ACKERT ‘The Innervation of © ue he i si ihe Integument of Chiroptera . i. Zoology ts PLD ee ee ost 29180 oe an UNIVIOR | TLELIN OLS AOR ARSE THE UNIVERSITY OF ILLINOIS LIBRARY 913 eee) Digitized by the Internet Archive in 2013 http://archive.org/details/innervationofintOOacke THE INNERVATION OF THE INTEGUMENT OF CHIROPTERA BY JAMES EDWARD ACKERT A. B. University of Illinois, 1909. A. M. University of Illinois, 1911. THESIS Submitted in Partial Fulfillment of the Requirements for the Degree of DOCTOR OF PHILOSOPHY IN ZOOLOGY THE GRADUATE SCHOOL OF THE UNIVERSITY OF ILLINOIS 1913 Sk > J \ TVEMUSSTHL SPIO Mbit AASZTSO MAD SS - i, oo) Nt Bot : ; RUC YS TISIADA CAA Was eR AL a siondil ts winesviel) FA . i eet oni] lo wistevint! iA ALGT elendutT sd. 10) eenmauyedl ais to tnomillated leitreS | 2} io ta2getl YHIOZOAING IO BOTIOI ~ st YOOQUOOS a] JOOHI2 STAUGASD SP 0" be I9\3 Acd UNIVERSITY OF, ILLINOIS THE GRADUATE SCHOOL Mey fs. 10g 3 | | HEREBY RECOMMEND THAT THE THESIS PREPARED UNDER MY SUPERVISION BY SAuard (heheh | ENTITLED eer i of the Le Lepismnt eeeeeErreD AS FULFILLING THIS PART OF THE REQUIREMENTS FOR THE are 4) q DEGREE OF . Racker - Phrlert hay +. Ww. bei i In Charge of Major Work re J ra . Mae ea Department Committee on Final Examination 1 <=. (2 Zo bie 4 u — Sa; t a 7 “TiIZEa vine Ue Ae Th wy = 2 es) Je a —— ar 4 fy > *. _ r .~ * -. * - a { a 7” - ee. 2) —a ee a fe we « UIUC 7 a %, : = = - TABLE OF CONTENTS. Introduction cecsccceccccvercscccccvevrsesesesseceesceseeess Physiological and Anatomical Evidence of the Extreme Sensi- tiveness of the Skin of Bats wccveccsevvcccsescesseees Material and Methods ...cccsccesesvccccccesccscccesessesecs Observations and DISCUSSION coeeeevesesccccsavecvsessvecees I.-General Structure of the Integument ..csccsvscscccee 1. Integument of ris hale bidlole s/0 Hew Vie #6 16'S Fee Kae aiaem 2. Flying and Interfemoral Membranes .ccccccccccccee II.-Nerve Layers of the Integument .cccccccsccccceceves 1. Nerve Layers of the Body Integument .wcccccccceee 2. Nerve Layers of the Flying and Interfemoral Mem- branes @eseovee2eoedse ees oeaeeaseeeeeeee2028028080280880873808082093 III.-Nerve Endings in the Integument @e2eee¢0280808808880809282808886 1. Free Nerve Terminations in the EpidermisS ...eccoee Be Nerve Endings on Hairs .cccccsveseoscccecscvvvsecsecees 5. Special Sensory End-OrgansS ..cccocccvcccsccccccoce Be ENG—BulLDS sccccceccseccccccccccvccscscccccccceese © Bb. Parmingal Corpuscles .ceccececeveeveecesvcesccne 4. Motor Nerve Endings on Striated Muscles ..cccccee 5. Nerve Endings on Modified Sweat Glands ...ceccoee IV.-What Sensory Organs are Concerned when Blinded Bats Avoid Obstacles While on the Wing ? .ccccccccececee 49 Summary @eereeeeeeeeeeseesee eset esoaesseeseeseeeooseseeoevses Sseoeeene028 48 - - - « Cae S 4 = 2 * 8 4 . + 7* 7 aA coe ase at Co. a - . - Oe =e eaete we ea fe ¢ Ce ne 7 - TT ss «A « - 46 = - a ¢ a yy £4 3 + [Ww oe? oe eae ’ t«a~< Seukdiy tiyich e's Ee ee ¢ bm qo +. 4 , ys j n@ee + + & 414° 8 @€:4 2 e * 2 4 Cr at. 3 & @ «& i ety oh ’ , A > ¥ "Z ° ? - ‘ iw t : Th cae ee oes a] : aoe’ FY 6 et ‘ fed ay oe we a tM Chie a el rn we ing PP % < = Ae Fj " 7 oo © , «© ; = . 7) : ea AMOS be i. lk e “ay! ' vie Co : tm 4 © ¥26 46 2 ae ee is evi fa =i re ; ie soo ree BOR GRRETIOY sari ' mn a utbod ‘ Ke au, * adil 2) Beak a iil oe ; i ‘ 4 “Ee , ! TAL. 4 ae j aay) Ate Y a, i iw ir Bibliography e@eeseeeeeveeoeveeeeeeeeaeeeneeeeeeeeeeeneeeneaeeee ee eee Explanation of Figures .wccccccccescccccsvesscsessssesesees 5G INTRODUCTION. The ease and precision with which blinded bats avoid obsta- cles while on the wing attracted the attention of eighteenth century investigators, who, at that early date, thought the wing membranes were sensitive to external stimuli. Cuvier, in 1796, set forth the theory that the patagium and ears were capable of perceiving air currents set up between the object and the ap- proaching animal. Later, Sch8bl (1871) described special sensory Organs, "“Terminalkérperchen", at the base of each hair. As both end-organ and hair were thought to be richly innervated, they were supposed to form the mechanism for the perception of obsta- cles. Recently, attempts have been made to explain this phenom- enon by other means. Rollinat and Trouessart (1900) attributed this power to a sixth sense, that of direction; while Hahn (1908) was convinced that objects were perceived chiefly through sense organs located in the internal ear. Responses of captive bats to tactile stimuli applied to various parts of their bodies and membranes are very vigorous. The lack of agreement among observers on the nature and location of the perceptive organs of bats, the extreme sensitiveness of the integument, and the possibilities of modern technique seem- ed to justify a further search for sensory structures in the skin of these animals. Furthermore, at the time this work was begun, no investigator had made an extensive study of the inner- @e@e eee © + $F to OOOH 9 6 2 ERS Re 4s Re Tere ree y ant oy 4. «4-30 a, 2 eee . . a ee a y y* => £ > _ ‘ vation of the skin of bats since Sch8b1l published in 1871 his account of the terminal corpuscles in the flying membrane. The work has been carried on during the last three years in the Zoological Laboratory of the University of Illinois un- der the direction of Professor Frederic W. Carpenter, to whom I am indebted not only for his personal interest in the progress of the work, but also for his constant advice and helpful criti- cisms. PHYSIOLOGICAL AND ANATOMICAL EVIDENCE OF THE EXTREME SEN- SITIVENESS OF THE SKIN OF BATS. The first investigation of the sensitiveness of the skin of bats, so far as the writer has been able to ascertain, was the well known experiment of Spallanzani in 1793, This investigator blinded bats, and observed that they avoided with accuracy not only large obstacles placed in their way, but even silken threads stretched in such a manner as to leave only sufficient space for the bats to pass between with their wings expanded. In 1796 Cuvier called attention to the exquisite sense of touch in the membranous skin covering the wings and ears. Upon examination he found the wings to be supplied with an enormous number of nerves. He inferred that during flight the blinded bat, on approaching the object, sets up air currents, which, reacting on the sensitive patagium and ears, enable the animal to perceive and to avoid the obstacle. Jurin, in 1798, performed experiments similar to those of Spallanzani. The blinded bats avoided the obstacles success-— a ~ WS ~ \ \ 4 oY ‘ e a : ' 4 / c < XY} Rah Ah” A a ” * ‘ ey ae sed “ine if ater iia ty dived cdc’ pete f acdtenbh vie ae ade senate Beat” i eis resi tents hay trent a hs he ai iden? Abell ‘any 2 a BR 4 ie: ehh Se cowie eit \ wi elias c= cy Be i? bes i a* j > -— + 3 fully, but were unable to do this when their organs of hearing were destroyed. Leydig (1859), who was of the opinion that the nerves of the flying membrane were not more numerous than those of the ordinary skin, thought that Cuvier had mistaken the elastic bridges (Balken) for nerves. Sch8Bb1 (1871) experimenting on a bat kept for a year in his living room confirmed Spallanzani’s findings. This investi- gator made an extensive anatomical study of the flying membranes of Chiroptera. He found not only an abundance of nerves, but also an intricate network of nerve fibers and, at the bases of the hair follicles, numerous end-organs, "Terminalk8rperchen", which in his opinion were closely allied to the touch organs (TastkBrperchen) of other mammals. In the same year Boll, work- ing with Sech8b1, confirmed the latter's findings. Stieda (1872) seriously questioned Sch8b1's results. He emphatically denied that Sch8bl1's "TerminalkBrperchen" were found as a rule in all bats. Moreover, he treated these struc- tures as hair growths (Haarkeime) and not as nerve organs, During the same year, Veleeky repeated Sch8bl1's work, us- ing the latter's method. This investigator also failed to find the so-called "Terminalk§rperchen". Furthermore, he used an- other method (gold) and still failed to find the structures in question at the bases of