ZOOLOGY AND BOTANY, MICKOSCOPY, ETC. 717 



secondary ctambers of the organ of Bojanus are studied. The anthor 

 shows that it is principally the blood from the lower parts of the body 

 which traverses this organ. The vascular system within the organ is 

 formed from modified lacunse. Distributed in the kidney are cells with 

 green concretions, and others granular and ciliated. 



Careful attention is given to the course and structure of the reno- 

 pericardial canal. The glandular character of the pericardial wall is 

 noticed. Uric acid is absent from the kidney, and the author's observa- 

 tions on this head agree with those of Barfurth. He has also proved 

 that neither by kidney nor by pericardium can blood flow to the exterior. 

 The globules of the concretionary gland consist almost entirely of uric 

 acid. The formation and absorption of the concretions is discussed. 

 The gland has no excretory canal, is filled with bacilli, is a reservoir for 

 uric acid, which is afterwards eliminated by the kidney. The bacilli 

 appear to act as true symbions. 



The pedal glands are next described in detail. The supra-pedal 

 exhibits a curious histological diversity in its walls. Sections of the 

 concave wall show a network of pericellular canals, opening on one 

 side into the general cavity, on the other into the excretory canal of the 

 gland. This communication between interior and exterior raises 

 interesting morphological and physiological problems. 



The anatomy and histology of the nervous system was investigated 

 in great detail, but the results hardly admit of summary. The difterent 

 forms of muscular fibre, the nerve terminations, the apparently olfactory 

 epithelium of the tentacle extremity, the otocyst and the eye, and 

 the special olfactory organ of Spengel, &c., are described, and the 

 structure and development of the egg discussed. The follicular cells 

 are not formed from within the ovum. The oviduct and uterus are fully 

 described. 



Finally, the male reproductive organs are dealt with. The sperma- 

 togenesis was not fully elucidated. The spermatocytes result from 

 the repeated nuclear division of spermatogonia. The nucleus of the 

 spermatocyte forms the head of the spermatozoon, after the elimination 

 into the protoplasm of a portion of its substance. 



Effects of Lesion of Supra-oesophageal GangUa in Snails.* — M. L. 

 Petit has made some observations on the rotatory movements produced 

 by the lesion of the supra-oesophageal ganglia in Molluscs. This group 

 has been hitherto neglected by physiologists. The form selected for 

 experiment was Helix aspersa. The animal takes about three weeks or 

 a month to recover from the effects of the operation. A snail which had 

 its left siipra-oesophageal ganglion removed on the 26th of June began 

 to crawl about on the 29th of July. The right tentacle was normal, 

 and 18 mm. long, while the left was partly retracted and only 6 mm. 

 The animal described spirals, turning from right to left, or from 

 the uninjured towards the injured side. The removal of the right 

 ganglion produced corresponding results. A snail which had its left 

 cerebro-pedal-visceral connectives cut crawled about in curves, which 

 were broken in upon by short circles, in which it turned towards the 

 left. Five months after the operation it crawled about almost normally. 

 When the commissure connecting the supra-oesophageal ganglia was 

 cut the tentacles preserved their normal length ; in one case the snail 



* Ck>mptes Eendus, cvi. (1888) pp. 1809-11. 



