.25 1.3 2.1 2.4 1.8 |
1.7 1.3 1.3 0.9 0.8 0.8 1 |
1.5 |
1.7 |
U.9 |
Ü.3 |
r,.7 |
1.0 |
20. |
25. |
1.0 |
A\ |
^erag"( |
-\ |
1.1 |
(111.) Jvipple.s. E.W. Component.
No. |
Amplitude. |
1 |
^ERlOr |
. |
Max. V |
EL. |
Max. Acc. |
|||||
Surf ' 'P^^ |
Surf. Pit |
Surf. |
Pit |
Surf. |
1 Surf. |
Pit |
Surf. Pit |
Surf. |
Pit |
Surf. Pit |
||
Pit |
||||||||||||
1 |
.95 |
rr .- JO |
1.3 |
. . . |
i ... |
|||||||
9 |
1.05 |
.94 |
1.1 |
.54 |
.73 |
U.7 |
12. |
8.1 |
1.5 |
I4U. |
70. |
2.0 |
3 |
.0 |
.34 |
1.8 |
.39 |
.46 |
0.6 |
, 9.7 |
4.7 |
2.1 |
16U. |
65. |
2.5 |
4 5 |
.6 .56 |
.16 |
3.8 |
.29 .25 |
M |
0.4 |
13. 14. |
1.0 |
9.3 |
28U. 35U. |
14. |
25.0 |
6 |
.5 |
.19 |
2.6 |
.25 |
.6 |
0.4 |
13. |
2. |
6.5 |
320. |
21. |
15.0 |
7 |
1.24 |
.78 |
1.6 |
.34 |
.6 |
0.6 |
23. |
8.2 |
2.8: |
430. |
86. |
5.0 |
8 |
.51 |
not |
.45 |
7. |
lOo. |
|||||||
9 10 |
.92 .75 |
exist- ing. |
.4 .4 |
15. 12. |
230. 190. |
|||||||
11 |
1.2 ; .82 |
1.5 |
.75 |
.9 |
0.8 |
10. |
5.7 |
1.8 |
83. |
40. |
2.1 |
|
12 |
.98 .90 |
1.1 |
.4 |
.7 |
0.6 |
15. |
8. |
1.8 3.7' |
240. |
73. |
3.3 |
|
A |
verag |
0. |
1.9 |
0.6 |
7.8 |
KAUTH QUAKE MEASUREMENTS IX PIT AND OX SUTtPACE.
2nd
(I\'.) lvi])})l('s. X.S. (Jdmponeiit.
No. |
Amplitude. |
Pkriod. |
Max. Yel. |
Max. Acc. |
||||||||
Surf. |
Pit |
Surf. Pit |
Surf. |
Pit |
Surf. Pit |
Surf. |
Pit |
Surf. |
Surf. |
Pit |
Surf. Pit |
|
Pit |
||||||||||||
1 |
.50 |
.25 |
2.2 |
9 |
.28 |
0.7 |
18. |
5.4 |
3.3 |
550. |
120. |
4.6 |
2 |
.7 |
.64 |
1.1 |
.28 |
.55 |
0.5 |
16. |
7.3 |
2.2 |
370. |
83. |
4.4 |
3 |
.32 |
.29 |
1.1 |
.4 |
.31 |
1.3 |
5. |
6. |
0.8 |
78. |
120. |
0.6 |
4 |
.59 |
.:17 |
1.6 |
.32 |
.38 |
0.8 |
12. |
6.1 |
2.0 |
230. |
100. |
2.3 |
•5 |
1.05 |
.87 |
1.2 |
.5 |
.55 |
0.9 |
13. |
10. |
].3 |
170. |
120. |
1.4 |
ß |
.41 |
.31 |
1.3 |
.25 |
.36 |
0.7 |
10. |
5.4 |
1.9 |
260. |
94. |
2.8 |
7 |
.59 |
.65 |
0.9 |
.53 |
.8 |
0.7 |
7. |
5.1 |
1.4 |
83. |
40. |
2.1 |
A^ |
'oraf^ |
B. |
1.3 |
.8 |
1.8 |
2.7 |
III (irr.), tlic two rip]»!*'-^ in;irk('(I 4 mikI n in tlic snrf:i('0-<:.T()imd <li:i2r;!iii liriNc unite»! into one in tlic ])it dinu'i'iiin, and tliose marked S. 9, 10 in tiic fornuT do not exist sej);irately in tlie latter.
ri'tliese ealenlations l)e eori'eet, or at least a])])roxiniate, it wonld a])]iear that tlie maximum Ncloeities and maximum ae<'elerations are eonsideral)Iy uTeater tor ri])])les tlian lor l:ir£>'e undulations. Sucli a ditterenee will he found also to l)e tlie ca.se witli otlier severe eartli- (iuake.s.
(2.)~A])ril 16th, 1S87.— A very small earth(|uake
Max. Ampl. |
Period. |
Max. Vel. |
Max. Acc. |
||||||
Surf. Pit ^'""^ Pit |
Surf. Pit |
Surf. Pit |
Surf. |
Pit |
Surf. Pit |
Surf. |
Pit |
Surf. Pit |
|
E. W. Cump. N. S. Comp. |
.1 .13 0.8 .1 .15 jO.7 |
1 .6 11.2 |
.5 |
1.1 |
.8 |
1.4 |
12. |
4. |
3. |
260
SEEIYA AND OMOTîT.
(3.) — May 2ii(l, 1S87. — 'l'hi>; is n o-ood ex:nu])]e of :i small carrli- «[luikc. The motion iii<licatr(l liv tlie pit I'en^rd :i]>|)e:irs lo l)e snuiller than that indicated hv the surface record.
X. S. (\)]n]")orierit.
)l. |
Aver. Period. |
Max. Period. |
||||||
Surf. |
Pit |
Surf. Pit |
Surf. |
Pit |
Surf. Pit |
Surf. |
Pit |
Surf. Pit |
21. |
21. |
1. |
.5 |
.5 |
1. |
.7 |
.9 |
.8 |
Max. Ampi.. |
Period. |
Max. Vf.l. |
Max. a. |
'C. |
|||||||
Surf. |
Pit. |
Surf. Pit. j |
Surf. |
Pit. |
Surf. Pit. |
Surf. |
Pit. |
Surf. Pit. |
Surf. |
Pit. |
Surf. "Pit. |
.1 |
.06 |
1.7 |
.0 |
.6 |
.8 |
1.0 |
.6 |
0^ |
16. |
6. |
o o. |
I'l. W. CornjK^neiit. — Maximum am])litude is not greater than 0.1 mm. both in the sin-face .-md ])il di:ioTams. The waves :u-c 1c,o flat h) 1)e C()uiih'(l dcfinitelw
(4.) — May 7th, 1887. — A small earth(juake wliose extent c motion appears to be rather greater in tlie pit tlian on the surface.
a. |
Aver. Period. |
Max. Period. |
|||||||||
Surf. |
Pit |
Surf. Pit |
Surf. |
Pit |
Surf. Pit |
Surf. |
Pit \^ Pit |
||||
E. W. Comp. X. S. Comp. |
22. 19. |
19. 18. |
1.2 1. |
.46 .5 |
.53 .56 |
.9 .9 |
1. .7 |
||||
Max. Ampl. |
1 |
'ERTOn |
Max. Vei,. ! 1 |
Max. Aco. |
|||||||
Surf. |
Pit |
Surf. Pit |
Surf. |
Pit |
Surf.i Pit |
Surf. |
Pit |
Surf. Pit .6 1.6 |
Surf. Pit |
Surf. Pit |
|
E. W. Comp X. S. Comp. |
•1 .15 |
.1 .13 |
1. ' 1.2^ |
.6 r- |
.4 1.0 |
1.5 .7 |
1. 1.4 |
1.6 .9 |
11. 13. |
25. 6. |
.44 2 2 |
EARTHQUAKE MEARüRElMENTS IX PIT AXD OX SURFACE. '261
(5.) — riiMO 2nt1i. 1SS7.— A small carrtuninkc.
Max. Ampi,. |
Period. |
Max. Vel. i :\rAx. Ac. |
||||||||||
Surf. |
Pit |
Sui'f. l'it |
Surf. |
Pit |
Surf. Fit .9 •0 |
Sni-f. |
Fit |
Surf.: Pit |
Surf. |
Pit |
Snrf. Pit |
|
E. W. Comp. X. S. Comp. |
.1 .1 |
.07 .1 |
1.4. 1. |
I. 1.1 |
.7 1.:^ |
A ..-.8 |
i.n i 2.8 |
5. in. |
2.8 3.4 |
1.8 5. |
(().) — Till,.' ?,Otli, 1887.— A very small ('artli.|n:.k.'.
K. A\\ ( 'i)]ni)Mii('iit : — Almost insiLi'iiiilcanr, the maxiiimm aiiipli- tndo lu'iiiL!,' ii«»l UTcatcr tlian .().") mm, in the surface diaLii-am. and ohscairo in tlic ])ir one.
X. S. (\)m|)(^iioiit : — ill tlio surface (liaaram, rlic maximum amplifndc is .OH mm., and in tlie pit diaiiram ])r<)l»al)lv n<tt un':il«r lliaii .07) m]ii.
(7.). -July 2nd, 18S7.— A small eMrlli(inak(
Max. Ampl. |
Pertop. |
Max. VeI;. |
Max. Acc. |
|||||||
Surf. |
Pit |
Surf. Pit j |
Surf. |
Pit |
Surf. Pit |
Surf. |
Pit «'"■<' Pit |
Surf' Pit '^"^^ i'it |
||
E. W. Comp. X"^.. S. Comp. |
.10 .25 |
.10 .22 |
1. i 1.1 i |
.0 |
.7 |
1. .9 |
2.1 2.6 |
2.1 1. 2.1 1.2 |
2K. 27. 27. 22. |
1. 1.2 |
(8.) — Inly 22nd. 1887.— An cartlKinake of uwruisc oxivui of iiK/tion, but of slow period. The charar-ter of this éartlu|nakc is iiilenvtino'. Inlike mosf oaiilxpiakes, wliieli lu'U'in with (juir-k vil)ra- tions, <his begins very genfly, witli waves of small amplitude aiid oi' ](^/rio- ])eriod. After .about 10 seconds from the start, the motion becomes largei' and irregular, and ripples a])pe;u" superimposed on p"r-incipal undulations. All Ihe irregul.ar \va\elets are t;d"»u|ated.
262
SEKT Y A AND OMORI
n. |
Aver. Period. |
Max. Pïirtou. |
|||||||
Surf |
Pit |
Surf. Pit |
Surf. |
Pit |
Surf. Pit |
Surf. |
Pit |
Surf. Pit |
|
E. Vr. Comp. X. s. Comp. |
3G. 28. |
14. 20. |
2.6 1.4 |
.3 .36 |
.7 .5 |
.4 .7 |
1. |
1.6 1.7 |
.6 |
E. AV. Componeiit.
Xo. 1
2
.-> o
4
•5
6
S
0
10
11
12 13
14 15 16 17
IS 19 20 21
Amplitude.
Surf, Pit
.15 .25 .11 .21 .15
.15
.21
.14
.2
.15
Surf.
Pit
.18 .24
.18 .11
.1 I .1 I.
. 1 i
.09
13 .11
.12 .14 .15
.08 .15 .08 .20 .21 .16 .21 .34
.12 .15 .15 .05 .12 .05 .19 .15 .23 .25 .31
Averao'e.
1.0 1.2 0.8 1.1 1.0 0.8 1.6 1.0 1.6 1.2 1.0 .9 1.0 1.6 1.2 1.6 1.0 1.4 0.7 0.8 1.1
1.1
Period.
Surf. Pit
.0 1.1 1 .64 .95
1.2 1.2 1.1
.93
.83
.83 1.1
.83
.74 1.0
.7 1.3 1 1.1 1 1.3 1 1.3 1 1.5 2
Surf. Pit
0.6 1.1
1.0 1.0 1.0 0.9 1.1 1.1 1.0
Ô1.1
.94
.0
.94
.8
.9
.64
.5
.4
.4
.6
.0
0.9 1.1 .9 0.9 1.1 1.1 0.9 0.8 0.9 0.8 0.8
1.0
Max. Vel.
Surf.
Surf. Pit
Pit
1.9 1.2 1.6
1.4 1.3 I.l
1.1 1.4
1.3 1.4
1.4 1.4 1. 1.2 1. .6
.8 9
0.8 0.9 1.0 0.8 1.7 .9
) 1.5
.9
.9
.8 1.1 1
.7
.9
1.1 1.1 .9 1.1 1.8 9 .8 1.1 7 .5 1.4 1. .8 1.3 1.2 .7 1.7 .8 1.0 ,0.8 1. 1.0 'l.O 1.4 1.0 1.4
1.2
Max. Acc.
Surf. ! Pit
24. ! 9.4
8.5 I 8. U. 14.
12. 5.
5.
10.
13. 6. 3.6 4.6 5.5 6.5 4.4 7.4 i 7.7 7. 4.6 8.7
0.
6. 7. 3. 6. 5.
4.7 3.4 7. I 3.1
3.8 4.t
5. 3.8
6. 3.1
Surf. Pit.
2.6
1.1
0.8 0.8 0.9 0.8 1.4 0.8 1.5 1.0 1.4 0.8 1.2 2.0 1.0 1.2 1.4 2.2 0.9 1.3 2.0
1.3
EARTHQUAKE MEASUKEMEXT.S IX PIT AND OX SUKFACE. 2ßo
X. S. Coiiiponeiit.
No. |
Amplitude. |
Period. ; Max. Vel. |
Max. Ago. |
||||||||
Surf. |
Pit |
Surf. Pit |
Surf. |
Pit |
^-^- Surf. Pit |
Pit |
Surf. Pit |
Surf. |
Pit |
Surf. Pit |
|
1 2 |
.37 .13 |
.35 2 |
1.0 .7 |
.7 .G |
.9 1.5 |
.8 3.3 .4 1.3 |
2.5 .8 |
1.3 |
29. 13. |
18. 3.5 |
1.6 3 7 |
Ave |
rage. |
.9 |
.6 1 |
1.5 |
2.7 |
Tn the latter part of the inoticju, the amplitude seems to he Jar"er ill the pit diagram than in the surfaee diau'ram. Dut the period was mueh loiiij'er in the former than in the latter.
O
(9.) — Septemher 25th, 1887. — A moderate earthipiake, like the preceding" one. The extent of motion a] »pears to l)e larger in the ])it than on the surface, and consecpiently also the duration of motion is lono-er in the former than on rhe latter.
n. |
Aver. Period. |
Max. Period. |
|||||
Surf. |
Pit |
Surf. Pit |
' Surf. Pit S"*-^ ! Î Pit |
Surf. 1.1 1. |
Pit |
Surf. Pit |
|
E. W. Comp. N. S. Couip. |
28. 3U. |
10. 17. |
2.8 1. |
.35; 1. .4 .oo .(J .6 |
1.8 1. |
.0 1. |
E. ^v. Coi
iipoiicnt.
No. |
Amplitude. ; Period. |
31 |
ix. Vj |
;l. |
Max. Acc. |
|||||||
Surf. |
Pit |
Surf. Pit |
Surf. Pit , '"^""■^■• Pit |
Surf. |
Pit |
Surf. X^it |
Surf. Pit ^"'■^• Pit |
|||||
1 |
.25 |
.46 |
0.5 |
1.5 |
1.5 1.0 |
1.1 |
1 .0 |
0.6 |
4.1 8. |
0.6 |
||
2 |
.08 |
.1 |
0.8 |
.6 |
.7 0.9 |
.S |
.1» |
0.9 |
8.8 8.1 |
1.1 |
||
3 |
.09 |
.22 |
0.4 |
1.4 |
1.5 |
0.9 |
.4 |
.9 |
0.4 |
1.8 |
3.9 |
0.5 |
4 |
.09 |
.15 |
0.6 |
1.2 |
1.3 |
0.9 |
.47 |
.73 |
0.6 |
2.5 |
3.6 |
0.7 |
5 |
.12 |
.21 |
0.6 |
.73 |
.76, 1.0 |
1. |
1.8 |
0.6 |
9. 15. |
0.6 |
||
6 |
.05 |
.07 |
0.7 |
.5 |
.57 0.9 |
.6 |
.8 |
0.8 |
7.4 8.5 |
0.9 |
||
A^ |
'erag'c |
i. |
0.6 |
.9 |
0.7 |
0.7 |
26 i
SËKIYA AND OMOKI.
X. tS. Couipoiicnt.
Xu. |
Amplitude. |
J |
^ERIüU. |
Max. Vel. |
Max. Acc. 1 |
|||||||
Siuf. Pit |
Surf. Pit |
Surf. |
Pit |
Surf. Pit |
Surf. |
Pit |
Surf. Pit |
Surf. |
Pit |
Surf. Pit |
||
1 |
.17 .19 |
0.9 |
.56 |
.69 |
0.8 |
1.9 |
1.7 |
1.1 |
21. |
15. |
lA |
|
2 |
0 |
.25 |
0.8 |
.51 |
.42 |
1.2 |
2.5 |
3.8 |
0.7 |
31. |
58. |
0.5 |
'o |
.1 |
.15 |
0.7 |
.46 |
l.O |
.5 |
1.4 |
.95 |
1.5 |
19. |
6. |
3.2 |
4 |
.08 |
.1 |
0.8 |
.54 |
.6 |
.9 |
.9 |
1. |
0.9 |
11. |
11. |
1.0 |
Ö |
.lo .15 |
0.9 |
.7 |
.66 |
1.1 |
1.2 |
1.4 |
0.9 |
11. |
13. |
0.8 |
|
6 |
.1 .1-1 |
0.7 |
.6 |
.66 |
0.9 |
1.0 |
1.3 |
0.8 |
11. |
12. |
0.9 |
|
7 |
.1 1 |
.15 |
0.7 |
.8 |
1.0 0.8 |
.9 |
.95 |
1.0 |
6.9 |
6. |
1.2 |
|
8 |
.05 |
.1 |
0.5 |
.44 |
.53 |
0.8 |
.7 |
1.2 |
0.6 |
10. |
14. |
0.7 |
0 |
.17 |
2 |
0.9 |
M |
.6 |
1.1 |
1.7 |
2.1 |
0.8 |
17. |
22. |
0.8 |
10 |
.1 |
.15 |
0.7 |
.6 |
.6 |
1.0 |
1.0 |
1.6 |
0.6 |
11. |
17. |
0.6 |
11 |
.19 |
.18 |
1.0 |
.5 |
.48 |
1.0 |
2.4 |
2.4 |
1.0 |
30. |
32. |
0.9 |
12 |
.06 |
.08 |
0.8 |
"5 |
.57 |
0.9 |
.8 |
.9 |
0.9 |
10. |
9.7 |
1.0 |
13 |
.00 M |
1.0 |
.45 |
.43 |
1.0 |
.8 |
.9 |
0.9 |
12. |
13. |
0.9 |
|
M |
.09 .!<■) |
0.6 |
.6 |
.71 |
0.9 |
X) |
1.4 |
0.6 |
10. |
12. |
0.8 |
|
\ô |
( 1 7 aliuobt •'-" nul. |
... |
.45 |
.41 1.0 |
1. |
13. |
1.1 |
|||||
A^ |
eragc |
.8 |
<'.9 |
0.9 |
(10.) — J)c(viii])L'r IGlli, 1887. — -An ctirllKiiüike of inodcmk' in- Icii.sily, At ;i lilaiKV, \\\c iiioiioii on tlic surface appears to be larger aijd more irregular than that in tlie pit.
n. |
Aver. Period. |
|||||
Surf. |
Pit |
Surf. Pit |
Surf. |
Pit |
Surf. Pit |
|
E. W. Comp N. S. Comp. |
41. 41. |
20. 18. |
2. |
.24 .24 |
.0 .67 |
.5 .4 |
EARTU(^UAIv[': 3IEA!SUJiEMENTS IX PIT AND OX H'JRFACE.
•J{)D
K. W . ( oii»[)()iieiit.
Xo. 1 |
AmPIjITUDE. |
1 |
'ERIOr |
IVJ |
AX. Vet,. |
Max. Acc. |
||||||
Siu-f. |
Pit |
Siui. Pit |
Surf. |
Pit |
Sni-f Pit |
Surf. |
Pit |
Surf Pit |
Su if |
Pit |
Surf. Pit |
|
.77 |
.7 |
1.1 |
•9 |
.9 |
1.0 |
5.4 |
4.9 |
1.1 |
38. |
34. |
1.1 |
|
2 |
0 |
.25 |
0.8 |
.5 |
.8 |
O.G |
2.5 |
2.0 |
1.2 |
31. |
16. |
2.0 |
.-b |
09 |
1.1 |
.65 |
.8 |
0.8 |
2.4 |
1.6 |
1.5 |
23. |
22. |
1 0 |
|
4 |
.07 |
no. |
2 |
2.2 |
... |
70. |
||||||
5 |
.1 |
.14 |
0.7 |
.5 |
.7 |
0.7 |
1.3 |
1.3 |
1.0 |
il 6. |
12. |
1.3 |
6 |
.14 |
.14 |
1.0 |
.7 |
.7 |
1.0 |
1.3 |
1.3 |
1.0 |
12. |
12. |
1.0 |
7 |
.15 |
.18 |
0.8 |
.0 |
1.2 |
0.5 0,8 |
l.G |
■ |
1.8 |
17. |
5. |
3.4 |
A\ |
erag-c |
Î. |
.9 |
1.3 |
1 .6 |
]S . S. Coinpoueiit.
Xo. |
Amplitude. |
Period. |
Max. Vei,. |
Max. Acc. |
||||||||
Surf. |
Pit |
Surf. Pit |
Surf. |
Pit |
Surf. Pic |
Surf 6.5 |
Pit 6.3 |
Surf. Pit |
Surf. |
Pit |
Surf. Pit |
|
1 |
.55 |
.53 |
1.0 |
.53 |
.53 |
I.O |
1.0 |
77. |
75. |
1.0 |
||
0 |
.3 |
.24 |
1.2 |
.55 |
.72 |
0.8 |
3.4 |
2.1 |
1.6 |
38. |
18. |
2.1 |
3 |
.33 |
.05 |
6.6 |
.4 |
.42 |
1.0 |
5.2 |
.75 |
7. |
82. |
11. |
7.5 |
4 |
.25 |
.25 |
1.0 |
.5 |
.54 |
1.0 |
3.2 |
2.9 |
1.1 |
41. |
34. |
1.2 |
5 |
.25 |
.15 |
1.7 |
.55 |
.8 |
0.7 |
2.9 |
1.2 |
2.4 |
34. |
10. |
3.4 |
6 |
.24 |
.1 |
2.4 |
.8 |
.67 |
1.2 |
1.9 |
.95 |
2.0 |
15. |
9- |
4.7 |
7 |
.16 |
.03 |
5.3 |
.25 |
.26 |
1.0 |
4.0 |
.73 |
5 5 |
100. |
18. |
5.5 |
8 |
2 |
.11 |
1.8 |
.42 |
.83 |
0.5 |
3. |
.84 |
■3.6 |
45. |
6.4 |
7.0 |
A^ |
'crag< |
ü |
2.6 |
0.9 |
3.0 |
3.7 |
L^GG
SEKIYA AND OMOKl.
(11.) — Jauiuiry lltli, 1888. — A very .small eurtlKjajike. In each ctjiuponeiit on the surface, the maximum amplitude is 0.1 mm. ; while for tVie motion in the pit, it is not greater them .06 mm. The motion seems here to he much more pron(junced on the surface than in the pit.
(12.) — April 5th, 1888. — A tolerahly severe earthcjuake, in Avhich the amplitude is not very large, hut the viljrations are very (juick.
