Sept. 2 2, 1881] 



NATURE 



499 



masses in vertebrates. The neural chords and ganglions con- 

 tinued therefrom baclavards in inverte')rate<, answered to, or 

 were homologous \\'ith, the myelon or spinal chord of verte- 

 brates, in which the ganglionic structure was more or less con- 

 cealed, save in some fishes, by superadded neural substances. 



Now the supra-oe-iophageal mass, or "fore-brain," in inverte- 

 brates is divided from the su'iresophageal masses, or "hind- 

 brain,'' by the production of a tubular portion of the fore part 

 of the primarily closed alimentary cavity, which, extending 

 between those parts of the neural axis, opens upon the surface of 

 the head so attained, and there establishei the permanent mouth ; 

 the tu'juUr extension therefrom similarly retains its functional 

 or a3-ophageal relations with the alimentary cavity. The neural 

 chords, connecting the so-separated "fore-brain" with the "hind- 

 brain," traversed the sides of this gullet; as the chords or 

 "crura," proceeding to expand into the ".fore-brain" of verte- 

 brate-^, traverse the sides or walls of that persistent part of the 

 conario-hypophyseal tract known in anlhropotomy as the third 

 ventricle. The large relative size of the embryonal brain-ve>icle 

 in this connection is significative of the homology of the parts 

 extending therefrom. 



Pa^'-ing next to the consideration of the characters which had 

 been held to determine the " back " and " belly " of the animal, 

 the .author cited: — "Colour," the "relative position of the 

 body of air-breathers to the ground they stood or moved upon,"^ 

 and the criterion, which Cuvier adopted to determine these as]:)ects 

 in the notable conti-oversy with Geoffroy St. Hilaire in 1830." 

 That criterion was the cerebru.n in vertebrates, and its homo- 

 logue, the super-resophageal ganglion, in invertebrates. In an 

 enlarged copy of the diagram by which Cuvier illustrated his 

 position, the author pointed out the grounds on which the great 

 French comparative anatomist exclusively applied the term brain 

 (cer'jcatt) to this part of the cerebral centres ; moreover, Cuvier 

 expressly rejects the homology of the spinal cord of vertebrates 

 with the ganglionic chord of the body in invertebates ; and he 

 concluded that, however his opponent might turn about his 

 articulate or molluscous subject, the so-called brain would be on 

 opposite sides of the alimentary canal in the two groups 

 compared. 



Now, to reconcile this difference, the author pointed out that 

 it only needs to add to Cuvier's diagram of the brain of the 

 maminal the conario-hypophy»ial tract omitted in that diagram ; 

 and, if the facts and deductions in his paper were allowed to be 

 valid, the actual difference would lie in the atrophy of the em- 

 bryonal homologue of the invertebrate gullet and mouth in 

 vertebrates, and the establishment in them of a new entry into 

 the alimentary cavity. 



In the vertebrate embryo this anterior entry makes its first 

 appearance as a capacious branchial or water-breathing organ, 

 and traces of this destination are determinable in the higher 

 vertebrates, in which the respiratory function is ultimately other 

 wise located and performed in relation to an aerial medium. 



The entry to the alimentary cavity in Amphioxus is both a 

 breathing and a feeding mouth : it is a vertical or longitudinal 

 slit bounded by a pair of styles, in which is made the nearest 

 approach to gristle of any part of the sclerous sy--.tem in that 

 primitive vertebrate. This "mouth" seems to be, or to be 

 formed by, a confluent pair of the branchial openings, such 

 as those which follow after it. To what pair of the costal, 

 hce.nal, or vertical side-walls or supports of the higher piscine 

 vertebrate oral cavity, scapular, hyoid, tympano-mandibular, or 

 palato-maxillary ribs, the parial styles of Amphi 5xus may be 

 homologous, it is hard to say in tlie absence of skull or brain in 

 that animal. In fi,,hes the double function of the mouth is 

 retained — all are "branchiostomous." In air-breathers the ver- 

 tical entry becomes exclusively respiratory, and is more or less 

 divided from tlie alimentary mouth beneath, and the opening or 

 inlet to this bee >mes transverse by the production of the tym- 

 pano-mandibular arch and its apposition tj the palato-maxillary 

 one above. In ancient forms of vertebrate air-breathers the 

 entry to the nariil passage, or respiratory mouth, as it may be 

 termed, is by a pair of openings h omologous with a piscine pair 

 of branchial ones, but admitting air instead of water. To these 

 "antorbital nostrils," as they are termel, in Pie io- and Ich- 

 thyosaurs, a more anterior single or confluent pair of inlets 

 is added in Teleosaurs. In recent crocodiles the latter becomes 



' The anatomists who adopt th'.s criterion call the haemal aspect of the 

 lobsterits " back," the neural one its '" belly " ; the right side of the ani:nal 

 is its k ft side, and -.■!c.- 7vrs,} 



z Reference was here made to the nineteenth vol. of the Antta/es c/es 

 ScicKu-s A'atunlks for 1830 (March), p. 241, PI. XII. 



