PREDETERMINATION OF SEX 303 



.cells in the cases here figured, when an X passes to each pole, 

 may seem rather to favor the other view, namely, that the size 

 of the cell is determined by the chance direction taken by the X 

 chromosome. 



If cells like these with duplex number of chromosomes should 

 produce functional spermatozoa, and one such spermatozoon 

 should fertilize a normal egg, the number of somatic nuclei would 

 become nine instead of six and the resulting female would have 

 three X chromosomes instead of two. In subsequent genera- 

 tions the number of X's might be further increased, if, in fact, 

 viable forms could be produced in this way. It does not seem 

 probable, however, that a condition like that described above for 

 the phylloxerans, in which four X's are present, could have 

 arisen through irregularities of this kind, because the chance that 

 such a rare phenomenon could supplant the normal type seems 

 too small to make such a view possible. Still, the possibility of a 

 tetraploid organism, arising through failure of a spermatogonial 

 or oogonial cytoplasmic division must be conceded, especially in 

 the light of the sudden appearance of tetraploidy in Primula 

 and Oenothera. If it be assumed that some advantages, such 

 as an increase in size, give the new type an advantage, then it 

 might in time obtain an independent footing. 



A most striking and interesting relation is shown in this tetra- 

 ploid cyst, namely, the chromosomes are only half as large as 

 are those at the corresponding stage of the normal spermatocyte 

 stage, as seen in other cysts of the same testis. This relation 

 might be interpreted to mean either that the original mother-cell 

 of the cyst, having divided (incompletely) one time more than the 

 other mother-cells of the other cysts, never made good the size 

 loss of the chromosomes. If the growth of the chromosomes be 

 directly related to the size of the cell that contains them, owing 

 to the amount of substance available in such a cell, the smaller 

 size of the chromosomes in the tetraploid cyst might find a rea- 

 sonable explanation. Such a conclusion would indicate that the 

 stage reached by a cell at a particular phase is determined by 

 the cytoplasm, rather than by the size of the chromosomes. 



