750 SUMMARY OF CUEBENT RESEARCHES RELATING TO 



region. On the smaller of these, four regions — head, neck, body, and foot, 

 can be distinguished. These are alternately dark and clear. Long 

 cylindrical bodies (somfetimes with a lateral protrusion), of a pale colour, 

 delicate contour, and with an internal clear spot also occur. They recall 

 the albumen cylinders found in the urine of nephritis patients. The 

 yellowish-brown substance also occasionally secretes irregular purple 

 bodies with an internal clear spot. 



General structure. — From his investigations Herr Eawitz has come to 

 the conclusion that the green gland consists not of one much-coiled tube, 

 but of two, which are only united just before the entrance to the sac. Of 

 these the longer forms the green and white substance, while the second 

 forms the yellow-brown substance and a small portion of the white. There 

 is never any direct communication between the green and the yellowish- 

 brown portion. As to function, the author thinks that as yet, in the absence 

 of more complete physiological investigation, it is premature to say that 

 the green gland of the crayfish functions as a kidney. 



Castration of Decapodous Crustacea by parasites.*— Prof. A. Giard 

 describes the effects produced by the parasitic PJiyxus paguri on the external 

 sexual characters of Eupagurus. 



The normal male hermit crab differs from the female in the arrange- 

 ment of the abdominal appendages, amongst other things ; but when infested 

 by Phyxus, the male Eupagurus presents a similarity, in size and number 

 of its abdominal appendages, to those of the normal female. The testes are 

 filled with imperfect spermatozoa. Curiously enough, Peltogaster paguri 

 produces no such effect on the male Pagurus, although rendering it sterile ; 

 but the females have their abdominal appendages modified in the direction 

 of a normal male. 



The author believes that Peltogaster fixes itself to its host at a later 

 period than does Phyxus, rather than that the activity of the former is 

 slower than that of the latter. Moreover, Phyxus attacks its host at a time 

 when the embryonal abdominal appendages are still present. He considers 

 that the Ehizocephala "have, in the phylogenetic series, introduced the 

 Bopyrids into the Decapoda ; the Isopods, originally parasitic on the Rhizo- 

 cephala, at first infected the higher Crustacea through these, but later 

 became parasitic directly on them." 



Prof. Giard has seen only one specimen (from Naples) of Gyge 

 hranchialis infected by a Bopyrid : this is a male, which possesses the 

 simple first abdominal appendages characteristic of the normal female. 

 The Brachyura, infested by Cepon, and Porcellanus longirostris, infested by 

 Pleurocrypta porcellanse, show no appreciable modification of external sexual 

 character. 



Vermes, 

 a. Annelida. 



Development of Ovum of Hirudinea.t— Herr C. Chworostansky finds 

 that the wall of the ovary of Hirudo and Aulastoma consists of the outer 

 membrane of connective tissue with a quantity of blood-vessels, a muscular 

 layer which forms a plexus, and the internal cellular layers found by lijima 

 in Nephelis ; the last is lined by flat epithelial cells. The blood-vessels 

 form various stages towards Lankester's vasofibrous tissue ; the muscles are 

 either broad with a thick clearly visible plasma and a central finely 

 granulated plasma with large elliptical nuclei, or they have no distinctly 

 granular plasma and their nuclei are small. There are two cords ; the end 



* Comptes Eendus, civ. (1887) pp. 1113-5. f Zool. Anzeig., x. (1887) pp. 365-9. 