The difference of appearance between the surface aud the pit diagrams is striking, the small shtu'p waves whicli exist in the former beini»' mostly flattened in the latter.
n. |
Aver. Period. |
|||||
Surf. |
Pit |
Surf. Fit |
Surf. .18 .19 |
Pit |
Surf. Pit |
|
E. W. Comp. X. S. Comp. |
57. 54. |
25. 25. |
2.8 2.2 |
A .1 |
.5 .5 |
E. \V. ( 'ompoiieut.
Xo. |
Abiplituue. |
Per. OD. |
Max. Vel. |
ÄIax. Ago. |
||||||||
Surf. |
Pit |
Surf. Pit |
Surf. |
Pit |
Surf. Pit |
Surf. |
Pit |
Surf. Pit |
Surf. |
Pit |
Surf. Pit |
|
1 2 3 4 5 |
.4 .05 .o .35 .35 |
.35 .37 .1 .25 |
l.i 1.7 3.0 1.4 |
.7 .52 2 .33 .24 |
.8 .05 • O .42 |
0.0 0.8 0.7 0.0 |
3.6 7.8 9.4 0 7 9;. |
2.7 3.6 2.2 3.8 |
1.3 2.2 4.3 2.3 |
32. 95. 300. 120. 240. |
22. 34. 50. 00. |
1.5 2.8 6.0 4.0 |
Av |
eragt |
\ |
1.8 |
0.8 |
2.5 |
'èA |
EARTHQUAKE MEASUlîEMEXTS IX PIT AND ON SURFACE. 2^7
N. S. C'oiiipoiiont.
Xo. |
Amplitude. |
, 1 |
'eriod. |
M |
AX. Y |
EL. |
Max. a |
:c. |
||||
I Surf, |
Pit |
Sin-f. Pit |
Surf. |
Pit |
Surf. J it |
Surf. |
Pit |
Surf. Pit |
jSurf. Pit 1 |
Surf. Pit |
||
1 |
.4 |
.38 |
1.1 |
.43 |
.53 |
0.8 |
6. |
4.5 |
1.3 |
j 90. |
53. |
1.7 |
2 |
.3 |
.1 |
3.0 |
.21 1 |
.27 |
0.8 |
9. |
2.3 |
4.0 |
270. |
53. |
5.1 |
3 |
.22 |
.08 |
2.8 |
.2 |
.o |
0.7 |
7. |
1.7 |
4.] |
220. |
35. |
6.3 |
4 |
.65 |
.35 |
1.9 |
.71 |
.7 |
1.0 |
1 ^ _ 5.^ |
3.2 |
1.8 |
50. |
29. |
1.7 |
5 |
.5 |
.26 |
1.9 |
.47 |
.7 |
0.7 |
0.7 |
2.3 |
3.0 |
90. |
21. |
4.3 |
G |
.2 |
.26 |
0.8 |
.27 |
.56 |
0.5 |
4.7 |
2.9 |
1.6 |
110. |
32. |
3.4 |
7 |
.15 |
.15 |
1.0 |
.24 |
.35 |
0.7 |
3.9 |
2.7 |
1.5 |
100. |
49. |
2.0 |
8 |
.24 |
.15 |
1.6 |
.24 |
.44 |
0.5 |
1 6.3 |
2.2 |
2.9 |
165. |
32. |
5.2 |
9 |
.18 |
.23 |
0.8 |
.24 |
.45 |
0.5 |
4.7 |
3.2 |
1.4 |
120. |
45. |
2.7 |
10 |
o .•J |
.16 |
1.9 |
|||||||||
11 |
.31 |
0 |
1.0 |
.7 |
.75 |
0.9 |
1 2.8 |
1.7 |
1.7 |
25. |
14. |
1.8 |
12 |
9 |
2 |
1.0 |
.24 |
.56 |
0.4 |
1 5.8 |
2.3 |
2.3 |
140. |
25. |
5.0 |
13 |
.25 |
.15 |
1.7 |
.47 |
.8 |
0.6 |
Î 3.4 |
1.2 |
2.8 |
46. 9. |
5.1 |
|
14 |
.4 |
.18 |
2.2 |
|||||||||
15 |
.34 |
.2 |
1.7 |
|||||||||
16 |
.22 |
.25 |
0.9 |
, . . |
||||||||
17 |
.3 |
.18 |
1.7 |
.73 |
.7 |
J.O |
2.6 |
1.6 |
1.6 |
22. |
15. |
1.5 |
Av |
era Of c |
1.6 |
0.7 |
2.3 |
3.6 |
(18.)— April 29tlu 1888.— A severe enrtlKHinke. Tliis i.. very like the precedino- (^ne. liuf mur-li more intense. The beo-hinino- portions of liotli sets of diagrams are given in D. XXXA^TT, Fig. 5. and Fig. G, The glass ]i]ate of tlie surface-ground instrument made one revolution in 88 sec., .and tliat of tlie pit instrument in 70 sec. In tlie early ])art of the shock, the vibrations are very (juick, and witli the exception (^f the wave marked A in the E. W. com- p )n('nr llierc is no promincntiv lai'i^'c wave, ihoiigli ihc ripples :\vo
268
SEKIYA AND OMORI.
distributed more or less in groups. Here ngain the pit diagrnm appears niucli smoother than the surface one ; compare, for instance, the portions marked a, b, c, d, e, f, g, iii the E, AV. comjionent. To- wards the end, tl\e motion becomes slow.
E. AV. Component.
H. |
Aver. Period |
|||
Surf. |
Pit !^"."f- 1 Pit |
Surf. |
Pit |
Surf Pit |
49. |
30. ! 1 .0 |
2 |
.33 |
.0 |
(I.)— Ripples.— E. W. Component.
No. |
Amplitude. |
Pebiot |
). |
Max. Yel. |
Max. Acc. |
|||||||
Surf. |
Pit |
Surf. Pit |
Surf. |
Pit |
Surf. Pit |
Surf. |
Pit |
Surf. Pit |
Surf. |
Pit |
Surf. Pit |
|
1 |
.55 |
.21 |
2.2 |
.23 |
.22 |
1.0 |
15. |
ß. |
2.5 |
410. |
1 70. |
2.4 |
2 |
.3 |
.04 |
7.5 |
.2 |
.19 |
1.0 |
j 9.5 |
1.3 |
7.3 |
300. |
4U. |
7.5 |
3 |
.27 |
\ |
2 |
' |
8.5 |
\ |
270 |
j |
||||
4 5 |
.4 .35 |
.55 |
.2 .25 |
.8 |
13. 8.8 |
'4.3 |
3.0 |
400. 220. |
34. |
12.0 |
||
6 |
.25 |
1 |
.22 |
1 7.2 |
210. |
|||||||
7 |
.5 |
.35 |
1.4 |
.17 |
.47 |
0.4 |
19. |
4.7 |
3.9 |
690. |
63. |
11.0 |
8 |
.4 |
.25 |
1.6 |
.3 |
.23 |
1.3 |
8.4 |
69 |
1.2 |
180. |
190. |
1.0 |
9 |
.3 |
.28 |
1.1 |
.44 |
.43 |
1.0 |
4.3 |
4.1 |
1.1 |
62. |
60. |
1.0 |
10 |
.5 |
.4 |
1.2 |
.25 |
.8 |
0.3 |
13. |
3.2 |
4.0 |
320. |
25. |
15.0 |
11 |
.55 |
.48 |
1.2 |
.27 |
.47 |
O.G |
13. |
6.2 |
2.1 |
300. |
80. |
3.7 |
A\ |
^orao'c |
2.3 |
0.8 |
3.2 |
6.7 |
EARTKQÜAKE MEASUREMENTS IN PIT AND ON SURFACE.
269
(IT.) T>aro;e AV:i\ps. K. AV. ( 'i)iii]M)iierit.
No. |
Amplitddk. |
Period. |
Max. VEr, |
M |
.ax. Ace. |
|||||||
Surf. |
Pit |
Surf. |
Surf. |
Pit |
Surf. Pit |
Surf. |
Pit |
Surf. Pit |
Surf. |
Pit |
Surf. Pit |
|
Pit |
||||||||||||
1 |
2_ |
1 .G.J |
1.2 |
1. |
.8 |
1.3 |
13. |
13. |
1.0 |
80. |
94. |
0.9 |
2 |
.42 |
.3.-) |
1.2 |
.5 |
.5 |
1.0 |
5.3 |
4.4 |
1.2 |
G (3. |
55. |
1.2 |
o •J |
.57 |
. / |
0.8 |
.93 |
.9 |
1.0 |
4. |
5. |
0.8 |
26. |
34. |
0.8 |
1 |
.63 |
.85 |
.7 |
1. |
1. |
1.0 |
4. |
5.3 |
0.8 |
25. |
.>r> |
0.8 |
5 |
.53 |
.5S |
.9 |
1.2 |
1.1 |
1.1 |
' 2.8 |
3.3 |
0.9 |
15. |
19. |
0.8 |
A^ |
-e rag- |
0. |
1.0 |
1.1 |
0.9 |
! |
0.9 |
(III.) ]'i])])les. X. S. Component.
No. |
Amplitude. |
I |
^ERIOD. |
Max. Vel. |
Max. Acc. |
|||||||
Surf. |
Pit |
Surf. Pit |
Surf. |
Pit |
Surf. Pit |
Surf, |
Pit |
Surf. Pit |
Surf. |
Pit |
Surf. Pit |
|
1 |
.27 |
.18 |
1.5 |
.22 |
.23 |
1.0 |
7.7 |
4.9 |
1.5 |
220. |
1 30. |
1.7 |
2 |
.6 |
.55 |
1.1 |
.32 |
.43 |
0.7 |
12. |
8. |
1.5 |
240. |
120. |
2.0 |
3 |
.55 |
.31 |
1.8 |
o .•J |
.35 |
0.8 |
12. |
5.6 |
2.1 |
240. |
100. |
2.4 |
4 |
.37 |
_2 |
1.9 |
.25 |
.35 |
0.7 |
9.3 |
3.6 |
2.6 |
230. |
65. |
3.9 |
5 |
.54 |
.04 |
14. |
.4 |
.3 |
1.3 |
8.5 |
0.8 |
11. |
130. |
16. |
8.0 |
6 |
.58 |
.15 |
3.9 |
.24 |
.3 |
0.8 |
15. |
3.2 |
4.9 |
400. |
68. |
6.0 |
Averao-e. |
4.0 |
0.9 |
3.9 |
4.0 |
270
SEKIYA AND OMOl.'T.
(T\ .) Tjîiiyc AVavos. X. S. r(^in])()iieiit.
In (T), tlie ripple-^ mimbered 3, 4, 5, (! whicli are distinct on the surface have united int(i one wave in tlie ])it. In taking- the ratios of niaxinuun velocities and maximum accelerations, this sin^'le wave is compared w^th the greatest of the C(^rresponding' ripples.
(14.) — June 8rd, 1888 — An eartliqu-dve of moderate amplitude.
N. S. Coiujionerit.
n |
Aver. Period. |
||||
Surf. |
Pit |
Sarf. Pit 2_ |
Surf. |
Pit |
Surf. Pit |
33. |
17. |
.•J |
.<3 |
.5 |
EAliTlK^UAKE MEASUÜEIMENTS IX PIT AND UX SUKFAOE.
•271
Xo. |
Amplitude. |
Period. |
Max. Vel. |
Max Acc. |
||||||||
Surf |
Pit .4 .45 .32 |
Surf. Pit 0.8 1.1 1.4 |
Surf. |
Pit |
Surf. Pit |
Surf. |
Pit |
Surf. Pit |
Surf. |
Pit |
Surf. Pit |
|
1 2 3 |
.3 .5 .46 |
1.2 1.5 1. |
1.2 1. 1. |
1.0 1.5 1.0 |
l.G 2.1 2.9 |
2.1 2.8 2.0 |
0.8 0.8 1.5 |
8.5 8.8 18. |
11. 17. 13. |
0.8 0.5 1.4 |
||
Av |
erao-e |
].] |
1.2 |
1.0 |
0.9 |
E. \y. Coiiipoiioiit.
Max. Ampl. |
||
Surf. |
Pit |
Surf. Pit |
l.l |
.95 |
1.1 |
(15.)— ()ctol)er i'Otli, 1888.— A small cnrtli(juake. In this case the amplitude seems to be mueli u'reater in the })it tliaii on the surface.
/( |
AvEE. Period. |
Max. Period. |
|||||||
Surf. |
Pit |
Surf. Pit |
Surf |
Pit |
Surf. Pit |
Surf. |
Pit |
Surf. Pit |
|
E. W. Couip. N. S. Comp. |
31. 28. |
20. 21. |
1.6 i.o! |
.33 .45 |
.5 .5 |
0.7 0.9 |
.0 .5 |
.9 .6 |
0.7 0.8 |
Ti'I
ÖEKIYA AND UlNlOßl.
E. A\. Couipoiieiit.
Xo. |
Amplitude. |
Period. |
Max. Vel. |
Max. Acc. |
||||||||
Surf. |
Pit |
Surf. Pit |
Surf. .7 .O |
Pit .Ü .7 |
Surf. Pit |
Surf. Pit |
Surf. Pit |
S art. |
Pit |
Surf. Pit |
||
1 2 3 5 6 |
.12 .1 .06 .18 .11 .14 |
2 2 .21 .26 .21 .21 |
0.6 0.5 0.3 0.7 0.5 0.7 |
0.8 0.7 |
1.1 1.3 ... |
1.4 1.8 |
0.8 0.7 |
10. 16. |
10. 16. |
10. 10. |
||
Av |
crag- |
e. |
O.Q |
0.8 |
0.8 |
1.0 |
N^. S. C(Jiiipoiieiit.
No. |
Amplitude. |
Period. |
Max. Vel. |
Max. Acc. |
||||||||
Surf. |
Pit |
Surf. Pit |
Surf. |
Pit |
Surf. Pit |
Surf. |
Pit |
Surf. |
Surf. |
Pit |
Siu-f. Pit |
|
Pit |
||||||||||||
1 2 3 4 5 Ü 7 8 9 10 |
.16 .1 .1 .1 .1 .1 .3 .11 .1 .1 |
.15 o 0 .16 .16 .21 .1- .28 .27 .25 |
1.1 0.5 0.5 0.6 O.G 0.5 0.8 0.4 0.4 0.4 |
.4 .4 .7 .4 .5 .5 |
.5 .6 .5 .5 .5 .5 |
0.8 0.7 1.4 0.8 1.0 1.0 |
2.5 1.6 0.9 1.6 1.3 1.3 |
1.9 2.1 2.5 2.0 2.0 2.6 |
1.3 .8 0.4 0.8 0.7 0.5 |
39. 26. 8. 26. 16. 1 6. |
24. •)2 31. 25. -5. 32. |
1.6 1.2 0.3 1.0 0.6 0.5 |
A^ |
^erag( |
=» |
0,6 |
1.0 |
0.8 |
0.9 |
(10.) — Xoveinbe'v 2ii(l, 1888. — A small L'artli([uake. Tlic pit (liaiJfrjim is much suKJotlier than the surface one.
E.VIiTIigUAKi: MEASUKEMENT.S IX PIT AXD OX öUlil'ACE.
21\
Max Ampl. |
|||
Surf. |
Pit |
Surf. Pit |
|
E. W. CumiJ. N. S. Comp. |
.19 .15 |
.16 .14 |
1.2 1.1 |
(17.)— Jaiiuarv Isl, 1S8D.— A small o:irlh(iiiakev
Max. Ampl. |
|||
Surf. |
Pit |
Surf. Pit |
|
X. S. Comp. |
.04 |
.05 |
1. |
(18.) — Fcl)riiary IStli, LSSÜ. — A severe eai'tli(|(iakr, in which there was a considerahle aiiiouiit of vertical motion. The earlier p(jrti<)ns of the cliagrains of the E. AV. component are given in PI. XXXVII, Fig. 7. The glass plates of the surface and ])it instruments made revolutions in 108 sec. and 95 sec. res])ectively. The periods of the ^ibration are very short and the motion on the surface seems to be much sharper than in the ])it.
E. W. Comp. |
X. S. Comp. |
|||||
Surf. |
Pit |
Surf. Pit |
Surf. |
Pit |
Surf. Pit |
|
"5 |
40. 35. 20. 10. 12. |
28. 21. 15. 19. 11. |
1.5 1.7 1.3 1.0 1.1 |
50. 49. 39. 20. 15. |
30. 23. 14. 20. 16. |
1.7 2.1 2.8 1.3 .9 |
In this table ii^ nl .... are the number of irregular wavelets in the successive 10 sec. intervals.
'274:
yEKIYA AND ÜMüKl.
(I.) Uipple«. E. W. Component.
Xo. |
Amplitude. |
Period. |
Max. V] |
EL. |
Max. Acc. |
||||||||
Surf. |
Pit |
Surf. Pit |
Surf. |
Pit |
Surf. Pit |
Surf. |
Pit |
Surf. Pit |
Surf. |
Pit |
Surf. Pit |
||
1 |
.24 |
.23 |
1.0 |
.28 |
.27 |
1.0 |
5.4 |
5.4 |
1.0 |
120. |
130. |
1.0 |
|
2 |
1.05 |
.8 |
1.3 |
.7 |
M |
1.1 |
9.4 |
7.7 |
1.2 |
84. |
74. |
1.1 |
|
3 |
1.35 |
1.3 |
1.0 |
||||||||||
4 |
2.4 |
2.17 |
1.1 |
||||||||||
5 |
.73 |
.4 |
1.8 |
. |
|||||||||
6 |
.95 |
1.05 |
0.9 |
... |
|||||||||
7 |
.3 |
.06 |
5.0 |
||||||||||
8 |
.82 |
.52 |
1.6 |
||||||||||
9 |
.8 |
.32 |
2.5 |
||||||||||
10 |
1.3 |
.8 |
1.6 |
||||||||||
11 |
.7 |
.35 |
2.0 |
.24 |
.25 |
1.0 |
18. |
9. |
2.0 |
180. |
220. |
2.2 |
|
12 |
.05 |
.25 |
2.6 |
.32 |
.23 |
1.4 |
13. |
7. |
1.9 |
250. |
190. |
1.3 |
|
13 |
1.05 |
.8 |
1.3 |
.35 |
.73 |
.5 |
19. |
/ . |
2.8 |
340. |
60. |
5.7 |
|
14 |
.31 |
.2 |
1.6 |
.27 |
.29 |
0.9 |
7.2 |
4.4 |
l.ß |
170. |
100. |
1.7 |
|
15 |
1.15 |
.72 |
1.6 |
.55 |
.54 |
1.0 |
13. |
8.4 |
1.6 |
150. |
100. |
1.5 |
|
16 |
.8 |
nul |
.5 |
10. |
130. |
||||||||
17 |
1.2 |
.7 |
1.7 |
.33 |
.3 |
1.1 |
23. |
15. |
1.6 |
440. |
320. |
1.4 |
|
18 |
.4 |
nul |
.18 |
14. |
490. |
||||||||
19 |
.85 |
mil |
|||||||||||
20 |
1.73 |
1.5 |
1.1 |
||||||||||
21 |
.78 |
.6 |
1.3 |
.26 |
.64 |
0.4 |
19. |
6. |
3.2 |
460. |
60. |
8.0 |
|
22 |
.75 |
.45 |
1.7 |
.36 |
.6 |
0.6 |
13. |
4.7 |
2.8 |
230. |
50. |
4.7 |
|
23 |
.3 |
.00 |
5.0 |
2 |
2 |
1.0 |
9. |
1.9 |
4.7 |
280. |
60. |
4.4 |
|
24 |
.87 |
.75 |
1.2 |
||||||||||
25 |
.71 |
.6 |
1.2 |
.3 |
.7 |
0.4 |
15. |
5.4 |
2.8 |
320. |
50. |
C.o |
|
26 |
.95 |
.79 |
1.2 |
.6 |
.8 |
0.8 |
10. |
6.2 |
1.6 |
100. |
50. |
2.0 |
|
27 |
.88 |
.75 |
1.1 |
.55 |
.58 |
1.0 |
10. |
8.2 |
1.2 |
110. |
90. |
1.3 |
|
28 |
.5 |
.55 |
0.9 |
.3 |
.58 |
0.5 |
11. |
6.0 |
1.8 |
220. |
6ß. |
3.3 |
|
29 |
.47 |
.3 |
1.6 |
.5 |
.32 |
1.5 |
6. |
6. |
1.0 |
80. |
120. |
0.6 |
|
30 |
.84 |
.56 |
1.3 |
.6 |
.8 |
0.8 |
8.8 |
4.4 |
2.0 |
92. |
35. |
2.6 |
|
31 |
.32 |
.23 |
1.4 |
.4 |
.5 |
1.0 |
5. |
3.n |
1.4 |
78. |
56. |
1.4 |
|
A^ |
'^eragc |
3. |
1.7 |
.9 |
2.0 |
2.8 |
EARTHQUAKE MEASUREME^sTS IN PIT AND ON SURFACE.
275
(TT.) Large Waves. E. W. Component.
No. |
Amplitude. |
Period. |
Max. Vel. |
Max. Acc. |
||||||||
Surf. |
Pit |
Surf. Pit |
Surf. |
Pit |
Surf. Pit |
Surf. |
Pit |
Surf. Pit |
Surf. |
Pit |
Surf. Pit |
|
1 |
4.1 |
2. |
2.1 |
|||||||||
2 |
1.7 |
1.4 |
1.2 |
1.5 |
1.7 |
0.9 |
7.1 |
5.2 |
1.4 |
30. |
19. |
1.6 |
3 |
1.75 |
1.5 |
1.2 |
.72 |
.79 |
0.9 |
15. |
12. |
1.3 |
1 30. |
m. |
1.3 |
4 |
2. |
l.G |
1.2 |
2_ |
2 |
I.O |
6.3 |
5. |
1.3 |
20. |
16. |
1.2 |
5 |
1.4 |
1. |
1.4 |
2.5 |
2.4 |
1.0 |
3.5 |
2.6 |
1.3 |
9. |
6.8 |
1.3 |
G |
.92 |
.95 |
1.0 |
1.0 |
1.0 |
1.0 |
5.8 |
6.0 |
1.0 |
■Jt . |
38. |
1.0 |
7 |
.8 |
.92 |
.9 |
1.4 |
].3 |
1.1 |
3.6 |
4.5 |
0.8 |
16. |
22. |
.7 |
8 |
1.4 |
1.1 |
1.3 |
1.4 |
1.3 |
1.1 |
6.3 |
5.3 |
1.2 |
28. |
26. |
1.1 |
9 |
1.8 |
1.35 |
1.3 |
2, |
1.9 |
1.0 |
5.7 |
4.5 |
1.3 |
18. |
15. |
1.2 |
10 |
2.05 |
1.75 |
1.2 |
3.9 |
3.7 |
1.0 |
3.3 |
3. |
1.1 |
5.3 |
5.1 |
1.0 |
11 |
1.45 |
.9 |
1.6 |
2 |
1.9 |
1.0 |
4.6 |
3. |
1.5 |
15. |
10. |
1.5 |
12 |
1.2 |
.8 |
1.5 |
1.7 |
1.7 |
1.0 |
4.5 |
3. |
1.5 |
17. |
11. |
1.5 |
13 |
1.4 |
1.3 |
1.1 |
2.7 |
3. |
0.9 |
3.3 |
2.7 |
1.2 |
8. |
5.6 |
1.4 |
14 |
1.65 |
1. |
1.7 |
3. |
o. |
1.0 |
3.7 |
2.1 |
1.8 |
8.3 |
4.4 |
1.9 |
15 |
2.2 |
1.25 |
1.8 |
2.4 |
2.6 |
0.9 |
5.8 |
3.2 |
1.8 |
15. |
8.2 |
1.8 |
Aa |
^erao- |
e. |
1.4 |
1.0 |
1.3 |
1.3 |
(III.) Ivipples. X. S. Coniponeiit.
No. |
Amplitude. |
Period |
Max. Vel. |
Max. Acc. |
||||||||
Surf. |
Pit |
Surf. |
Surf, |
Pit |
Surf. Pit |
Surf. |
Pit |
Surf. Pit |
Surf. |
Pit |
Surf. Pit |
|
Pit |
||||||||||||
1 |
.85 |
.7 |
1.2 |
.43 |
.52 |
0.8 |
12.5 |
8.5 |
1.5 |
180. |
100. |
1.8 |
2 |
1.65 |
1.2 |
1.4 |
.6 |
.56 |
1.1 |
17. |
14. |
1.3 |
500. |
150. |
3..3 |
3 |
.4 |
.09 |
4.4 |
.2 |
.23 |
0.9 |
13. |
2.5 |
5.0 |
400. |
70. |
5.7 |
4 |
.72 |
.65 |
1.1 |
.3 |
.3 |
1.0 |
15. |
14. |
1.1 |
320. |
290. |
1.1 |
5 |
.4 |
nul |
.15 |
17. |
700. |
276
SEKIYA AND OMOEI.
Ripples. |
N. S. Component. |
(Continued) |
||||||||||
No. |
Amplitude. |
Period. |
Max. Vel. |
Max. Acc. |
||||||||
Surf. .85 |
Pit |
Surf. Pit |
Surf. |
Pit |
Surf. Pit |
Surf. |
Pit |
Surf. Pit |
Surf. |
Pit |
Surf. Pit |
|
6 |
.78 |
1.1 |
||||||||||
7 |
.75 |
.85 |
0.9 |
.33 |
1.0 |
.3 |
14. |
5. |
2.8 |
270. |
34. |
8.0 |
8 |
.1 |
.14 |
.25 |
0.6 |
14. |
3. |
4.7 |
600. |
60. |
10. |
||
0 |
.4 |
.6 |
0.7 |
.17 |
.6 |
0.3 |
15. |
6.3 |
2.4 |
550. |
66. |
8.3 |
10 |
.05 |
.55 |
1.2 |
.1 .o |
.5 |
0.6 |
14. |
7. |
2.0 |
290. |
87. |
3.3 |
11 |
.4 |
.12 |
">.3 |
.14 |
.25 |
0.6 |
18. |
6.0 |
800. |
80. |
10. |
|
12 |
.5 |
.56 |
0.9 |
.46 |
.4 |
1.2 |
7. |
9. |
0.8 |
93. |
110. |
0.8 |
13 |
.0 |
.4 |
1.5 |
.46 |
.45 |
1.0 |
8. |
6. |
1.3 |
110. |
80. |
1.4 |
14 |
.6 |
.5 |
1.2 |
.4 |
.4 |
1.0 |
0. |
8. |
1.1 |
150. |
120. |
1.3 |
15 |
.5 |
.3 |
1.7 |
.44 |
.4 |
1.1 |
7. |
5. |
1.4 |
100. |
74. |
1.4 |
16 |
.65 |
.45 |
1.4 |
.73 |
.7 |
1.0 |
6. |
4. |
1.5 |
48. |
46. |
1.0 |
17 |
.94 |
.74 |
1.3 |
|||||||||
18 |
.66 |
.33 |
2.0 |
|||||||||
19 |
.28 |
nnl |
.24 |
7. |
... |
190. |
||||||
20 |
.99 |
.89 |
1.1 |
.53 |
.58 |
.9 |
12. |
9.7 |
1.2 |
1 10. |
no. |
1.3 |
21 |
.65 |
.59 |
1.1 |
.24 |
.4 |
.6 |
17. |
9. |
1.9 |
450. |
150. |
3.0 |
22 |
.67 |
.42 |
1.6 |
.24 |
.3 |
.8 |
18. |
8.8 |
2.0 |
460. |
180. |
2.5 3.8 |
Ay |
eragM |
-} |
1.6 |
.8 |
2.2 |
(FV.) l.:n*o-(' Waves. N. S. Component.
