~)4 SUMMARY OF CURRENT RESEARCHES RELATING TO 



*. Crustacea. 



Spermatozoa of Crayfish.* — E. A. Andrews gives ;i clear and ad- 

 mirably illustrated account of the remarkable spermatozoa of Cambarus 

 affirm. He describes the well-known " vesicle " which takes up about 

 one half of the bulk of the sperm. It is set in the body of the sperm 

 somewhat as a very small inverted cup might be held in the hollow of 

 one's closed hand. This vesicle is evidently a new formation that comes 

 to lie in the cup-shaped nucleus. It is inferred that the nucleus becomes 

 like a hollowed hand holding the vesicle like an inverted bowl on the 

 palm, and enveloping all but the bottom of the bowl by long, spirally 

 coiled prolongations of the palm, the 4 to 7 "arms 1 ' of the sperm. 



Study of the spiral uncoiling of the " arms " shows that there are 

 at least two kinds of sperm among spermatozoa from the same male. 

 Some show the arms unwinding from right to left and others from left 

 to right. The author has some remarks on the spermatozoa of Astacus. 

 He notes finally that the form of the sperm at any stage seems 

 dependent upon osmotic pressure. 



Phagocytic Cells in Amphipods.f — L. Rruntz finds that in Gam- 

 mar us pulex and Talitrus loeusta there are three kinds of phagocytes, 

 viz. pericardial nephrocytes, cells of the hepatic artery capillary net, 

 and young blood-cells which are mechanically arrested in the adipose 

 tissue. These last are the " little cells " of the fatty tissue described by 

 Kowalevsky. 



Distribution of Niphargus.J — W. F. de Vismes Kane reports the 

 occurrence of the blind Niphargus Jcochianus Bate in the open waters 

 of Lough Mask. It may have come from subterranean channels and 

 reservoirs which communicate with the lough. The author also reports 

 the occurrence of N. subterraneus Leach from five out of eight wells 

 examined in the vicinity of Lynsted in Kent. 



Development of Sacculina.§ — P. Abric gives some interesting facts 

 regarding the early development of this form. The division of the 

 vitellus is total at first, and the egg is divided into two parts. The 

 second plane is perpendicular to the first, and up to stage six the 

 segmentation is symmetrical. After this, however, in a very large pro- 

 portion of cases there are irregularities of segmentation, dependent on 

 two causes : (1) cells which in a normal case arise in pairs of the same 

 age do not arise at the same time, so that an uneven number results ; 

 (2) precocious division of cells may occur before the preceding pair 

 have reached equilibrium, thus establishing irregular equilibrium. It is 

 an interesting illustration of the indetermination of blastomeres, since 

 whatever the mode of segmentation, all the eggs give rise to nauplii. 



Fresh- and Brackish-water Crustacea of East Norfolk. || — Robert 

 Gurney gives an annotated list of the Crustaceans, except Ostracods, of 

 the Broads district. He has, inter alia, notes on the seasonal distri- 



* Auat. Anzeig., xxv. (1904) pp. 456-G3 (7 figs.). 



t Coraptes Rendus, cxxxix. (1904) pp. 368-70. 



X Aim. Nat. Hist., xiv. (1904) pp. 274-83(1 pi.). 



§ Comptes Rendus, cxxxix. (1904) pp. 430-2. 



1| Trans. Norfolk and Norwich Nat. Soc, vii. (1904) pp. 037-60. 



