ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 273 



zone of differentiation, the origin from the primitive germ-nuclei of 

 the yolk-cells and the ova. In the next region of the tubes, by the 

 intervention of the follicle cells, successive chambers are formed con- 

 sisting alternately of a single ovum and a group of yolk-cells ; it would 

 appear that 48 of these nutritive cells correspond to one ovum. In 

 regard to the fate of the nutritivo cells, an important point is that for 

 a time they increase rapidly in size, secreting food-material which is 

 transmitted to the ovum by means of a prolongation of the ovum, which 

 perforates the follicular wall, and so enters the yolk-cell chamber. There 

 is, however, no gradual diminution in size of the yolk-cells, for just 

 before the eggs enter the oviduct the whole contents of the yolk-cell 

 chamber is suddenly evacuated into the egg-chamber. The egg in 

 consequence exhibits within its cytoplasm the degenerating remnants 

 of the yolk-cells. In commenting upon his results, the author notes the 

 rarity of karyokinetic figures in the zone of synapsis, in spite of the 

 fact that active cell-division is going on there. He believes that, as 

 already indicated by others, the yolk-cells divide by an amitotic pro- 

 cess, as is generally true of actively assimilating cells. The peculiar 

 engulfing of the yolk-cells by the ovum he explains as necessitated by 

 the rapid production of eggs in the queen-bee. Further, he is of opinion 

 with Weismann, that the distinction between future yolk-cells and future 

 ova is determined by heredity and not by diiferences of nutrition. 



Studies on Ants.* — Prof. A. Forel describes (1) a number of ants 

 from Japan, including several new species; (2) the nests of Camponotus 

 senex Sm. and Macromischa sallei Guerin ; (3) Strongylognafhus hnberi 

 Forel and its related species ; (4) a natural triple colony, Formica pra- 

 tensis, Poly erg us rufescens, and F. fusca ; (5) Cypliomyrmex wheeleri 

 sp. n., whose mushroom-gardens Prof. W. M. Wheeler has discovered ; 

 and (6) some foreign ants imported into Hamburg. 



Symbiosis of Caterpillars and Ants.f — Prof. H. Shomann finds that 

 the caterpillars of Lycsena argus live in company with Formica cinerea 

 on Oxytropis pilosa and Hippophae rhamnoides, the ants continually 

 crawling over the bodies of the caterpillars. The chrysalids also often 

 occur in the nests of the ants, and the butterflies may be observed 

 emerging from the nests without interference on the part of the ants. 

 The symbiosis apparently protects the caterpillars from the attacks of 

 ichneumons, while they secrete from the third body-ring a thick liquid, 

 of which the ants are very fond. Similar cases of symbiosis have been 

 observed in India and America, but this is the first time it has been 

 noticed in Europe. 



Artificially-produced Colour-change in Butterflies.^ — Dr. T. Fischer 

 subjected chrysalids of Arctia caja L. to a temperature of — 8 D C, and 

 obtained a number of aberrant imagos. He was successful in breeding 

 from these, and found that the new generation exhibited the parental 

 characters, and did not revert to type, although their chrysalids were 

 not subjected to an abnormal temperature. This interesting phenomenon 

 the author regards as explicable only on Weismann's theory, maintain- 

 ing that the low temperature affects the sex-cells at the same time and 



* M.T. Schweiz. Entom. Ges., x. (1900) pp. 267-87. 



t Arch. Sci. Phya. et Nat., x. (1900) pp. 505-6. J Tom. cit., pp. 562-5. 