the hairs. Jobert (1872) was of the opinion that the touch apparatus of bats was located in the flying membrane, and that these touch organs, viz., the richly innervated hairs, played an im- t tod pees ae nee Peed “ o Te SEEN test ois ia wat te ae on? AAG .2o oe tan ero ; by 70 Sad aves ac ARONA “reie) f A iw) e ee Ee steed ott weds: then sone Tee cr ras: vem Ande eA ee Th : tdasy ath ac ote ah Au oh Oey eves te aiawt ow 04 ola Jie. Kap f in: Sheena caee ds ‘oa (iesols ot oe axe hei oud O20) gt)! Leen seteg Te” | te Sa ap bbe) “ete ied ott. Baws? Tao Oy Ce er ‘ahem date ea 3 bine kre ; Be Se ! | ~ ees » fae ae ee a! Sa CO aate ee: #th ' sgh ode. pera, Soa ado nay A a riod 3 tek ited eet area) ate oty: eet J t [aug en aah Veep iey gee: Aetna BRE we 7 be iat ofl s Vote thee h eS olay sites aint tale , Pranks or TEES eco tt Labametee bag ‘oe he t Gers. ot he Lia TL Sa ata ae Gite | ip Lak wot 26) poem” + ec oi) aha BU re a ots dma jp ea qnialt wd Aff i 4 F 4 hed gem dane ee car fan" portant part in determining the habits of the animals. Accord- ing to this investigator each movement of the hair was trans- mitted to the nerve ring which surrounded it. In this way ner- vous impulses were originated, and objects were perceived and avoided. In 1873, Redtel repeated Spallanzani's experiments. Threads, etc., were stretched across a small room, in which a normal bat was liberated. The animal flew with great speed. While it sel- touched the thread with its wings, it never touched the threads with its head. The bat was then blinded and set free again. Its flight was now somewhat less accurate, but it avoided the threads just as it did before. He then clipped the vibrissae from the face, but the flight of the bat was not affected. From the abundance of nerves found by Sch8bl1 in the flying membrane, and from his own experiments, Redtel inferred that it was possi- ble for bats to perceive the slightest change of air pressure upon the wings. He explained the few failures to avoid the ob- stacles in the following way: Ordinarily, the flying bat begins to prepare itself for turning away from the obstacle when it is approximately at the distance of a meter from it, but when fly- ing rapidly there is not always sufficient time for the avoid- ing movement to take place. Arnstein (1876) investigated the innervation of the flying membrane. He found nerve trunks, closely interwoven nerve net- works, free thread-like fibers extending up from the networks into the epidermis, and perceptive corpuscles. Flower and Lydekker (1891) advanced the view that it is the ies Pte ‘pea | re. , are iP hs De al hike -~ j 3 , . Sataeenr Bosh ars . Tis 4 ® = a > , ~ E 1 Pe | ab ott: a palpce hil ts " ~/* at . iv + he eee «te debe: oir? étoeg Foch any ; , a ‘. “ 0h amet te oa yg . aCe ; a ees! ue no fer re , iy ‘te " ott ig bac Shae = ieesee ‘ ret ring rt delicate sense of touch which enables bats deprived of sight, hearing and smell to avoid obstacles. They were of the opinion that tactile organs exist in connection with the vibrissae of the face, in the ear conchs, and in the wing membranes. In 1907, Schumacher mentioned the presence of a large num- ber of layer-like corpuscles (LamellenkBrperchen) among the phalanges of bats. Hahn (1908) carried out extensive experiments in which he caused a large number of mutilated bats to make a given number of flights in an enclosure through which numerous wires had been stretched. His experiments showed that the destruction of the sense of sight does not seriously impair their ability to perceive objects, nor does the loss of external ears and tragi. As the hairs of the body and flying membrane were supposed to have a sensory function, Hahn coated them with thick vaseline, which caused them to adhere to one another,and, hence, to be less sensitive to slight stimulation. The results of this ex- periment are given thus in Hahn's paper: "Five examples of My- otis lucifugus with the hair so coated struck 34.6 per cent.of | the chances. Five M. sublatus struck 39.6 per cent. of trials with hair covered, and 24.4 per cent. when normal. For five Pi- pistrellus subflavus the proportions were 32.4 per cent. and 25.2 per cent." Thus it is seen that in this experiment the av- erage number of hits of all the bats whose hair was covered, was approximately 10 per cent. greater than that of normal bats. From this and other experiments Hahn concluded that the organs of touch located in the skin and probably associated with the hairs are of value in enabling the animals to avoid objects, - oS aden mnt Un a?) tet aE aie ©) 7 “a * 7 = =) F cia ayia —— t by see ye ys ‘ r a | a) ,o a, 4 \ 7 x ”“ 4 ’ r + Gane P] iv + ¥ U - ' : ’ ‘ ' 4 4 — Ph bik yy Phe. : ies wrk 4] a i, a ed f i ) ~ a, though of less value than the auditory organs. He also states that the tactile sense located in the vibrissae and in the lips is very delicate, and doubtless aids the animal in locating its food. MATERIAL AND METHODS. The material for this investigation consisted of forty-one bats of which thirty-one were cave bats (Myotis lucifugus) from Indiana. The remainder, the common red bats (Myotis sublatus), were taken the vicinity of Urbana, Illinois. As the greater part of the material was prepared by an in- tra vitam methylene blue method, the latter is here given in de- tail. Etherize or chloroform the animal until it is deeply nar- cotized, but not quite dead. To secure free circulation (free circulation) of the staining fluid through the wing and inter- femoral membranes it is best not to fasten the bat to the in- jection board. Open the thoracic and pericardial cavities and make an incision in the left ventricle (being careful not to ‘eut into the right ventricle). After allowing the blood to flow out through the cut, swab out the thorax with a bit of absor- bent cotton, and place a loose ligature around the base of the aorta. For injecting, a syringe with a detachable rubber tube and a small glass canula is very satisfactory. Insert the can- ula through the left ventricle into the base of the aorta, and tie it with the ligature. For an overflow make a small opening in the right auricle. Inject Ringer's solution warmed to body io, a ~. ‘ ; ¥ i oo f 4 ah ee 4 / : ’ ees N : ibe ‘ Ma ‘an ates ~+er: + ane ty “9 i. Cr. a Po oP =, tel a. ee 7 \, é rs ‘4 \ Pre fu beware at if terG Be temperature into the aorta until most of the blood is washed out, i.e., until the clear solution comes out at the right au- ricle. Inject a 1% solution of methylene blue in distilled wa- ter warmed to body temperature into the blood system until the integument looks blue. Clamp the right auricle. With the blood vessels still full of the staining fluid leave the animal free- ly exposed to the air three-fourths of an hour for oxidation. If, at the close of the injection, the integument is not a deep blue, inject more of the methylene blue solution after a period of ten minutes. After allowing ample time for oxidation, wash the methylene blue out of the vessels with Ringer's solu- tion (warmed to body temperature) and remove the apparatus. Small pieces of integument may now be taken off, exposed to the air for a few minutes, and then placed in a cold 8% solution of ammonium molybdate in distilled water. (Must be made fresh). Leave the pieces of skin in the ammonium molybdate (fixing) so- lution at least twelve hours. Wash in running water three hours, For this purpose small porcelain Sieves with minute perforations and cork stoppers are very serviceable. Pass the tissues through the alcohols, 70%, 95%, 100%, leaving them for a period of three hours in each. To prevent the methylene blue from dissolving out, the tissues should be kept cold (5 to 10° C) while they are in the alcohols. Clear in xylol (3to5 hours). A mixture of two parts hard paraffine to one part soft is best suited for imbedding the flying membrane, while for the skin of the body which is more cornified, hard paraffine is preferable. Sec- tions cut 20 micra are thick enough to enable one to follow — _ ee pa ry ak is x a, @ ea : Tote : ; : “aN 3); 7 ag ¢ e 4 . - wi 4 ttitewe” : oe, a rd ae vb) detey of Ate sie “Ge vat . r « Y Lo Pee at ey i: fay s2og PAG: @ ay: ba agent off Pum reine fC i) AL ee ni therey Bait : | rae? Fe : a7 Fh ae A oe “te idy es ie nerve fibers some distance, and sufficiently thin to admit am- ple light. Mount in balsam. The following short method of affixing the sections to the slide may be used to good advantage. Place on a clean glass slide a small drop of fixative prepared by mixing equal parts of oil-of-cloves and collodion,. Rub until a thin coating is formed. Lay upon the slide the paraffine ribbons of thick (20 micra) sections, and flatten them out by pressing down with the tip of the finger. Place slide in xylol until paraffine is dissolved off and mount in balsan. Other killing and fixing fluids used were corrosive subli- mate and acetic acid, Zenker's fluid, ammoniacal alcohol (8 to 10 drops of aqua ammonia to 1000 cc. 95% alcohol) and 10% for- mol. Besides methylene blue the following stains were used: sil- ver nitrate (Cajal method for nerve fibrils), carmalum as a counter stain for methylene blue, Mallory's connective tissue stain, Heidenhain's iron haematoxylin, Delafield's haematoxylin and eosin, and Hanson's haematoxylin and orange G. OBSERVATIONS AND DISCUSSION. : I.