dele? W. R. B. ROBERTSON 
No. 3 chromosomes to the smaller No. 4 chromosome is as 1 to 
0.97. This shows the smaller No. 4 diad to be even smaller than 
the No. 3 chromosomes. I believe that the larger diad of this 
abnormal No. 4 tetrad is the normal No. 4 chromosome, since 
its ratio, 1.18, is so near to the normal ratio, 1.14, and that the 
smaller diad is abnormal and has lost a part of its distal end; 
(my reason for thinking the distal end deficient will appear later). 
Its ratio, 0.97, instead of 1.14, gives it a shortage of 0.17, or nearly 
one-sixth of 1.14. It seems therefore to have lost one-sixth of 
its normal length. 
The size of this deficient No. 4 chromosome is constant for 
this individual. All division figures which occurred in lateral 
view showed the members of this unequal pair in practically 
the same relative sizes. Not only the germ cells but also somatic 
cells (fat body) exhibited the same proportions. The fact that 
the size ratio is constant in all germ cells and even in body 
cells seems to point to its germinal origin; i.e., 1t must have been 
present in the fertilized egg from which this animal developed. 
There is no constant relation between the members of this 
unequal pair of chromosomes and the sex chromosome, as the 
cells of the maturation division show (figs. 5, 6, 8), for the sex 
chromosome passes as often to the pole which receives the small 
No. 4 chromosome as to the pole which receives the large 
member. . 
Another very noticeable evidence of the abnormality and 
defectiveness of this No. 4 chromosome is shown in its manner 
of contact with its larger normal mate in the first maturation 
spindle (figs. 5, 6, 7c). In these three figures its attachment 
is not strictly terminal, as it should be. This, it seems to me, is 
evidence of a deficiency at the distal end of this chromosome. 
This will be better understood if I describe briefly the method 
of chromosome pairing in the Tettigidae (Robertson 715). 
During the period of synapsis, which occurs in the early part 
of the growth period of the first spermatocyte, homologous chro- 
mosomes pair side to side (parasynapsis), as shown in figures Aj, 
A» (pl. 3). After this period of synapsis, during the growth period 
which follows, a separation of the pairing chromosomes takes 
