550 SUMMARY OF CURRENT RESEARCHES RELATING TO 



(2) There is some evidence, both from comparative anatomy and 

 embryology, for believing that the oesophagus has undergone an actual 

 twist ; 



(3) Monstrosities which retain the pallial complex in a ventral 

 position shoAf a tendency to form an exogastric coil. 



The innervation of the mantle is shown to be equally difficult to 

 interpret on either hypothesis. Against the first view is also urged the 

 insufficiency of the evidence upon which Biitschli bases his conclusions 

 with regard to zones of unequal growth. 



With regard to the phylogenetic cause of the vertical twist, em- 

 bryology can only give negative evidence ; while in considering the 

 ontogenetic cause we are thrown back upon unsolved problems of 

 heredity, and must confess our ignorance. 



Relations of Kidney in Haliotis.* — H. J. Fleure finds that Baliotis 

 luberculata has two separate kidueys right and left of the pericardium, 

 opening externally by separate apertures ; that the gonaduct opens into 

 the right kidney, which is the functional excretory organ, while the left 

 kidney is partly degenerating into lymphatic tissue, and is becoming 

 connected with the efferent branchial vein by direct blood-channels ; 

 and that the right or functional kidney communicates with the peri- 

 cardium, while the left one does not. The author discusses generally 

 the difficult question oi the kidney homologies in Vertebrates, and sup- 

 ports the view that the kidney which is reduced is that of the pre- 

 torsional right (post-torsional left) side. 



Purple of Purpura lapillus.j — A. Letellhr refers to the conclusion 

 of Dubois in regard to the purple of Murex brandaris, — that the chromo- 

 genic substances produced the purple colour only under the combined 

 influence of light and a ferment. Letellier has made careful experi- 

 ments, but finds no evidence of a ferment in the case of the dug- whelk. 

 The chromogenic substance becomes purple under the actjBn of light 

 only. A similar transformation is kuown in other cases, whereas we 

 have no knowledge of a ferment which acts in presence of absolute 

 alcohol, and is not sterilised in the heating chamber at 120°. The 

 author concludes that if Dubois is right in regard to Murex, his results 

 do not apply to Purpura. 



Structure of Limnsea emarginata. + — F. C. Baker has made a 

 careful study of this species (var. mighehi), comparing his results with 

 those reached in regard to the few others that have been studied 

 anatomically. The extraordinary variability of the shell is well illus- 

 trated ; the animals themselves are wonderfully uuiform. 



Bivalves with Red Blood-Corpuscles.§ — L. Cueuot notes that in a 

 number of Lamellibranchs there are numerous corpuscles with haemo- 

 globin. This has been recorded for Area tetragona, A. (Argina) pexata, 

 A. trapezia, and two undetermined species of Area, for Pectunculus 

 gli/cimeris, Tellina (Gastrana) fragilis, Tellina planata (doubtfully), and 

 for Solen (Pltarus) legumen. Cuenot tested Pectunculus gli/cimeris from 



* Quart. Journ. Micr. Sci., xlvi. (1902) pp. 77-90 (1 pi.). 



t Arch. Zoo!. Exper., x. (1902) Notes et Revue, pp. xxxiii.-xxxvi. 



X Bull. Chicago Ac. Sci , ii. (1900, received 1902) pp. 191-211 (6 pis.). 



§ Z'.ol. Anzei-., xxv. (1902) pp. 543-4. 



