213 First Maturation Spindle of Allolobophora Foctida 



Aiisbildung mid Funktion dcr Kerne in den Beiderlei Zellen erkliiren,'' 

 p. 5T9. 



There has been a recent revival of interest in the theory that the 

 chromatin destined for the chromosomes of the first maturation spindle 

 is stored at an earlier stage in one or several nucleoli. In a recent 

 paper Blackman, '03, sums up the weight of authority for this view/' 

 and to his list of authors may be added recent papers by Goldschmidt, 

 '02, Hartmann, '02, Bryce, '01, and especially Le Brun, '01, '02, 

 whose extensive publications on the maturation stages of Batrachians 

 are illustrated by many figures demonstrating this point. The evidence 

 furnished by the egg of AUoJohophora cannot be interpreted as a sup- 

 port for the above theory. It must unquestionably be classed as support- 

 ing the interpretation of the many authors who claim that the chro- 

 matin destined for the chromosomes of the spindle is at no time aggregated 

 into a large nucleolus. In Allolohophora the chromosomes are formed 

 by a gradual segregation of the chromatin which is dispersed throughout 

 the germinal vesicle, and in order to maintain the theory that the 

 nucleolus is the storehouse of the chromatin there should be a definite 

 and constant relation between the formation of the chromosomes and the 

 breaking down and disappearance of the nucleolus. This, however, is 

 not the case in Allolohophora, the two processes do not invariably occur 

 in unison. If the chromosomes have their origin in the nucleolus Ave 

 should never find the chromosomes formed while the nucleolus is intact — 

 before it shows any evidence of breaking down. Photos. 37 and 38, 

 Plate II, 51 and 53, Plate III, and 68 to 73, Plate IV, demonstrate that 

 the chromosomes can be formed in the germinal vesicle Avithout any 

 marked morphological disturbance of the nucleolus, these nucleoli not 

 differing essentially from those of the ovarian eggs and from the nucleoli 

 of those eggs in the receptaculum ovorum in which the chromosomes are 

 still unformed. This is demonstrated also in the dried germinal vesi- 

 cles. In Photos. Ill and 113 to 115, Plate A^II, the chromatic spireme is 

 formed and the principal nucleolus is still intact, showing no evidence 

 of having contributed to the chromatin of the spireme; and in those 

 cases in which the large nucleolus loses in staining capacity, while the 

 chromosomes increase in staining capacity, the phenomenon is probably 

 due to the normal disintegration of the former, and not to a contribu- 

 tion of its substance to the chromosomes. As a rule the principal 

 nucleolus has disappeared, or is in process of disappearing when the 



" " Blachmann, Carnoy, Davidhoff, Hermann, Holl, Sobotta, R. Hertwig, 

 Wilson and others,' p. 197. 



