NUCLEOLI IN PEDICELLINA AMERICANA. 357 



opposite parental sides, thus giving rise to six tetrads, viz; : 



a b c d e f g h i j k I 



, -, -, -, - , , and through a subsequent ro- 



n\o p q r s t u v w v - 



tation these become 



an c\p e 



g t i\v 

 ku' w' 



The 



y 



bo' d q' f 



second or reducing division distributes these in such a manner 

 that the egg and the second polar body each receives twelve 

 chromosomes (six bivalents) of which six single elements are 

 paternal and six maternal ; thus, an, cp, er, gt, iv, kx, go to the 

 now matured egg while the rest go to the second polar body. 



There is, however, but little probability for such an interpreta- 

 tion as it entirely ignores the significance of the primary synapsis 

 which from the figures of Riickert, '04, and Hacker, '95, himself, 

 undoubtedly takes place at the beginning of oocytic growth. 

 This undoubtedly results in the reduction of the chromosomes 

 during this period. From the highly probably results of Mont- 

 gomery and Sutten (which have received strong corroboration 

 from all sides) the twelve bivalents of the first maturation pro- 

 phase would represent the union of homologous paternal and 

 maternal chromosomes and not, as Hacker assumes, of the same 

 parental side, /. ^..paternal with paternal, maternal with maternal 

 On the first of these hypotheses the two ensuing maturation divi- 

 sions would produce conditions quite analogous to that observed 

 by the great majority of workers on the germ-cells of both ani- 

 mals and plants. But what is far more convincing is the fact, 

 that on the interpretation of Hacker, there would result, in the 

 great majority of cases, an egg with such a chromatic constitution 

 that the potentialities of one group of characters would often be 

 doubled, while those of another group would be entirely lacking. 

 This would not only make Mendelian results impossible but, as 

 Boveri has shown in his work on " Multipolar-mitoses " might 

 lead to the production of defective larvae. 



We must therefore conclude that the segregation of the chro- 

 matin in the spermatid of Pedicellina is without particular sig- 

 nificance and that the gonomery or autonomy of the parental 

 chromatic contributions continues at most only up to the begin- 

 ning of the growth period of the germs-cells, the mingling having 