No. |
Amplitude. |
Period. |
Max. Vel. |
Max. Acc. |
||||||||
Surf. |
Pit |
Surf, i'it |
Surf |
Pit |
Surf. Pit |
Surf. |
Pit |
Surf. Pit |
Surf. |
Pit |
Surf. Pit |
|
1 |
2.75 |
2.3 |
1.2 |
1.6 |
1.6 |
1.0 |
11. |
9. |
1.2 |
41.. |
35. |
1.3 |
2 |
2.9 |
3.3 |
.0 |
2.0 |
1.9 |
1.0 |
9.1 |
11. |
0.8 |
29. |
•>7. |
0.8 |
3 |
.8 |
7. |
1.1 |
.() |
.42 |
1.4 |
8.4 |
11. |
0.8 |
88. |
170. |
0.5 |
4 |
.5 |
.25 |
2.0 |
6 |
.7 |
0.9 |
o.o |
2.3 |
2.3 |
56. |
21. |
2.7 |
EARTHQUAKE MEASUREMENTS IN PIT AXD OX SURFACE.
277
(TV.) Large Waves. X. S. ( '(^niponent. (Continued.)
No. 5 |
Ampeitdde. |
Period. 1 |
Max. Vel. |
Max. Acc. |
||||||||
Siu-f. |
Pit |
Surf. |
Surf. |
Pit |
Surf. Pit |
Surf. 7.2 |
Pit 0. |
Sui-f. Pit 1.2 |
Surf. |
Pit |
Surf. Pit 1.1 |
|
Pit |
||||||||||||
.85 |
M |
1.4 |
.74 |
.60 |
1.1 |
61. |
57. |
|||||
6 |
.85 |
.8 |
1.1 |
.6 |
.8 |
0.8 |
8.9 |
6.3 |
1.4 |
93. |
50. |
1.9 |
7 |
1.4 |
1.25 |
1.2 |
.8 |
.8 |
1.0 |
11. |
9.1 |
1.2 |
87. |
72. |
1.2 |
8 |
1.4 |
.7 |
2.0 |
1.1 |
1.2 |
0.9 |
8. |
3.7 |
2.2 |
46. |
19. |
2.3 |
9 |
1 .05 |
1.4 |
1.2 |
.77 |
.8 |
1.0 |
14. |
11. |
1.3 |
110. |
87. |
1.3 |
10 |
1.15 |
1.1 |
1.3 |
|||||||||
Am |
^era,^( |
i |
1.3 |
1.0 |
1.2 |
1.3 |
The ri])])les numbered 16, 18, 19 in (T) aiid ihose imtnlx'red 5, 19 ill (HI), wliieli are (li.-;tiiici on tlie surface, «Id not exi-r in llie ])it,
(19)-- May 6th, 1S89. — A small e.arth(|nake, on wliosc iindii- lations are sii]>erpose(l minute irregularities. ITerethe motion appears to \)v ratlier greater aii<] oi' longer dni'ation on tlie surl'aee than in the pit.
n. |
Aver. Period. |
||||
Surf. |
Pit |
Surf. Pit |
Surf. Pit |
Surf. Pit |
|
E. W. Comp. X. S. Comp. |
43. 50. |
33. 22. |
1.3 2.3 |
.23 .3 .2 .4 |
0.8 0.5 |
278
SEKIYA AND OMOK'T.
E. W. Component.
Xo. |
Amplttdde. |
Periob. |
M |
AX. Aoc. |
M |
AX. Acn. |
||||||
Surf. |
Pit |
Surf. Pit |
Surf. |
Pit |
Surf. Pit |
Surf. |
Pit |
Surf. Pit |
Surf. |
Pit |
Surf. Pit |
|
1 |
.1 |
.1 |
1.0 |
1. |
.7 |
1.4 |
.6 |
.9 |
0.7 |
4. |
8. |
0.5 |
2 |
.05 |
.05 |
1.0 |
1.3 |
1.7 |
0.8 |
.2 |
.2 |
1.0 |
1. |
.7 |
1.4 |
3 |
.07 |
.07 |
1.0 |
1 1.6 |
1.4 |
1.2 |
.3 |
.3 |
1.0 |
1. |
1.5 |
0.7 |
4 |
.08 |
.09 |
0.9 |
1.3 |
1.4 |
0.9 |
.4 |
.4 |
1.0 |
2. |
2. |
1.0 |
Ö |
.0.5 |
.07 |
0.7 |
1.3 |
1.4 |
0.9 |
.24 |
.32 |
0.8 |
1. |
1.5 |
0.7 |
6 |
.05 |
.00 |
0.8 |
' 1. |
1.2 |
0-8 |
.3 |
o .'J |
1.0 |
2 |
2 |
1.0 |
A^ |
'era,i^( |
3. |
0.9 |
1.0 |
0.9 |
0.9 |
X. S. Coniponpiit.
Max. Ampi,. |
Perfod. |
Max. Vel. |
INFax. Ace. |
||||||||
Surf. |
Pit |
Surf. Pit |
Surf. |
Pit |
Surf. Pit 1.6 |
Surf. |
Pit |
Surf. Pit |
Surf. |
Pit |
Surf. Pit |
.13 |
.09 |
1.4 |
.8 |
.5 |
1. |
1.1 |
0.9 |
8. |
14. |
O.G |
(20.)— :\[:iy nOth, 18S1).— A smnll otirtliqiinke.
)i. |
Aver. Period. |
|||||
Surf. |
Pit |
Surf. Pit |
Surf. |
Pit |
Surf. Pit |
|
X. S. Comp. |
32. |
21. |
1.5 |
.1 .o |
.5 |
0.0 |
E. W. Comp. X. S. Comp.
Max. Ampl.
Surf.
0.8
.3
Pit
Surf.
Pit
0.8
2.0
Period.
Surf.
.33 .9
Pit
Surf.
Pit
.46 0.7 .4 2.3
Max. Vel. |
M |
AX. Acc. 1 |
|||
Surf. |
Pit |
Surf. Pit |
Surf. |
Pit |
Surf. Pit |
1.5 2.1 |
1.4 2.4 |
1.1 0.9 |
28. 15. |
20. 38. |
1.4 0.1 |
E.VUTllgUAKb: MEASUKEMEN'TS IX PIT AXD OX SURFACE.
279
(21.) — Tune 1st, 1889.— A very small e:irtli(|iiake. Ill the E. W. and X. S. Ci)Uipoiients ofljoth tlie surface and pit diau'ranis, the niaximuin amplitudes are aliont .Oo mm. and .02 mm respectively.
(22.) — dime ord, 1(S89. — A very small eai'tli(piake. In the E. W . Component of the l)()th the surface and pit diiiü-rams, the maxinunn am}>Iitude is about .03 mm.
X. kS. Component.
Max. Am PL. |
Period. |
Max. Vel. |
Max. Acc. |
||||||||
Surf. |
Pit |
Surf. Pit |
Surf. |
Pit |
Surf. Pit |
Surf. |
Pit |
Surf. Pit |
Surf. |
Pit |
Surf. Pit 1. |
.1 |
.05 2. |
1. |
.1 |
1.4- |
.6 |
.5 |
1. |
4. |
4. |
(23.) — dune 15th, 1889. — A small earth(juake.
Max. Ampl. |
Period. |
Max. Vel. |
Max. Acc. |
||||||||
Surf. .07 .07 |
Pit |
Surf. Pit |
Surf. |
Pit |
Surf. Pit |
Surf. |
,,, s^ |
Surf. |
Pit |
Surf. Pit |
|
E. W. Comp. X. S. Comp. |
.07 .05 |
1.0 1.4 |
.8 1.0 |
.8 .6 |
1.0 1.6 |
.55 .44 |
.55 .53 |
1.0 0.8 |
4.3 2.8 |
4.3 5.G |
1.0 0.5 |
(24.) — June Kith, 1889.— A small eartlnpinke.
I']. ^\ . ('omponenl. Uji the smvfiice, the maximimi atii])lilude is not greater than .02 mm., and in the pit if is al)out ,0') mm.
X. S. Cijmponent. On the surface, the maxinumi amjtlitude is aljout .07 mm., and in the ])it it is aljout 0.1 mm.
(25.)— June 20tli, 1889.— A smalf earthcpiake. In this case, the amplitude seems to be rather greater in the pit than on the surface.
280
SEKIY.V AND OMOKl.
n. |
Aver. Period. |
Max. Period. |
|||||||
Surf. |
Pit |
Surf. Pit |
Surf. |
Pit |
Surf. Pif |
Surf. |
Pit |
Surf. Pit |
|
E. W. Couip. N. S. Couii>. |
35. 48. |
25. 21., |
1.4 2.3 |
.3 |
.4 .5 |
.8 .4 |
.(3 |
.7 |
.9 |
Max. Ampl. ' |
1'eriod. |
Max. Vel. |
1 Max. Acc. |
|||||||||
Surf. |
Pit |
Surf. Pit |
Surf. |
Pit |
Surf. Pit |
Surf. |
Pit |
Surf. Pit j |
Surf. 13. 17. |
Pit |
Surf. Pit |
|
E. W. Couip. X. S. Comp. |
.08 .07 |
.14 .11 |
0.6 O.G |
.5 .4 |
.7 .5 |
.7 .8 |
1. 1.1 |
1. 1.4 |
1. .8 |
12. 18. |
1. 1. |
(26.)— June '27\\\, 1889.— A .snu.ll earthquake.
Max. Ampl. |
Period. |
Max. Vel. |
Max. Acc. |
|||||||||
Surf. |
Pit |
Surf. Pit |
Surf. |
Pit |
Surf. I'it |
Surf. |
Pit |
Surf. Pit |
Surf. |
Pit |
Surf. Pit |
|
E. W. Comp. N. S. Ouujp. |
.1 .1 |
.05 .03 |
o 3. |
1.4 1.2 |
1.2 .5 |
1.2 2.4 |
.5 .5 |
.3 .4 |
1.7 1.3 |
2. 2.7 |
1.3 4.8 |
1.5 0.0 |
(27.)— July ord, 1881).— A small eartlujuake.
Til the E. \\ . Coiiipoueut, the uiaximuiu aiiijviitude is .13 iiiiii. on the surface, and .1 nun. in the pit.
(28.)_Fel)ruarv loth, 1890.— A very small earllKiuake.
E. W. Component, lioth on the surface and in the pit the maximum amplitude is not greater than .05 mm.
N. S. C(miponent. lîoth on the sm^fuce and hi the pit, the maximum amplitude is ahout 0.1 mm.
EARTHQUAKE MEASUREMENTS TX PIT AND OX SURFACE.
^29.)— April 11th, 1890.— A siualJ earthquake.
281
Max. Ampl. |
|||
Surf. |
Pit |
Suvf. Pit |
|
E. W. Comp. X. S. Comp. |
.13 .1 |
.15 .or, |
0.9 1.7 |
(^30.)— A])ril 18th, 1889.— A very Hinal] earthquake.
Max. Ampl. |
|||
Surf. |
Pit |
Surf. Pit |
|
E. W. Comp. X. S. Comp. |
.07 .00 |
.04 very small. |
2. |
Summary of Results.
It is .generally heUeved that the earthquake motion is considerahly less m a pit tlian on tlie surface. From the fore,<?<^ing calculati.^ns it .seems prohahle that this is true for some earthquakes and not true f.n- .^tliers. Among the thirty earthquakes we examined, there are three which were especially severe. These are (1), (13), and (IS). The rest are small earthquakes of the kind that daily occur in Japan. The ratios of the amplitudes, periods, maximum velocities and
282
SEKIYA AXD OMORI.
maximinn nccelerntioiis f(ir some of these Isitter era'tlujiinkes :is observed on the free snrfice ground to those ol)served in the ])it are collected in the following t:i1)le, average values being nsed when a number of waves liave been calculated for a single earthquake.
(\o.) |
Katio op Amplitudes |
Katjo of Periods |
Ratio of Max. Vel. |
Eatio of Max. Acc. |
|||||
E. W. |
X. 8. |
E. W. |
X. s. |
E. W. |
X. s. |
E. W. |
X. s. |
||
{■■i) |
0.8 |
0.7 |
.5 |
1.4 |
3. |
||||
(3) |
1.7 |
.8 |
2.0 |
3. |
|||||
(4) |
1.0 |
1.2 |
1.5 |
.7 |
.6 |
1.6 |
.44 |
2 2 |
|
(-') |
1.4 |
1.0 |
0.9 |
0.5 |
1.6 |
2.3 |
1.8 |
5.0 |
|
(7) |
] .0 |
1.1 |
1.0 |
0.9 |
1.0 |
1.2 |
1.0 |
1.2 |
|
(8) |
1.1 |
0.0 |
1 .0 |
0.6 |
1.2 |
1.5 |
1.3 |
2.7 |
|
(9) |
o.n |
0.8 |
0.9 |
0.9 |
0.7 |
0.9 |
0.7 |
1.1 |
|
(10) |
0.9 |
2.6 |
0.8 |
0.9 |
1.3 |
3.0 |
1.6 |
3.7 |
|
(12) |
l.S |
i.n |
0.8 |
0.7 |
2.5 |
2.3 |
3.6 |
3.6 |
|
(14) |
1.1 |
1.1 |
... |
1.2 |
1.0 |
... |
0.9 |
||
(15) |
(».<) |
0.6 |
0.8 |
1.0 |
0.8 |
0.8 |
1.0 |
0.9 |
|
(IG) |
1.2 |
1.1 |
|||||||
(19) |
0.0 |
1.4 |
1.0 |
1.6 |
0.9 |
0.9 |
0.9 |
0.6 |
|
(20) |
0.8 |
2.0 |
0.7 |
2.3 |
1.1 |
0.9 |
1.4 |
0.4 |
|
(22) |
2.0 |
1.4 |
1.0 |
... |
1.0 |
||||
(23) |
1 .0 |
1.4 |
1.0 |
1 .6 |
1.0 |
0.8 |
1.0 |
0.5 |
|
(25) |
Of) |
0.6 |
0.7 |
0.8 |
1.0 |
0.8 |
1.0 |
1.0 |
|
(26) |
2.0 |
3.0 |
1.2 |
2.4 |
1.7 |
1.3 |
1.5 |
0.6 |
|
(27) |
1.3 |
. |
|||||||
(29) |
0.0 |
1.7 |
... |
||||||
Ay en |
Ige. ... |
1.00 |
1.4 |
0.9 |
1.1 |
1.2 |
1.4 |
1.3 |
1.9 |
Average for bot] Components. |
1 |
2 |
1. |
0 |
1 |
3 |
1. |
6 |
EARTHQUAKE MEAöUKEMEXTsi IN I'lT AXiJ OX 8UKFACE.
1>83
This tabic .'seem.s In shew that li»i- . mnll (':iflh(jiiak(,'.< the aiii|)htiide aiid the period are oii the \vh(j]e nearly tlie same on the free surface and in the pit, there Ijcing a slightly greater motion on the surface. This confirms the result which Prof. Milne previously obtained. In the above are not included those very small earthquakes, whose measure- ments are difficuH ; these li(_)\vever shew tliat the motion in the pit is also small when tlie motii^n obser^■ed on tlie surf see ground is small.
It must l)e noticed that the diagram taken in the pit appears always to be smofjther tlian that obtained on the surface, and //, or the number of irregular wavelets occurrinii' in 10 seconds, is f )und in every case t(j l:ie greater for the latter, l)eing often twice as manv as for tlie former. 'J'his is very remarkaldy shown in the three severe earthquakes mentioned above, for which calculât ioii;; ha\e Ijcen made separately as regards large undulations and small ;;uperposed ripples. The ratios of the amplitudes, peric)ds, maximum velocities, and maximum accelerations for the surface and pit motion of these three eartliqiiakes are gi\en in the fjlloAving tables.
(I.) Large undulations.
(Xo.) |
Ratio of Amplitudes |
Eatio of Pkriods |
Ratio of Max. Vel. |
Ratio op Max. Ace. |
|||||
E. W. |
X. s. |
E. -W. |
X. s. |
E W. |
X. s. |
E W. |
X. s. |
||
( 1) (13) (18) |
2.3 1.0 1.4 |
1.1 1.2 1.3 |
1.2 1.1 l.(J |
I.l 1.0 |
2.1 0.9 1.3 |
1.0 1.2 |
2.1 0.9 1.3 |
0.9 1.3 |
|
Aver |
\ge. ... |
l.G |
1.2 |
1.1 |
1.1 |
1.4 |
1.2 |
1.4 |
1.1 |
Average for bot! Components. |
1. |
4 |
1. |
1 |
I. |
3 |
1. |
3 |
284
SEKIYA AND OMORL
(ir.) IJipple-s.
(No.) |
Ratio ok Au)j)litiKles |
Ratio of Perious |
Ratio of Max. Vel. |
Ratio of Max. Ace. |
||||
E. W. |
N.S. |
E. W. |
X. s. |
E. W. |
N. >S. |
E. W. |
N. 8. |
|
( 1 ) (13) (18) |
1.9 2.3 1.7 |
1.3 4..0 1.6 |
o.r, 0.8 0.9 |
0.8 0.9 0.8 |
3.7 3.2 2.0 |
1.8 3.9 2.2 |
7.8 6.7 2.8 |
2.7 4.0 3.8 |
ig-e. . . . |
2.0 |
2.3 |
0.8 |
0.8 |
3.0 |
2.6 |
5.8 |
3.5 |
Average for both Comj)oneats.
2.2
0.8
2.8
4.7
It will 1)e tliiLs observed tliut for principal iindiiLitions of severe eartli(|iiake.5 tlie raiii^e of motion is somcwliat o-reater on the surface than in the pit, Ijiit there is no great difference of inaxiniiiin velocities and niaxiinuni accelerations Ijetween the two sets of observations. This seems io he due to the fact that for the larger nndulatic^ns tlie period will .'.omewhat increase with the amplitude. In fict, tal)le (I.) would ap[)ear to iiidic:he some slight increase (of period on the surface. Tlie case is different with ripples, for which tlie results are more uniform and llie difference of surfice and imderground effects more decided. From Taljle (H.) the average extent of liorizontal motion in the pit is only half that on the surface gnnind, and the period for the former seems rather greater than f )r the latter, which arises from the fict that veiy many of the ripples disappear in the pit. Tlie maximum velocities and maximum accelerations on the surface are respectively ahout tliree and live tunes those in the pit.
Our conclusion tlien is that for small eartli(|iudves there is no practical difference between the surfice and undergr(3uiid ol^servutions ; for the principal undulations of severe eartlujuakes this difference may exist, L>ut not to any marked degree ; but for the small quick
EARTHQUAKE MEASUREMENTS IX PIT AND OX SURFACE. 285
vi1)ratioiis tlic difference is coiLsi(leral)Je. Xow, tlioiigli only ap- proximate tlie calcultition for the ripples may l)e, their maximum velocities and mtixinuim acceljrati<jns are found to he very _UTe:)t, and, in fact, many times greater than those for the principal undulations. And thus', if these ripples are really in great part smoothed away in the ])it, it is \cvy likely that in times of such severe earthquakes as discussed aho\'e, there might ])e less destructive action in deep pits than on the free surface.
We shall n(jt venture here to discuss what these ripples may be. They exist only in the early part of the sIkjcIvs and seem to be the continuation of the tremors which occur at the beginninii' of earth- quakes. The aj>})earance of the diagrams of the severe earth(|uakes is very much like that of the disturljances in the sea where minute ripples are siiperp<r>ed ou large undulations. If the ripples l3e regard- ed as waves travelling on the surface, then the whole thing will admit of an easy explanation,
AVe must state ho\ve\er that these observations were made at li(jngo, where the gr()und is hard, and it is needless to say that tlie character of the earthquake motion depends in a great measure on the nature of the soil. Hence it is ([uite possible that observations in different places may lead to scnnewhat different i-esults than those oljfained here. Thus, for instance, at I liiotsul)ashi, where the soil is soft, the range of miction is two or three iimes greater than that at llong(j, and yet the e;!rth(juake diagrams oljtaiiiecl ihere seem to be conq)aratively free of superposed wavelets.
In the above the observations were confined ro the horizontal conqxjnent motion alone. The usual argument lljr tlie supposed sniallness of the motion at a suljterranean ])oint is derived from the behaviour oi' a row oî ivory balls in ctjntact with each otlier when one at the end is sharply struck. This argument appears to apply rather
â86 SËKtYA AND OMÔEt.
to the vertical component than to the horizontal. It is our intention to continue these observations we have been making and in addition to investigate the nature of the vertical motion in the pit.
Laboratory Notes,
By
C. C. Knott, D. Sc, F.R.S.E.
Professor of Physics.
1. Electric Resistance of Cobalt.
The manner in wliich the electric resistance of cobalt varies with ]\\(j:]\ temperatures does not seem to have been studied with any great care. The peculiar beha^'iour of nickel and iron as regards their change of resistance with temperature is now well knowri'^ With a view to see if cobalt presented anv similar peculiaritv, I set ^Ir. Omori, one of the graduating students in Physics, to investigate the (juestion.
The piece of cobalt used was cut from a sheet of rolled cobalt which had been given me by l^rofessor Tait. T)r. E. Divers, F. R. S., kindly determined its composition by an analysis of a very small quantity (about 20 grains) sup])h'ed lu*m. Tlie result of the analysis is as follows :
Carbon ft)und 0'77 7o ^^"^^.Y ^^ ^^ much as 1-00%
Silicon 0T5
Iron 0-73
with a minute quantity of manganese and perhaps ^vVo *^^ ^ metal undetermined. Dr. Divers regarded it as of remarktd)le purity for a furnace product.
I) See my pajDer On thn Electric Resistance of Nickel at ITitjh. Temperatures, Trans. Royal Soc, Edin , Vol. XXXIir (1880)— also abstract in the Journal of the Colleije of Science, Tokyo, Vol. I.
288 0. G. KNOTT.
Tlie method of experiment was essentially the same as that des- cril)ed in my earlier paper on nickel. Four stout copper rods, 60 cm. ]ony and 0'7 sq. cm. cross section, were fixed in a vertical position some little distance apart. Their lower extremities were joined in pairs hy two coiled wirei^', one of which was a specimen of nearly pure platinum and the other the cobalt strip that was the special ohject of investiga- tion. The upper extremities of the rods were joined 1)y stout copjX'r sti"i])s to a commutat(^i', which was in connectiori with a Wheatstone Th'ido'e resistance l)Ox of ordinary construction.
Tn one series of experiments the lower ends of the rods with their c(ii meeting wires were dipped in a vessel of i^il wliich could he heated u]) to a temperature of nearly 240° C. A thermometer, centndly placed so that its Indh lay at the mean level of tlie ]>latinum and rohalt coils, was used for measuring the temperature. The <^il was heated very gradually and was kept briskly stirred until a few seconds before a rending was to be taken. One of the wires was niennwliile thrown irito the Wheatstone Bridge, and the resistance adjusted slightly in advance. The temperature was then allowed to rise very slowly until reversal of the commutator in the galvanometer branch gave no deflection. AVhen the equilibrium was thus attained the thermometer reading was noted. In this experiment chief attention was given to the cobalt ; a few measurements of resistance were made with tlie platinum, sufficient to give the most important temperature coefficient.
The resistance curves for the cobalt and the pl;itiiuun are shown in the diagram (p. 298), Curves Nos. 1 and 2. All corrections have been carefully applied and tlie resistances are in legal ohms.
lîy interpolation amongst a number of contiguous measurements the resistance for each of the temperatures 100°, 140°, 180°, 220" C. was calculated as shown in Table I.
LABOliATOKY NOTES.
289
Table I.
Resistance of a Cobalt Strjp in Legal Ohms at DIFFE RENT TeMPEEATÜKES. |
|||
Température. Resistance. 1 |
First Differenoe. |
Ratio. |
|
1 00° C. 1 40 180 220 |
.12:340 .1:3094 .15210 .10851) |
.ol;354 .01510 .01 049 |
1.1097 1.1109 1.1084 |
Since the second differences have appreciably ditferent values, it i> iinpcjssihle to represent the law oi" chani^'e by means of a paralxjiic liinction. ]>ut the reniarkaljle ('oustancy oï the ratios of successive pairs of resistances sugi^'ests an exptjnential function of the temperature as the expression for the resistsiuce.
Thus we may put
it. — il,, a from which we tind, if / is the temperature in degrees Centigrade,
k = -OOi^GOo, R, = -09519 The measured resistance at 7°*5 C. was 0*09604, which doe.> not diilcr ivom the value given by the f)i'nuil;i 1)V more than 1 ])er cent.
In my ])aper already referred t(j \ fxuid that the same form of ex})ression held for the case of <jne of the nickel wires investigated, the only essential difference Ijcing in the vahie of the coefïicient k, which for the nickel was .003.
The resistance of cobalt therefore d«)es not change so quickly with temperature as does the resistance of nickel.
Tn the second series of experiments the lower ends of the rods with their connecting wires were insei-ted into a porcelain vessel. Asbestos was wra])ped r<nmd the wires ; and the whole was heated in
290
C. G. KNOTT.
u charcoal furnace. The observations of resistance were made as the system was coohng, the Cfjljalt and platinum being thrown alternately into the Wheatstone Bridge. The instants at which the Ijalancing was effected were carefully noted, so that it was an easy matter to inter]:>olate between two successive measurements for the (3ne wire that resistance which correspc^nded to the intermediate measurement for the other.
By this means more than twenty distinct pairs of measurements were obtained, every C(jbalt resistance having its corresponding plati- num resistance. After all corrections were made the platinum resis- tances were di\'ided l^y the resistance of tlie |)latinum at 7°C. ; and similarly all the cobalt resistances were di\ideil by the resistance of the cobalt at this same tempérât lu'e. The numbers were then classified into groups so as to afford the means of calculating by interp(3lation the cobalt resistances which corresponded to assumed convenient values of the platinum resistances. These are the numbers given in Table II. which epitomises the results of four distinct experiments. The measurements were all made during cooling, and the higher values are accordingly tabulated first. The first column contains the platinum resistances, taken as convenient multiples of the resistance at 7° C. measured afler the experiment ; and the ()ther columns gi\'e in order the corresponding resistances of the cobalt.