-General Structure of the integument. — aon: <—c—nsnEanERiaeiocs=s calles cimaabeags 1. Integument of the Body. The skin of the body of bats is covered with hair which, as Allen (1893) has found, varies in different regions in text- é ure and amount. In general, the crown of the head, the neck, a the sides of the under surface of the body, the rump and the pubis have a thick pelage, while the distal portions of the ears, the soles of the feet, the mammae and external genitalia are al- most naked. The snout is scantily clothed, but shows a limited number of vibrissae which arise from wart-like structures. In different regions of the body the skin varies greatly in thickness. The integument of the face is the deepest. That of other parts of the body diminishes in depth gradually in the following order: palmar region, plantar region, rump, ventral thoracic region, crown, and dorsal thoracic region. As a rule some difficulty is experienced in distinguishing all the layers commonly found in the human integument. In the epidermis the Malpighian or deeper stratum can be readily made out. Its deepest layer is made up of subcolumnar cells. The in- termediate layer of polygonal cells is for the most part absent, though in places (e.g., the face) it appears as a single sheet of isolated, more or less flattened cells, whose nuclei are somewhat reduced in size (Fig.1). Numerous pigment granules are present in this layer (Fig.2,pg). The stratum corneum is thickest in the palmar and plantar regions. It is made up of several layers of cornified epithel- ium, the outer ones of which are usually in the form of loose scales, The deeper layers are more compact, and appear to con- sist of flat, enucleate cells. In certain regions of the body (lining of the mouth, lumbar region) these layers resemble to some extent the stratum lucidum of the human skin, but the pres- ence of this stratum can be made out definitely only in the pal- mar and plantar regions. (Fig.2,s1). Fal a fi ®. 22% ahs’ ~) 1 Ss”) thed 18 Le o8et rremngolse ota the he Lim V cvmpaal ag : ! A Oto em RES ae ais . cahp is qi haan = a a s ray } . « t }? é 54 . ) ' me - r . ( ' roy . - el » - + « . i 5 my . rl . Epleitd 9 timye Mae, caiee wh as Lei ete, anure? _ rir ae 1 es |) AI a il inte ¥iy. eoae ea! : ji . eerie Hace eae sboxel 3 - tt { oe ; , LU ai Fi 2) JBhie we giesta Seite. ba eigen, mee haa The surface of the epidermis is frequently interrupted by hairs, and also by the openings of ordinary sudariparous and of modified sweat glands as Diem (1907), Porta (1910) and others have shown. The ordinary sweat glands and the modified sweat glands may open into the hair follicle, or independently on the surface, The distribution of skin glands over the body is very variable. Though not numerous in the region of the rump, sweat glands are, however, present. This is in accord with Diem's findings, but opposed to those of Hoffman (1898). The writer was unable to find sweat glands in the sole of the foot, and a- grees with Toldt (1907) that these glands do not occur in the ball of the thumb. Toldt found numerous glands in the "Sauge- scheibe", and also large groups of glands in the region of the neck and of the external genitalia. The upper lip is more abun- dantly supplied with skin glands than any other part of the body. As is frequently the case the superficial layer of the corium, the stratum papillare, is raised into ridges and papil- lae which project into the epidermis. These are most marked in the upper lip, where simple and compound papillae are present. The interlacing strands of connective tissue and the reticulum of elastic fibers which together form the ground work of the co- rium are comparatively fine and closely packed, thus causing this layer to be somewhat dense. Preparations stained with Mal- lory's connective tissue stain show that the general direction of these strands and fibers is parallel with that of the stra- tum Malpighii. While it is not possible to determine a boundary between the stratum papillare and the stratum reticulare, yet the deeper connective tissue bundles of the latter are obviously HW af as 4 ie oe ctehiqn edtets 2am 4 "! ‘1 tiro-% oR AEROS eho 2 > ie , oer) eae ame aa - i‘ : f én t i. &s ee ' i ) ; y : ’ 3 4 >t i" o> * ; : +2 -Ufeompe ee ee ,e2et lias Quien bad ' 8820. Bi sane “Sern bast ren he sented Lisidiltn od! cS woot * ais &, — ws 2 ie i iad caret ve penne pe titnaba ote Son Oe Lethe r rm wf? bit wee “oy wat hifvd. oie | . ee | 3 yw 11 more loosely interwoven than those of the superficial layer of the corium. As in other mammals, the corium contains blood ves- sels, hair follicles, sebaceous glands, sudariparous glands, striated and smooth muscle fibers, nerve trunks, medullated and non-medullated nerve fibers, tactile corpuscles, and nerve end- ings. The last three structures mentioned will be described in detail later. The upper lip of the bat is richly supplied with skin glands As one type of these, the modified sweat gland, differs somewhat from the typical sweat gland a description of its structure may not be out of place here. Compared with a hair follicle, this gland is enormous in size. It consists of a long, uncoiled, se- creting portion with an extended funnel-shaped duct. The secre- tory portion is lined by a single layer of columnar cells with finely granular protoplasm and round or oval nuclei (Fig.3,cc). Leydig, Sch8bl and Sabussow (1910) have called attention to the fact that these large modified sweat glands ( in the flying and interfemoral membranes) have a coating of smooth muscle.fibers, ‘which by their longitudinal course cause a slight spiral strip- ing of the gland. This coating of muscle fibers (Fig.3,mf) lies between the layer of columnar cells and an external covering or basement membrane (Fig.3,bm). The latter is homogeneous and without nuclei. The duct of the gland is lined throughout by short, somewhat irregularly cubic cells, arranged in a single layer, and surrounded by a delicate basement membrane. Not in- frequently secretion products are found in the lumina of the glands. The products are more or less similar in appearance to what Wimpfheimer (1907) terms degeneration products ("detritus") ‘ a ger as fo ey hy ww ie, eae en nat bres ry had Ned | i aude é 4 off ‘ L f iq 1 a pyre i ‘ ¥ ‘ft hake on 3 mee E "} ‘ ] By . eR . oe t en Mee tet | bail aionkong % ; t 4 Ae) Ly Bae - gant <8 piney ns found in uncoiled sweat glands in young moles. It is worthy of remark that pigment cells occur in the co- rium both of the body integument and of the flying and inter- femoral membranes (Fig.2,pc). These cells are more or less sim- ilar to those pointed out by Kohn (1910) in the hypophysis of man, and closely resemble the pigmented corium tissue cells of the pia mater of sheep described by Krause (1911). In the cori- um of the integument they are numerous, and appear to be scat- tered about promiscuously. Their form is very variable. They may be spherical, oval, elongate and slightly spiral, heart- shaped, pear-shaped, raggedly lobulated, and with or without processes (Plate III, Fig.5). In size they vary from 34 micra in length and 25.5 micra in width to 374 micra in length and 60 micra in width. The cell body is filled with fine brown granules. In haematoxylin-eosin preparations a few of the granules usually take the dull blue stain of the haematoxylin, while in the meth- ylene blue material some or all of the granules may stain a bright blue. Plate III, Fig.5,b represents a pigment cell con- taining stained and unstained granules. 