118 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
There seems to be a great amount of disagreement as to just what 
constitutes individuality, but I believe that we may class as instances 
of individuality all cases where it can be shown that the substance of 
any telophase chromosome gives rise to one and only one prophase 
chromosome. In that event, any one of the three theories mentioned 
above would support the theory of individuality. I believe that I 
have demonstrated individuality for chromosome-pair A, and have 
shown good evidence for it among the other chromosomes of Phryno- 
tettix. Besides, it seems to me much more logical to regard the con- 
stant reappearance of the same architectural conditions of a given 
chromosome as a result of continuity of that architecture in some 
form or other through all the cell-divisions, than to assume that the 
organization is entirely destroyed and reestablished between successive 
mitoses. 
C. CHROMOSOMES AND HEREDITY. 
Any discussion of the relation of the chromosomes to heredity must 
deal to a considerable extent with theory and speculation. Yet there 
are many facts which tend to the belief that the chromosomes are, 
after all, directly concerned with the transmission of hereditary 
qualities. A few facts and some theory will be considered in the 
following paragraphs under the two heads: — (a) Mendelism and 
maturation, and (b) some experimental evidence. 
a. Mendelism and Maturation. 
Wilhelm Roux was apparently the first to formulate, in the early 
eighties, a theory in which an attempt was made to localize the 
carriers of hereditary qualities in the chromosomes; this was later 
elaborated by others, especially by Weismann, who postulated a 
reduction division which has since been identified with one or the 
other of the maturation divisions. Montgomery (’01) pointed out 
that the chromosomes of the diploid series occur in pairs, the members 
of each pair being of the same shape and size. There are thus two 
similar series of chromosomes. He concluded that one series was 
derived from the maternal, the other from the paternal ancestor. He 
concluded further that the members of each pair unite to form the 
bivalent chromosomes of the first spermatocytes. Boveri (’02) de- 
cided from the results of his experiments on dispermic echinoderm 
