1886.] 



Early Development of Julus terrestris. 



73 



Table VIII. (Special Data.) 



Number of cases in which the Stature of individual Brothers was 

 found to deviate to various amounts from 1 the Mean Stature of 

 their respective families. 



■ . - 

 !N limber of brothers in each lamily 



4 



5 



6 



7 





39 



23 



8 



6 





Amount of deviation. 



Number 

 of cases. 



Number 

 of cases. 



Number 

 of cases. 



Number 

 of cases. 





88 

 49 

 15 

 4 



62 

 30 

 17 

 3 

 ^3 



20 



s 



2 



21 

 14 

 6 

 1 













II. " The Early Development of Julus terrestris"* By F. G. 

 Heathcote, M.A., Trin. Coll. Cam. Communicated by 

 Professor M. Foster, Sec. R.S. Received January 6, 1886. 



The following are the principal results of my investigations on the 

 early development of Julus terrestris since June, 1882. 



When laid the eggs are oval in shape, white, and covered with a 

 thick chitinous chorion. The nucleus is situated in a mass of 

 protoplasm in the centre of the ovum. This mass of protoplasm is of 

 irregular shape, but its long axis corresponds with that of the ovum. 

 From it, anastomosing processes radiate in all directions, forming a 

 network throughout the egg. The yolk-spherules are contained 

 within the meshes of this network. The nucleus is not a distinct 

 vesicle but its position is marked by chromatin granules. There is no 

 nucleolus. 



Early on the second day the nucleus and the central mass of 

 protoplasm apparently divide into two parts. But this division is not 

 complete, the two resulting masses with their nuclei remaining con- 

 nected by a network of protoplasm. Each of these divides in the 

 same incomplete manner, so that we now have four segments all 

 connected together. This process is continued until there are a 

 considerable number of segmentation masses present, and early on the 



* Mr. J. D. G-ibson Carraichael, F.L.S., has kindly identified the species for me as 

 Julus terrestris, Leach, 1814. 