Table II.
Platinum Resistances. |
CoBALi' li |
E3I STANCES |
||
Exp. r. |
Exp. II. |
Exp. in. |
Exp. IV. |
|
2.0 |
5.8047 |
5.799(3 |
5.9748 |
0.0361 |
1.8 |
4.5101 |
4.3423 |
4.4511 |
4.4580 |
1.0 |
3.1822 |
3.0536 |
3.0932 |
3.2210 |
1.4 |
2.2029 |
2.1 795 |
2.1111 |
2.2002 |
1.2 |
1.5329 |
1.5337 |
1.5050 |
|
1.0 |
1.0000 |
1.0000 |
1.0 000 |
l.OOUU |
LABORATORY XÔTEy.
291
If we p.s:>mne thîit the change« in the platinum re>«i«tance follow the same law n^i in the earlier experiment with the oil, the rise of tem- perature which will just (l(juble the resistance is about 680° C; and the interval from 1 to 1.2 may be taken as c<jrresponding approximately to a rise of tem})erature (jf 136°C. According to the ex])eriment in oil, the resistance of the cobalt would ha^'e Ijeen increased in the ratitj 1.42-48 to unity by this rise of temperature. It is p.pparent then that under the influence of the first excessive heating tlie cobalt has been considerably altered in its pro])erties, so tliat the average temperature cœfficient for resistance up to 150°C. has been increased by a quarter.
That the successive heatings caused a marked change in the structure of the wire <jr strip is shown l)y the variations in the measur- ed resistance at 7°C. These are given in Taljle III.
Table III.
When Measured. |
Resistance of Platinum wire |
Resistance of Cobalt Strii). |
At the be^'inuiuu' |
.8525 |
.09724 |
After 1st heating |
.85028 |
.09135 |
2!id |
.85028 |
.09354 |
ord |
.85013 |
.09(374 |
„ 4th „ |
.85232 |
.09978 |
The fall in resistance alter the first heating is no doubt due to some change in the contact resistances. It characterises both the platinum and cobalt. !Subse(pient heatings howe\er do not change the platinum to any great extent until the very last experiment ; but their effect on the cobalt is very marked. After the experiments were completed the col);dt was found to be nuich ahered l)v oxidation. It was exceedingly brittle and broke into small pieces when it w^as beinij-
292
c. G. KXOTT.
detîiched f"r<Jin the copper rods. AMiile the oljservatioii« were being made, it was noticed that the loiu'th experiment was much inferior in point of regularity and steadiness to the others, a fact sufficiently ex- plained l)y the tinal condition of the met;d.
It is not sin"])rising, tlien, that there is considerable divergence Ijetween the \alues of the tem])erature coefficients a« obtained from the earlier experiment in oil and the later series in the charcoal furnace.
What is surprising is, that in spite of the great alteration in structure going on in the sti-ij), the general behaviour of the cobalt as show^n in the first three experiments is essentially the same. This is well seen from the tabulation of the rates of change themselves. These quantities were calculated by tlie same general method of interpola- tion as was used in calculating the resistance. They correspond to the values of dy/dx if y/ and x are taken to represent respectively the corresponding resistances of cobalt and ])latinum. They are given in Table IV, the first column containing the \alues of the platinum resistances to which the tabulated rates of change correspond.
Table IV.
Platinum Rcsistaucu (Ar- bitrai-y Touip'r scalo). |
Ratks uf Change of Cohaivi' Resistanck i'Ei; uxrr Change of Platinum Resistance. |
|||
Exp. I. |
E.\p. U. |
Exp. III. |
Exp. IV. |
|
2 1.8 1.6 1.4 1.2 |
7.02 0.1'J 5.45 3.70 3.58 |
7.80 7.24 5.57 3.58 3.23 |
10.33 0.7 i 0.03 3.65 2.78 |
9.15 5.09 6.10 3.60 |
I have thought it sufficient to give the condensed numerical results as contained in Tables I, Hand 1 \'. The indi\idual observations U])on which these results are based are shown iiraphicallv in the diagram.
LABORATORY NOTES.
29B
; i 1 : i ' I ! |
! |
1 |
® |
|||||||||
V.Ü |
-0.17- |
Electric Resistance of Cobalt (1) C()l):ili la's. — 'r('iii])CT:itnre (2) IM.'itiiiimi lies. — 'rein])er:itnre (3) ('o1):ilf :ni(l IMtitinuin llesistniiccs . - Exp. I. X = „ II. 0- „ III. 1 O = » IV. |
? |
/ |
||||||||
o 0 ^ 0 / |
/ |
|||||||||||
6.0 |
-0.16- |
(, |
/ |
|||||||||
A- |
||||||||||||
-0 15— |
— c |
|||||||||||
5.0 |
1 |
/ 1 / è / .r |
||||||||||
-0.14- |
/; |
|||||||||||
/ si |
||||||||||||
4. f) |
n n |
1 |
~7' / |
S (3) . 1 |
||||||||
2i' -dl SI |
/ |
® |
||||||||||
CO |
p Resistances (1) |
/ |
/ / |
® |
(2),/' |
1 |
||||||
o 8.0 |
/ |
© |
® |
^ |
X |
|||||||
-n 11 |
e 0 |
/' |
||||||||||
o 1 |
/ |
/ |
®v |
° |
||||||||
J |
/ |
^ |
® 1 ° |
|||||||||
ÜU =§ |
0.10 ^ 9 y^ |
® |
r^: °" |
Teni |
perature |
Soalefor (1) an |
1(2) |
|||||
0°.e 2 |
0» 40,^^" 6 |
O" 80" 100° 120" l^C 160" 180° 200' 220° 1 1 ! 1 ! |
||||||||||
i |
' 1 ! Platin-um Resistance (3) |
1,10 1.20 1.30 1.40 1.50 1.00 1.70 l.SO 190 8.00 2,10
294 C. G. KXOTT.
Curves 1 and 2 luno already l)een mcntii^ried. Tliey sliow tlie mareli of resistance with temperature as measured on a mercurial centigrade thermometer. \\i Xo. 3, tlie ])latiiiiim resistances are vir- tnally used as temperatures, and form the al)scissa?. The ordinate« are tlie corresponding cohalt resistances. The points belonging to the various experiments are distinguished by special mark.
It will he seen at a glance tliat in ovie ])articular cobalt behaves very like iron and nickel. There is a ra])id increase in the steepness of the curve at the higher temperatures. Fn iron and nickel this rapid increase is followed at still higher temperatures l)y a distinct decrease, the curves bending so as to present a concavity toward the temperature (or platirium resistance) axis, Ta.ble IV. gives no hint of such a tendency in cobalt. The curves all iDCCome steeper with rise of temperature, if we except the distinctly irregular indications of Experiment TA'.
It Avill be seen from Table TV. that Experiments T. and H. are in fiir agreement throughout ; arid that all four experiments point to the existence of a critical temperatm-e, at which the resistance begins to increase rapidly with rise of temperature. This critical temperature is al)out the stage 1.5, which corresponds approximately to 350° C. Tlie same conclusion may l)e drawn from Table IE and expressed in these terms. Between the temperatures 400° and 700° C. the resist- ance of a collait strip increases on the average at a rate nearly twice as great as the average rate of increase loetween 0° and 300° C
2. The Thermoelectric Positions of Cobalt and Bismuth.
So fir as I know, the only satisfictc^ry determination of the position of the Cobalt line on the thermoelectric diagram was made by
LABORATORY NOTES. 295
Professor Tnit's students in the l^hysicnl T/il)ornt(~)rv of Edinhuro-li University some fifteen ^^ears ao;o. The position of Ihe C^ohalt line, so I'onnd, was o'iven alonof with the positions of certain alloys in a ])a])er 1)V Professor J. Gordon ^lacGreg'or and myself ])ul)Iished in ihe Transactions of the Poyal Society of Edinhnr£;-li, A'ol. XXVIIT (1878). The particidar specimen of Cohalt used in tliese early experiments wa« a short rod ohtained hy electrol^^tic deposition. The noteworthy ficts reo'archn«^'' its thermoelectric line were that it lav helow nickel on the diagram, and that its inclination to tlie lead line was mnch u'reater than the inclinations of the iron and nickel lines.
As a Lahoratorv exercise I gave to ]\Ir. Sawada, one of onr stu- dents of physics, the task of studyin!^ tlie thermoelectric properties of the sheet cohalt descrihed in tlie precedinii; note. The plan ado])tcd was to f'irm a nudtiple arc of Palladium and Pismuth and ])v ])roper adjustment of tlie resistances in these l)ranclies to ohtain an inter- mediate line which should cut thrcnig-h the cohalt line at tempérai ures within easy reach.
Such an iiitermediate line passes tlu'ougli the neutral point of the component metals. It di\ides the region hetween Iheir lines so that any transversal is cut into ])(^rtions which are directly as the resistances in the Ijranches of the nndti|)le arc. Thus hy varying the ratio of the resistances in tliese hranches we may sweep through the region hetween the two coi'responding diagram lines, interpolating so to speak any iiitermediate line suitahle lor our pur])ose. The extreme accuracy with which we can measure elc'tric resistance enahles us to fix the position of this intermediate line a.s a.'-curately as the positions of the component lines are known.
The low jiosition of cohalt on the diagram very much circum- scrihed the choice of metals for the multiple arc. lîisnuith had to he one of them, as it alone was known to he heh^w cohalt. The other
296 C. Cx. KNOTT.
meta] fixed ii])oii was ralladiiiin. a snhstnnce convenient in every way. Its (liauTani line is strai^'lit u]) to liii^ii tein])eratnres ; aiul its character does not perceptil)ly clumge even after severe heating-s. Un- forlunatclv, however, the necessity of nsin,o- ])ismnth ]iniit('(I tlie investigation t(^ moderate temperatnres.
The l)isninth was l)roken np into small pieces, which were packed tightly into the l)ore of a si]>hon sliaped glass tube. Gentle heating in 11 Ihmsen flame sufficed to melt the metal, which ran together and solidified (^n cooling into a fiirly unifnan rod. The junction wires were fused into the ends of the hisnmth rod.
As tinallv set up, the a])paratus consisted of a triple Cohalt- Bismuth-Palh'.dium junrtion dippirig in oil. This formed the "hot junction." liesi;4ari<'e boxes were included in the p:dla(ham and bisnuith bi-andies. because of the magnitude of the thermoelectro- motive i\mv:' between these three metals and cojiper, great prec:nition was necessary in keeping tlie various cold junctions at the same tem- perature.
The palladium branch always contained 100 ohms resistance. The resistarir-c of the l)i:anuth Irninch varied from infinity to 200, lower values c:u"rvirig the intermedia.te line too fu" below the coltalt line. For each of tlie seven selected ratios of resistances, a, careful series of thermoelectric observations was made. A delicate high resistance galvanometer was used ; and the temperatures were mea- sured bv a mei-(au'ial thermometer. The electromotive forces between the cobalt and eadi intca'inediate "equivalent metal" were in this way measured directlv. From these the thermoelectric powers at chosen ttanpci'aiures could be calcul-ated. lîut one of tliese " e(pii- valent metals" was ])alladiiim itself, when tlie re:;istance in the bisnuith branch ^vas made intiiiite. Siil)tracting 'dl llie oilier tluaanoeleetric powers from this one, we obtained the thermoelectric powers lietween
LABORATORY NOTES.
297
palladimn aiid llic other equivaJciit iiicta].<. The Ya]iie.> of the therinoelectric powers "were eaJculated for 0° C aiid 100'" C and are given ill the followiiii:- Table. The symho] Pi staudo for ijioinutli, Co for cobalt, aiid Pd for palladiuiii, Tlie variou;> " etjiiivaleiit iiietafs " are repre.seuled by the ;<yiiil)ol Pd Pi „ where tlie ijiindier n represent« the ratio of the reniistaiice in Um l)i.;niiilh ])raueh to the refdstanee in the pa]Ia(b"iini branch. Tdui;^ Pd JJio means that, iince the palladium ahvay.r; contained 100 ohms resistance, the l)is]nuth contained in this case 200 ohms. The electromotive forces are measm-ed in microvolts.
Thermoelectric Powers referred to Palla.dium.
Metal. |
'J'lieruioelectric Power at O'C. at 10(/0. |
NeiiLial Point with Cobalt. |
|
Co |
7.00 |
17.ol |
|
Pd Bi,3 |
5.98 |
(3.4(3 |
-10°.4C. |
Pd Big |
9.;38 |
OM |
+ 2P.5 |
Pd l^i. |
] 1.45 |
\ 4.(i0 |
74.1 |
Pd Bi, |
17.44 |
17.4i |
101 .4 |
Pd Bi,, |
21.73 |
22. 1 o |
1 18 .0 |
Pd Bi, |
20.10 |
20.55 |
224 .0 |
Bi |
8(3.0 |
88.8 |
The numljers in the last row liave heeu calcidated from the numbers in all the six Pd Pi rcjws. Tor if p is the thermoelectric power between Pd and Pi and p,i the same Ijetween l*d and Pd Pi,j we know that
P - Ih
p,
or
p = {ll + 1) pn
Thus from Ihe six sets of values corresponding- to p^ we obtain the following values for p at ifC. and lOO^'C.
298
C. G. KNOTT.
n + 1 |
1\ |
Pm |
14 |
83.7 |
90.4 |
9 |
81-. 4 |
89.0 |
6 |
80. 7 |
88.1 |
5 |
87.2 |
87 2 |
4 |
80.9 |
88.0 |
3 |
87.3 |
88.7 |
Means |
80.Ü ± .8 |
88.8 + .7 |
'riii.< t-able i.^ uljviour^ly an indication of the accuracy of the experiment.
And now, referrin.^; everything to the Lead line, and expre.^>ing the thermoelectric power in the form
P
^ = Ä + Bt dt
we ohtain for tlie coetHcientiJ .4 and P» tlie foUowinu' V'due:s.
A B X 10'
Lead 0 0
Palladium - 0.18 - 3.55
Cobalt -13.18 -13. 9
Bismuth -92. 2 - 6. 4
According to the nundjer.s deduced by Fleeming Jenkin from Mattlde.sen'y experiments, Ijismuth lie^ four times further from lead than does cobalt. Here we have it seven times. Professor Tait's electroly- tically deposited C(3balt lies 4 J times further from lead than does p:d Indium. Here we have it a little over tAvo times. According to Lecquerel's nundjers given at the end of the English translation of Mascîut and Jcndjert's FJcciriciiij and ^Liguelism, the rati(3 at 50° C. of the thermoelectric powers of palladium and bismuth relatively to lead is as 7 : 40. Here we have 1:16.
LABORATOEY NOTES. 299
These di.scre});iricies nve not .snrpri.siiio-. We know how varia1)Ie are tlie thermoelectric properties of .stähle alloy.s^^ intended t(_) ha^•e tlie .same composition, and h(3w a very sh<^-ht eliange in com[)0.sition may he accompanied hy a very large change in thermoelectric position. The present experiments mnst therefore he judged of •dt(_)gether on their own merits. A simple comparison shows us that Professor Tuit's c()l)alt will fit in to the regi(3n hetween lead and l^i.smatli ^•ery much as Matthiessen's cohaJt fits in io his own .series. Thus tlie cohalt inves- tigated liere seems to ditter from tliese other specimens in much tlie aame wa3\ The new col)alt indeed hes so high in tlie diagnim that its line is higher than the line of Ta it'. s nickel, for which A = — 21.S.
This unexpected result was at once tested. A rougli experiment was made witli the couple nickel-cohalt and a neutral point was oh- tained a.t a temperature below 100° C. This cohalt line therefore, at ordinary temperatures of the air, is ahove nickel ; l)ut because of its greater downward inclination 'j:et:^ below it at temperatures above
100° c.
As regard.-; the inclination <jf the coljalt line, the present result agrees as well with the earlier result as ci^uld ]'easonal)ly Ije expected with two quite dillerent specimen;' of the metal. I'hus, expressed in tlie same units, the thermoelectric power ;/f Professor Tait's coljalt is given by the formula.
p=—26:S — i).\ Mi / Avhereas for the present specimen
2j=-13.f8-U.lo86 t \\'ith tlie exception of the .sharp upward Ijend in ni'^kcL ihi.- gives the greatest inclination yet ohtained for a thermoelectric line. It would
1) See tlie pnpei- by MacGre^'or aud myself already referred to, also my paper ou T/«' Electrical Proi)crtu'^ of Uydrogcnisicd Falladinia (Traus. \l. S. E., Vol. XXXIII., 18SGJ— abstract in this Journal, Vol. I.
300 C. G. KNOTT.
be interesting to establish Ijy direct ex})erinient that the Thomson Effect is exception;! ]ly laru'c in cobalt.
The downward trend and cDinparatively large inclination (^f the bismnth line are also worthy of note. Uecanse of the ])osition of the line as a whc^le, lying far below tlie lines of all other metals, this large inclination does not greatly influence the electromotive fjrces, so that with bismuth C(juples the electromoti^'e force is very approxi- mately proportional to the temperature. This fact of course prevents us from making a very accurate determination of the coefficient 15, which in the present experiments has a large probable error. Its mean value is a little greater than the ^•alue indicated in liattelli's direct measurement of the Thomson Effect in liismuth^'.
liio'hi has shown-^ that the electric resistance of lUsmuth is altered in a strcjiig magnetic field. To find if any thermoelectric change accompanied magnetisation in nickel, a bismuth palladium cou])le was set up IjetAveen the poles of a p(3werful electromagnet. Xo effect whatever was obtained, although the arrangement (slightly modified) was sensitive enough to show with great ease tlie thermomagnetic effect discovered by v. Ettingshausen and Xernst^\
1) See Wied. Beiblätter, Vol. XI, 1887.
2) See Wied. Beiblätter, Vol. XIII, 1884.
3) See Wied. Annaleu, Vol. XXIX, 1886.
Diffraction Phenomena produced by an Aperture on a Curved Surface.
By
H. Nagaoka.
In ordinnry prohlems on diffraction of liglit produced liy nper- tnres of varions shapes, the diffracting- apertures are snp]:)Osed to lie on a plane. The rm^re _£i'eneral prol:)Jeni of diffi-action prodiKXMl 1)y aper- tures on a known _o-eonietrical surface lias noi, so fir, beeri touched. It has been my object to fill in this gap, althc^ugh the expression for the intensity of diffracted liglit is integrable oidy in a few ]X!rticuI:u' cases.
In the following, I give a general expression ibr the intensitv of light diffracted by nn aperture on a known surficc, ])otli inr Frauu- lioi'cr's and Fresnel's diffi'action ])lienonu'iia. 'i'he expression is tlieii a])})lied to find tlie (b'stribution of light after its ])assage tliroiigh a small slit cut ]X'r])endi*Md;ir to the generating line of a right circiifir cylinder.
Expression for the Intensity of the Diffracted Light. '•
Let L be a source of light, and A B an apertinx* on a known geometrical surfice. Llie ray of liglit pro])agnted irt^ii L i- dilfracteil by the aperture A B, and the diffraction plicnonK'na thu- ])i-oduced may be seen either projected on a screen at 1) (^Fig". 2 ), (^r o1)ser\('(l by
* Tn the deduction of the expression for the intensity, T follow F. Xeuniann's method.
302
H. NAGAOKA.
Fin-. 1.
Fig. 2.
means of n telesoope placer! at T, and s(^ fc^ciissed that the ohserver sees a, distant ])()int ]J (Fio-. 1) ; in other words, D is the so-caDed diffraction ])oint.
In order to find the a'eneral expression for tlie intensity of light after it is diffracted hy an a])ertnre on a cnrved siirfjice, T shall assnme tliat the diffracting apertm-e is very small compared with its distance from the source of light, and from the ])oint at which the intensity of diffracted light is ciHisidered. Conserjuently the amplitude of N'ihraiion of the hght coming from different ])oints c^f the aperture will not ^ ary at the ]ioint considered.
I shall first discuss Fraunhofer's (telescopic) diffraction pheno- mena. Referring to Fig. 1, let the vihration at L he represented hy eus 2r ^r ; tlien, at any ])oint P on tlie diffracting a])ertiu'e, it will he proportional to
No\Y considering the ray in the directi(on DP, tlie vihration at anv \)ohi\ C in the line FT due to tlic small element da at /' is propoi-tional t<»
ox CEKTAIX Dli'FKACTJOX l'UEXOMEXA. 303
/ t LP I'C \ ., _
\r / /, /
Describe a sphere with D as centre, and jtassiu^- throuuii C ; tlieii the time taken ]jy the ray U) go from the s|)]iericaJ surface to the eye will he constant, provided D be siiüicientJy distant. I.et (his constant time be denoted by " ; the vibration at T is thus ])roportional to
an cos [ — TT, — ^ — ^- J 2 -.
\ similar expressitjn holds for the light ])ropagated from every element of tlie aperture, so that the total effect at T will be given l)y the inteii'ral
(1
I <((7 COS I rn — ^ — — — : — ) 2 /T,
./ \ i / / /
where the integ'raiion extends (jver the whole aperture. Taking any point 0 near the :iperture, we may write
PC = DC - DP,
= DC + {DO - DP) - DO, LP = LO - {LO - LP).
Denoting the c(jnst;int distances LO, DU hy U and IÎ' res[)ec- tively, let LO - LP -- JPi, and DO - DP = JPi!
Introducing these syndjuls in the expressions for PC and LP, we find
PC - DC - R -{- JR\ LP = R - JR.
Substituting tliese in (1), we get for the vibration at T the integral
,os r , n ~ - DC R- W JR - JR' \ ^ (2) J da COS {-^^ . ^ + . )2..
Since r, DC, R — R' are all constant, we can put
t - T DC R -- R' -T J 1 ='^'
304 H. XAGAOKA.
and the above expression for the vibration becomes
( 3 ) Ida cos ( b -I ^ J 2-.
The intensity of Hght at T is, therefore, given Ijy the expression
or more simply by
( I ) 1= MocUfda e ' ^ (-J^- ^«')
Wlien the diffraction point is sitnated on the (_)ther side of the surface from the source of light, and the phenomenon is seen projected on a screen at I), ^ve must slightly modify the expression for the in- tensity of light.
Troceeding in exactly the same way as Ijefbre, the vibration at I) due to a small element da at P ("Fig. 2j, will he proportional to
, / t LO PV\ ,, d(T cos {^Y^ J —\ 2-,
which can be written
/t _ LP , LO-LP OD-PD\^_
\T ~r^ I + I )-
da cos
Puttinii; as before
LO - LP == JR, OD - CD = JW,
we get
/t LP PD\,, /, . Jli + JP'\,
Conse(piently, the total effect at I) is gi\'en by I da cos la-] ^ j 2-.
ON CERTAIN DIFFRACTION PHENOMENA. 305
Thu.s, the intensity (A' diffracted light at D is given by
or uioYd briefly by
(II) I = MocPfdn c ' ^ (^^^ + ^^')-
Tlie abo\(' expressiijn gives tlie intensity of diffracted light for Fresnel's diffraction phenoinena.
To evaluate the integrals given in (I) and (II), assinne 0 as the origin oï three rectangular c<3-ordinate axes x, ij, z. Let the coordi- nates (jf the points L, 1>, i^ referred to these axes be denoted thus : —
L : a, h, c, D : a , b', c,
P : X, y, z,
and let the ecjuation of the surface referred t(.) the same axes be
F (x, y, iij —const. Thus, we have
LO = ^ a^ + h- + c' = II,
OD = ^ a'+ 6"-+ c- = W,
LP ^ V (^» - ^f + (^ - Vf+ (^- - =2)' = 1^ - ^^^^
PD = ^ (rt'- xf^- {b'- yy'-{- {c'- y.)- = W - âli\
Expanding the expressions for LP and PD Ijy means of the binomial theorem, we have
LP ^ E j^ - -^yfj^iax -Vby ■]r cz)--\- ^, + ,
T„ ax + b'y + c'z 1 , , ,, , ,., ./;-+?/-+ 12'" .
PD = K ^^-jf^ ^j^a^«'^+^^+^'^^)''+ ^-^4^^ — +■
or
306 U. NAGAOKA.
âR = ^ + -^-^ {ax + by + r.^)- .,7^
.j^, a'x + b'y-^c z , 1 , / , ?' , / n- à:^+ (/'+ f-'^
-i)
Let the direction cosines «jf OL be }c, u., v, ;in(l those oï OD be ;/, /^', y' ; then ( 4 ) becomes
i')
J22 = (;r a: + //. y + i^z) + -:^-rr {" x + n y + •. z)-— j' — -,
^ it 1 i\
1 / / / /so ^" + ?/ + •'^'
M/ï'= (;/a; + u-'y + v's) + -^-jr, {nx + //.'^ + v'a)- —
2ii;'
In Fraunhofer's diitraction phenomena, // and B! are supposed to l^e very large compared with a;, y z, so tli:it we can neglect the terms containing B, <3r Pi in the denominator. 'Huis
âli - âR = {)( - ;/) X + {/J. - //) y + 'c^ - v') ?:.
Writing
0 -
- ^') = n,
the expression for the intensity of the dittVacted Jiglit becomes (T) I = Mod-.fdae'^'-'"-'"^-""^
where the integration extends o\er the wh(jle aperture.
