NATURE 



[A/ay 19, 1 88 1 



" Cameos from the Silver-Land," by Mr. E. W. While, 

 F.Z.S., will shortly be issued in two volumes by Mr. Van Voorst. 

 It relates to the author's experience in the Argentine Republic, 

 and will be specially full on the natural history of the country. 



We regret to learn the death of Admiral La Ronciere le 

 Noury, president of the Geographical Society of Paris, who died 

 on Saturday after a protracted illness. He was born in 1813. 

 In 1S56 he went to the Arctic Ocean in the Heine Hortense on a 

 scientific exploration professedly conducted by Prince Napoleon, 

 who was on board. On the death of M. Chasseloup Laubat the 

 Admiral was elected president of the Paris Society of (Geography, 

 in which office he continued w ithout opposition up to the last 

 election. The Admiral took great interest in scientific geo- 

 graphy, as well as in zoology and botany. 



Dr. Gerhard Rohlfs, who has been travelling in Abyssinia, 

 has returned to Berlin. 



THE HYPOPHYSAL GLAND IN ASCIDIANS 

 CINCE the publication of Kowalew sky's remarkable discovery 

 of the course of development in Ascidians, and its confir- 

 mation, in all the leading features, by Kupffer and others, any 

 morphological work on the Tunicata is naturally regarded with 

 great interest on account of the possibility of its throwing light 

 on the difficult problem of the relationship of that group to the 

 Vertebrata. 



Embryological investigations have clearly demonstrated that 

 the fully-formed larval Ascidian (in most genera, at least) pos- 

 sesses an axis occupying the centre of the tail, and comparable 

 with the vertebrate notochord ; that the dorsal region of the body 

 contains a neural canal — of epiblastic origin, and formed by the 

 rising up, arching over, and coalescence of "laminje dorsales" — 

 expanding anteriorly as a vesicle, in the walls of which certain 

 sense-organs are developed, and being continued posteriorly as a 

 fine canal running along the tail on the dorsal surface of the noto- 

 chord. The ventral region of the body is occupied by the alimen- 

 tary canal, lying below the nerve vesicle, and, in its most posterior 

 prolongation, below the anterior extremity of the notochord, 

 which in this locality separates the neural and visceral canals. 

 These developmental researches have also shown that in the 

 adult Ascidian the branchial aperture must be regarded as homo- 

 logous with the vertebrate mouth, and the branchial sac with the 

 pharynx. 



An excellent paper by M. Charles Julin ^ in the last 

 number of the Archives de Biologie (tome ii. fascicule i , 

 188 1 ), of which a preliminary account appeared lately in the 

 Bulletin of the Academic Royale de Belgique (3™ ser., t. i, 

 No. 2, Fevr. 18S1), adds to this interesting list of homologous 

 organs by showing strong grounds for the belief that the little- 

 understood "neural gland" in the Ascidians represents the 

 glandular portion of the hypophysis cerebri, or pituitary body of 

 Vertebrates. 



M. Julin gives a minute account of the structure and relations 

 of the peripharyngeal bands, the dorsal lamina, the nerve 

 ganglion, and that enigmatical organ generally known as the 

 olfactory tubercle ; the most important section of his paper, 

 however, is that dealing w ith the neural gland. This structure 

 was first discovered by Hancock, and more recently its glandular 

 nature was demonstrated by Ussow, who called it the olfactory 

 gland, and stated that it was connected with the olfactory 

 tubercle by a narrow canal, an observation since confirmed by 

 Nassonoff. Julin contends that the so-called olfactory tubercle 

 is not a seme organ at all, but merely the curiously complicated 

 opening into the pharynx of the duct of his " hypophysis." He 

 states that he has been unable to find any nervous connection 

 whatever between the tubercle and the ganglion, and that the 

 nerve which has frequently been observed and described as sup- 

 plying the supposed sense-organ really passes behind it without 

 communicating, and that therefore he cannot confirm the inner- 

 vation described and figured by Ussow. The histological striic- 

 ture of the tubercle is also opposed to the probability of its 

 sensory function, as no modified cells are present, the whole 

 surface being covered by normal ciliated columnar epithelium. 



The reasons which M. Julin advances in support of the homo- 

 logy of the neural gland with the pituitary body are its structure, 

 its position on the ventral surface of the ganglion, and its rela. 



