54« 



NA TURK 



[Ai'Rii, lo, 1902 



Animoctvte of GfOlria anstraiis^ the New Zealand lamprey, and 

 subsequently lie found similar orcans in sections of an Am- 

 mocfote of Petromyzon in the zooloi^ical laboratory of Owens 

 College. The grooves in question run along the roof of the 

 brain-cavity from about the hinder margin of the posterior 

 commissure lo the ncesstts sitbpinealis. They are lined by a 

 sharply defined epithelium of very long columnar cells, and their 

 concave surfaces are covered with short cilia. The function of 

 the.se organs is apparently to promote the circulation of the lluid 

 in the brain-cavily, and this view is supported by the arrange- 

 ment of the choroid plexuses. In the New Zealand Ammoco-'le 

 the choroid plexus of the mid-brain dips down into the ilir in 

 the shape of a highly vascular longitudinal septum dividing the 

 upper part of the brain-cavity in this region into right and left 

 halves, and it is significant that the ciliated grooves are so 

 arranged as probal>ly to direct a stream of brain-fluid along each 

 side of the septum. It has been already suggested that the 

 choroid plexuses of the vertebrate brain are concerned with the 

 gaseous interchanges which take place in the cavities of the 

 ventricles. In the young Ammoctete the first choroid plexus, 

 which may be supposed to be especially concerned in the 

 respiration of the fore-brain, is not yet developed ; the second 

 and third choroid plexuses, belonging respectively to the mid- 

 and hind-brain, ate, on the other hand, already extensive. We 

 need not, therefore, he surprised to find that the fore-brain at 

 this stage is dependent to a large extent for its means of respira- 

 tion, and perhaps also for its nutrition, upon the choroid plexus 

 of the mid-brain, and that a special apparatus in the form of 

 ciliated grooves is developed for securing a forward flow of the 

 necessary fluid in the brain-cavity. 



March 20. — " On the Development of the Layers of the 

 Retina in the Chick after the Formation of the Optic Cup." 

 By John Cameron, MB., Ch. B. (Edin.) Communicated by 

 Prof. Macintosh, F.R.S. 



The inner wall of the retinal cup in a fourth-day chick has 

 e.xactly the same structure as the wall of the embryonic cerebral 

 vesicle or spinal cord at the same dale. All the slruclures which 

 His has described in the wall of the embryonic spinal cord 

 can be also recognised here, and may, therefore, receive 

 similar names — thus, there is a network (the myelospongium) 

 which is formed by spongioblasts, and between the fibres of 

 the myelospongium are found germinal cells which divide 

 to form neuroblasts. From the latter ate formed the cells 

 of the outer and inner nuclear layers and the ganglion 

 cells of the retina. On the eighth day the internal molecular 

 layer appears, and on the ninth day the external molecular 

 layer. The first appearance of these layers is due to a re- 

 arrangement of the myelospongium, and they map out the three 

 cellular layers. Three kinds t>f cells are found in the internal 

 nuclear layer at the twelfth day — amacrine, bipolar and basal 

 cells. The cells of the external nuclear layer become rod and 

 cone cells, and from them rods and cones begin to develop on 

 the twelfth day of incubation. The hexagonal pigment cells 

 develop from the outer wall of the retinal cup, ami their 

 processes also appear on the twelfth day. 



Linnean Society, March 6. — Mr. Herbert Druce in the 

 chair, succeeded by Mr. i\. D. Michael. — Mr. J. E. Harting 

 exhibited and made remarks upon some unpublished coloured 

 drawings by Messrs. J. G. Miliars and \. Thorburn of British 

 freshwater Anatida; illustraiing intermediate phases of plumage, 

 through and irrespective of moulling, not hitherto figured. — A 

 paper by Prof. A. Gruvel, of Bordeaux, was read, dealing with 

 some cirrhipedes preserved in the British Museum of Natural 

 History. The chief feature of the paper was the introduction 

 of several new families into the group Lepadidr as accepted by 

 Darwin, and modified by Ccrslacker by the separation from it 

 of the AlcippidK for a single species. — The zoological secretary 

 gave an abstract of a memoir by Prof. Elliott Smith, of Cairo, 

 "On the morphology of the brain in the mammalia, with 

 especial reference to that of the lemurs, recent and extinct.'' 