2. Flying and Interfemoral Membranes. The flying membrane of bats appears as a skin duplicature formed by the lateral extension of the dorsal and ventral integ- ument of the body, The proximal parts of the membranes are cov- ered with fine hairs similar to those of the pelage, while over the distal areas extremely fine, more or less modified hairs oc- cur sparsely. In the natural condition there is a manifold wrink- pe ee - ie Sed ee ei% rea Ts < - igo teat, 24H. a > AS teeter ool Qnurts Sen hee ee heal! beige : Yivrewal Bik. ita’ rt p » } ¢ / 4 » a 5 rT a 7 yas wr een, ay i : at ae Lenggan) (eee : Lh. ag oe Teaneeciger a4! i ; dl? 9 i yf eee iw . fh ehat 3 aes et ; 13 ling and pleating due to numerous elastic bands within the mem- brane (Sch&8b1). Externally the flying membrane is seen to be made up of small hexagonal, plate-like cells which form a continuous mem- brane. Each cell contains pigment granules which are collected into an intramarginal zone much as Sch8bl has described (p.4). This investigator repots that the center and border of the cell (in Vesperuga serotinus) are free from pigment granules, In My- otis lucifugus and M. sublatus the writer found pigment in both of these regions, but in smaller quantities than in the intra- marginal zone. The cells of the outer (dorsal) surface of the flying membrane contain more and darker pigment granules than do those of the inner (ventral) surface (SchSb1). In fact this Surface in places contains almost no pigment at all. As in the integument of the body the epidermis of the fly- ing membrane stands out in the sections in contrast to the cu- tis. The Malpighian layer also can be readily distinguished from the stratum corneum. According to Sch8bl's findings the Malpighian stratum is composed of two layers of scattered cells, The writer, however, finds that one layer of cells occurs quite as frequently as two. The nuclei of the deep Malpighian layers of both dorsal and ventral sides are slightly more oval than those of the more superficial layers, the latter being somewhat flattened. From the shape of the nuclei one would infer that when a Single layer occurs it is the outer one. In the Malpigh- ian stratum of the dorsal side of the patagium numerous pigment granules are present, while in this stratum on the ventral side very little pigment occurs. Aside from being somewhat thinner, — =m i i ui es» r wee o ™ > (eg gt on | ew ca ¥: ; eB. i 7 - 7 ; } ; : * wiz pS r ei “ae pate: $0 henogteen. mibiiea tents Be , owed, sahil trite Gitte ris ae ond @ A , Woe vin are ing’ Xo ahs eaten eal i wy f i 1 abe iM 14 the stratum corneum does not differ from the corresponding struc- ture in the skin of the body. The tissue enclosed between the dorsal and ventral Malpigh- ian strata of the patagium constitutes the corium, which var- ies in thickness in different regions. In both the flying and interfemoral membranes it is thickest near the body, while in the more distal areas it gradually becomes thinner. The corium is made up of three poorly defined strata of connective tissue--a central,somewhat loose one, corresponding to the stratum reticulare of the body integument, and two others- one on either side--of denser tissue, more or less similar to the stratum papillare. The chief arteries, which are accompan- ied by the larger veins and nerve trunks, cause this stratum to be much thicker in those regions where they occur than else- where. Although the outer surfaces of this stratum is throw in- to folds to some extent, the writer has been unable to find pa- pillae. In the stratum reticulare are contained the larger blood vessels and nerves, and the striated muscle bundles and elas- tic bands (Balken) first described by Leydig, whose findings were later confirmed by Sch8bl. Here also are found the secret- ing portions of sweat glands, and the proximal third of hair follicles. The outer stratum of the corium contains the central portions of the hair follicles, their sebaceous glands, and the sweat glands. Each follicle, with the sebaceous, sudariparous and modified sweat glands associated with it, is surrounded by a capillary network. A shan, iy eae ‘ ee es te = Fe ite ‘ ss 7 7 i i y } vu c , a ag ee "4 ] Pa a oe ie fhe a, = pi SL : oa DEL Ls a os uf whon ? i/ 7W eS j VN WY RG Se a ay, 4 peu.) we nek: & > ie Pity Pa ‘ ty ei 1 nl : ‘ i ‘ , rit) ae | Rs. ee hae * % hen nara ne 6 4 S i a ee | ro vee - " A Vf aay atainorida Mbapsp, TAR aa) € au 4 4 a 7 - tp pee ee L vey II.-Nerve Layers of the Integument. 1. Nerve Layers of the Body Integument. In the sub-cutaneous tissue and in the reticular stratum of the body integument, are found large medullated nerve trunks and branches which, for convenience, are called the first nerve layer. By dichotomous branching these nerves break up into a loosely intertwined meshwork consisting of an enormous number of medullated nerves. These interweren nerves, which are not actu- ally united in a plexus, constitute the second nerve layer (Fig. 4,snl). Arising from the latter are medullated nerves which pass toward the periphery. Near the outer surface of the corium they begin to divide, The resulting branches pass directly to the Malpighian stratum forming the third nerve layer (Fig.4,tnl). Ordinarily so much pigment is present here that it is impossible to follow the fibrils to their endings. However, in places where the epidermis has accidently been torn, one can readily trace the fibrils well into the Malpighian stratum, noting branching fibrils which pass outward and terminate in or between the cells of the stratum granulosum. As these can be traced more readily in the membranes where little or no pigment is present they will be considered more fully later. Varicosities are numerous both in the second nerve layer and along the fibers which pass to the third layer (Figs.14,15,16,17). The greater number of these en- largements, however, occurs on the smaller fibers. Varicosities in the third nerve layer, i.e., on the surface of the corium or in the Malpighian stratum, have not as yet been observed by the ads Qc oy ear telnet 3 i “hy a J 2 . - ' - oe - —- 3 y . +! 7 a 7 ‘ Ces : ¢ arn, rhe > dj iu ¥ . * ¥ | 4 # + (ai a i. ’ : Poe. fg ote Hees t - f ot se - ' ‘ . e2 a ‘ tl be tay 6 0 VP hs is * a... ew ee fh. e 74g ep: ate selay a2 ¢ ie , 2 > 4 . ( Th a Pe om pina
hip Bite el: Bite Ve)
art Gorgas “Caan a wt iid
; i 2 a is "
is! Se ae Latomdet sede nia
ti ad Find Nasty Bo ;
>. S¢ what “ she n agen ne ae
aie) yy tentin cml? fea ie Sonate ne SS ue
D4 ice 2 Pet Pe Refer *
(As Arial ot An seein ada
a ie eo" of on Rad
“T=. —
LY
meshwork in this layer, however, arises not by an interlacing
of fibers, as is the case in the other two layers, but by di-
rect anastomosis of single non=medullated fibers. On certain
fibers of this layer Sch8bl noted a number of enlargements or
swellings ("Krootenpunkten"), which were triangular, square, or
polymorphic in form, having a fine granular appearance, but ex-
hibiting no nuclei. He also occasionally saw more or less sim-
ilar spindle-shaped enlargements in the course of a single fi-
ber, especially the larger ones. The fifth and last nerve layer,
also double, lies immediately over the previous one on the sur-
face of the cutis, ordinarily remaining attached to the deepest
cells of the Malpighian stratum. The fibers of this layer are
likewise non-medullated, and have a diameter ranging from 0.9
micra to immeasurable fineness. This layer arises from the pre-
vious one by the division of the finest fibers of the latter.
