ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 349 



the giant cell. There is no plasrnodial communication between the 

 sex-cells and the Verson's cell ; nutrition takes place by diffusion 

 through the membranes. The pear-shaped appearance is due not to the 

 giant cell but to the mutual crushing of the cells. After maturation 

 each of the " primordial spermatogonia " divides into a certain number 

 of spermatogonia which give rise to spermatozoa. The cyst cells appear 

 soon after the Verson's cells. They are spermatogonia which do not 

 receive from the giant cell the same nourishment as the sex-cells. They 

 divide by karyokinesis, and for lack of nourishment cannot recuperate 

 the original volume in the period between two divisions. Some of them 

 surround the primordial spermatogonia and form a multicellular mem- 

 brane which stretches and becomes thinner as these increase in size. 

 One of the cells situated in front of the heads of the spermatic elements 

 increases greatly in size and appears to play a nutritive role. 



« 



Hymenopterous Parasites of Aphis evonymi.* — -A. Malaquin and 

 A. Moitie have studied the Hymenopterous larvse which infest this 

 black blight. No fewer than seventeen different species were found, of 

 which Trioxys ductus and Aphidius crepidis were the commonest. The 

 infected wingless Aphides pass into a characteristic cystic condition. 

 Reference is made to experiments which show the great effectiveness of 

 the Hymenoptera (Aphidiidaa, Proctotrupidse, Cynipidas, and Chalcididse) 

 as checks on the Aphides. 



5. Arachnida. 



Eyes of Arachnoids, f — Ludwig Scheming describes the minute 

 structure of the eyes of Phalangida? (Phalanghcm) and Araneidaa (many 

 types of spiders). He deals with the structure of the main eyes and 

 the lateral eyes of spiders, with their function, and with the move- 

 ments of the retinal pigment. After a careful comparison of the 

 various kinds of Arachnoid eyes, Scheming comes to the conclusion 

 that the main eyes of Scorpionidte are homologous with the main eyes 

 of Pedipalpi and the lateral eyes of Araneidae ; that the lateral eyes 

 of Scorpionidae are homologous with the eyes of Hydrachnids ; that the 

 lateral eyes of Pedipalpi are homologous with the eyes of Pseudo- 

 scorpionidas ; and that the main and lateral eyes of Solifugas are 

 homologous. 



'&' 



Reproduction in Acercus.J — Karl Yiets has made careful observa- 

 tions on the behaviour of the males of species of the water-mite, Acercus, 

 when brought into the vicinity of the females. The third appendage is 

 applied to the genital aperture and loaded with a sperm-packet. A small 

 clump is seen at the tip of the appendage, consisting of a number of 

 straight spines surrounded by a glutinous material. Below the apex of 

 the spines the club-shaped spermatophores are attached by a thin stalk. 

 The sperm-packet is pushed into the female genital aperture. 



* C.R. Soc. Biol. Paris, lxxvi. (1914) pp. 803-5. 



t Zool. Jahrb. Abth. Anat., xxxvii. (1914) pp. 369-464 (4 pis. and 16 figs.). 



X Internat. Rev. ges. Hydrobiol., vi. (1914) Biolog. Suppl. No. 3, pp. 1-10 



(4 figs.). 



