ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 473 



layer, but pass them out again into the sea-water. The cells in the 

 neighbourhood of the chamber-pores take up particles suspended in the 

 incoming sea-water more readily than the other cells. 



Protozoa. 



Sporulation in Amoeba.* — Herr C. Scheel describes and figures this 

 mode of multiplication in Amoeba proteus. The pseudopodia are drawn 

 in ; a spheroidal form is assumed ; a layered cyst is secreted ; within 

 this the amoeba rotates rapidly, once a second, for several days, and then 

 rests ; the nucleus divides till there are about 500-600 arranged peri- 

 pherally ; cell-boundaries gradually appear, and the small amoebae — 

 10-14 fx. in diameter — break out of the softened cyst. The whole pro- 

 cess takes from 2^ to 3 months. 



Senility of Infusorians.j — Prof. N. Kulagin studied the generations 

 of a species of Paramcecium, and observed the diminution of size and 

 agility. But he also noticed that, if an individual is removed to a 

 fresh vessel, there is immediate recuperation or rejuvenescence. This 

 led him to a conclusion somewhat different from that of Maupas and 

 others. He believes that when Infusoria have lived for several genera- 

 tions in the same water, they have, so to speak, spoilt the water by the 

 excretion of substances analogous to toxines, and that these gradually 

 accumulate until they affect the health of the nuclei. 



Eye-Spot in Euglena.J — Mr. Harold Wager has obtained some inter- 

 esting and novel results from the study of this structure. He finds that 

 the eye-spot consists of a mass of pigment-granules apparently imbedded 

 in a protoplasmic framework. It is placed in close contact with the 

 gullet, which is found to open into the large excretory reservoir. The 

 flagellum is attached by a bifurcated base to the posterior side of the 

 reservoir, and one of the forks has on it an oval swelling, which lies 

 close to the eye-spot. It would appear that the light absorbed by the 

 eye-spot acts upon this swelling, and so modifies the movements of the 

 flagellum. If this be so, then Euglena possesses a very simple form of 

 light-organ, consisting of a sensitive region — the swelling on the flagel- 

 lum — and a light-absorbing pigment-spot. Special mention should be 

 made of the figures, which are in every way worthy of this clear and 

 precise piece of work. 



Tick Fever Parasite. § — Mr. R. Greig Smith gives a general account 

 of this wide-spread parasite Apiosoma (Pyrosoma) bigeminum, a haemato- 

 zoon which destroys the red blood-corpuscles. In consequence of the 

 degradation and disintegration of the corpuscles, the capillaries become 

 clogged, the internal organs intensely swollen ; and the liver and kidneys 

 being frequently unable to cope with the task of eliminating the pro- 

 ducts of the corpuscle disintegration, death results from what is essen- 

 tially capillary congestion. So far as is definitely known, the disease 

 occurs only among cattle, but two diseases of sheep have been described 

 which appear to be caused by the same parasite. Infection occurs by 



* Festschrift C. von Kupffer, Jena, 1899. See Amer. Nat., xxxiv. (1900) p. 332. 



+ Physiol. Kusse. i. (1899) pp. 269-75. 



X Journ. Linn. Soc, xxvii. (1900) pp. 403-81 (1 pi.). 



§ Proc. Linn. Soc. N.S. Wales, xxiv. (1900) pp. 585-95. 