At the places of division of the fibers, the swellings which
were found so frequently in the last nerve layer seldom occur in
this one, and the spindle-shaped variety is lacking entirely.
This layer of extremely fine non-medullated nerve fibrils lying
immediately at the surface of the corium partly between the low-
est cells of the Malpighian stratum, Sch&bl holds as a terminal.
He further states that in preparations in which the lowest cells
of the Malpighian stratum remain undisturbed on the corium, no
free endings of the finest non-medullated nerve fibrils are
found, and that fibrils passing further toward the surface be-
tween the cells of the stratum granulosum, are never to be found
either on the surface of the preparation or in cross section.
fe oa ee
s to. v . "Z ry
A mh exw tel
$ : ce eae et?
a
$ ce ee ai@ nie
" t
ig? tee
\ ; .
(“ d o a. ,
t 7 a2 ie
- z ,
= bal ;
— — * 7
_— jee ; J
; 4
€
i {
> q
F
¢
- ij cs. a7 bles
e P 7 ii,
{ L * % “ae ' ive TA =4im
a ' ) eu 4
‘ er. i
‘ewe j Br £
! nt mt . ts is
foxy
whe ite ea ry RD
* ; EL ahirigtetie a sent a
an 4 . sd % ‘+ = -s a
— +, 4 open hp tay i a ae
18
However, he pointed out that, occasionally, round or elliptic-
al swollen structures resembling fine nerve endings are to be
seen, but these almost always prove to be nodal points of divis-
ion of nerve fibrils. These minute swellings occurred so seldom
that Sch8b1l attributed their presence to faulty technique.
Sabussow (1910), working on the innervation of the flying
membrane, did not wholly accept Sch8bl's idea of the distribu-
tion of the nerves of this part of the body. This investigator
found large nerve trunks in the innermost stratum of the pata-
gium, but held that Sch8bl1's second nerve layer lay in the same
plane as the first, and consequently could not be said to exist
as a separate nerve layer. Concerning Sch8bl1l's third layer Sa-
bussow simply stated that it is not double. But the existence
of the fourth nerve layer of Sch8bl1 this investigator confirms,
adding that no matter how the membrane is torn, this layer can
be seen to be double. He also confirms Sch8b1's fifth layer,
which is non-medullated and double; but instead of the few"swell-
ings" which Sch8bl observed, Sabussow found numerous varicosities.
The latter sums up the layers he found as follows: (1) a simple
layer including the first two layers of Sch8bl; (2) a broadly
meshed double network with triangular enlargements in it; (3) a
network of varicose fibers also double. Consequently, according
to Sabussow, there are five nerve layers in the pategiun.
In a acpexae sections of my own preparations of the fly-
ing and interfemoral membranes there can readily be seen here
and there regions which are approximately twice as thick as that
of the remaining area of these membranes. It is in these thick-
ened regions that the chief arteries, veins, nerve trunks and
i?
pt
de ea
sepa A
Pa
ab
.
t =
-
1
= *
A
* . \
4
b
4
4
1
=
i a
. /
y >
Bs i :
Pee ¥
Y Lon, ; é
wn iy a 42
4 . x
‘ Mi hab ee
ae s
‘ 7
‘ i my
4 eed A
Pi > § m3)
. . | mia" 4 4
oat ¥ “ar 7)
ie ; i ‘ i ay e *y lh COREE
iM
“ea 12") bia ies
19
frequently the principal muscle bundles are found. These partic-
ular regions contain, as will be shown, one more layer of nerves
than do the others.
The main blood vessels, accompanied by the chief nerve
trunks, pass out from the body through the flying and interfem-
oral membranes in the stratum reticulare, giving off, here and
there, important branches, which, as stated, are frequently
found with the muscle bundles. These blood vessels, partly be-
cause of their own size, and partly on account of the increased
amount of connective tissue around them, cause the elongated
thickenings or ridges in these membranes already etaees to.
The medullated nerve trunks and their chief branches, both found
in the innermost stratum (reticulare) and existing only in the
aforesaid ridges, constitute the first nerve layer. The second,
a double layer of nerves, arises from the first by repeated di-
chotomous branching, traverses the deeper part of the coriun,
and spreads throughout the entire area of the flying and inter-
femoral membranes. In methylene blue preparations this layer is
seen to consist of a loose harman ot medullated nerve fibers,
many of which contain comparatively large varicosities (Plate
III,Fig.13,va). The third and last nerve layer is likewise dou-
ble. Numerous medullated fibers arising from the second nerve
layer pass toward the two external (dorsal and ventral) sur-
faces of the membranes. Many of these fibers on approaching the
Malpighian stratum divide dichotomously; others do so at the
surface of the corium. Both lose their medullation. The forked
branching continues to some extent in the Malpighian stratum,
a
Tenney
é F
peer Ti
% peyitene
eh ee ee |
iq iat "on aM w Ta
ar aaah
ad
>
Ts
c J ¢
’
—
4
'
\
l
‘
> é
w :
at fyi
f
mil Aci no y
. >» b+ j ea
1 ‘fr
A *
*
- 5
“ ae | tae)
i
= o
’ 7 . 14
' : - me
i
Ly
y wr
i r/
; ‘ evi Bie.
%
*
nptoe ata : in hi 4
é
ohn it, San Oy
20
the larger fibrils giving smaller ones until finally delicate
nerve threads are seen to end in minute enlargements, which will
be described in detail later. These branchings of non-medullated
nerve fibrils at the surface of the corium and in the stratum
Malpighii constitute the third nerve layer. While varicosities
of different sizes (Figs.13,14,15) appear in the nerve fibers
leading up to this layer, the writer has not observed them in
the latter. |
According to the present observations, then, certain re-
gions of the flying and interfemoral membranes are supplied with
three layers of nerves, others with but two. Briefly stated
their number and distribution are as follows:
1. A layer of medullated nerve trunks and numerous medul-
lated branches, occurring in the stratum reticulare, but only
in the elongated ridges containing the largest blood vessels
and much connective tissue.
2. A double medullated nerve layer in the deeper part of
the corium extending throughout the membranes.
3. A layer, likewise double, present in the entire Malpigh-
ian stratum, and consisting of numerous branches of non-medul-
lated nerve fibrils.
A comparison of the foregoing findings shows that the first
nerve layers of Sch8b1 and of the writer coincide; that Sabus-
sow's first layer included Sch8bl1's first and second layers
and the writer's first, together with the innermost branches
of his second nerve layer. A study of sections from the differ-
ent parts of the membranes has convinced the writer that SchU8bl's
;% J is “4 o
> 4
wey reed etn Lag eae
= oe ie Le ate re ey
a i
a ee
at he } ES eS aa Oy Pee earygey ne uae gn'e sa
Aye) eae MU eee me Paes sd
a PU eT A a eres. “Oy
r ar SMA nO DPeReiN i a ee e
- Linh i ito Ceo: eee & ome leP eat
rare a
{te gud rey vis heer ev he taeda pe: ary. ee
fs iu
"
ph Et Ca Oe) See Ore wh Lee Tae) ig.
aia
i.
e . 1 “i tied af tae owe age a
a Tien kt. ee tonbyoauinge a a
ae meen
x a
3
— \
.
* .
= (
’
« s ‘
= ’ ri
var)
.
6 ea T
*
wake
wt
; .2. TOS
ethene eimbalrg ote
af a yo ) =
4 le OY Ae Ney ot
J
b
a ea) o4
i ¢ i. TAR rey
‘oak et!