In Fresnel's diffraction phenomena, we can no Jonu'er neuiect the
terms -5- and -^. Thus tlie expression f(.)r AR + âR' ljec(3mes very
complicated. It is, however, somewhat simphfied Ijy taking 0 in the Une LD as shown in Fig. 2. Thereby ;/= — )(, //= — ti, >= — v, because OL and OD are in one Une. Tlius
ON CERTAIN DTPFEACTION PHENOMENA. 807
AR + AR = ^ (;. .r + fUJ + i^zy-- {X'-+ j/ + ..2)^^_L_ ^ _I_\
Introdncino- fin's v.-iliic in (TT), we o'et for the iutensity of h'oht ;it D ( 11') / = MocP. fda .^^[(^^' ^ "'-^ + ''^^' - (^' -^ y^ + ■^^)](-zr + -7p)^
where the inteo-rntion extends over the whole npertnre.
Thus the pro1)leiii of the ditiVnctioii of lio-ht produced hy nn n]ierture on n curved suriace is reduced to the inte^Tntion of expres- sions (I') nnd (TT') for Fraunhoter's and Fresnel's diffraction phenomena respectively.
Fraunhofer's Diffraclion Phenomena produced by a narrow Slit on a cylindrical Surface.
Let us now discuss Fraunhofer's diffraction phenomena produced hy a narrow slit cut on a right circular cylinder and perpendicular to the generating line of the cylinder.
Tn order to calculate the intensity of liglit for different positions of the telescope, dro]i a perpendicular on the axis of the cylinder from the centre of the slit. Assume the centre as the orio-in of co-ordinate axes. Fet the x axis he parallel to the axis of the cylinder, and the z axis perpendicular thereto, hoth drawn through the centre of the slit.
The axes heing thus fixed, we have, 1)y ( T'), to find the integral
/•
^^^^i(U + viy + nz)
where the integration extends over the whole ajierture, and /, vi, n are determined ])y tlie (hrections of the incident light and of the <)T)servirig telesco])e referred to the rectangular axes ahove specified,
308
H. XAGAOKA.
and by the wnve leno-th of light employed in tlie oh^^ervntion. In addition to this, there is the equation of condition
ii/2 + «2 _ 2 az -=0
expressing the faet that tlie aperture lies on a cylinder of radius a.
In actual calculation, it is more convenient to use polar co- ordinates. In the right circular section of the cylinder, assume polar co-ordinates with the pole on the axis, and take
y — a sin /? , z = a {1— cos ß),
Then da = a dx da.
Thus fß^'-""y-^'"'\h = ae'^'jdx e'Y^//.'"('" "■" ^ ^ " '-'' ^^■
where 2/> denotes the hreachli of the slit. The integral
idx e =
Ü
2 sin Ih
I It thus remains to find the integral
taken between proper limits.
Introduce an auxihary angle â', such that
a m — 5 si)i (Y , a n = c cos />'
where c = a ^ni- + n'.
ox CERTAIN DIFFRACTION TUEXOMEXA. 309
riicii a {in sill 'V — n cos â) = ç cos [r) + I'J') = ç cos c,
where ç stands i'or ij + />'.
Thus fdn e'"^'" "'" ^ - " ''' ^' ^ fdif e' ' '"' '^•
'J'lie Jiiiiit.s of integral ion with respect to (f are fljiind ir«Mu ij' and the known limils witli respect to ü.
The dithcuJl y of the })ro1j]eni hes simply in fin<linu- the inteu-ral
I shall hencef(.)i-th put J ~-= K + iL, where
K — I cos (-f COS (f) d(f,
L =- /sill (ç cos (f) dç.
Evaluation of the Integral '^ = fif c ^ ''' f^
There are various ways of evaluating tlie ahove integral. The siin}»lest way would l)e lo lind a differential e(jualion which is satisfied hy J, and hy this means to expand it in a scries proceedinuf accordin"' to ascending powci*« of ^.
îSincc every integral of tlie form fdire^'""^ hctween known limits can be decomposed into a smn of two separate integrals of the
/•a ■ .- , ,
form id(r c ^ "'" '^ , I sliall (jnly consider
•/o
*ultinu'
cos ç — U, cos (J. — c, J = - / 4zz=rr- du.
■h ^\ - i(^
310 U. NAGAOKA.
Ditfcrciitiatiug with respect to ç, wc have
_ J ] (I J i .s cos (<• E) !^ sin (r ç)
Ç d Ç Ç Ç
wliere .s staiids for ^l — c^ = sm a.
Tliu.s tlie diitereiitial c'ljiiations ^^atisßc(l l)y A' ami L are res[)ect!vely
d' K 1 d, K ,, s sill, fc c)
a Ç Ç a Ç Ç
1 d' Tj 1 (Z L ^ s cos (f ci and -^^^ + T -. \- L = _'
To find the expression for K a.nd L, assume a series proeeediii_ij,' aceonhuy to ascendin,^' powers of |. Diffrreiitiating and pro[)er]y chootfiiiL!' tlie eoiistauts, we easily Hud that
+ ^ Vi-
J' / r" (•■' c- 1 \
+
irs II + 1 /■ ,,2 II ..5 II - 2
]
where n stands for — (cs + a).
»)X CERTAIX DTFFRAL'TIoX I'lIEXOiMEXA. 311
It is to he remarked th:it when a = r, 7v beconios eqii:il to - J°(c), wliore .7° denotes Ijessel'.s function of tlie Hrst kind witli index 0. Tliiis the .'d)ove expression for Jv reduces to
K
_ / Ç- Ç' ç*' ç*^ ' \
Tlie expression within the hracket is the well-known form for -7°(ç).
Tt is easily seen that the above two series f )r 7v and L convero-e ra]>idly so lon^' as ^ is small ; hut when ç becomes lari^-e, it wonld be advaiitau'cons to em])loy other expres.^ions fn* K and L.
The usual process of calrulatini^- / e ^ ^"* "^ dç is to ex|)and c'' ^"' ^
in a Fourier series, and integrate eac-h term of tlie series sejiaralcly. Thus
1
• A) ^
1
E(piatinr;- the real and imau-imu'V ])arts to K and Tj respectively, we ha^•e
(c) A' = o..!" (,-) + 2 V (- 1)" r-- (ç
2 «
The f(^rm li'iven above is not r.a])idlv C(^nveru'ent. The values of J"(ç) can l)e easily c:d(adate(l from the values of J°(^) and 'P{^) g'iven in the tables of Hansen and Meissel u]) to certain values of the argai- ment ^. \\\\\ for hig-hcr values of ç, we should have to calculate -/^"(c) and 'J\:). ^loreover, when n exceeds ç, the value of '/"(ç) deduced successively from J°(^) and -/^(ç) becomes inaccnrate, and we are thns compelled to undertake the calculation se])arat('ly. Tliese considéra-
312
H. XAGAOKA.
lions îiinkc tlic foniiiihic jiist Lj'ivcri less r-onvcuioiit for (■.•ilciihilion tliîiii llic i(<i'iniil:i(' ü'i\('ii lu'low.
As :ili(':i(lv iiUMilioiicd, tlic Inrin of tlio intOL'Tal /sliows \]\:\t wlioii llie liniirs lie iVoiii o to -, il Ik'couk,'.-! ('(|ii;il lo - J °(ç). Tiiiis J iiirliidc:-! IV'ssel's i'iinctioii oi'ilic llr.u kind willi index 0 :im :i |):ii'1 i('id:ir case. l>v a s])f'(:'i:d transiocnialion, J can Ix' inadc to d('|)('nd on J° ()iz) as will now 1k' shown. Tuttinii' Il ^ cos if , wc \v.\\v
nu — I dii.
J
Expanding'
V^ I — \C-
:zir m a r Olivier series.
1
1 "^
^ [ — li- ]\Inlti])l_vinii' tin's l)y ^' ^ ", and intea'i'atin^-
After a simple reduction, "we liave
/:
ju - —
?' ./?«/ 1
Ivjiiatino- the real and imaginary ])arts of both sides of tlie
equation
(0 /:^^*,, = -Lj
V
z h - ~ sin ^ M >
1
Ç- — n- --
2 r ro.s ç ?/, V
^nJ° [n ~) sin [n - ii]
Ç- — n- --
I
ox OEUTAIX DIFFl.'.VC'rioX I'llEXoMEXA. -U.')
/ ,.x rf<in (: ii) , 1 l' ros ^ II . . ^^ J°{ii z) cos n z u
+ 2 - sin (. .) 2^ .._,,.-. |-
Tlieise two cxj^vssioiis ( (• ) nnd ( /') nrc v(\vva\ to — /v •iinl — Tj
Tims 7v and L are iiiadt' to dcju'iid oii J°(», r), wliidi can 1)0 ('al<adated o\\(\' loi" all ; tlic rest involvini;- siiiiplc aritliiiU'(i<-al and triti'oiK/iiU'trical calculations.
The ex])rossions ( ^' ) and ( /') above dcdncod for K and Jj ro<|uiro special consideration M'licn ^ is a multiple of -, since both then contain terins of the form ---.
Let us suppose that | ^^ m - ^^ y. Then the expressions for K and L assume f)llo\vini'" f nans.
wl lere
1 I sin zu. ^ _ . . "^\^J [n-^cosin-ii) ^ , . . ^ J {n-)cos{nzu)
. I -_ \--' sin C II. > —. :,—T, \--ZSUlZUy ;;; t, 7,
'1 V^ z V -- — n--- ^, c- — n- ~-
1 ' mrl
-, ^ '"■C^^nJ''{n■ z)sin(nz ii) ^ ,^ ^ ^nJ°xn -)sin{n-n.)
— 1 - cos C ?( > X., .,- ., ~ COS iC 11.) > i-.r ^-9~ .,
j^' _ J. ^ sin (? u) cos (y ii.) — y cos {: u) sin (y u) "?=>' Ç- - r- •
^ 11 cos z V. . „^ . i-^ 'T in-)cos(7i-n.] ... . -P5 J (/?.-) ros ;*-'
ij = — i-l :: + 2 C COS C Ii > —, 7, — 7, |--"COSC« > —, —r, — 7,
2 l_ Ç ^ Z-— n- -- ' ^j Ç-— w- --
, -, ... ,r,l7°(72n-) st/i (/i;r?«") , -, . , .^^ J° (nz) sin iiz' + 2z sin':ii)y — ^ — ~, — -^^ \- 2 :: suiji z iny -. 7^—7,
+ 2 7/J°0//-)T
?)14
H. NAGAÜKA.
where
/^i, u., (]cuo\\u<j^ the limits of intei^Tntion witli resper-t to //.
Ev:iln:iiiii£;' tliese two iiidetenniiiatc forin.-; K' •nul L', we find
K
2 ;- n. + sin (2 ;- ii)
L' =
sin y (?fi + 71.,) sin y {il., — iii)
Thn.-! tlu' expressions nhove deduced cnn 1)e employed fnv cnleulnting' A' ;iiid L ïifV nil values of ç.
I may here remark, tliouo-h it has nothing' to dn with theqnestion of ditfra''tion, that a m<^re gvneral integ'ral of the firm
/'', i ? ens (f . 2 V d(f e ^ sui (f,
the limits lying' between - and —z can he made to depend on ./"(nr), hy exactly the same process as al)ove given. Tn fu-t, r^essefs function of tlie first kind with index v can he expressed hy means of the f )llowing f )rmula,
J\.2.ö...{-2v-l) yi? sinç 2çsinç^ n + l J^jn::) \
ox CERTAIN DIFFUACTIOX PHENOMEXA.
315
For coiivciiieiice of calculation, the following- values of J°(/tr), for successive values of n, have ])eeu calculated aud tabulated.
n |
J°(«r) |
log J°(«-) |
n |
J\n-) |
log .r{>i-) |
1 |
- 0. 3U4242 |
(-) 1.483219 |
26 |
+ 0.062329 |
( + ) 2. 791691 |
2 |
+ 0.220277 |
( + ) 1.342969 |
: 27 |
-0.061168 |
(-)â. 786523 |
3 |
-0. 181212 |
(-) 1.258186 |
28 |
+ 0.060069 |
( + )î^. 778650 |
4 |
+ 0. 157507 |
( + ) I. 197300 |
1 29 |
-0.059027 |
(-) 2. 771051 |
5 |
-0.141182 |
(-) r. 149779 |
30 |
+ 0.058038 |
( + ) 2. 763710 |
0 |
+ 0. 120064 |
( + ) T. 110804 |
31 |
-0.057096 |
(-) 2. 756608 |
7 |
-0.110609 |
(_) T. 077765 |
32 |
+ 0.056199 |
( + ) 2. 749732 |
8 |
+ 0. 111068 |
( + ) 1.049093 |
33 |
-0.055343 |
(-) 2. 713066 |
9 |
-0. 105625 |
(-)T. 023768 |
31 |
+ 0.054525 |
( + ) 2. 736599 |
10 |
+ 0. 100251 |
(+) 1.001089^ |
35 |
-0.053743 |
(-)2. 730320 |
11 |
-0.095621 |
(-) 2. 98U555 |
36 |
+ 0.052993 |
( + ) 2. 724216 |
12 |
+ 0. 091579 |
( + ) 2.961796 |
37 |
-0.052273 |
(-) 2. 718280 |
13 |
-0.088010 |
(-) 2.944530 |
38 |
+ 0.051582 |
( + ) 2. 712501 |
11 |
+ 0.034827 |
( + ) 2.928535 |
39 : |
-0. 0509] 8 |
(-)î^. 706872 |
15 |
-0. 081967 |
(-) 2. 913638 |
40 |
+ 0.050279 |
^ + ) 2. 701386 |
16 |
+ 0.079378 |
( + ) 2.899697 |
41 |
-0. 049663 |
(-) 2. 696035 |
17 |
-0.077019 |
(-) 2. 886597 |
42 |
+ 0.049070 |
( + ) 2.690812 , |
18 |
+ 0.071859 |
( + ) 2.874243 |
43 |
-0.048497 |
(-) 2. 685712 |
19 |
-0.072871 |
(-) 2.862554 |
44 |
+ 0. 017944 |
( + ) 2 680729 |
20 |
+ 0.071033 |
( + ) 2.851462 |
45 |
-0.047109 |
(-) 2. 675858 |
21 |
-0. or)9328 |
(-) 2.810910 |
46 |
+ 0.016892 |
( + ) 2.671094 |
22 |
+ 0. 06)7740 |
( + ) 2.830846 |
47 |
-0.046391 |
(-) 2.666432 |
23 |
-0.066-257 |
(-) 2.821228 |
48 |
+ 0.015906 |
( + ) 2.661868 |
24 |
+ 0.064863 |
(+) 2. 812017 |
49 |
-0.015136 j |
(-) 2.657398 |
25 |
-0. 063560 |
(-) 2.803183 |
5j |
+ 0.011980 |
( + ) 2. 653018 |
ol6 Ü. XAGAOKA.
Jieturiiiiii,'' io our [H'oblciii on FrüUiihofer's ditfrnction phcnoinena, we iz'tit for the exiR'ession of the iuteiisitv
I — 4 a- — ß — (A-+ L-)
With a hoinoo'eneouy tsonrce of Jiu'ht, the iiiteiisity always vanishes whenever I h is a nuiJtipJe of -. The fringes arising i'roni the term sill' lb are exactly the same as those given hy the ])lane slit. When the surface on which the slit is cut is cylindrical, the additional factor K- + L'' enters into the expression for the intensity of the ditfracted li^dit. This factor has maxima and minimu f )r ditierent positions of tlic telescope, and moreover depends on the length of the slit. Thus, wlien the Hmits (jf integration lie from 0 to -, K -■= - J°{^) and L = 0, and there would be places of darkness for .such positi(His of the teles- C(3pe as are determined by the values of ç corresponding to the roots; uf /■>(?).
For a great numi)er of ecpiidistant slits, the expression for the intensity would be tlie same as that for ordinary grating, multiplied by the factor K- + L'\
The case which calls f)r sjjccial attention is when the ray is normally incident, and tlie telescope turned so as always to lie in the plane xij. Tlicn ;c = 0, //. := 0, v = 1, and // = 0. Thus I = ^^4^ sin. (0, where w is the angle made by the axis of the telescope with z axis. The places of darkness are given by
n /
Sm (I) =- — r • — r-
2 6
The maxinra and minima arising from the term K- + L" must be separately determined f )r the ])arlicular slit in question.
ox C'EKTAIX DIFFKACTTOX PHEXÛMEXA.
317
Fresnel's Diffraction Phenomena produced by a Slit on a Cylindrical Surface.
Fiff. 3.
Let A B he n section of tlie slit, cut by ;i plane passino- throiio'h the sonrce of lig-lit L, and the point D at which the illumination is recpiired. I shall -X suppose that the point D is not YQvy far from tlie line joining- any ])oint on the slit with the source of light. Also, the problem will be still further
simplified if the plane L A B is made to contain the axis of the
cylinder.
For calculating the intensity of the ditfracted Hg-ht, assume tlie
point 0 wliere L I) meets the cylindric:d surfice as tlie origin of
coordinates. Let the x axis be parallel to the axis of tlie cylinder,
and y perpendicular to the plane LAB.
In this case, where d is very small,
a = 0,
Thus
H = cos LOA = Ö,
and
1 nearly
{}( or- + /j.y 4- i.z)-= 2 Ö x s + :2^
neglecting d' u]i wards.
Recurring to formuhi (II).
A 11 + A R= Q ÖXZ- {x'Jr ?/)] (^ + ^).
'>1-'^ H. XACJAOKA.
Tlu'VcCorc, l)_v lorimil;i (11'). ( T ) / = ModJ a fh .' 1 [- '^ •- - (-^ + ?/')](!+ -}p)-
Sinrr ''A .r, üiid ,: nro nil very .-;mn11, ^\c rrin writo
wliovo c stiiiids for -4- ( -7— + ,,/ Y
'l\'ikiiiu' ])()l:!r coordiiKites in llio riulif circuLir ^ediDH (.>(' llie (■yliii(l(i- willi the ])n\r on tlio axis, we in:iv writ«'
d(T = a dx d(f,
y = a sin c, z -- a {] —cos ç).
Trdrodnrina' Ihoso expressions in (1), we o-ot Cor 1lie intensily oC Ilic difiV:ieled rny
( 2 ) Z = Mod.' a fj'dx dif e' ^ ^'' + ""' •''""' *^\ 1 + / 2 rr /> ,- ,r (1 - cos ^')]
Tn intcgrnting tlie above expression with resper-t to rr, we mnsl (]is- tingnish two eases according as D lies williin or witliout Ilic geometrica I shadow.
Let 0/1=^5, and A B = h ; tlien the integratimi willi resj^ect to X ninst extend, vvlien D lies within tlie geoinetrical shadow, from
ß to ß + h.
When D is onlside tlie geometrical shadow, tlie limits ot" integratioii must he trom
— ß to h — ß.
The iritegration with respect t(T tr mnst extend oyer the wliolo lenath oi' the slit.
ON CERTAIN DIFl'KACTiON PHENOIVIENA. oU)
I shall tirsl pci-l(jrm llie intégrât ion with rcspccl to ^^. We can write
/* i 6 a' s/«"- (p , /■ / ^ (1 - t-us 2 (f ) , I / ^' /• - / ^' füÄ '2(f> , ,-, ,
/e ^ay^ = je - dç = —p— c - /c ^ a (I if).
The intégral thus ohtained corresponds to /, Avhicli was already investifTîited in connection with Fraunhofer's (htîVaction ])henoniena. I sh:d], therefore, write ibr simplicity
(3) p^''''"'''^dir =.K + iU
Again
/e ^ " ''"' *^ cos (f d(f = — J -\ cos {a^T~ sin (f)- d {ii ^yi~siii (f)
+ i I sill {a -y/ Ç sin if)- d {a y/ 5 sin <.ç) I.
l')ii( /'^'^ ((t a/1~ -s-i/i cr)-(^ (a^/ysmcr) are derivahle in terms of Frcsnel's J sin
integrals, for whicli the series oljtained by Knochenhaucr, <iilbcrt, Cauchy, or Lommel can be used for calculation. 1 shall, ihereibre,
})Ut
( i ) e ^ cos (f dif ^ I + I 1
Xext [)eriorming the integration with respect to x, we liave to iind
le ^ '*" dx and c ^ ""^ x dx.
The ürst is an ordinary Fresnel integral ; and can, therlbre, be written
( 5 ) p ^ ""' dx = C + i S,
wliere
320 H. NAGAOKA.
C= —j^lcos {^T xy- d (\/ ? x), S = lain (^T x)- d {^T x).
The second iuteural is intei'TaljIe : thus,
= j' + i a.
Introducing the expressions ( 3 ) (4) (5) (0) in ( 1' ), we lind inr the intensity,
/ = Mod- a (C + i S) {K +i L) + i2 a '/ : {y +i^)\ [K + i L) - f / '+ 1 2') [ .
In hndin,u" Mod.'-, we can neglect tlie terms in\<)Iving />"'. J'husj we get for the expression of the intensity
(7) I ^ir^[C- + S-}{K'+ L-) + iafl^\C[Pr-Qr7) + S{(Jy + Pn)l'l^.
where
r - A' 1' - L 1 \
(J = K [K - /') + 7. (L - 2').
Tlie expression f<jr the intensity of light dittVacted hv a A\l on a circular cylinder ditfers from that for the ])lane slit hy the intro(hiction of the fictor K- + L-, and a small athlitional term multiplied Ijy ''K lîoth K and L remain constant proyided the distances of the slit from the source of hght and the point at Avhich the intensity is recpiired do not change. If we observe the fringes in a plane parallel to the axis of the cylinder, /v and L will remain scnsihly constant. Aeglecting the term multiplied hy '''', the positions of maxima and minima wiJl be the same :is those pnxbiccd l)y ])lane slit of the same l)readth.
If the observer approaches or recedes from tlie sht, the intensity of light at u point directly opposite the slit will differ from that of the plane slit, for the intensity is affected Ijy the fictor K- + L'\ wliich is ijo lonu'er constant.
ox CEUTAIX DIFFKAC'I'ION PHENOMENA.
821
Ob.servation shews that the small additional term is of very small eÜ'ect. Calculating the minima of C' + S' by means of Knochenhauer's series, I find that the agreement of caleiilation with observation is quite close, except when the point considered lies outside the geometrical shadow.
In order to test the result of calculation with observation, the following experiments were made with a slit of 90^ aperture, cut on a right circuit) r cylinder of 5.0 nun. i-adius. Sunlight was admitted into a darkened room. After passing tlirough a small vertical slit, and a lens, it was analysed by a prism. The spectrum thus formed was projected on the slit of a spectrometer. The slit, howcNer, was cl(jsed by thick paper, and only a small liole was pierced, throng] i which light was passed to the slit under examination. The spectriun. was so distinctly formed, that one could easily make the light c<jrres- ponding to any one of the principal Frauidiofer's line illuminate the slit. The following oljservations were made for the positions of zero intensity of the fringes formed by the slit.
Width of the slit l>^ = 0.5745 mm. Wave leno'th of liHit X = 0.000-1861 mm.
Obser\red Angle of Deviation. |
Calculated Angle of Deviation. |
Obs. — Cale. |
||
1st |
Miu. |
U4.3 |
93.3 |
+ I'.'u |
2nd |
" |
191.9 |
186.6 |
+ 5.8 |
3rd |
283.6 |
279.9 |
+ 3.4 |
|
4tli |
377.8 |
373.2 |
+ 4.6 |
|
5 th |
473.8 |
466.6 |
+ 7.2 |
|
eth |
566.9 |
559.8 |
+ 7.1 |
|
7th |
652.7 |
653.1 |
- 0.4 |
9 9
H. XAGAüKA.
I 11 i)l)S(,'r\ iiiLi' I'ix'sirTs (litfractiiju phcuoincii;!, tlic ()pli(';il Ijcncli was used. The iiitcr\:ils Ijctwccu the fringes were measured by iiieau« of ;i iiiierometer. The iollowing table _ii'ives the observed uuiidjers.
R^= 324.0, E'^= 285.4 mm.' 26 = 0.347; ;i = O.00048() mm.
Obs. Distance. |
Calcul. Distance. |
Obs. — Gale. |
|
1st Miu. |
1.4o mm. |
1.00 mm. |
-0.17 |
2 lid „ |
:3.18 |
3.19 |
-0.01 |
ord „ |
4.70 |
4.80 |
- 0.04 |
4th „ |
0.39 |
G.40 |
-0.01 |
5tli „ |
8.0o |
8.00 |
+ 0.03 |
(iih „ |
0.58 |
9.59 |
-0.01 |
7th „ |
11.22 |
11.19 |
+ 0.03 |
Sih „ |
12.81 |
12.79 |
+ 0.02 |
9th „ |
14.45 |
14.39 |
+ 0.00 |
10 th „ |
1 i;.(m; |
15.99 |
+ 0.07 |
1 1 th „ |
17.01 |
17.59 |
+ U.U2 |
12 th „ |
19.21 |
19.19 |
+ 0.U5 |
Effect of Magnetization on the Permanent Twist of Nickel Wire.
H. Nagaoka.
PI. XXXVIII.
Professor Wiedein;iiin, in a course oï experiments on tlie mutual relation l)2t\veen torsion ;in<l magnetization, found that there was a reciprocal relation between the two. lie found that wliereas torsion changed the magnetization of ir(jn, magnetization, on the other hand, clianged the torsion. To establish the relation between the two, he made a series of experiments, whicli seemed to indicate main^ other intimate relations between the two. Experiments relating to tlie change of twist by longitudinal magnetization have been, so far as I am aw-uv, tried only with iron and steel wires. The curious effect of torsion on the magnetization of nickel has induced me to try experiments in the same line, and find if there also exist simiLu' reciprocal relations Ijetween magnetization and torsi(3n in nickel wires. Want of a])paratus did not allow me to try experiments on the effect of magnetization on nickel wires under different conditions of twist. The present ])aper is confined oidy to the discussion of the effect of magnetization on the permanent twist of ru'ckel wires.
