394 Naohide Yatsu. 



(I) There are a few plasmosomes in the germinal vesicle. Each 



of them is usually found associated with a chromatin 

 granule. 



(3) The reduced number of chromosomes is 18 or 19 ; the somatic 



number, 30 or 38 (in C. marginatus the reduced num- 

 ber is 16 according to Coe and Kostanecki). 



(4) Chromatin diminution is accomplished by the fading away 



of some of the chromatin granules at the prophase of the 

 first maturation mitosis. 



(5) The spermatozoon contains a centriole in the middle piece. 



(6) The middle piece swells into a vesicle and the centriole 



escapes from it, giving rise to the centre of the sperm 

 aster. 



(7) The centrosome does not divide. The centriole divides in 



the centrosome. Each daughter centriole acquires its 

 own centrosome, and the mother centrosome fades away. 



(8) The centrosome of the fourth generation becomes that of 



the second cleavage. 



(9) Crossing of rays takes place between the degenerating rays 



of egg-nncleus and sperm-rays. 



(10) An ;mtis])iiidle figure, such as occurs in C marginatus at 



the aiui])hase of the first cleavage, takes place very seldom. 

 Such a figure may be an artifact. 



(II) Sheath rays are formed surrounding the spindle at the 



anaphase of the cleavage mitoses. 



(12) The first maturation figure remains unchanged for four or 



five hours if the egg is not fertilized. 



(13) The sperm aster may ])ass unchanged from the alveolar 



into homogeneous plasm. 



(14) A spindle may be formed between the maturation and 



sperm aster. 



(15) The cytoplasm along the future cleavage plane is rendered 



less dense (partly by the nuclear fluid). 



(10) Sheaf rays with the mid-body granules arc formed at the 

 telophase of the cleavage mitoses. 