\
ta base aly sailed ee
a Neon» . -
23
misinterpreted by Sch8bl, who, on observing in the stratum Mal-
pighii a very limited number of minute round swellings resem-
bling fine nerve endings, concluded that they were foreign par-
ticles due to faulty technique.
The end=-knobs take a deep blue stain similar to that of or-
dinary axis cylinders, and appear to be homogeneous in structure.
As to shape they are oval or spherical. Their size varies from
0.5 micra in length and 0.4 micra in width to 0.9 micra in length
and 0.8 micra in width. In the sections studied, these end-knobs
appear to be numerous. Ordinarily, one to a cell is observed,
though occasionally even two are seen close to a single cell
boundary. It also happens sometimes that a tiny fibril appears
to end without any enlargement (Fig.7,x). This, however, may be
due to the failure of the methylene blue to differentiate the
end-knob, as those who have worked with this stain will readily
understand.
That these diminutive enlargements or end=kmobs are real
nerve terminations and not the nodal swellings sometimes seen
where fibers divide has been satisfactorily proven. For example,
in focusing on the surface of the transparent stratum corneum
no knobs nor fibrils can be seen. A deeper focus brings into
view end-knobs with a fine nerve fibril running into each. A
still deeper focus shows tissue below the end-knobs and enables
one to follow the nerve fibrils from the now indistinct terminal
swellings back to the branch from which the nerve fibrils are
given off. Where little or no pigment is present, these nerve
terminations can be seen without difficulty.
» “el 7 Es i :
ad ry cy anes io 7 : * ’,
= a wae foal
. vaM ied
ai? a
io. , ase Seeds
= Pai i
Peder tym rat ey
& | Oa) oR 0 Clie
VVN A
SA? hemp iat: Yas
7 : i %
oe pt ohne at
\ - : :
T2.d aeBers
3 . 5 Ee vie Gye
t od ?
’ °
F j ve
- ’ enh? (aoe ee
a , i 44 . . L
Lot) a ta of) Te ceee ame, aae ci en bea
F is T
Sov) NT ptay att ans 40
} Ty Ts QE Eady i a“ pe Tv aN or
Cah) Gag, ba : << |
= fs! at ayeodts ert a a,
; ” rede) kigtybe.
; See Gite) & ror arid
j hy
7 ws. iy ‘ 3 ray tg ‘bn ke area
Dae) ve ()
wrrets ee soo hbbae re
a us yi i
; at oe ‘D4
Cd ¢4 ‘ ee ont iy
eae re ‘7 i on ae
: pe ees Fs eet
24
For a time the writer was unable to determine whether the
nerve end-knobs are situated in the stratum Malpighii or in the
deepest layers of the stratum corneum. At length, however, a
section was found in which a part of the ventral surface of the
interfemoral membrane curled up permitting an oblique view. The
methylene blue stain was deep enough to show the margins of a
number of consecutive superficial cells of the stratum granulo-
sum (Fig.6), and little pigment was present. By focusing upon
this obliquely turned portion of the surface of the membrane, it
is comparatively easy to distinguish the flat, elongate, scale-
like cells constituting the stratum corneum from the more oval,
clearly defined, superficial cells of the Malpighian stratum. By
focusing upon the curved surface it is possible to see a number
of nerve end-knobs on or near the surface of the stratum granu-
losum, but as yet no end-knobs have been seen by the writer in
the stratum corneun.
The question of the exact position of the end-knobs in re-
spect to the epithelial cells naturally arises. It is certain
that a large number of the structures in question are situated
on the surfaces of the cells (Fig.7,es). Others appear to be
within the cytoplasm. However, it is frequently possible by fo-
cusing to see that these end-knobs are after all on the borders
of the cells. If all were completely stained, it is not ioceke
ble that the remaining end-knobs could be shown to be intercel-
lular.
So far as the writer has been able to ascertain the only
reference to free nerve terminations in the epidermis of bats
« ¢€
)s
©
¢ x :
<
;
7 oh, “Aty
ae at a. ;e ia ia rae hee ys
4 is he she aaa —
ts
, lena hehe i a Rig
7
A ~ j
* ‘4 f
hy be — pry eg :
, OF yy ease
2) 3
‘ - P- 59) a
is that of Botezat (1908). The study of this investigator was
made principally on the nerves in the epidermis of the dog's
nose, but he mentioned the finding of intracellular end-knobs
("EndkmBpfen") in the skin of the nose of the bat. He held that
the free nerve terminations in the epidermis not only of bats,
but of all classes of vertebrates, are intracellular, though
none of his figures indicate it, Retzius (1892) in his monument-
al work on the nervous system showed free nerve terminations in
the epidermis of the lip of the human foetus and made the follow-
ing statement: "The fine, varicose nerve fibrils branch and end
intercellularly without any direct connection with the cell." He
found the same to be true of the free nerve endimgs in the skin
of the mouse and of the rabbit. Van Gehuchten, in 1893, describ-
ed free nerve terminations in the epidermis of the face, lip,
ear, paw and tail of the white mouse and white rat. He likewise.
the free nerve endings to be intercellular. He stated, "Partout
nous avons trouvé 1' existence de fibres nerveuses intra-epider-
migues se ramifiant et se terminant librement entre les cellules
epitheliales." While Dogiel (1903) did not hold intracellular
endings as out of the question, yet he was strongly of the opin-
ion that the free nerve terminations are intercellular.
2. Nerve Endings on Hairs.
While the innervation of hairs has for some time been a
field of fruitful investigation, there still remain some unsol-
ved problems in connection with the hair of Chiroptera. In re-
cent years especially, more attention has been directed toward
a a ss Te
ie i
"4 lee 08d in re
a ptt de ay ais a oe fa }
: eit ee tae aioe
oT a ‘oe araed Te natal
—
‘ a ’ aa “we oun © “Orr eee ad
coon he igiae i eadke foe hae
50% EG Leh Ce ce ite ie ee
Rediounpae: J er eee ie ats
Cran eMA ditt. ot heath, of even
ea itiopdel acl oe wi ag dat > bee
+e
Oo Soarpeigene a0 Ss) TCR Doni) ae
d } i: i
- Low. Sue Sauber, we Pde 8 ah Fee ee
; et
=
te bal Bee ede ed iv ei he
bh ages ob gegatiiee es entire
Parag?) tC Paes tees 26 oF Ft sau t alhs vag
ee a sae gs Peat ae esa
7
ceaeieet Gog) de onan (eres ba aailg
NE ae Large ey ne sro
ry
i
‘ bad, Seta Fama | eat let Be
ie, Ste ee
26
the innervation of tactile or sinus hairs than toward that of the
hairs of the pelage. The writer's descriptions will be confined
wholly to the latter.
Observations made by different investigators on the inner-
vation of the hairs of bats have been so conflicting that it
seems advisable to give a brief review of the literature. Schtbl
(1871) studied the innervation of the hair of the flying mem-
brane, and set forth the following principal points: In the hairs
of the bat, the nerves terminate in special corpuscles ("Termin-
alkBrperchen") situated at the bases of the hair follicles. The
hair receives a bundle of nerves which consists of from 2 to 5
medullated fibers. These twist many times in a spiral about the
hair shaft forming a nerve wreath or ring. From this spiral ring
two to four nerve fibers are given off, and these extend down-
ward ending in the terminal corpuscle beneath the hair follicle.
A superficial nerve ring which consists of from one to two coils
is formed by fibers from the fourth nerve layer. Boll (1871)
working on similar material confirmed Sch8b1'’s observations.
The following year Stieda took exception to Sch&8bl's find-
ings, especially in regard to his "Terminalk&8rperchen", This ob-
server concluded that the structure in question was not a ner-
vous apparatus but rather a differentiated part of the hair fol-
licle ("Haarkeime"). The nerve ring was not mentioned by Stieda.
Beil (1871) also denied the existence of Sch8b1l's end-cor-
puscles, although he was able to see the nerve ring. Concerning
the structure of the latter, its course, or the endings of its
fibers, he could determine nothing definitely. Above the seba-
“3 + , ’
. : he od ote
t ty ore Pee | a a 6 .
