84 HELEN DEAN KING. 



of the germinal vesicle disappears. The twelve chromosomes 

 which later arise from a coalescence of the chromatin granules are 

 at first very irregular in shape and they are scattered all along 

 the spindle fibers ; subsequently they undergo a double longi- 

 tudinal division in preparation for the giving off of the polar 

 bodies. Any chromatin not used for the chromosomes is ab- 

 sorbed by the cytoplasm. 



Although there are always twelve chromosomes on the first 

 polar spindle in the egg of Triton, Carnoy and Lebrun find only 

 8-10 chromosomes in the equatorial plate of the first polar 

 spindle in the egg of Bnfo vnlgaris, and but 45 chromosomes 

 at each pole just previous to the giving off of the first polar 

 body. The failure of these investigators to find the definite 

 number of chromosomes that must be present unless the egg of 

 Bnfo vulgaris is a marked exception to the rule that the number 

 of chromosomes is constant for a given species, may possibly be 

 accounted for on the supposition that some of the chromosomes 

 were lost when the eggs were sectioned or that the sections of 

 the egg were made so thick that some of the chromosomes were 



o o 



not visible. 



In a more recent paper, Lebrun (13) gives the results of a re- 

 examination of the maturation processes in the egg of Triton. 

 He states that the double longitudinal division of the chromo- 

 somes does not take place in the complicated manner previously 

 described by Carnoy and Lebrun, but according to the scheme 

 represented by my text-figures 1-5. The late maturation changes 

 in the egg of Triton are, therefore, strikingly similar to those I 

 have found taking place in the egg of Bnfo lentiginosus. Lebrun 

 still believes that in the eggs of Rana temporaria and of Bnfo 

 vnlgaris a certain number of the nucleoli are reserved to form the 

 chromosomes of the first maturation spindle. A reexamination 

 of the maturation stages in the eggs of these amphibians would 

 probably show that in these forms also the chromosomes are de- 

 rived from fused masses of chromatin granules and that they 

 have no connection whatever with the true nucleoli. 



I have examined a large number of the eggs of Bnfo at the 

 stages of Figs. 34 and I can see no reason for believing with 

 Carnoy and Lebrun that a division of the chromosomes takes 



