122 W. R. B. ROBERTSON 
and showed that they retained the same size and were as free 
from terminally attached fragments as they were on entering the 
pairing process. mh 
In regard to the question of pre- and post-reduction, I have 
evidence here that the first maturation division is the reduction 
division so far as regards three of the seven pairs of chromosomes 
of the Tettigidae subfamily of grasshoppers. These pairs are the 
1’s, the 4’s and the sex chromosomes. The abnormally long No. 1 
chromosome is seen in Tettigidea separating from its normal mate 
(figs. 12, 13), the deficient No. 4 is seen separating from itsnormal 
mate (figs. 5-8), and the unpaired sex chromosome (paired in the 
female, figs. 1, 11) is seen passing over whole to one of the poles 
in the male cells in similar manner, just as if it had had a mate 
from which to part at this division, where such parting is being 
carried out by the members of the ordinary chromosome pairs 
(figs. 2, 3, 5, 6, 8, 10,12, 13). The other chromosome pairs (the 
2’s, 3’s, 6’s, and 7’s) behave similarly to the 1’s and 4’s in every 
respect during the synapsis, prophase, metaphase, and anaphase 
periods of the first spermatocyte divisions. This leads one to 
think that probably the first spermatocyte division is the reduc- 
tion division for all pairs of chromosomes, in the Tettigidae sub- 
family of grasshoppers at least. 
4. THE DEFICIENT NO. 4 CHROMOSOME AND THE LOSS OF 
UNIT CHARACTERS 
The most important of these unequal tetrads are those in which 
one member of the pair is of less than the normal size (figs. 4-8). 
The importance lies in this, that such a deficiency may be the 
result. of the dropping of a part of a chromosome and in this way 
may furnish the basis in the germ cell for the loss of unit factors 
in heredity. 
In animal and plant breeding there are many unit characters 
which might be considered to have resulted from the loss of 
something from the germ plasm, whether this something be an 
enzyme of some sort or a substance upon which an enzyme might 
act. 