 The author has examined either the brain or cast of the brain- 

 cavity of every lemuroid genus living and extinct, and his work 

 is the result ol an investigation of the collections of the Koyal 

 College of Surgeons Museum, the British Museum, the Zoo- 

 logical Society, aided by gifts of material by Captain Stanley 

 Flower, Mr. Hose, and other persons named. A crilic;d ;.////;.' 

 of the literature of the subject is followed by a detaile<l con- 

 .sideration of the sulci, the calcarineand sylvian fissures receiving 

 special attention. The author shows that the simplest lemuroid 



NO, 1693, VOL. 65] 



type of brain is that of the Galagina-, the most specialised that 

 of the Indrisina; and Lorisin;c. He shows that in Cheiromys 

 the individual variation of the sulci is so great that the supra- 

 sylvian and lateral fissures alone remain unchanged, and he 

 finds proof in this genus of ontogenetic retrogression, which 

 substantiates the conclusions of Forsyth-Major originally deduced 

 from the study of the living Galagin^e, the Tertiary genus 

 Microchfcrus, and more recently from that of the Madagascar 

 genera Globilemur and Megaladapis. For Tarsius he shows, 

 while the brain, in respect to its occipital overlap and the 

 presence of a po.steiior cornu, as also to the assumption of the 

 microsmatic condition, is the most pithecoid of that of all 

 lemurs : conversely, in the characters of its corpus callosum, 

 hippocampus and cerebellum, it is shown to conform to the 

 lowest Eutherian type. Regarding Tarsius as a lemur, the 

 author concludes that the lemuroid brain is intelligible only on 

 the supposition that it has advanced along the main primate 

 stem and later undergone retrogression. A caudo-occipital 

 curtailment of the hemisphere is regarded as the dominant change 

 which the lemuroid brain has undergone, with accompanying 

 structural simplification ; and evidence is adduced to prove that 

 while the lemuroids were ancestrally macrosmatic, the macro- 

 smatic condition at present found lo exist in them has been 

 .secondarily acquire<l trom a pithecoid microsmatic state, of the 

 order of that retained in (he tarsier. Beyond this, the memoir 

 deals exhaustively with the comparative morphology of the 

 pallium of the chief mammalian orders, with especial reference 

 to confusion of ideas concerning fissures to which the term 

 " sylvian '' has been applied. 



March 20. — Prof. S. H. Vines, F.R.S., president, in the 

 chair. — Prof. J. C. Bose read a paper on electric response in 

 ordinary plants under mechanical stimulus. He first ex- 

 plained his apparatus and methods, and then performed, 

 with the aid of his assistant, a series of experiments .showing 

 electric response for certain portions of the plant organism, 

 which proved that as concerning fatigue, behaviour at high and 

 Ijw temperatures, the effects produced by poisons and an;Esthetics, 

 the responses are identical with those hitherto held to be 

 characteristic of muscle and nerve and of the sensitive plants. 

 He drew the final conclusion that the underlying phenomena of 

 life are the same in both animals and plants, and that the elec- 

 trical responses which he had demonstrated are but the common 

 physiological expression of these. — Dr. O. Stapfread',a paper 

 on the fruit of Melocanna bambusoides, Trin., an endospermless 

 viviparous genus of Graminere. Fruits of this very singular grass 

 collected last year were forwarded through Mr. Wild, Conser- 

 vator of Forests, Bengal. They are of the shape and size of 

 small apples or inverted pears, usually terminating with a short 

 or long beak, the longest measuring as much as 5 inches in 

 length. They consist of a hard, thick, fleshy pericarp, which 

 contains a great deal of starch stored in a parenchymatic tissue, 

 of a testa developed as nutrient layer and present in the mature 

 fruit in an " obliterated " condition, and an embryo possessing 

 an enormous ellipsoid scutellum which fills up the large central 

 cavity of the pericarp, or is partly empty. The epidermis of the 

 scutellum is developed as haustorial epithelium of the kind 

 characteristic of grass seeds, so far as it is in contact with the 

 pericarp or, rather, the nutrient layer. It is traversed by 

 numerous vascular strands which start from a plate of tangled 

 strands in the axis of the embryo, and send out innumerable 

 branchlets near the surface of the scutellum. The fundamental 

 tissue in which the strands are embedded is delicately walled 

 parenchyma, lull of starch. There is no endosperin. CJermina- 

 tion starts while the fruits are still on the tree, and the young 

 shoots may attain a length of as much as 6 inches, whilst a bundle 

 of roots is formed simultaneously. During germination, the 

 scutellum acts on the pericarp as it acts in typical gra.sses on the 

 endosperm, depleting not only the store of starch and other 

 nutrient matter deposited in the cells of the parenchyma, but 

 finally inducing also the partial solution of the cell-walls. This 

 structure of the fruit of Melocanna is almost unique in gra.sses, 

 and was not known before. It is probably repeated, although 

 with some modifications, in the genera Melocalamus and 

 Ochlandra, which the author intends to make the subject 01 

 another paper. — Messrs. A. (). Walker and Andrew Scott read 

 a paper on Crustacea Malacostraca from the island of Abd-el- 

 Kuri, in the Red Sea, collected by Messrs. H. O. Forbes and 

 W. Ogilvie Grant during their expedition to Socotra in 1899. 

 The .specimens described wire picked out of the residue from a 

 collection of Alga; procuied in April of that year, in rock pools 



