222 INVERTEBRATA CHAP. 



the adult female; but Lycosa cannot be induced to breed in 

 captivity. 



Kishinouye's method of dealing with the eggs is as follows. The 

 earlier stages were plunged into water of a temperature of from 70 to 

 80 C., the later stages were placed in cold water which was gradually 

 heated to this temperature. When the eggs had become opaque and 

 white they were removed, and when cool they were placed at once in 

 70 per cent alcohol. After 24 hours in this reagent, they were 

 examined under the dissecting microscope and the egg membrane 

 pricked with a needle, the hardening was then completed in 

 ascending grades of alcohol. It was found that after staining in 

 picro-carmiue the paraffin penetrated better than after other stains. 

 It is clear that the celloidin-paraffin method of embedding would be 

 more suitable than that of pure paraffin, which Kishinouye employed. 



n 



FIG. 169. Three stages in the segmentation of the egg of Agelena. (After Kishinouye.) 



A, stage before the division of the zygote nucleus has taken place, showing the ends of the radiating 

 columns of the yolk ; B, stage in which the zygote nucleus has divided once ; C, stage in which the 

 zygote nucleus has given rise by repeated divisions to a considerable number of nuclei, n, nuclei 

 surrounded by islands of cytoplasm ; y.r, yolk rosette. 



The egg possesses an inner thin vitelline membrane and an outer 

 chorion, and the surface of the latter is beset by a mosaic of very 

 fine granules. At the centre of the egg there is an accumulation of 

 protoplasm, which contains the zygote nucleus, and is termed by 

 Kishinouye the centroplasm. There is also, as in all centrolecithal 

 eggs, an outer rind of protoplasm, which Kishinouye terms the 

 periplasm (per, Fig. 11). Between the centroplasm and periplasm 

 the yolk is arranged in a series of radiating columns, each column 

 consisting of a radiating series of short tangential rows of yolk 

 granules. Between adjacent columns Kishinouye surmises the 

 existence of radiating sheets of protoplasm connecting the centroplasm 

 with the periplasm, but he was not able certainly to demonstrate 

 their existence. 



The periplasm is marked out into polygonal areas which corre- 

 spond to the yolk columns, and indeed form caps to them. These 