The apparatus used for twisting the wire and measuring the effect due to magnetization was essenti:dly different from tliat (jf Professor Wiedemann. I employed an arrangement made on the s;nne ])laii as that used ])y Professor F. Kohlrausch* in his ex])erimenis on the torsional elasti«; after-effect of wires. Fig. 1 shows flie front view
* Poojo'. Ann. 128.
324
H. NAGAOKA.
of the appnratiis. On a firm stand furnished witli three levelling screws (III), two stout pillars (pp) were erected. A cross bar of wood (hh) was fixed to these pillars. At the middle point of the cross piece, a torsion circle (t) Avas attached, wdth an arrangement for fixing the wire. Below this stood a magnetizing coil (c) on an auxiliary stand. To keep the wire twisted, two stout rods (rr) were raised vertically from a thick brass plate of circular shape, which was screwed to the stand (s). These rods were fastened to alidades, which were movable
Fig. 1.
^
^
m.
m
^T
^T
p
Fig. 2.
D
0
'W
about an axis at the centre of the plate. Thus the rods could be fixed in any desired position, and made to catch the cross attached to the lower end of the wire. The cross was made of tw(^ rc^ds at right ano-les to each other. The A-ertical rod had an arrano-ement for hold- ing a small plane mirror (7h). The horizontal rod was capable of sliding in the vertical, «and could be clamped firmly to it by means of a screw. A vane (v) was attached to the lower end of the vertical
EFFECT OF MAGNETIZATION ON THE PERMANENT TWIST OF NICKEL. 325
rod. It dipped into a vessel filled with water, which served to stop the torsional oscillation of the wire, when the twist was released. The torsion circle had a stout rod (a) for vertical axis. This was capable of up and down motion by means of ratch work, and could be clamp- ed by a screw. The lower end of the axis was cut, and made to bite the upper extremity of the wire. The wire is shown in Fig. 2. Two small pieces of thick brass plate were attached to the extremities of the wire. The upper end was placed between the terminal cleft of the axis, and clamped by a screwing nut, while the lower end was similar- ly caught at the upper end of the cross, and fixed by a screw which went through a hole in the plate, as shown in the figure.
In front of the mirror was placed a circular scale divided into half millimetres. The radius was 85.8 cm., so that one scale division corresponded, when seen by reflection, to one minute of arc. The scale was illuminated by gas jets, and the reflected image was observed by means of a telescope.
The magnetizing coil was 30 cms. long, ;ind gave a field of 36.7 C. G. S. units by passage of a current of one amj)ere. In addition to the magnetizing coil, a small coil was inserted within the solenoid. Through this coil, a steady current was mainttdned to compensate the vertical component of the terrestrial magnetic force. The magnetizing current was generally olitained from Bunsen cells, and made to vary continuously by placing a liquid slide in the circuit. It was measured by a Thomson graded galvanometer. The difterent parts of the apparatus being as described above, the experiment was conducted in the followins^ manner.
A carefully anneided nickel wire was fixed witliin the S(3lenoid, its upper end being screwed to the axis of the torsion circle, and its lower end to the cross as before mentioned. While the wire was being set in position, the magnetizing force was zero within the solenoid, the
ÖJ,(1
26 H. NAGAOKA.
vertical component of the terrestrial magnetic field being neutralised by a current in the dmall coil placed within the main coil. The reading of the tor.sion circle was then taken, and the two vertical rods (rr) were so placed, that they just touched the horizontal r(jd (d) of the cross on its opposite sides. The wire was now twisted by turning the torsion circle, and held in the twisted condition for ,S(.)nie time. The reading of the scale was noted. The circle was then turned in the opposite direction so ;is to make the cross free of the vertical rods. When the residual twist was small, the torsi<jn circle was brought back complete- ly to its original position, and the small amount of residual twist was given by the difference in the initi;d and final scale readings. For l-irge residual twists, however, turning the torsion circle back to its origin;d position would have thrown the reflected hcmn off the sc;de. Accordingly the torsion circle was turned back tlu'ongh a convenient and known angle, so that the wire hung free, and the reflected l^eam remained on the scale.
In the preliminary course of experiments, after the wire was freed from torsional oscillations, the elastic ufter-efFect was measured by simultaneously noting the successive scale readings and the corres- ponding times after the release. Wlien the untwisting due to the after- effect had become very slow, the magnetizing fjrce was applied, and the corresponding scale readings noted.
Before entering' into the in\ estin'ation of the effect of magnetiza- tion on the permanent twist, it was desirable to have some knowledge of the torsional after-effect of nickel. In every experiment, the wire was twisted and left for some time in this state. On releasing the torsion, torsional oscillations ensued. After its cessation, the wire continued gradually to untwist in virtue of the elastic after-effect. It was then necessary to know when the untwisting due to the after efïect should cease, for otherwise the untwistings due to magnetization
EFFECT OF MA<JN'ETLZ VTIOX OX THE PEUMAXEXT TWlST OF XlOlvEL. 327
;ind to the elastic after-effect would l)e mixed together.
As a general rule, the after-effect for the same angle of twist is smaller as the wire becomes thicker. For this reason, Professor Wiedemann used tolerably thick iron wires. Althouo-li much cer- tainty is gained as to the effect due to magnetization only Ijy usinn- thick wires, yet there is the great disadvantage that the amount of untwisting is ^ ery small. A\'itli nickel wires, the elastic after-effect is very small, and we can use tliin wires without iiicurring tlie risk of mixing the effect due to magnetization and tliat due to elastic after- effect.
A nickel wire 0.51 mm. thick and 27 cms. l<jng was kept twisted through 60° for an hour, the longitudinal ])ull acting on the wire being the weight of the cross before mentioiied. When released from torsion, the wire had a permanent twist of 2° 38'. On the cessation of the torsional oscillations, the f(j] lowing deiiections with simultaneous readings of the chronometer were taken.
Time Torsion
3'' 19'".0 p. m. (Uth \]n-\] 1889) 2° 38'.()
ol'.G ('remperature)
o7'.4 0".5
37'.2
37'.0 a. m. (12th) 3(r.2 (1)^2)
The readings show that the after-effect in nickel is very small. The wire above tested would have been untwisted through a few minutes mtjre, if we had waited for some weeks or months. J^oading the wire, however, increases the after-effect, 1)ut when C(jmpared with the after- effect in iron under similar circumstances, it is very small. It is un- necessary to give the result of numerous similar experiments. Suffice to say, they all lead t(j the same conclusion. The precautions which must
20.5 |
55 |
22.0 |
35 |
24.0 |
'5 |
36.0 |
55 |
42.0 |
a. n |
328 H. NAGAOKA.
be taken in discriminating the untwistings due to magnetization and to after-effect in nickel is greatly lessened as compared with the pre- cautions necessary in the case of iron. If sufficient care be taken to wait till the after-effect l^ecomes very small, we may use thin nickel wires in the investigation of the effect of magnetization on torsion. Generally I waited an hour after the cessation of torsional oscillation, but if the wire was loaded, it was left for a night.
The thicknesses of the wires used in the present investigation varied from 0.34 to 0.72 mm. Most of the experiments were tried with the thinnest, for with it the effects were greatest. The wire was always carefully annealed by means of a Bunsen flame. It so happen- ed, that when the twist was very large, the wire once used assumed a spiral aspect as was observed by Himstedt.* Such wires were rejected, and other wires cut from the same specimen were used instead.
The experiment was first tried with the wires aljove mentioned, when the permanent twist was very small, and the wire was subjected to weak longitudinal stress. The following gives the readings of untwistino- due to man-nctization when the load was the weio^ht of the cross only.
* Wied. Ann. 17. pg. 712.
EFFECT OF MAGNETIZATION ON THE PERMANENT IWIST OF NICKEL.329
r^ |
0.17 |
r:= |
0.24 |
r ^ |
0.35 |
Perm. Twist = 1'.6 |
Perm. Twist — 7'.2 |
Perm. Twist = 3'.3 |
|||
Ô |
r |
S^ |
7 |
» |
- |
7.1 |
9'.3 |
6.0 |
4'.7 |
4.4 |
2'.9 |
9.8 |
17M |
10.3 |
1 2'.3 |
6.3 |
5'.8 |
13.2 |
25'.6 |
13.2 |
16'.4 |
8.2 |
9'.1 |
15.9 |
30'-0 |
16.7 |
20'.6 |
10.3 |
12'.4 |
20.7 |
37'.3 |
24.1 |
25'. 9 |
13.4 |
15'.9 |
25.2 |
43'.0 |
35.4 |
29'.8 |
16.0 |
IS'.l |
31.3 |
48'.0 |
42.2 |
31'.3 |
18.5 |
] 0'.5 |
40.7 |
52'.G |
54.1 |
32'.9 |
25.8 |
23'.0 |
52.0 |
55'.5 |
67.2 |
34'.0 |
38.4 |
26'.7 |
65.0 |
57'. 6 |
157.8 |
34'.6 |
53.2 |
28'.1 |
82.9 |
59M |
<)6.7 |
28'.8 |
||
112.7 |
60M |
... |
103.0 |
29'. 7 |
|
184.3 |
60'. 7 |
... |
184.3 |
29'.9 |
The above table shows how the iiiïtwi.stiiig' proceeds as the streno^th of the field is increased. AVith the increase of the mao-netizino- force, untwisting becomes greater and greater, until at a certain point, the ratio of the untwisting to the corresponding magnetizing f^rce reaches a maximum ; in other words, the curve of untwisting has a Wendepunkt. After this, the untwisting takes place very slowly, so that ultimatel}^ the curve (Fig. I, PI. XXXYIII) becomes almost straight. Up to ^ = 180, the curve doesjnot reach a maximum.
In comparing the curves obtained with different wires, we easily see that the untwisting is greater for tlie thinner wire. Fc^r it will he noticed in the experiments first given that the permanent twist is greater for the thicker wire. Nevertheless, even with sucli liandicapping, it is tlie thinner wire which has the greater untwisting as shown at a glance on the curves.
330
H. NAGAOKA.
If after the magnetizing field has attained a certain value, it lie grad- ually decreased, the wire again twists back. Tlie twisting produced hy the removal of the magnetizing force is, however, far smaller than the untwisting produced by the increase of tlie magnetizing force. Con- sequently, the return curve goes above the other, as is shown hy the dotted line in curve (1) Fig. I. This fact can be briefly expressed by saying that there is magnetic after-effect in the twisting which becomes conspicuous l)y the removal of the magnetizing force. So long as the îimount of permanent twist remains very small, the curve showing the torsional etfect of a continuously changing magnetie force reseml)les the ordinary curve of magnetic hysteresis.
The al)ove remark does riot hold wlieri the permanent twist exceeds a certain limit. The decrease of twist with increase of mag- netization soon reaches a maximum. After this, the wire begins to twist in spite of the increase (^f magnetizing force. The amoimt oi' twisting of course varies witli the ])ermanent set of the wire as well as with the amount of pulling stress. The following tal)]e gives the amount of chano'e of twist with the wire of 0.17 mm. radius.
Perm. T |
wist 6'. 7 |
Perm. Twist 10'.6 |
Perm. T |
wist scr |
|
4.7 |
r |
>> |
7 |
>> |
r |
11 '.5 |
2.7 |
7'.0 |
6.7 |
26'.5 |
|
7.U |
18'.2 |
•3.9 |
1 5'.8 |
1 ().0 |
38'.6 |
10.0 |
24'. 7 |
8.8 |
19'.G |
12.3 |
45'.5 |
13..'3 |
26'.8 |
12.8 |
23'.0 |
15.1 |
52'.ü |
17.0 |
20'. 9 |
17.1 |
25'.8 |
17.7 |
54'.9 |
18.2 |
2()'.9 |
20.5 |
26'.8 |
23.1 |
61'.0 |
27.1» |
26'. 2 |
:}2.0 |
28'.1 |
:îl.6 |
64'.2 |
42.2 |
25'.1 |
1.7.0 |
26'. 9 |
5U.1 |
GO '.9 |
G2.3 |
24'.7 |
72.«i |
22'.(» |
62.8 |
56'. 1 |
125 |
24'.2 |
12.4 |
11 '.5 |
88 157 |
4G'.2 19'.0 |
EFFECT OF MAGNETIZATION ON THE PERMANENT TWIST OF NICKEL.
331
These reading« are plotted in curves (1) (2) (3) Fig. 2. respec- tively. Curve (4) is plotted from an experiment made with a wire of the same thickness, with a permanent twist of 1621°. These curves shoAv that tlie untwisting on the first application (jf the magnetizing foi'ce is very large. AVhen the twist is small the untwisting im- mediately becomes very small, and the wire 1)egins to twist, liut the further increase of the magnetizing force is of very little effect. The curve, shortly after the maxinum is attained, liecomes nearly ])arallel to the line of no twisting.
This appearance is confined to those cases where the ]3ermanent twist is small. With a residual torsion of 10°.6 in the same wire, the curve acquires quite n différent appearance. The I'ate of increase of untwisting with the increase cjf magnetizing force liecomes less, so that the untwisting gradually approaches the maximum. Thereafter the twisting takes place gi'adually and steadily. On removing the mag- netizing force, there is at first untwisting Avhich reaches a maximum in a magnetizing Held less than that corresponding to the maximum untwisting on the first a])plication of the magnetizing force. The wire then again begins to twist, Imt on the complete removal of the magnetizing force, the Avire remains untwisted relatively to its first position. The most striking difference between the curves in Fig. 1 and those of Fig. 2 is that the latter has a maximiun ])()int and the former has none. This maximum which seems to be closely connected with the amount of residual torsion occurs in weak magnetizing fields when the twist is small, l)ut as the twist is increased, it occurs in stronger fields.
When the permanent twist is very large, the features of the curve do not change essentially. Curves (3) (4) Fig. 2. show the state of things for the twists of 861° and 1621° respectively. From these it will be seen that the untwisting does not increase ])roportionally with
332 H. NAGAOKA.
the periuînieiit twist. On the coiitrary, the luitwisthig for the twist of 861° is greater than that for tlie twist of 1021°. The course of the curve, after passing the ur.txiiuuni becomes steeper with tlie larger per- inauent twist as the coui|)arison of (1) (2) with (o) (4) will show. Thus, when the twist is large, and the magnetizing force sufticiently great, the curve may he expected to cut the line of no twisting.
Another difference in the curves of torsion ol)t: lined f )r different permanent twists consists in the course of the ciu'\'e on the removal of the m;ignetizing f^rce. In curve (2), we find tliat the "off"' returns below the " on " curve, while in curve (3), it returns above it. In the former there is hysteresis or lagging, in the latter priming or negative hysteresis. This distinctive feature in the curves obtained for different twists also varies with the thickness of the wire.
It is unnecessary to give numerical details f )r the various experi- ments made with different wires and with different twists. The characteristics above descrilied are illustrated in the curves of Fig. 3, which gives the results f)r nickel wires of diameters 0.5, 0.4, 0.7 mm. For these also the untwisting re-iches a maximum f )r a comparatively low field, and a hoisting liegins to set in, and continues to the highest field used.
The f )llowing experiment shows that this twisting may proceed so fir as to result in a final condition of twistednrss relatively to the original condition of the wire. The wire, 0.34 nriu. thick and 30 cms. long was twisted through eight complete revolutions of the torsion circle, and then released. It thus acquired a ])ermanent twist of 2548°. The magnetizing current was derived from a shunt dyn-niio. The current strength was ndjusted l)y the li([uid slide bef )re described.
EFFECT OF MAGXETIZATIOX OX THE PEEMAXEXT TWIST OF XICKEL. 333
Field. |
Untwisting. |
14.3 |
+ 20'.0 |
3G.0 |
49'.0 |
68.0 |
53'.0 |
81). 4 |
51'. 0 |
152.0 |
34'.0 |
200 |
24'. 0 |
245 |
12'.3 |
308 |
+ CO |
361 |
- 4'.0 |
432 |
-lO'.O |
ïlie application of the iiiaii'netiziiiijf force .showed at tir.st an un- twisting, which reached a niaxiniinu in a field strength of ahont 65 C. G. S. units. The wire then began to twist. In a field ofal)<)ut 335 units, it came back to the condition in which it was after release before the magnetizing force was applied. Thereafter the wire continued steadily to twist with the increase of magnetizing force, so that when §=432, the wire became twisted 10' from its initial position of ec[uilibrium. Thus a nickel wire with large permanent twist can he twisted by applying sufQciently great magnetizing force. As the course of the curve after passing the maximum is less steep in thick than in thin wires, still stnniger magnetizing fields will l)e necessary to twist the former.
The next set of experiments has to do with nickel wires under longitudinal stress. The only change in the process of experimenting consisted in loadirig the wire. Tlie vane was detached from the lower end of the cross and a short hook placed in its stead. A pan of weights hung from this hcx^k, and was completely immersed in the water.
334
H. NAGAOKA.
Different experiments were tried with wires oï various thicknesses, and with different amounts of twist. lS(3me of the results are shown plotted in Figs. (5) and (6). In all of these the untwisting by mag- netization becomes greater l)y ]oa(hng. When the permanent twist is small, the curve representing change of torsion reaches a maximum quite aln-uptly. The course of the curve immediately after passing the maximum is quite steep for some time, but after the magnetizing force attains a certain value, the return twist l)ecomes very small. More- over, there is hysteresis on the gradual removal (3f the magnetizing force. An inspection of the figures will be of more service than mere verbal description.
With large twists, the features of the curve of torsion do not
greatly differ from those obtained with the unloaded wire. The chief
change wrought by the loading is that after the maximum untwisting
has been passed, the curve goes down more steeply than in the case
when there is no load. This evidently suggests the possibility that
the curve for the loaded wire will cut the line of ntj untwisting in
mao-netizinof fields smaller tlian those needed to effect the same for un- es o
loaded wires. And this I f(3und to be the case, as shown by the readings on the following page, which were made on a wire of 0.17 mm. diameter under a load of 342 grm. Aveight.
The former readings are shown plotted in curve (2) Fig. 4, and the first part of the latter in (4) Fig. 6, and the readings in strong fields in curve (3) Fig. 4. The comparison of these two curves with (1) sliows that with the loaded wire the initial position is reached at smaller mao-netizintr fields than with the iud(xaded wire. Moreover, there is hysteresis when the permanent twist is moderate, but priming when the twist becomes large.
Finally the effect of transverse magnetization on the permanent twist was investig-ated. The \v\re beinir treated as before described,
EFFECT OF MAGXETIZATEOX OX THE PERMAXEXT TWIST OF NICKEL.
335
Perm. Twist 95°. |
Perm. Twist 583'. |
||
Field |
Untwisting |
Field |
Untwisting |
5.8 10.8 14.6 19.4 24.6 28.6 33.5 38.8 44.1 52 2 61.5 72.6 98.1 125.7 182.1 |
16'.1 26'.2 32'.7 36'.8 4r.o 42'.6 42'.8 4r.6 40'.0 36'.4 32'.0 27'.0 16'.9 9'.5 -r.3 |
6.1 7.5 10.9 14.1 17.4 24.5 39.4 50.3 54.4 66.7 85.6 98.6 164.2 191.9 271 328 |
8'.0 15'.0 23'.5 33'.0 39'.4 53'.6 73',0 76'.2 77'.2 7ô'.0 69'.5 62'.0 25'.0 17'.0 - 4'.0 -12'.2 |
was placed between two Hat coil.-s, through which niagiietizing currents of various strength were passed. The wire, liowever, did iKjt show the least sign of being affected by transverse magnetizati<jn, although the apparatus was capable of measuring 0/1 of deflection.
The next point of inquiry was a comparison of these effects with those produced by twisting magnetized nickel wires. The apparatus used for examining the latter was similar to that used by Professor Wiedemann, in his investigation on tlie effect of twist on magnetiza- tion, and described in his ' Elektricität ' Ikl. 3. A nickel wire 1 mm. thick and 30 cm. long had two pieces of stout brass wire soldered at the ends. The wire was placed magnetic east and west, and carefully
336
H. XAGAOKA.
niineîik'il in this positùju. It was then slid into a magnetizing coi], and its extremities firmly clamped to the twisting apparatus. The magnetizing current was gradually increased l)y means of the liquid slide, and then slowly remoyed. Thereupon the deflection of the magnetometer mirror with corresponding angle of twist was read. The following table giyes the changes produced on the permanent masfnetism in arbitrary scale unit, the amount of permanent maof- netism being proportional to tlie numl)er of scale diyisions when the twist is zero.
Twist |
(I) |
(11) |
(III) |
( IV ) |
(V) |
0 |
589 |
455 |
183 |
83 |
41 |
5° |
549 |
410 |
161 |
74 |
27 |
10^ |
550 |
885 |
159 |
78 |
20 |
15= |
554 |
378 |
173 |
88 |
19 |
20^ |
558 |
384 |
194 |
102 |
24 |
25° |
560 |
393 |
212 |
119 |
33 |
;30° |
559 |
402 |
224 |
131 |
40 |
35° |
554 |
405 |
233 |
141 |
47 |
40'^ |
551 |
405 |
238 |
149 |
52 |
45° |
404 |
238 |
153 |
||
50° |
540 |
403 |
239 |
155 |
62 |
60° |
529 |
397 |
237 |
I5,s |
68 |
70° |
235 |
1 61) |
71 |
||
80° |
... |
160 |
|||
90° |
161 |
74 |
|||
120° |
1()() |
75 |
|||
180° |
76 |
||||
270° |
74 |
EFFECT OF MAGNETIZATION ON THE PERMANENT TWIST OF NICKEL. 337
The examination of the ab(3ve talkie shows that the first effect of tAvist is always to decrease the magnetism of the wire. This decrease soon ceases, and an increase sets in as the twist becomes larger. AVhen the perm:ment magnetism is large, the increase is small, and the oricrinal value of tlie mau'netic moment is not recovered. On theotlier hand, for small values of permanent magnetism, the increase is consi- deral)le; and as the twisting continues the wire acquires a greater magne- tic moment than it had originally. When the wire is further twist- ed, the magnetic moment reaches a maximum, and begins to decrease. The maximum comes earlier for greater values of permanent magnetism. The maximum increase ivi weakly magnetized wire occurs at tolerably larf>'e twists, as an examinati(3n of the above tal)le will sliow. In addition to this, the range of change in permanent magnetism l)y twisting does not increase, but rather seems to diminish with the auKHint of permanent magnetism, for moderate angles of twist.
The experiments hitherto described show close relations between the effects produced by twisting the permanently magnetized wire, and those produced by magnetizing the permanently twisted wire. The relation between the two can be most clearly represented by collecting the results in the f)l lowing parallel statements.
1 The permanent magnetism I. The permanent twist of nickel of nickel wire is at first dimini- wire is at first diminished by shed l)y twisting. magnetization.
2. With Zan/t' ])ermanent mag- II. With swzaZ/ permanent twist, netism, the decrease incre;ises with the untwisting increases with the increased twist. strength of magnetizati(jn.
3. Unless the permanent mag- III. Unless the permanent twist netism is very large, tlie decrease is very small, the untwisting pro- produced by twisting reaches a duced 1)y magnetization reaches a maxhnum. Further twisting in- maximum. The twisting produced
338 H. NAGAOKA.
creases the m;!<rnetisin, so th;ît it by farther increase of nni^'netiza- hecomes greater than its original tion is so large, that the wire ac- value. (juires greater twist than it ori-
ginally had.
It a|)])ears from the readings given above for the changes in permanent magnetism, tliat there is a tendency to a decrease ugain setting in at the higher twists. This suggests that there may be un- twisting in very strong fields, after the wire has been for some time twisting under tlie influence of m;ignetization. The current at my dis])Osa] did not allow me to try ex{)eriments with fields much c)ver 400. Up to that limit, the twisting ccjntinued. It still remains un- decided if further increase of magnetizing force gives a maximum twisting, corresponding to the maximum value of ])ei'manent magne- tism obtained by twisting.
When the subject is viewed from tlie theory of rotating molecular magnets, we fall into difficulties which cannot be easily explained. Professor Wiedemann in coordinating the nnitual relatii^ns between twist and magnetization of iron and steel wires, assumes that the mole- cules are subject to disturl)ances in trying to point tlieir poles in the directicm of magnetization. Drawing an analogy from the effect of mechanical disturbance ap])lied to the twisted wire, he concludes that the disturbance caused by magnetization must untwist the iron or steel wires. This easily ex]>lains the efiect of inagnetization on the per- manently twisted iron wire. It seems (juite ])ro])able that a, similar explariation can be applied to the untwisting observed in nickel wires. The effect of magnetization, however, is not so sim])le in nickel as in iron. It seems very difficult to explain the luaximum untwisting ob- served in nickel. Moreover the disturbance caused in molecular group- ings is not limited to longitudinal magnetization only. Transverse magnetization must likewise produce similar changes am<mg the
EFFECT OF MAO>'ET]ZATTOX OF TUE FETîMAXENT TWTST OF XTOKEL. .^39
molooiilos. Thus tlio pormnnont twist would ho afl'ectod by trnnsvorsnl :is well :is 1)\- loiigitii(liii;il iiiuLjiioti/.titioii. In my cxjM'i'iincnts, lr;iiis- \(Ts:il iiingTiC'tizutioii 1)\- 1l;it coil Ik-mI no sensible eft'eet.
riie ('liaiiii'e oi jn'rinnncnt niii^'nctisni by twistiiio- is nmre eoni- plex in nickel tlinn in iron. Tf we Imve to explain the nitixiinnni (Iccrense in ])erin:inent in:iL!'n*'tisni on \\'ie(l('ni:inn's rlicorx-, we nnisi nssiiine th:it tlie iiiekcl niolccnles n^tîitc only tbrono-]) ;i eert;iin niiiilc l)y twisting, l)nt lieyoiid th;it niigle, tliey move ])nek townrds the orininnl jiosition. 'I'liis we lime no i-iglit to nssuine. It seenis bojieless to find :iny ex])lan:ition of tlie ^':lrio^s relati(^ns ])etweeii twist and mauTieiization in tiTins of* a really satisi'aetorv theory of i-olaling nioleenles.