,
‘ + die Bu. .
| ad i c OB
_
Li
4 i mam Fi
HLT 3G TRON Malis hheee
wh ead Sat ieaers ars yliniee ae
At. eae
t rere ta Bese eae See Opges
ay ) a2 a v. < i 7 4
g. Sotal pete ha tae are ie
C a : , Ms i
\y . bat a4 , wees Sat
. ee eo ie
’ , 7 : y 5m sf
; Sc Oi Baty ae ae,
} : ' 7 pa rel
28 gS eae
ies “ees
‘
= Le
ceous glands, however, Beil noted the entrance of two or three
bundles of non-medullated nerves into the hair follicle.
Using the method described by Sch8b1 himself, Veleeky
(1872), investigating the flying membrane, likewise did not
find the so-called end-apparatus; nor did the use of gold dis-
close these "TerminalkBrperchen". By the latter method, however,
he demonstrated non=medullated nerves which approach, from be-
low, the cells of the epithelium of the outer root sheath of
the hair, and spread into the intercellular spaces, forming a
net.
In the same year appeared a more important piece of work
by Jobert in which he described in considerable detail the in-
nervation of the hair in the bat's wing. The principal points
brought out were as follows: (1) All the hairs of the skin are
supplied with nerves and are perceptive. (2) The affirmation of
Sch8b1 that into each hair follicle there enters one nerve is
not true. Each hair is supplied with many nerve fibers, five to
six or more, which approach the follicle, together or separate~
ly, and from different sides. They may unite into two or three
small trunks. On reaching the neck of the hair the nerves di-
vide, lose their medullation, and are distributed on the hyaline
membrane more or less like radiations, ending freely at about
the same level. (3) The nerve ring of Sch8bl does not exist,
neither does the "TerminalkBrperchen". (4) At the level of the
superficial subepithelial network of nerves, minute threads are
Seen which surround the follicle and disappear in the epithel-
ial sheath.
e
4
7
,
Tipe
= let Sek rae eae ~ eae el ga -
2i~ephas mitt bo Seg ee
tow af ot ots Cire “a So
a {a bod Ldvage Segitut
. Caggieadt het et re '
3 ri a. My
tes pare hee bi |
bean ‘tet aod wt Fee Ae Geen
Te rip eS ee
y ad credit tee ot) ra an
: it y tal! ‘ i bya ae rege hel 5.
; ir
. oes
, 4 x ‘ " # * 1 PF Ods Myr “yao ster
vius
¥
ii @ : ‘ Ve ‘ i » ae i9" Fabs Cs et
: ; & sale CW Mee yt eat Wit to
2 el
* i zk pe or a
; ‘eel ot ike ete yer sh bes
al on oon art. a Orv it ‘
. fs. fet Pogoo SE eee eee
rit if Ont Geog Gye; AO Oe ct tas
hen fee, vr. ae 4 Cc aee a r er,
4
3 resis shad. OF wees, ae wean
Si yk) (ee hee acktpe thes jieda A
i wt
Lith ape Pa Beet whee aye: we
Sos Se aris wat hei
. = x . 7 ¥ uP +
Pe) wear i lnm ae .
% \ as yf ans
712 boats ‘ie iran tee rt
ard jena Var team
-
28
Arnstein (1876) recognized two different kinds of nerve
terminations on hairs: (1) The free endings on the hyaline mem-
brane in the form of a "palisade". (2) The nerve network which
occurs in the outer root sheath.
Bonnet (1878), who investigated the innervation of the
hair follicles of a number of mammals including the bat, con-
firmed Arnstein's observations on the endings of nerves on the
hyaline membrane. Bonnet's idea was that a nerve ring exists
in connection with each hair. The small fibers which constitute
this structure lie outside of the straight fibers, which ter-
minate in a “palisade”, and surround them much as hoops sur-
round a barrel, in the form of a ring consisting of six or more
pale fibers. Of the root sheaths in the region of the sebaceous
glands Bonnet says, "This is a rendezvous of the various small
medullated nerve fibers which come to the hair partly above
and partly below the sebaceous glands. These fibers going to
the follicle spread out forming a woven net of minute medullat-
ed fibers". |
In describing the innervation of the hair of certain mam-
mails including bats, Szymonowiez (1901) pointed out that the
medullated fibers approach the follicle below the sebaceous
:
:
glands, divide, losing their medullation, and penetrate to the
hyaline membrane, where some of the fibrils encircle the hair,
while others end on the hyaline membrane. The latter fibrils
branch regularly, and run parallel to the long axis of the hair.
This investigator observed perceptive menisci in a strongly de-
veloped outer root sheath of a common hair in the face of Ves-
»
‘
ae ve ak x
if
le
vhs
Laat has
OF hes tll cee
an
perugo serotinus.
According to the observations of Sabussow (1910) the hair
of the flying membrane of bats is supplied with several medul-
lated nerve fibers whose number is never less than two, These
fibers approach the hair follicle, divide, spread around the
hair spirally, more or less in the form of a ring, give off
small fibrils from the latter, branch, and finally end in the
form of a"palisade" on the hyaline membrane. The fibrils of the
"“palisade” may contain varicosities along their courses, or
their distal ends may be lance-shaped. The spiral ring around
the “palisade" consists of small varicose threads. This Sabus-
sow holds as a second kind of nerve ending on the hair. He as-
serts that he never saw these two kinds of endings, viz., the
"palisade" and the varicose threads of the spiral ring, at the
same time in the same hair. From this he concludes that there
exist two kinds of hairs, each of which is supplied with one of
these nerve terminations.
Parallel with the spiral ring just described and more su-~
perficial, Sabussow observed a broadly meshed network of fibers
resembling a merve ring, and apparently surrounding the hair
above the sebaceous glands, This network or ring, which belongs
to the second nerve layer, could by deeper focusing be seen to
give off more or less flattened fibers resembling the "palisade”,
Being unable’ to find any definite connection between the "pali-
sade” apparatus first described and this one which comes from
the subepithelial network, Sabussow inferred that the two were
independent.
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In the writer's deeply stained methylene blue preparations
of the bat's skin, both of the body and of the membranes, the
hair follicles with their numerous nerves stand out in bold con-
trast to the surrounding, weakly stained connective tissue (Figs.
8,9). The nerves which supply the hairs arise from the second
nerve layer, pass outward to approximately the level of the in-
ner third of the hair follicle, where, at first, they appear to
pass along from one hair to another. But upon close examination
it is seen that nerves may be distributed in one of two ways:
A. The whole fiber may end directly in a single follicle (Figs.
8,9,ff). B. Upon approaching hairs the nerve may divide, one or
two branches going to a follicle, the others passing out to the
epidermis (Figs.8,9,fe). By far the largest number of the nerves
in question are distributed in the first way. The numerous fi-
bers form a veritable network, which might justly be termed a
nerve layer, but which for simplicity is not so considered by
the present writer.
As to nerve endings on the hair, it may be said that they
occur at three different levels and in three separate layers of
the follicle. 1. A superficial nerve ring situated above the
orifice of the sebaceous glands and giving off nerve threads in
the connective tissue sheath (Fig.9,sn). 2. Fine varicose or
flattened nerve fibrils which lie immediately. the sebaceous
glands, and end on the hyaline membrane parallel to the long
axis of the hair (Fig.9,eh). 3. Nerve fibrils at the level of
the lower third of the follicle, which take a horizontal posi-
tion in the outer root sheath (Fig.9,eo). A further consider-
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ation of these types of nerve endings follow.
1. Superficial nerve ring.- Medullated nerve fibers ap-
proach the hair above the opening of the sebaceous glands, At
the outer border of the connective tissue sheath, they divide,
spreading around the follicle and forming a loose ring of from
two to six or more fibers. From the ring are given off non-med-
ullated fibrils some of which are interwoven in a delicate net-
work, while others appear to end freely in the connective tis-
sue sheath of the follicle. This ring doubtless corresponds to
the “broadly meshed network resembling a ring” described by Sa-
bussow (1910) above the sebaceous glands. As is seen in Figure
9,f, the non-medullated fibrils show no tendency to pass down-
ward to. a nerve ring below.
