MULTIPLE CHROMOSOMES 533 



diploid complex. Before following out the later spermatogenetic 

 history I ^\dll briefly indicate the conditions in the female cell. 



Unfortunately it has not been possible to work out the history . 

 of the female germ cells, but the egg follicle cells show beautiful, 

 clear chromosome groups, some of which are represented in figures 

 43, 45 and 48. It is at once observable that the resemblance to 

 the male diploid group is very marked. Here again there are 

 twenty-two chromosomes, among which are also two Vs. A 

 more careful study however reveals a significant sexual difference 

 in the case of the two Vs. Instead of being unlike in size they 

 are of practically identical proportions. Owing to their some- 

 what sinuous course through the cell, with consequent foreshort- 

 ening, it is difficult, if not impossible, to represent them accu- 

 rately in drawings. Where they lie more nearly in the same 

 plane, as in figure 43, pi. 6, their equivalence is clearer. Under 

 the microscope there is no difficulty in appreciating the close 

 resemblance existing. On comparing these two Vs with the ones 

 of the spermatogonium (figs. 47, 49, pi. 6) it is seen at once that 

 in size and proportion they agi-ee with the larger one of the male 

 cells. In other words these are two multiples, the short arms 

 of which are the accessory chromosomes. The count for the 

 female complex, instead of the apparent twenty-two, is therefore 

 twenty-fouT; corresponding to the conditions in other species. 

 No differential beha\aor of the sex chromosomes was observed 

 in these female somatic cells and but little e\ddence of separation 

 at the point of fusion. 



Other species of Mermiria show no multiple chromosomes in 

 the first spermatocyte, and when the spermatogonial complex 

 is observed there are found twenty-three rod shaped chromo- 

 somes of the usual type. Absence of a multiple chromosome in 

 the spermatocyte is accompanied by the absence of V-shaped 

 chromosomes in the spermatogonium. Animals of this type 

 are not classified as bivittata, but, quite aside from their exact 

 taxonomic disposition, it is plain that they must be very nearly 

 related to bivittata. In such material, then, the direct rela- 

 tion between V chromosomes of the spermatogonium and mul- 

 tiple chromosomes of hexad nature in the first spermatocyte is 