On Certain Thermoelectric Effects of Stress in Iron.
By
C. G. KnoU, D. Sc, F.R.S.E.
Professor of Physics, Imperial University. And
S. Kimura, Ri^akushi.
Since the (li.^covery mrifle by Tlioni.^^on thnt the thermoelectric propertie.:! of wire:; of certain metal.^ were altered l)y tension, the sub- ject has lieen studied cxperimentnlly by various scientific men. Of these we may mention more particularly Le Ivoux, von Tunzelman, Colin, and Ewino;-. Tlie work done by Cohn and Ewing is of special im])ortance ; and the latter's investigation for iron is the most com- plete that lias been carried out. Eeference will be made to their results hereafter. It is sufficient at present to point out one respect in wliich the work of these experimenters lacks completeness. In all, the method (^f exjX'riment consisted in studying the effects of stress upon the thermoelectric properties of a wire, whose junctions with tlie other es.^ential wire of the circuit were kept at steady temperatures. The variations of stress were, in the best experiments, carried through a cycle ; and at different successive stages tlie thermoelectric current was measured on a suitable galvanometer. The observed changes in the electromotive force might be due to either of two quite different effects ; and the experimental methods adopted could give no criterioi^
342
C. G. KNOTT AND S. KIMURA..
by which to rlrnw the correct conclusion. The nature of tlie prol:)]em is most sini])ly expressed in terms of the Jnng-nnge of the thermoelec- tric (liag'rnm. In this diagram tlie thermoelectric relations of the ditfererit metals are represented l)y liries (usnally straigdit) in such a manricr that the electromotive force existing in any circnit of two metals is cqnnl to the area included between the appropriate metal lines arid the two lines drawn perpendicular to the temperature axis and throngli the j^oints representing the temperatures of the two junc- tions. The (pie;!tion pr(^pounded aliove is tlicn this. AYhat chp.nge does stress applied to a given metal produce upon tlie jjosition of the line in the tliermoelectric diagram ? Does it translate it as a Avliole u\) or down ; d<X's it rotate it as a whole about some definite point ; or does it effect a cond)ination of these so that the line is deformed as well as shifted ? In other words does stress cliange the Thomson .Effect in a wii-e, or does it sim])ly change the l\'ltier Effect with reference to an unaffected second wire ?
Now it is (piite clear that the only way to answer this problem is to arrange an apparatus in which the electromotive forces due to (lifcrnit differences of temperature can l)e measured siinnlfaneouslij on a wire under given conditions of stress. This could be accomplished only by having tlie gradient of temperature along the wire both steady and gradual. Junctions could tlien be made at several points along tlie Avire ; and the electromotive forces due to the several cir- cuits so olitainable could be easily measured and compared, once the temperatures were steady. The sim])lest way of realizing these condi- tions seemed to be to stretch the wire inside a metal tube, and then to heat the metal tube as in the Forbes Experiment on the conduction of heat along bars.
For ease in manipulation the tube, which was of iron, was made in two semi-cylindrical parts. The upper part or lid fitted accurately
ON CEUTAIN THERiMOELECTiilC EFFECTS OP STKEri.S IN IRON. 343
upon the lower part whieli rested lioriz(jiit'i]ly on oliar[) edged ;uip[)ort«. The lower part wa.s somewhat longer than the up[)er ])art, the extra length being a solid cylindrieal piece of iron which during the ex[>eri- nient was sustained at a IjriLZ'ht red heat in a charcoal furnace. To render the fitting secure a ridge cut out longitudinaJIy on each plane surface of the semi-cylindrical lid fitted into a groove cut out on the opposing surface of the lower part. At suitable intervals along this lower part small radial notches were cut. These became IkjIcs when the lid was set in positit^n, and through them wdres were led from the interior of the tube. The wire to be used was stretched alonij' the axial line of the tube ; and it and all the various junction wires were arranged and adjusted l)efore the lid was laid in position. Each junc- tion was a junction of three wires — ( 1 ) the axial wire to be tested, ( 2 ) a tliin wire of the same material, ( 3 ) a thin wire of some (jther metal. The tw(j last formed what we shall call the Thermometric Circuit. Its indications served to measure the temperature of the junction. The circuit, formed Ijy the axial wire and the thin wire of the same materia], was the essential element in the experiment. We shall call it the ThernKjeiectric Circuit.
The tension was ap[)lied by means of a screw at the extremity of the wire, Avhich projected some distance from the (jpen end of the tube ; and was measured on a spring dynamometer set in line. To ])revent currents of air circulating in the tube, the open cold end was plugged with cotton wo(j], and the side IkjIcs, tlnvjugh which the thin wires came, were filled up with asbestos. The liot end of the tube was closed naturally by the Acrtical face of the solid cylindrical portion îdready menti<jned. The end of the wire was clamped to this face.
The current were measured on a hiu'li resistance double coiled galvanometer, which was carefully gauged after every single day's experiment.
â44
C. G. KXOTT AND S. KIMUIIA.
The g-eiiei'al pliiii of (jx[)uriiiieiitiiig w.u oiiiiple eiKJUg-h. After the tulje und coniaiiied wire h'id attained a ;iteidy coiidici(jii a.i regard« temperature, a «eriei of reading.^ of the différent thermoelectrie and thermouietrie enrrent« were taken a« rapidly a.; poy.-sible, with a .suf- ficient nunilier of repetition« of the same to yield a good mean for each individual circuit. Thi.s operation wa« carried through for a series of ascending and descending value« of tension. The small value of the current in the thermoelectric circuit as compared with that in the thermometric required that only a small shunted portion of the latter should be taken through the galvanometer. This neces- sitated a somewhat complicated arrangement of resistances and com- mutators, which hoAvever it is unnecessary to describe.
In the earlier experiments the thermometric circuits were of copper andiron, and the thermoelectric of iron and iron. J5y using copper and iron, we expected to be able to get good measurements of the true temperature values of the junctions ; and this because of the existence of a neutral point at an easily attainable temperature. It was found, however, that the uncertainties of reduction from the parabolic temperature scale of experiment to the linear scale of accepted use far (outweighed the advantag(3s of having an (_)b-ierved neutral point as a guide. Accordingly a.fter many experiments had been made the Copper Iron thermometric jiUiction was aljandoned in favour of a Gierman- silver Ir()n junction. As is well known, the elec- tromotive force of this pair of metals varies in ;in approximately linear manner with temperature up to a dull red heat. The graphical com- parison of the thermoelectric with the thermometric currents will not in tliis case differ greatly in appearance from wliat would be the case if an accurate aljsolute scale of temperature were used instead. Ultimately, of course, the thermometric readings were reduced to the ordinary temperature scale by calculation frcjm the results of direct ex[)eriment.
ON CERTAIN THERMOELECTRIC EFFECTS OF STRESS IN IRON. 345
It wu.s deteriniucd to experinient tir.st with injii wire. Previous worker« liad all Ibiind that the thernioelectric effects of stress were much more prouounced in this metal than in others. It seemed natural therefore to begin with it. Sh(3uld the experiments prove promising', it was intended to pursue the en(|uiry in regard to copper, nickel, platinum, etc. A few experiments were indeed tried with copper and nickel wires ; but in the latter its viscosity under the influence of sustained stress pn^duced a gradual decay in the value of the stress, applied as it was by a tightened screw. It was obvious that a steady stress could be applied only l)y means of a load acting by its weight ; and ïov this the apparatus was not readily adjustable.
Several modifications in the mode of experimenting were repeated- ly tried before resiüts (jf a satisfactory character were obtained. In cer- tain experiments with the iron Avire, theruK^electric changes of very small amount were (jbtained by simply varying the tension without having established the temperature gradient. This thermoelectric éUect increased with the tension. The direction of the current was opposite to the direction of all the currents obtained when the gradient of temperature existed ah^ng the wire. In (jther W()rds, the current was such as miu'lit have resulted from a slight heating of the wire where it was gripped by the dynamometer clamp. The probable explanation of this effect is that the part of the stretched wire which lay outside the tube was a little warmer than the part inside the tube. ISuch a slight gradient of temperature might easily ensue under the influence of the air as it grew warmer with the advance of dav, the more massive tube changin£>' more slowly in tem])erature. If this is the true explanation, the elfect will have no existence in the real experiment, in which a steady temperature gradient is to be sustained. In any case, however, these initial currents, as they might be termed, were much smaller than the currents sul^secpiently oljtained.
346 C. G. KNOTT AND S. KIMÜKA.
After the be.st iiietliod of experinieutiiig had been by long trial decided ii[)on, the character oï the experiment td part of the rewearch ^y•dü in it.self very tediou.s ; and «ince month« of preliminary and other- wiöc futile labour had already been .spent it :-eemed be;^t to po.^tpone a .continuation of the experiment« till «ome future date. So far there have been no opportunities for renewing the attack, other work fully enL'TOs.sini>' our time.
Vie are now pre[)ared to di«cu8.s the result« of the fi nal set of experiment« with iron wire.
The dimen«ion« of the tube bar were a« follow« :
Total length of l)ar 102 cm.
,, ,, tubular part 90 ,,
External diameter (jf ,, ,, 4.4 ,,
Internal ,, „ „ „ 2.2 „
The diameter of the iron wire u«ed was 1.2 mm. It projected about a foot beyond the c<)ld (jpen eiid of tlie tul^e and wa« attached to a spring dynamometer measuring p(/unds- weight. The dynamometer wa« fixed to a «crew working in a lixed nut ; and Ijy thi« means the tension could be increased or diminished as desired.
In the final set of experiments each applied stress acted for at least one wIkjIc day before the thermoelectric observation« w^ere begun. The wire w;i« left ïnv this interval at the «nxlinary tempera- ture of the air.
The solid end of tlie cylinder wa« then heated to brio'ht redness in a cliarcoal furnace ; arid after 2 hour«' heating the temperature gradient l)ecame fdrly steady, as indicate«! l)y the thermometric cur- rents on the iz'alvanometer.
o
There were five pairs (jf jiuictions, ten in all — five thermoelectric and five thermometric. The [xjsitions of these juncti<jns along the
ON CERTAIN THERMOELECTRIC EFFECTS OF STRESS IN IRON. 347
iron Avire were so nrrancfed tlint the temperatures of two successive posirions difl'ered l)y 40°-60° ('. Tlie ]):iir:-; of junotious were distin- guished hv iiumlter, Xo. T. Ijcinu' tlie hottest niid Xo. V. the coldest.
The o])serv:itioiis were in:i(h' in tlie f )llowinü' order. First, tlie five thei'nionietric curi'ents wei'e measured in ra])id succession i'roui T. to y., eacli ciu'i'ent Ix'ing" measured first in tlie one and then in the other direction throuu'h the galvanometei'. [This was an invariable rule in the measurement of ;dl currents, the total ran^'e from the direct to the reverse reading- <i'ivinu- twice the true deflection.] Then followed a simi]:u' set of reading's of tlie fi\'e thermoelectric currents ; then a secoiid set of tlie thcrmoinctiâc ; and so on until 4 sets of tlie thermometric currents witli o iiiterpofsted sets of the thermoelectric currents had l)een comjtleted. Kxactly similar sets of ohservations were made for the series of tensions re])resenting t(^tal loads of 0, 5, 10, 15, 20, 24 and 0 pounds. Ke(hice(l to kilou'ram-weiu-ht per square millimetre, these tensions are a little L'Tcatcr than 0, 2, 4, G, (S, 9*6, and 0 respectively.
In Tal)le T, the ohservations are given in full ior the üve ])airs of junctions ; T stan(hng for the thermometric junctions wliose indica- tions form an arbitrary tem])erature scale, and E f n- the thermoelectric junctions whose e]ectr(^motive forces are the real sul)jects of investiga- ti(^<n. Tlie tensi(^n, the temperature of the cold junctions, and the factor fn- reducing tlie deflections to electromagnetic units of electro- motive fn'ce, are given in the space to the left of the tal)ulated numhers.
348
C. G. KNOTT AND S. KIMURA.
Table I.
Scale. rendings of the Galvanometer-deflectioriS of the E. ]\I. F. of Iron-Copper junctions (T), and of Iron-Iron junctions (E) in the live Tlaces.
Tension 0 |
I |
IT |
III |
TV |
V |
|||||
T |
E |
T |
E |
T |
E |
T |
E |
T |
E |
|
170 |
134 |
100.7 |
75.15 |
50.55 |
||||||
Cold tpuip. l^^°.0~l'' |
140.75 |
109.5 |
87.3 |
09 |
49.2 |
|||||
Galv. Factor 147.5 |
174.5 |
138 |
104.15 |
78 |
53.(5 |
|||||
14th Oct. 1889 |
174 173.5 |
141 111 |
137.7 137.5 |
111 111 |
104.2 104 |
89.75 90 |
78.5 78.4 |
72.25 72.75 |
54.25 54.5 |
52.2 53.5 |
158,5 |
123.4 |
91.5 |
07.5 |
4 k 5 |
||||||
Tensio 1 5 |
130.75 |
101.3 |
79 |
01.7 |
42.2 |
|||||
Cold temp 14°.4-15'.5 |
159.9 |
125.5 |
94.15 |
70.5 |
47.5 |
|||||
Galv. Factor 143 |
137.25 |
103.25 |
81.75 |
05.3 |
•10.5 |
|||||
Tension applied |
100.7 |
120.75 |
95.75 |
72.25 |
49.3 |
|||||
11.30 a. m. Oct. 14tli |
139.75 |
105.25 |
83.75 |
08 |
48.75 |
|||||
to 1 p. ni Oct 15th |
103.75 |
129.25 |
97.8 |
73.7 |
50.5 |
|||||
100.9 |
125.75 |
94.5 |
70.5 |
47.95 |
||||||
Tension 10 |
142.2 |
105.0 |
84.9 |
07.95 |
40.5 |
|||||
Cold temp. IG'-IT'.S |
101.25 |
120.75 |
95.7 |
72.15 |
49.05 |
|||||
Galv. Factor 143.3 |
140.5 |
104.5 |
84.5 |
08.95 |
47.8 |
|||||
Tension applied |
159.2 |
125.5 |
94.85 |
71.5 |
49 0 |
|||||
7 a. m Oct. 17th to |
130.5 |
101.95 |
82.0 |
08.2 |
47.9 |
|||||
9 a. m Oct. 18th |
155.5 |
122.75 |
93.25 |
70.8 |
49.25 |
|||||
103.25 |
120.55 |
93 |
08 |
44 |
||||||
Tension 15 |
144.1 |
105 |
81.5 |
02.25 |
39.7 |
|||||
Cold temp. 13' 8-15'.2 |
172.2 |
1.34.75 |
10075 |
75 |
50.25 |
|||||
Galv. Factor 143 05 |
143.75 |
107.05 |
85.3 |
08.5 |
44.75 |
|||||
Tension applied |
171.5 |
135.5 |
102.5 |
77.15 |
52.9 |
|||||
11 a. m. Oct. 18th to |
145.15 |
108.3 |
80.5 |
70.4 |
47.2 |
|||||
9 a.m. Oct. 19th |
174.5 |
138.5 |
105.25 |
79.1 |
54.5 |
ON CEETAIX THERMOELECTRIC EFFECTS OF STRESS IX IRON. 340
Table I. (Continued)
I |
II |
III |
TV |
V |
||||||
T |
E |
T |
E |
T |
E |
T |
E |
T |
E |
|
170.8 |
134.5 |
101.5 |
76.85 |
52.8 |
||||||
Tension 20 |
150.25 |
114.5 |
92.75 |
76.75 |
54.5 |
|||||
Cold tomp. 17'.3-18 .5 |
171.75 |
135.35 |
102.5 |
77.45 |
53.7 |
|||||
Galv. Factor 14:î.5 |
152 |
116.5 |
94.75 |
79.65 |
56.75 |
|||||
Tension applied |
171.2 |
135 |
102.5 |
77.5 |
53.75 |
|||||
9 a. m. Oct. 2lst to |
151.75 |
116.75 |
95 25 |
80.4 |
57.95 |
|||||
10 a. ui. Oct. 22ud |
169.25 |
134 |
102 |
77 |
53.45 |
|||||
1G1.G5 |
126 |
93.1 |
69 |
4.->.5 |
||||||
Tension 25-22.5 |
145.75 |
107.5 |
82.95 |
64 |
41.7 |
|||||
Cold temp. 14'.8-1GM |
171 j |
133.75 |
100.15 |
74.7 |
50.4 |
|||||
Galv. Factor ? |
148.5 |
112 |
89 |
71 |
48 |
|||||
Tontion applied |
173.5 |
136.75 |
103 |
77.25 |
52.75 |
|||||
10 a. ui. Oct. 23rd to |
14G.05 |
111.7 |
90.5 |
74.3 |
51.8 |
|||||
2 p. m. Oct. 2-ith |
1GS.7 |
133.3 |
102 |
76.65 |
52.75 |
|||||
164.1 |
127.95 |
95.3 |
71.25 |
46.25 |
||||||
Tension 0 |
143 |
108.7 |
8.>.5 |
63.3 |
43 |
|||||
Cold temp. 1G°3-17'.0 |
171 |
1.34.5 |
101 |
76.25 |
50.7 |
|||||
Galv. Factor 138.7 |
144.95 |
111.75 |
89 |
67.55 |
49.05 |
|||||
Tension released |
173.7 |
137.5 |
104 |
79.05 |
53.15 |
|||||
11 a. m. Oct. 25th to |
145 |
112.25 |
90.3 |
69.5 |
50.8 |
|||||
10 a. m. Oct. 31st |
173 |
137.25 |
104.5 |
79.55 |
54.5 |
1 |
It may now be n.^sunied tliat the mean <ifanv set of four iinml)eiN for T will correspond to the mean of the .set of three iiiimhers loi- rlie J'] of the same jiinotion-])nir. Tlie.se means are then to 1)e rcihiccd to tem])eratnre in the one ca.se, to electromotive force in the otiier. For tlic re(hictioii to temj^eratnre independent exjX'rimcnts were made to determine the constanrs of tlie ir(-)n u'erman-siKei- circuits ; ;ind in llie final reduction full account was taken of the slii^-jit \ai'i:irions in the \alue of the cold junction tem])erature. The residts of the reduction are emliodied in Tahlell., all the cold juncti(^n t(Mn])eratui'es heino- reduced to lo°.ô C.
350
C. G. KNOTT AND S. KIMÜRA.
Table II.
E. M. F. between stretched and unaffected Iron wires, at various Tensions and Temperatures.
Ten- |
Cold |
Hot |
E.M.F. IN |
Ten- |
Cold |
Hot |
E.M.F. IN |
sion |
Temp. |
Temp. |
MiCROVOLT.S |
sion |
Temp. |
Temp. |
Microvolts |
0 |
13°.:. |
2G7°.9 |
5G2 |
6 |
1 3°. 5 |
269°.4 |
589 |
2ir.7 |
437 |
2ir.o |
436 |
||||
159°.4 |
352 |
157°.5 |
344 |
||||
119°.7 |
282 |
160°.6 |
274 |
||||
82^0 |
205 |
77^5 |
179 |
||||
2 |
13^5 |
2.55°.0 |
562 |
8 |
1 3°.5 |
272M |
617 |
199^8 |
421 |
215^3 |
473 |
||||
149°.6 |
333 |
163M |
385 |
||||
iir.5 |
265 |
123^3 |
322 |
||||
74^7 |
187 |
85^2 |
230 |
||||
4 |
1 .3°.5 |
254^2 |
570 |
9ß |
13°.5 |
2 78°. 9 |
624 |
199".8 |
424 |
218°.7 |
468 |
||||
150°.9 |
343 |
164^2 |
366 |
||||
1 13".4 |
279 |
122°.2 |
29(> |
||||
78M |
193 |
86°. 7 |
2(»0 |
||||
() |
1 3°.5 |
281^0 22^.3 16 6°. 7 ^25^9 84^3 |
605 4<)6 371 281 203 |
The heading's of the cohunns sufficiently ex])lain themselves. Tlie lensii^ns are expressed iu kilourani-weio-lit ])er S(piare iiiilli- nietre. The hiii'liest tension atlained corrcsjiouds to :i |():id of 11.3
ox CER'l'AIX THEKMUELEOTRIC EFFEOl'Ö OF ,ST1{L:SÖ IN IliOX. o51
kilo^. actiiiii' aloiin' the wire. It will Ije iiotired that tliere i.s u wlixrht diminution in this liinliest tension as the experiment progressed, doubtless due to the yielding of the highly heated part of the wire. This yielding occurred at all the tensi(jns if tlie experiment were be""un soon alter the tension was applied. For this reason, eacli new tension was allowed to act at least for a wlujie day before the thermoelectric experiment was l)egun. Also just Ijefore the taking of the observa- tions tiie (hnamometer was carefully looked to, and the tension was raised to the desired value if any slight fall had occurred. Of course, once the experiment itself was entered upon tlie wire was not touched until the wliole series (jf observations had been completed. To go to higher teusioiis than those here recorded was not practicable because of the diminished tenacity of the wire at its blattest parts. Not a few experiments were spoiled by the Ijreaking of the wire at or near the highest tensi(Hi attempted.
For each tension we have determinations of electromotive fn'ces at five different temperatures. Some oï the results are shown in Figure T., IMate XXXIX. To prevent confusion of figure, only three are shown — the initial and final ïov no tension, and the fifth for tension 8. Of pai-ticular interest in the manner in which the initial and final curves cut each other at a temi)erature of about 150° or 160° C. In interpreting this result, we must know the thermoelectric rela- tion of the two kinds of iron used in forming the junctions. In tlie language of the thermoelectric diagram, in which tbe german-silver line lies below the iron line, the iron forming the small wires had its line also below the line of the iron that was or was to be strained. In other words, tlie current always fli^wed fr(;m the unaffected wire to the strained or to be strained through the hot junction. Xow from Fig. I., ^ve see that the effect (jf the stress is to increase the currents for all temperatures. The wire imder the stress 8 has therefore the
352 CG. KXOTT AND S. KIMUKA.
same relation to the iiiistrained wire wliich this latter has to the small unaftected wire. The stress, s(i to speak, displaces the liue upwards on the diagram. The eurreiit is acc<3rdiiJLi'ly from the unstrained to the strained ir(jn through the liot junction. On the stress bein,u' renKJN'ed, the wire is left permanently strained, or, as we shall for brevity call it, after-strained. And we sec that for temperatures below lo5°± the current is from the afterstrained to the unstrained throuii'h the hot junction ; but that al)ove 155° tlie current passes in the other direction, 'iliis Avould mean that tlie dia^'ram lines for the unstrained and after-strained wires intersect each other indicating a neutral tem- perature at a tem])erature of 85° oi- tliereab(juts. The directions of the currents as «iven above show that the diai»ram line for the after strain- ed wire is inclined at a less angle to the lead line. Hence the (nega- tive) Thoms(jn Eifect in this particular iron wire is numerically decreased after the application and withdrawal of longitudinal tension. Curves, representative of all tlie experiments whose results are given in Table II., were carefully drawn by free hand on a large scale ; and from these the electronKjtive forces corresponding to particular temperatures were picked «nit. A more pretensious process of inter- polation could hardly ha\e ])een more accurate under the circum- stances ; for the curves, though smooth, liaNc all a distinctly sinuous form, which it would Ik; ditHcult if not impossible to repfesent by an equation of degree lower than the Iburth. The electromotive forces corres])(jnding to convenient temperatures, picked out as just described by ins])ection of the curves, will be fbimd tabulated in Table 111. ; and in Tahle W. the result (jf subtracting each number in the zero tension coliunn from all tlie others in the same row is shown :
ox CEItTAlN THERMOELECTllIO EFFECTS OF STRESS IN IKON. o53
Table III.
E. M. F. hrtuceii the stretched and uiiatteeted Iron AVires, at cliosen Temperatures and at \ari(jiis Tensi(jns.
Hot Tkmi'. |
Tension ' 0 |
Tension 2 |
Tension 4 |
Tension 6 |
Tension 8 |
Tension 9.6 |
Tension 0 |
UM/ |
2J2 |
242 |
249 |
240 |
27() |
248 |
231 |
]-2(f |
28:3 |
282 |
294 |
282 |
81(3 |
294 |
270 |
1 oU° |
388 |
•sss |
842 |
838 |
800 |
842 |
885 |
180' |
887 |
884 |
392 |
881 |
410 |
891 |
396 |
20U° |
419 |
428 |
425 |
416 |
445 |
424 |
430 |
230° |
470 |
494 |
500 |
478 |
506 |
491 |
485 |
250^ |
515 |
548 |
557 |
581 |
556 |
514 |
529 |
Table IV.