2s
low the sebaceous glands medullated nerve fibers, chiefly of
type A. enter the region of the hair follicle, penetrate the
connective tissue layers, divide, losing their myelin, and en-
circle the hair in a nerve ring. The number of. constituting
the nerve ring varies from two to eight or even more. From the
inside of the ring fibrils are given off which divide dichoto-
mously. The branched fibrils assume a position parallel to the
long axis of the hair, and usually end in slight enlargements ©
(Pig.9,eh), some of which are merely small varicosities, while
Mitac) others resemble the minute end—knobs seen in the free
nerve terminations in the epidermis. In certain cases there are
no enlargements, but in these instances the terminal fibers
are flattened. This type of nerve ending undoubtedly corres-
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ponds to the well known nerve ring and "palisade" described
first by Arnstein (1876), and recognized since by Bonnet (1878),
‘Szymonowicz (1901), and Sabussow (1910). Merkel (1880) describ-
ed a similar end-apparatus on a common hair in the lip of a
cat. The "termaisons en fourchette" of the Hoggans (1883) and
the nerve rings of Retzius (1894), van Gehuchten (1896) and
Ostroumow (1900) are probably corresponding nervous structures.
3. Nerve fibrils in the outer root sheath.- At the level
of approximately the lower third of the root of the hair, med~
ullated nerves penetrate the connective tissue layers of the
follicle. When the hyaline membrane is reached they divide and
run for a short distance onor near its surface. These nerve fi-
bers give off a few strong non-medullated fibrils which pierce
the glassy membrane, and end in the outer root sheath, usually
taking a horizontal position in the latter (Fig.9,eo0). The
nerve endings of this type are found in a slight swelling of
the root sheath, which may. correspond’ to the superior swelling
described in typical sinus hairs. So far as the writer has
been able to ascertain nerve endings of this type have not pre-
viously been described in the pelage hair of the bat. While
Such examples are not numerous, yet they seem to him to be gen-
uine. Nerve endings in the form of tactile corpuscles were de-
scribed by Szymonowiez (1901) in the outer root sheath of a
hair in the face of Vesperugo serotinus. The same observer in
1909, mentioned the finding of Merkel's corpuscles in this lay-
er of the follicle in man. Retzius (1894) described a nerve
fiber in the outer root sheath of a hair of a mouse, and Vin-
ea
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cent (1913) found nerve fibrils in this layer of the sinus hair
of the rat.
3. Special Sensory End-Organs.
The literature dealing with special sensory end-organs in
general has recently been reviewed by a number of investigators
(Szymonowiez, 1895, Tretjakoff, 1902, Dogiel, 1903, Schafer,
1910). Therefore only a brief survey of the observations upon
such end-organs in the skin of bats will be given here.
Arnstein (1876) found in the flying membrane of a bat an
end=bulb which he thought resembled the well known cylindrical
end=-bulb of Krause. It was possible for him to trace an axis
cylinder into the organ, but he was unable to make out the end-
ing of the fiber. In one instance, however, he saw it break up
into fine fibrils. Arnstein was of the opinion that these end-
bulbs occurred in the flying membrane where no hairs were pres-
ent.
Schumacher, in 1907, mentioned the presence of a large num-
ber of layer-like corpuscles("Lamellenk&8rperchen") among the
phalanges.
Sabussow (1910) investigated the flying membrane of two
species of bats (Vesperugo noctula and Vespertilio Daubentonii).
He stated that in weakly stained preparations he could see ter-
minal bulbs which were divisible into two classes according to
Size. Some were so small that upon slight magnification it was
difficult to see them; others were comparatively large, had a
zigzag course, and could be recognized with ease. The latter
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40
or less regular end-net or arborization (Figs.11,12,ea). This is
in accord with the observations of a number of investigators in-
cluding Boeke, who described motor end=-plates on muscles in the
tongue of the bat.
At the point where the nerve fibers enter the enlarged
motor end-plate there is a slight elevation of the surface of the
muscle(Fig. 12,e1). The position of end-plates on muscle fibers
has been in doubt for some time. In the preparations used in
this study they appear to be beneath the sarcolemma (fig.11,sa).
This shows especially well in cross sections of muscle fibers in
the tongue (Fig.12,sa). Most investigators are now in accord in
regarding this structure as under the sarcolemma.
In weakly stained preparations the branched endings can be
seen to lie in more or less irregularly shaped matrices. The lat-
ter are of two kinds: (1) A weakly stained area containing nu-
merous deeply colored granules of various sizes. (2) A somewhat
smaller area without granules.
In shape, the former are irregularly circular or even tri-
angular. The granules, which vary greatly in size, stain almost
if not quite as deeply as the nerve fibrils themselves (Fig.1l,
mag). To structures corresponding to these Kitlhne (1887) gave
the name soles ("Sohlen"). The smaller areas or soles, which ap-
pear to be free from granules in this stain, are oval or pear-
shaped, the axis cylinders always entering the narrowed end.
Huber and DeWitt (1897), Dogiel (1890) and Retzius (1892) stated
that the sole does not stain in methylene blue preparations,
whether examined at once or fixed in ammonium molybdate and
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studied in sections. The material, from which the present obser-
vations were made, was prepared according to the latter method.
The irregularly shaped matrix in which the axis cylinder termin-
ates is typically granular, but the nuclei, seen by Huber and
others in such preparations countered with carmalum or picro-
carmine, do not stain with methylene blue. In each of the two
matrices or soles described above, the end=-arborizations are
nearly similar. The fact that Huber and the other observers men-
tioned failed to see soles whose granules stained in methylene
blue preparations, may have been due to the inconsistency of
the stain. This possibility, together with the fact that nerve
terminations in the motor plates are very similar in each kind
of sole described, and that the size of the so-called second
kind comes within the possible range of that of the first, leads
the writer to think that perhaps the apparently different kinds
of soles found by him in the striated muscles in the epidermis
of the bat are in reality one and the same type. In the one,
the granules have stained, in the other they have not.
5. Nerve Endings on Modified Sweat Glands.
Se far as the writer has been able to ascertain, the lit-
erature contains no reference to the innervation of sweat glands
in bats. As was noted elsewhere, the modified sweat glands (Fig.
10) have a coating of smooth muscle fibers which are arranged
longitudinally (Fig.10,mu). In a weakly stained methylene blue
preparation from the interfemoral membrane of a bat (Myotis lu-
cifugus), such sweat glands have been observed with numerous
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42
stripes running at right angles to the smooth muscle fibers (Fig.
10,fi). These stripes, which oceur at comparatively regular in-
tervals, extend hoop-like around the secretory portion of the
gland external to the muscle fibers. The structures in question
are much smaller than the muscle fibers, have a wavy course, and
take the deep blue stain characteristic of nerve fibrils. A num-
ber (2 to 5) of delicate non-medullated nerve fibers (Fig.10,no)
ean be traced to the sides of these glands, but whether they con-
nect with these circular stripes, the writer is at present un-
able to ascertain.
That sweat glands are under the control of the sympathetic
nervous system is generally recognized. As is well known, pre-
ganglionic neurites leave the spinal cord through the ventral
roots of the spinal nerves, and, after a shorter or longer course,
terminate in some sympathetic ganglion in a very characteristic
manner. Here the pre-ganglionic neurites branch repeatedly, di-
viding into numerous small varicose nerve fibers, which inter-
lace to form intracapsular plexuses around the cell bodies of the
sympathetic neurones. It is likewise well known that! the sympa-
thetic ganglia of Mammalia such intracapsular pericellular plex-
uses may be very simple, consisting of only a few varicose fi-
brils, as well as very complex. The general structure of these
pericellular plexuses, the absence of definite observations upon
endings of sympathetic neurites (post-ganglionic) on sweat glands,
and the striking hoop-like arrangement of these fibrillar stripes
around the glands, lead the writer to question whether, perhaps,
the post-ganglioniec neurites may not form simple plexuses about
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