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CHARLES L. PARMENTER 
far as known, has been lost from one homologue and joined to 
the end of its mate. Another case is the transposition of a piece 
of the II chromosome to the middle of the III chromosome. 
He has exhibited definite cytological evidence (unpublished) 
supporting a part of the above. This condition produces 
homologues of unequal length which parallels the observations 
in the germ cells of the Orthoptera and the apparent similar 
condition in certain somatic homologues of xVmbystoma. 
c. Constant relative size relations. In addition to verifying 
Montgomery’s (’01) and Sutton’s (’02) observations of paired 
homologous chromosomes of equal length in the germ cells, 
Meek (’12), Robertson (’16), and Hance (’17 b, ’18 a) confirm 
Sutton’s (’02) observation (based upon comparisons of camera- 
lucida drawings of many spermatogonial cells and upon measure¬ 
ments of early prophase tetrads) that the proportional difference 
in size between any two pairs in one nucleus is practically the 
same as that between the corresponding pairs in any other 
nucleus. In Ambystoma tigrinum, as is seen in figures 33 to 
37 and the table of percentages accompanying them, while 
the relative lengths are not exactly the same in every cell, there 
is in general a marked constancy of relative lengths. Were 
Meves’ and Della Valle’s measurements correct, the same would 
probably appear there. 
d. Summary of measurements. The. data here presented in 
connection with measurements upon the chromosomes of Amby¬ 
stoma tigrinum and Salamandra maculosa cannot well be inter¬ 
preted as a confirmation of Meves’ and Della Valle’s contention 
that pairing of the chromosomes and a constant organization of 
the chromosomes do not exist because: 1) Their data, on 
account of errors inherent in the material, are too unreliable to 
command confidence; 2) the differences in the lengths of the 
chromosomes of Salamandra maculosa are too small to permit 
one to deny or to affirm the existence of pairs, and, 3) it has 
been shown that because of obvious foreshortenings, individually 
mentioned above, which are unaccounted for in Meves’ measure¬ 
ments, there probably is a somewhat constant difference between 
chromosomes 8 and 9 in eleven out of the twelve cells which he 
