THE ACTIVATION OF GENES BY THE CYTOPLASM 353 



EMSt 



Figure 16.3 



Cleavage in Ascaris: a, beginning of the second cleavage, b; later stage of the 

 same cleavage, with the chromosomes becoming fragmented, and their ends 

 (e) lost in the cytoplasm, in the anterior AB cells; c, 4-cell stage from animal 

 pole; d later stage of 4-cell stage from the side, when cell P2 has moved 

 round; chromosome fragmentation and loss of ends is occurring in cell 

 EMSt. (After Boveri.) 



to its partners. The latter process gives rise to configurations such as those 

 which are best seen in the cells of the saHvary glands of dipteran larvae, 

 but which occur in a less perfectly developed form also in the Malpighian 

 tubules, the linings of the gut and elsewhere, hi nuclei with such 'poly- 

 tene' chromosomes, the genes must be represented many times over, and 

 diiferent degrees of polyploidy seem to characterise the different tissues. 

 It is theoretically possible that the relation between the quantity of gene 

 and its effectiveness is not the same for all genes, so that a multipHcation 



