WENRICH: SPERMATOGENESIS OF PHRYNOTETTIX MAGNUS. 107 
include under the term “ V-shaped” all the chromosomes which have 
a non-terminal spindle-fiber attachment. They may be regarded as 
rods which have become bent at the point of the spindle-fiber attach- 
ment. Broadly, therefore, we may look upon all chromosomes as 
rod-shaped, but it will make description easier to distinguish the 
types just mentioned. 
In attempting to show that chromosomes have a constant size and 
shape for each species, as well as a constant number, it will be well to 
call attention to the fact, so clearly stated by McClung (’14), that the 
point of the spindle-fiber attachment is, as a general rule, constant 
and therefore one of the indications of a persistent organization for 
each individual chromosome. 
Some groups of animals exhibit a high degree of uniformity in the 
shape and size of the chromosomes in any species, as for example, 
among the Crustacea and the Amphibia, while others show a great 
variety of forms (Orthoptera, mammals). In the groups with diverse 
shapes and sizes of chromosomes, the striking fact was pointed out by 
Montgomery (’01) that there are two of each different size. Mont- 
gomery reached the logical conclusion that of the two equivalent 
series existing in each cell, one had been derived from the maternal 
and the other from the paternal ancestor. 
That the same series of sizes and shapes reappears in each cell- 
generation, is recorded by nearly every observer whose material is 
favorable enough to admit of such comparisons. The work of Mc- 
Clung (’00, ’02, 04, ’08b, ’14), Sutton (’02, ’03), Baumgartner (’04), 
Nowlin (’08), Pinney (’08), Robertson (’08) on orthopteran material 
has done much to establish this fundamental feature of individuality. 
A very interesting series of observations on this point is that of Meek 
(’12a, ’12b) on Stenobothrus. He describes the results of a series of 
careful measurements of chromosome-dimensions in different genera- 
tions of cells, and as a result of these observations becomes convinced 
of the existence of persistent individuality. I may quote some of his 
conclusions (’12a, p. 24, ff.): —“(1) In all metaphases the relative 
positions of the chromosomes in the equatorial plate appear to be 
arbitrary. (2) The rods composing all ordinary chromosomes are 
cylindrical with rounded ends, and of an uniform and constant diame- 
ter, viz., 0.83 micra. In each species eight lengths have been found, 
and these constitute members of a series in arithmetical progression, 
of which the difference between consecutive terms is equal to the 
radius of the rod. The heterotropic chromosome does not belong to 
this general series, for, although equal in length to the longest rod, its 
