Sept. 9, 1875] 



NATURE 



417 



that bifidity which, to my thinking, is only one of several 

 instances of longitudinal fission in the fore part of the head, the 

 trabeculse presenting another instance of the same thing, and 

 the cleft between the maxillary lobe and the part of the head 

 above it a third ; while in the muscular system such longitudinal 

 cleavage or fission is common even in the trunk. In a chick of 

 the third or fourth day, when rendered very transparent, the 

 optic nerves can be seen extending from beneath the front of the 

 2 



Fig. I.— Embryo chick of 36 hours, a, primary optic vesicle ; b, optic com- 

 missure ; c, third cerebral vesicle ; d, ear ; e, heart 



Fig. 2. — Chick three days old. a, nostril ; b, hemisphere ; c, d, divisions of 

 first cerebral vesicle ; e, eye ; /, optic nerve ; g, optic lobe ; h, crenations 

 of third cerebral vesicle ; ;, ear ; k, first primordial vertebra. 



optic lobes ; while in front of the optic lobes there are placed 

 in series from behind forwards a posterior division of the first 

 vesicle, an anterior division, the cerebral hemispheres, and the 

 olfactory lobes. Thus there is a large supply of material pre- 

 sented in the brain for the study of segmentation ; the difficulty 

 to be overcome by future inquiry and careful collation of all 

 available facts is to determine the value of the parts placed one 

 in front of another. 



Perhaps I have occupied time too long with matters involving 

 a large amount of technical detail ; but I trust that I may have, 

 in some measure, illustrated that both in aim and in accomplished 

 work anatomy is no mere collection of disconnected facts, no 

 mere handmaid of the physician and surgeon, nor even of phy- 



FiG. 3.— Chick of fourth day. Letters the same as previous figure, 



siology. I do not doubt that it is yet destined, as dealing with 

 the most complex sequences of phenomena, to take the highest 

 place among the sciences as a gtiide to philosophy. One can- 

 not help noticing the increased importance now given to Natural 

 History studies as a part of education ; and it is worth while to 

 note that it is most of all in anatomy and physiology that the 

 close connections of matter with mind are brought under review, 

 —physiology exhibiting the relations of our own mental being 



to our bodies, and anatomy revealing a body of organised 

 nature, whose organisation points to a source ^of beauty and 

 order beyond. / 



The people of Bristol do well to rally round their Medical 

 School, They do well to furnish it with buildings suitable for 

 the prosecution of all the Natural History studies which adhere 

 to medical education ; and they do well to join with that school 

 a complete college of literature and science. Let us hope that 

 they will make it worthy of so wealthy and historic a city. But 

 if they will have their medical school the success which In so 

 flourishing a locality public enthusiasm may well make it, and 

 if they will have it aid as well as be aided by a school of general 

 education, let them follow the system latterly adopted in Oxford 

 and Cambridge, long carried out in the Universities of Scotland, 

 and recognised, though not in all instances sufficiently provided 

 for, in Ireland. Let anatomy, human and comparative, receive 

 its place as an important and fundamental science. Let thorough 

 and adequate provision be made for its being' taught as a science ; 

 and see that it do not, as in too many medical schopls which 

 shall be nameless, degenerate to the etymological and original 

 meaning of the word, a mere cutting up of carcases. 



Mr, H, B, Brady exhibited a series of micro-photographs 

 chiefly from physiological and pathological preparations, taken 

 by a new and simple process, devised by Mr. Hugh Bowman, of 

 Newcastle. The apparatus was also shown and described. It 

 consisted of a simple mirror of speculum metal, placed at an 

 angle of 45 degrees in front of the eye-piece of the microscope, 

 and directed downwards. The image was received upon a 

 collodion plate set in the frame of a common photographic 

 camera, and the photograph taken in the usual way. About 1 1 

 seconds was stated to be a sufficient exposure for the purpose. 



A paper was read by Dr. Martyn entitled Some New Researches 

 on the Anatomy oj the Skin. Dr. Martyn had discovered that the 

 cells which appeared " spinous " or "echinate," when isolated 

 from their connection, if they could be at any time seen in single 

 layers, were simply united together by delicate bands. These 

 are so constantly seen broken across that they assume the form 

 of tubercles or "prickles." As repeated observations confirmed 

 this, the name " conjoined epithelium" had been proposed for 

 this form or stage in the cell life. 



A paper On the Physiological Action of the Chinoline and 

 Pyridine Bases, by Dr. J. G. M'Kendrick and Prof. Dewar, 

 was read by the former gentleman. The following are the general 

 conclusions arrived at :— i. There is a marked gradation in 

 extent of physiological action of the members of the pyridine 

 series of bases, but it remains of the same kind. The lethal 

 dose becomes reduced as we rise from the lower to the higher. 

 2. The higher members of the pyridine series resemble in 

 physiological action the lower members of the chinoline series, 

 except (i) that the former are more Hable to cause death by 

 asphyxia, and (2) that the lethal dose of the pyridines is less 

 than one half that of the chinolines. 3, In proceeding from 

 the lower to the higher members of the chinoline series, the 

 physiological action changes in character, inasmuch as the lower 

 members appear to act chiefly on the sensory centres of the 

 encephalon and the reflex centres of the cord, destroying the 

 power of voluntary or reflex movement ; while the higher act 

 less on these centres, and chiefly on the motor centres, first, as 

 irritants, causing violent convulsions, and at length producing 

 complete paralysis. At the same time, while the reflex activity 

 of the centres in the spinal cord appear to be inactive, they may 

 be readily roused to action by strychnine. 4. On comparing the 

 action of such compounds as C9H7N (chinoline) with C9H13N 

 (parvoline, &c.), or CgHuN (collidine) with CgHijN (conia, 

 from hemlock), or CjoHipNa (dipyridine) with C10H14N2 

 (nicotine, from tobacco), it is to be observed that the physio- 

 logical activity of the substance is, apart from chemical structure, 

 greatest in those bases containing the larger amount of hydrogen. 

 5. Those artificial bases which approximate the percentage com- 

 position of natural bases are much weaker physiologically, so 

 far as can be estimated by amount of dose, than the natural 

 bases ; but the kind of action is the same in both cases. 6. 

 When the bases of the pyridine series are doubled by condensa- 

 tion, producing dipyridine, parapicoline, &c., they not only 

 become more active physiologically, but the action differs in kind 

 from that of the simple bases, and resembles the action of 

 natural bases or alkaloids having a similar chemical constitution. 

 7. All the substances examined in this research are remarkable 

 for not possessing any specific paralytic action on the heart likely 

 to cause syncope j but they destroy lif»-dther by exhaustive con- 