" " Recherches sur I'Organisation des Ascidies simples— aur I'hypciphyse 

 et quelques organes qui s'y raltachent dans les genres Corclla, Phallusia, 

 et Axidia. Par Charles Julin, Assistant du Cours d'Embryologie a I'Uni- 

 versiK de LiJge. 



tion with the pharynx. The glandular nature of this body was 

 first shown by Ussow, and its minute structure has been investi- 

 gated by Julin. It consists of branching glandular tubules 

 surrounded by connective tissue richly supplied with blood- 

 sinuses, while the excretory duct in its posterior part has a coin- 

 plete dorsal wall only, as ventrally it communicates freely with 

 the ends of the tubules, just as is the case with the duct during 

 the development of the pituitary body. 



J[ulin points out that in the Ascidians the duct, in running an- 

 teriorly towards the olfactory tubercle, is in direct relation with the 

 ventral surface of the nerve ganglion, no layer of connective tissue 

 intervening ; and this he states is also the case in Vertebrates. 



The position of the neural gland, or "hypophysary gland," 

 as Julin proposes it should be called, is constant. Wherever the 

 nerve-ganglion may be, — and it varies considerably in its position 

 in different species, — the gland is always situated on its ventral 

 surface. 



The excretory duct arising from the dorsal surface of the 

 gland, runs anteriorly, directly below the nerve-ganglion, to the 

 olfactory or hypophysary tubercle, w here it communicates with 

 the pharynx, probably within the region formed by the epiblast 

 involved in the oral invagination. 



It is evident that Julin's observations throw the gravest 

 doubts on the always somewhat questionable olfactoi-y nature of 

 the dorsal tubercle. A ciliated pit having no apparent nervous 

 relations, and connected by a duct with a body having a well- 

 marked glandular structure, has no claim to be regarded as a 

 sense organ. Its function, and that of the gland, remain a 

 mystery ; Julin states that he is unable to throw any light upon 

 this questitn. From the large size of the gland and the constant 

 presence and usually extraordinary complication of the tubercle 

 one would imagine that they performed an important function 

 in the economy of the Ascidian ; but what that function is, and 

 why the duct of a gland should have so elaborate an opening 

 into the pharj nx, are at present totally unknown. 



Julin gives us no information as to the development of these 

 organs. In 1871 Kowalewsky ' described, in the course of the de- 

 velopment of Ascidia mainmillala, the formation of an aperture 

 connecting the anterior end of the nerve vesicle wi'h the region 

 of the epiblast which was being invaginated to form the oral 

 funnel, and he declared that this aperture of communication 

 between the neunal and visceral canals persisted in the adult as 

 the ciliated tubercle. Kupffer," in the following year, while 

 referring to Kowalewsky's statement, declared that he had been 

 unable to discover any such aperture in the larva of Ascidia 

 mentiila. If Kowalewsky's observation is confirmed, and if the 

 canal is found to remain as the duct of the neural gland, 'the 

 course of its development would seem to differ considerably from 

 that of the hypophysis cerebri as described by Mihalkovics, 

 Balfour, and Kolliker, which are the views approved of by Julin 

 and confirmed from his own observations. 



In conclusion, the arguments in favour of the homology of the 

 Ascidian's neural gland with the glandular portion of the pituitary 

 body are very strong. The structure, position, and relations of 

 the two organs are, in a certain stage of development, identical — 

 admitting, of course, that the branchial sac is a modified pharynx, 

 and that the nerve-ganglion is homologous with the vertebrate 

 brain — and the only point required for the proof of the hypo- 

 thesis is the demonstration that the neural gland and its duct are 

 epiblastic in formation, and that their development corresponds 

 with that of the pituitary body. W. A. IIerd.man 



STORING OF ELECTRICITY 

 CECONDARY batteries to store up currents of electricity in the 

 '■-' form of chemical work promise to play so important a part 

 in the ultimate adoption of the electric light, that improvements in 

 their con traction are of peculiar interest. The latest innovation 

 is due to M. Faure, who has modified with great success the 

 secondary battery of Gaston Plante by covering the surfaces of 

 the lead plates with a coating of minium, thereby increasing 

 their capacity manifold. This device possesses the additional 

 advantage that it obviates the necessity of "foi-ming" the cells 

 by the tedious process of charging and discharging them for 

 many days, as in Plante's batteries. Two sheets of lead are 

 separately coated with minium and are rolled together in a spiral, 

 being kept apart by a layer "of felt, and are then placed in a 



^ ' ' Weitere Studien iiber die Entwicklimg der einf achen Ascidien " {A nh . 

 /. microsc.Aiiat., vol vii.). 



■^ ''Zur Ent\\ ickelung der einfachen Ascidien** {Arch. /. micriisc. A-Kat., 

 vol. viii. 1872). 