E. M. I'\ helween the unstretelied and stretdied Iron ^\''ire.- at chosen leniperatures and at various Tensions.
Hot Tejii'. |
Tension 0 |
Tension 2 |
Tension 4 |
Tension 6 |
Tension 8 |
Tension 9.6 |
Tension 0 |
100" |
0 |
0 |
7 |
_2 |
28 |
1 |
-11 |
120° |
u |
-I |
11 |
-1 |
bo |
11 |
-18 |
i5œ |
0 |
— 5 |
4 |
-5 |
28 |
4 |
-8 |
180° |
0 |
— 8 |
5 |
-6 |
23 |
4 |
+ 9 |
200" |
0 |
+ 4 |
6 |
— 3 |
26 |
5 |
11 |
230° |
0 |
24 |
30 |
+ 8 |
36 |
21 |
15 |
250" |
0 |
33 |
42 |
16 |
41 |
29 |
14 |
354
0. G. KXOTT AND .s. KIMÜKA.
In the last Table we see, almost at a glance, the pr();n'i'e.s.s of thiii"'.s as the tension increased. The graphs of Figure 11. are obtained by plot- ting the electromotive Ibrces c<)iTesponding to one temperature in terms of tensions. These sIkjuRI correspond in general features to tlie cm'ves obtained by Colin and Ewing. In a very general they do s«) ; but they are nuich more irregular. This perliaps is not surprisinu" if Ave bear in mind the fact that each graph is made up out of as many ditt'erent days' experiments as there are points. If we leave out of consideration the experiment for tensicm (>, the remaining points on each graph arrange themselves in a fairly regular manner. There does not, however, seem to be any sufficient reason for omitting this experi- ment. Tor the peculiar deviations of aJI the p<jints belonging to it cannot l)e easily explained as due to any errors in reduction either to temperature or to electrom<jti\ e force. The same pecidiarity appears if we use the unreduced thermometric readings in drawing the curves. Un the other hand, the galvanometer constant was almost exactly the same day aftci' day (as may be seen from Table I), excepting for tlie two last series (jf ex])eriments at the liighest tension and the ünal zero.
In draAving our conclusions we nuist liowever Ijear in mind the smallness of tlie cjuantities tal)ula(ed iu Table \\ . The probable errors of (jl)ser\ ation are of tlie order of tlie smaller cjuantities given in that Table; so that it would be out oi' the (juesti<ni to attach anv impor- tance to N'alues less than 5.
j\e\'ertheless, we ai'e able t<) recoi^'nize in the graphs fiu-ured a certain ordered succession of changes ; and there can be no doubt as to the signilicance of the values for the aftei'-strained Avire. Here Ave have a result apparently ncAV to the subject ; we are not aAvai-e that the possibility of such an effect has eyeu been hinted at Ijy })revious workers. We have already expressed the nature of this result bv saying that the Thomson Effect in an iron Avire imdergoes a permanent
ON CERTAIN THEßMOELECTRIC EFFECTS OF STRESS IN IRON. 355
change after the l(Higitudiiial tenswii lias been appHed and removed. Tf e is tlie electromoth e force between tlie after-strained and unstrain- ed wire, reckoned ]io^iti\'e wben the current flows from the after-strain- ed to the unstrjiiiied through the lu^t junction, Ave ma\^ represent the vahies in tlie l;ist cobuini of Table \\ . by tlio linear expression
e ^ + 34 - 0.21 t where t is tlie tem])er;itui-e in Centigrade degrees, and tlie unit is 1 microvoh. 'I'he de\iati()ii of tliis straight line from the curve drawn tln-ough the points is well within the errors of ob.servation. It would Ije unsafe to sttach any importance to the suggestion of t^vo vertices in the tabulated numbers, indicating two neutral points, one al)ove and one below 160° C. (6' = 0).
Thomson, ( ohn, Ewing, and other investigators have worked witli temperatures linver 1han the highest we used ; so that it is not possible to make a thorough compai-ison between these earlier results and ours. AVhere a satisfactory comparison can 1)e made there is (■om])lete agreement. For example in Ewing's tirst set of experiinents, tlie after-strained wire came out poî^itive to the unstrained wire with \\\e. hot junction at 100°C. Our residt is c =- -|- 13.
In his later series of experiments Pn^fessor Ewing was concerned wliolly with the thermoeleotric lieluniour of iron wii-e under the com- bined influence of stress and magnetization. He kept his hot junction at a temperature of 160°(' ; and it will be noticed that the after-strained wire comes out ^legalivc to tlie unstrained wire. Since however no observation is recc^i-ded for an uinuagnetized wii'c, and since Professor Jiving hiîiiself seems disposed to regard this negatiN-e character as due to the magnetization, it is im])ossil)le to make a satisfictorv comparisoii. The \alues of the eleetromotive forces given l)\- him are of the s:nne oi-dei' of (juantity as that just given.
Oui- experiments indicate a maximum current as occurring about
356 0. G. KNOTT AND S. KIMURA.
the tensi(iii ol'S, whioli corresponds to :i \on(\ of between 9 nnd 10 kilos — a resnJt in fair agreement witli some of IVofessor Ewing's.
The 2'eneral conehision that may be deduced is that the effect of tension on the tliermoelectric position (^f an iron wn-e is a complex function of the temperature. Not only does the line on the ther- moelectric diagram suffer dis])lacement u]) or down hui it also suffers rotation. In other words the Peltier Effect and Thomson Effect are both changed.
These results can only be regarded as preliminary. They are sufficient to show that the method is workable, and they have a dis- tinct value in themselves. Tt would be advisal)le to re])eat and extend the experiments with a much more massi\e irt^n tulx' tlian that liere used. A sniîdler gradient of tem])eratu]'e would l)e therein' obtained, and it would not be necessary to keep tlie one end of the wire at a very high temperature. JW such a modific:ition, mucli highei- tensions might 1)e applied.
On some Cretaceous Fossils from Shikoku.
By Malajiro Yokoyama.
With Plate XL.
The Cretaceous F<n-iii:i1i<)n iii Shikoku occurs in several places. These occurrences, however, are re^trictcl to two zones, lying one on each side of, and paridlel to, the central zone of crystalline schists, wliicli traverses tlie island from EXE to W8W along its longitudinal axis. The Cretaceous strata in tlie northern zone directly overlie these schists, and f )rni a long narrow helt along the whole nortliern coast of the island, interrupted only here and there hy alhivial flats. ]>e3^ond Shikoku, they continue on the e:ist over the southern portion of the island of Awaji to the Katsuragi ^[ouiitains in Kii, while on the west, vanishiiig partly uiider the sea arid partly under the voJcanic rocks of Kyfishfi, they seem to reappear on the islands of Amakusa. In the southern zorie, they are not so conti rmous. They rather fill up trough-like depressions in the Palaeozoic rocks, together with some other memhers of the ^lesozoic Grou]). Tliese depressions are known as the Katsnragaim Basin, the MonohiUjuwa Badu^ tlie Bijöschi Basin, and the Sakawa Basin. Ihit here also the zonal distriljution of the Cretaceous rocks is quite evident, as these basins all lie in one straight line parallel to the longitudin;d axis of the island.
The northern zone is essentially composed of alternatiiig layers of
sandstone and shale, for whicli complex Dr. lfarad:d' proposed the
/
1) T. ilarada. Die Japanhchen Inseln. — Eine topo(jv(t2)hisi-h.-tjt'oh>(ji^che Uehersiclit. I Lief. Pullislted by the Imperial Geological Survey of Japan, 1890.
358
M. YOKOYAMA.
name oï I zumi- Sandstone^ from tlie prédominance of a certain greenish- grey liard sandstone, locally kn(5wn under the name of Izumi-stone.
Fossils from this sandstone are very few. l>esides a laro*e so- called Fucoid which occurs at several places in Sanuki, we know only a Hdicoccras described below, and some fragments of a large Haiuitea- like Ammonite found by ^Ir. Suzuki at Okuzure in Awaji. Harada,'^ however, mentions also some F(^raminifer:i, bivahes, and conifers as occurring in this sandstone.
The Mesozoic Basin of the Kalsuragawd occu])ies tlie upper part of the ri\er of the same name in Awa. Tt wns freoloofically inves- tigated in 1883 by Mr. Y. Kikufhi, to wliom we owe tlie first dis- covery of the Cretaceous formation in Shikoku. Here it consists of sandstones and conglomerates, superposing tlie Jurassic plaiit-bearing series. The sandstone is hard, tine-UTained, and when fresh oTeenish- grey in coLnu', and has nearly the same appeai'ance as the Tzumi-stone, while on weathering it assumes a vellowish tint. It contains shells in great profusion, wliich hmvever belong to a very few species, aud are mostly found as casts. They are —
Trigonia jwciUifonnis, Trifjonia Kikueliiana, Trigonia rot undo fa .
Mr. Kikuclii also found a fragment of an evoliite as well as of a spirally rolled Ammonite.
The Monohegawa Basin is in Tosn. Its geological nnture is not well known. We possess only a block of sandstone like that of tlie Katsuragawa, (piite filled with casts of Trigonia pocilliforriiis.
The Bgöschi Basin is not far from the above, and occupies the southern portion of Xagaoka-gori, Tosa. Here the Cretaeecnis forma-
1) Loc, cit., p. 107.
ox SOME CRETACEOUS FOSSILS FKOM SHIKOKU. 359
tioii seems to consist solely of sandstone which is us usual frey to greyish-green, fine-grained and hard. It c(3ntains Trigonia pocilli- foiviis and Tr. KikucJiiana in tolerable abundance. Besides, it yields remains of many ether Lamellibranchs, some Gasteropods and Echi- noids, whose preservation, however, is very imperfect. The rock at Okuminodani directly overlies the Upper Jurassic C'idaris- Limestone.
Lastly, the Sakaiva Basin is situated in Takaoka-g<)ri of the same province, alj(jut 40 Km to the west of Kyöseki. Wliat is kncjwn of it we ow^e to the investigations of Messrs Xaumann^' and Xasa,--' the latter of wdiom planned the geological map"^^ of the district.
The Cretaceous Formation of Saknwa is wholly composed of sandstone, wdiich is quite similar to that of Hyôseki. On the south of the town of Sakawa, it lies partly on the Cidaris-Limcstone, and partly on a series of shales and sandstone, w'hich at Yoshida-Yashiki yields some plants.^^ Xear Ochi, however, it seems to overlie directly the Triassic sandstone of the district.
Besides Alectryonia, Lucina, Xucula, ISolen, Khynclionella and a Scaphites-like Ammonite, Trigonia pociUiforniis Tr. Kikucliiana, and Tr. rutundata were also obtained from the above sandstone.
From what has been said above, it will be seen that tlie number of fossil species in the Shikoku Cretaceous is rather small ; and these, moreover, are so imperfectly preserved that the majority of them are indeterminable. On this account, I can describe only four species in this paper, 'iliese four, however, are very important, as some of them not only show the undoubted Cretaceous age of the strata con- taining them, but at the same time, they give lis the probability that
1) Naumann u. Xeumajr. Zur Geoloiyie ii. Paläoiitohtjie von Jap'm. Dcnks. d. math.-natûrw. Classe d. K. Akad. d. Wissens., JVien, BX. LVll, 1890.
2) T. Nasa. lîejMrt. of Geol. Sure, of Saliawa)iiu]\i, Tosa^ 1SS5 (MS).
3) Given in Harada's Japanischen Inseln, 1. c.
•i) Nithorst considers these plants as Upper Jurassic. Vide Beitr. i. Mesoz. Flora Jaj^ans. Denks. d. Mith.-Nat. CI. d. K. Akid. d. Wissen.;. Wien, Bd. LVII, 1890.
360 M. YOKOYAMÂ.
at ]e;i8t the Irigoiiia-Samlstonc i.s to be considered as conteiiiporaiieolts with the Gauko-Ceiioinuiiiaii Formation of Hokkaido (Ezo). Ah-eady in my paper entitled " Versteinerungen aus der japanischen Kreide," ^' I have mentioned the occurrence of a scabrous Trigonia, alUed to Tr. alifonnis Park., in the Cretaceous of Kagahara Avhich I considered as probal)]y belonging to tlie^ame epoch as that of Hokkaido. It is this same Trigonia, 7V. jiocillifonitis as I call it, which is so profusely found in the soutliern Z()ne of Shiki^ku, playing so to say the role of the leading fus. 'il of the Sliik()ku Cretaceous. The above view is moreover justified l)y the fact tliat Mr. Jimbo has recently discovered the same form of Trigonia occurring together with Ammonites in the Cretaceous of Hokkaido. Whether the Izumi-Saiuhtone is also to be referred to the same age is at present unsettled, as it has not yet given any characteristic fossils.
The two species of glabrous Trigoniœ also described l)elow are pakeontologically very interesting. They are forms which, like some Liassic specie-^, exhiljit a great external resemblance to tlie Triassic genus Myophovia. Tr'ajouia Kikucltiana, whose only ally among the Trigoniie is Tr. LuKioiicnsis Bum. of the Lias of En^-land and France, reminds one strongly of S(jme forms of Myophoria glalnie, e.g. M. lœviga- ta Alb. The otlier s]}ecies, Tr. rotandala, has no kindred form among the TrigoniiL' hitherto descriljcd ; on the other hand, it has several corresponding ones among the glabrous ^lyophoria', such as M. plcheja Gich., M. orb:c:tI([ris Gold/., M . vuliuida Alb. In fict, this recurrence of Myophoria-like Trigonite in the Japanese Cretaceous seems to con- firm the view generally entertained by palaeontologists, that there is a close relationship between these two genera.
1). Palseoatoj;iMpliica, Bd. XXXVI, 18Ü0.
ox SOME CRETACEOUS FOSSILS FKOM SHIKOKU. oÜ 1
Description of the Species.
Trigonia pocilliformis H.sp.
VI XL, Fig. la, 11), 2, 3.
Tr'ninida sj>. Yokoyama, Vei-steincruugeu ans tier Japaiiisclieu Kreide, p. 19'J.
Shell subcrescentic, very iiiequilateial, iuflated auteriorlv, at- tenuated, iiarroAved, aiid tiattened powteiiorly. 1 leaks autero-iiiesial tuuchiuu', pointed, much incurved and also recur\ed. The anterior side of the valve is somewhat pr«xluced, and its margin is stron^'ly convex, gradually passing int() the convex ventral margin which is raised up posteriorly without any marked excavatitjn. The dorsid margin commences at the small ligamental a[)erture behind the beak, and descends posteriorly with a slight concavity to meet the truncated siphonal margin nearly at a right angle. The escutcheon is lengthen- ed, ovato-lanceolate when the valves are closed, broadest at about y., the distance from the beak, and concave for about -/-^ the length from the same point, beyond which it liattens. It is transversely or somewhat obliquely costellated : the costellai are sim])le and smooth, beinf- coarser, more elevated and distant in the p<jsterior than in the anterior ])(jrti(3n of the escutcheon. They are also sliglitlv curved out towards the posterior side, and somewhat oblicpie, with the marginal ends directed anteriorly. The number of these costella' is probably 15-18, but those situated near the beak p.re so fiint that thev are hardly visible. The area begins near the beak as a slight ridge which gradually widens posteriorly and l^ecomes broadest at the siphonal end, where it attains about 7^ the total heiglit of the shell, and forms at the same time its posteriijr boi-der. It is for the greater part of its length rendered bipartite Ijy a groove which runs a little above its median
•H 6 2 M. YoKOYAMA.
line and parallel to it ; each of the two somewhat iiiie({ual halves thus formed is moderately convex, and marked by fine transverse plications, some of which can become ^■ery coarse. The remaining- pcjrtion of the valve is ornamented with coarse, elevated, slightly flexuous, crenated ribs wh<3se number exivctly corresponds to that at' the costella} of the escutcheon, being, so to speak, the continuations of the same, although interrupted in their course by the intervention of the area between. Tiiey arise at the border of the ;a-ea as narrow crenulated ridges, aiid diverij'e in every direction, liettin"' hio-her and l)roader as thev ai)- proach the palliai border, into which they pass over withcjut any marked curvature. The interspaces are smooth. The palliai border is render- ed dentate by these ribs.
The internal characters of the shell are iiot well known.
The younger specimens of this shell are a little sliorter, and the ribs nujre straight and less in number (Fig. 2).
T have already compared this species, in the work above cited, with Ti'ujnuia alifvriuis Parli. It is nearer t<j the varietv called altcnuata by J^ycett (A Monograph (jf the British Fossil Trigonia,''' Xo. o, p. 117, pi. XXA , Fig. 6) than to its typical form. v>t\\\ there are marked ditferences between the two. The most striking lies in the ribs which, in the Eiii>lish form, are not onlv more numerous, but also describe concentric curves in the anterior portion of the shell, whereas in the fbipanese, although somewliat fiexuous in themselves, they all piss over straight to the palliai border without making any distinct curvature, lîesides, in the former, the marginal ends of the costelliii of the escutcheon are directed posteriorly instead of anteriorly.
A species called Tri'j mia Fi>rbesii Lycrtl (1. c. p. 122) from ^'erdachellum in Iridia seems to show similarity in the course
1) I'aheontofinijjhical Societi/, Vol. A' A' T'A', isaiied for 1875.
ON SOME CRETACEOUS FOSSILS FROM SHIKOKU. 368
of the rihs to the Jnpanese. I'ut it diifers in hnviiig n shorter shell and a broad costellated area.
Trifjonia pociUiformis occiirs sometimes in great aliiindanre, filling' tlie whole rock. Tt is, however, mostly preserved as casts, and even wlien tlie shell itself is loiuid, this is so firmly attaclied to the stone that it is impossible to isolate it without breaking it to pieces. Further- more, these casts are often so deformed that it is difficult to get specimens on whicli we could found a good diagnosis. The above figures'^ were taken from gv])sum pressings of an external cast of a young as Avell as of a full growri specimen, wlii^'h was considered as nearly perfect in slia])e.
This species is one of the characteristic fossils of the Japanese Cretaceous, being met with almost whereever the Cretaceous fossils are found. In Shikoku it is to lie found at the following ])l:ices :
Tanno in the Kntsuragawn l>asin ; Söy:nna and Okumin(^d:nii in the Kyoseki liasin ; llagino in the Monobegawa lîasin (Kamigor', Tosa) ; Sendachino and Mirano nenr Ochi, arid Yamanokanii (Xagano) near Sakawa, botli in the Sakawa IVasin ; Obama, Vokoliata-mura, Agawagori, Tosa.
Outside of Shikoku, it occurs in the Sanchü P)asin. and in Hokkaido.
Trigonia Kikuchiana n.i^p. V\. XI., Fig. 4, Ô, 6.
Shell ovately trigonal, obli(pie, very convex, lîeaks antero- mesial, ])rominent, incurved, and very slightly recur\ed. Anterior margin convex, gradually passing into a less convex ventral margin
1) The teeth which would be more or less visible in the dorsal as w<;ll as iu the poïtcrior view of this and of the following species are not shown in onr figures, as these ligures were f^ll drawn after gypsum pressings of external casts.
304 M. YOKOYAMA.
wliich ]30steriorly meets with the nearly straight, obhqnely ascending, si])hona] margin almost at a riglit angle, the corner being rounded. Hinge-margin obliqnelv sleeping on the ])osterior side, and going o\ er to the siplional margin without forming aiiv marked angle at the point of junction. Area and escutclieon not distinctly separated, forming one, more or less flat, surface whirli is slightly depressed along its median liiie. Tlie other |>orti<ui of the shell, which makes an anHe of about 90^ with tlie areal surf ice, is marked otf from the latter l)v a rounded edge, running from the beak to tlie postero-ventral corner and slopes to the anterior and ventral margins with a sliglit convexity. The entire surface of the shell is smooth, except near tlie lieak where n few coarse shallow coiicentric sulci are mostly f^urid.
The shell seems to have been moderately thick. The median depression of the posterior surfice is more marked in the adult tlian in the younger specimens. The interrial casts show two ftrong, transversely striated, diveroino* teeth.
Among the Cretaceous Trigonia? there is none Avhich can be compjired to this species. lUit in the Lias there is one, Trigomn Liiifjoitcnsis Dum. (T.ycett, Monogr. i^f lîrit. Foss. Trigonia, Xo. 8, p. 98, pi. X.Xn, Fig. 1-4), which shows a close affinity to it. The latter, however, has a little In-oader shell and tlie posterior side distinctly separated into area and escutcheon by a sharp ridge.
Trigonia KiJcnchiana, like Tr. Lingoîicnsis, is one of those forms of Trigonia which externidly exhibit a i;reat resemblance to the older genus MijopJioria.
It or-curs almost always as casts, and also often much distorted. The internal mould drawn on the ])late Iras the back acciden- tally depressed. Fig. 4 is from the largest specimen we got. This was a liroken one, but has beeii restored iri our figure. Its shape somewhat differs from that of Fig. 5, especially in its anterior
ox SOME CRETACEOUS FOSSILS FROM SHIKOKU. 365
margin. ]jut this difference is probably clue to the mode of preser- vation.
Very frequent at Tanno ; also occurs at Söyama near Ryöseki, and Yamanokami (iSTagano) near Sakawa.
Trigonia rotunciata n. sp. PI. XL, Fig. 7, 8, 9.
Shell subor])icular, slightly broiider than high, somewhat in- equilateral, convex. Beaks approximate, a little pushed anteriorly, prominent, pointed, and incurved, lioth the anterior and posterior margins convex, gradually passing into a less convex ventral margin. Hinge- margin also arched. The escutcheon is not clearly separated from the area, there being only a trace of a broad and flat ridge between, running from the beak to the upper end of the posterior margin, which makes the area slightly depressed along its median line. The other portion of the shell is moderately convex, and sepa- rated from the area by an olrtuse edge, and making with the latter an angle of about 120°. The entire surface of the shell is smooth, if we except a few coarse, shallow concentric sulci near the beak, and coarse, concentric rugce which sometimes appear on the posterior side near the ventral maroin.
Tn appearance of area and escutcheon this species is very similar to the preceding one.
Among the f^rms of Trigonia hitherto described, there is none which shows any relation to it. Among the Myophorise, however, there are several corresponding forms which have been mentioned before.
Like the two foregoing species, Trigonia rotundata occurs mostly
366 M. YOKOYAMA.
as casts, one of which is figured on tlie plate. It shows two strong, striated, divero'ino; teeth.
Quite as numerous as Trig niia Kikucliiana at Tanno ; occurs also near Sakawa at Ninomiya, Yamanukami, and Sendachino.
Helicoeeras sp. PL XL, Fig. 10, 10a.
A fragment of the body-whorl of a snail-like Ammonite, elliptical in section, somewhat higher than broad, and with the body-chamber occup3àng about one half of the entire volution. The external sculpture consists in fine, rounded, transverse ribs, slightly undulatory in tlieir course, and weakest on the umbilical side of the whorl, where some of them even disappear. Their number is about 50 in one circuit. The sutures on the external side of the whorl are indistinct, lîut as flir as they are seen in our specimen, they are deeply and much incised, with saddles and lobes bipartite ; the siphuncle seems to lie on the outer side, so tliat our fragment is that of a Helicoeeras which is, at least, closely akin to Helicoeeras indicum, Stol. (Cret. Cephalo- poda of Southern India, p. 184, pi. 86, Fig. 1-2). But as the specimen is imperfect, its exact specific determination is not possible.
Helicoeeras indicum occurs in the Arrialoor Group of India. . Our specimen was found in a very fine-grained shaly sandstone of Oumi, Ouchigori, Prov. Sanuki.
pig^ 2. — Comparison Diagrams of the East-West
Component Instruments,
Pit Instr.
Jour. Se. Coll. Vol. IV. PI. XXXV.
Swf. Instr.
Fig. 3. — Earthquake of January 15th, ISST. Easl-Wcsl Component.
Jour. So. Coll. Vol, IV. PI. XXXVI.
(Pit)
\
( Surface)
Fig. 5.— Earthquake of April 29lh, 18SS. ■""'■ «"■ ""'I- *'<"■ 'f. ''/. XXXVII.
East-West Component,
(Pit)
Fig. 7.— Earthquake of February 18th, 1880. East-West Component.
PLATE XXXVIII.
Fig. ]. Fig. 2.
( ] ) r=.0.17, r=r.7, w = 25. (1) r=0.17, T= (f. 7, w = 2b.
(2) r = 0.24, T = 7°.2, w = 25. (2) r^0A7, T= Kf.Q, w = 2ô.
(;3) r=0.:3G, T=-^.S, w = 25. (3) r = 0.17, r= SUl", ?ü = 25.
(i) r=0.17, r=l(32r, i<; = 25.
Fig. 3. Fig. 4.
(1 ) r=0.25, T= 626°, w = 2-). (1) r-0.l7, r = 2548^ iv= 25.
(2) r = 0.20, r=l'269^ m; = 25. (2) rr^0.\7,T= 0^, iv = U2.
(;]) r-n.a5, 7-1349°, iü = 2b. (3) r=0.17, r= 583', w = 342.
Fig. 5. Fig. 6.
(1) r = 0.36, r=: 4°.3, «0 = 218. (1) r=0.17, ^=18^5, «; = 156.
(2) r=0.20, T= 22.°, iü = 218. (2) r=0.17, r= 584°, mj = 156.
(3) r = 0.20, r=16^7, ?ü-411. (3) r = 0.17, r= 260°, it'-342.
(4) /•= 0.20, r= 968°, t<;:-218. (4) /• = 0.17, 2'- 583°, w = 342.
r gives radius in mm.,
T „ permanent twist in degrees,
tu „ longitudinal stress in grm. weight.
Jour. Sc, Coll. Vol. IV. PI. XXXVIII.
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Jour. Sc. Coll. Vol. IV. PI. XXXIX.
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Relation between. Electro- |
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SO' 100" 120' 140° 160° 180° L'"'(t =
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PLATE XL.
Plate XL.
Fig. la, Ih. Trigonia pocillif<n'inis. A full grown specimen.
,,2. ,, „ A young specimen.
,,3. ,, ,, Cast, somewhat distorted.
,, 4. Trigonia Ivikucliiana. A full grown specimen,
,, bab. ,, ,, A somewhat smaller specimen. 5h,
seen from the posterior side, showing the indistinct separa- tion of area and escutcheon.
„ 6. Trigonia Kikuchian-a. Cast, accidentally depressed on the back.
,, 7. Trigonia rotundata. Ivight valve.
„ Sal). ,, „ Left valve of a full grown specimen
partly restored, h, seen from the posterior side.
,, 9. Trisfonia rotundata. Cast.
,, 10. Helicoceras sp.
,, 10(/. ,, ,, Transverse section.
Yoloijainft . Ci-('la<y'(>iis Fossils.
Jour. Sc. Coll. Vol. IV. PI. XL.
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