exclusively the single, undivided, or partially divided breathing- 

 mouth. In lizards and birds it is commonly divided, or there 

 is a pair of "nostrils." In mammals the nostrils are commonly 

 appro-ximate. But the "feeding-mouth" remains below them as 

 a distinct transverse cleft. In all these modifications the aperture, 

 whether for breathing or feeding, or for both, is on the haemal 

 aspect of the brain ; the vertebrates are haeoiastomes ; the in- 

 vertebrates are neurostomes, and the chief part of their brain is 

 "ha;mad" of their mouth. 



Returning to the criterion of the dorsal and ventral aspects of 

 the ani nal body, the author maintained that the ganglionic 

 body-chord in invertebrates did answer to the myelon of verte- 

 brates ; and adding this to the totality of the brain, the so-called 

 " neural axis" was determined. So determined, he held that its 

 position was the true criterion of the dorsal or neural aspect of 

 the body, whither tlie animal moved with it next to, or farthest 

 from, the ground, or neither the one nor the other, as in the 

 human pedestrian. 



The part or aspect of the body opposite the neural one was 

 characteri^ed by the location of the centre, or chief centre-', of 

 the vascular system, and this had led Prof. Owen, at the 

 com nencement of his anatomical teaching, to term it the 

 " haemal aspect." 



Referring, finally, t> the diagram of the invertebrate and 

 vertebrate animals in corresponding positions, agreeably with 

 the above criterion, the author h owed that the so-called "brain" 

 (Cuvier), or the supra-ce^ophageal brain-mass of comparative 

 anatomy, was not ab)ve, but below, the mouth or gullet in 

 invertebrates, and that the sub-oesoph.igeaI mass was above the 

 mouth or gullet ; also that the reverse relative positions were due 

 to the atrophy of the primitive homologues of such entry in 

 vertebrates, and the substitution of another opening or conduit 

 to the stomach, whereby these anterior openings and condtiits 

 are on the lower or ha:mal side of the cerebrum in vertebrates, 

 on the upper or neural side of the cerebrum or fore-brain in 

 invertebrates. In briefer terms, the one division was "hoema- 

 stomous " ; the other division wa.s " neurostomous." The paper 

 was illustrated by drawings, of which enlarged diagrams were 

 exhibited to the Section. 



Dr. Montagu Lubbock's paper On >.ht Development of the 

 Colour Sense discussed the question of the evidence as to 

 the acquirement of the power of perceiving colour by man 

 within historical times, and also the question whether this per- 

 ception had been gradually acciuired by man or any animal at 

 any tiaie. He concluded that there were good grounds against 

 believing that any such gradual development in the case of man 

 could be proved ; and while it was probable that in those 

 animals which lived upon coloured food the power of appreciating 

 colour would gradually arise, yet there was no proof of this yet 

 available, and no idea c juld be given of the stages by which this 

 had been brought about. 



Prof. S. P. Thompson read a paper upon the Function of the 

 tiaa Ears in the Perception of Space, in which he stated his view 

 as follows : — Judgments as to the direction of sounds are based 

 in general upon the sensations of different intensity in the two 

 ears ; but the perceived difference of intensity upon which a 

 judgment i^ based is not usually the difference in intensity of the 

 lowest or fundamental tone of the c impound sound, or "clang," 

 but the difierence in intensity of the individual tone or tones of 

 the clang for whicli the intensity-difference has the greatest 

 effective result on the quality of the sound. Prof. Thompson 

 further remarked that now that the physical bases of the problem 

 were laid down, the acoustic perception of space might be greatly 

 elucidated by experiments upon persons possessed of abnormal 

 hearing, and upon the blind, in whom this perception is 

 abnormally developed. 



Prof. J. C. Ewart of Aberdeen gave an account of the 

 researches On the Influence of Bacilli on the Production of 

 Disease, which he has communicated to the Royal Society. 



Mr. W. A. Forbes read a paper On the Incubation of the 

 Indian Python (Python molurus), with special regard to the 

 alleged Increase of Temperature during that Period. This 

 paper g>ve an account of a large series of observations made 

 during the last season in the gardens of the Zoological Society. 

 The python laid about twenty eggs, and incubated for about 

 six weeks. Observa ions were made upon both male and female, 

 kept in adjoining cages under conditions approximately identical, 

 and it was found that there is an increase of temperature in the 

 incubating female analogous to that which occurs in birds ; the 

 amount of increase observed was not so great as others had 



