136 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
Various combinations of the allosomes in the same species occur 
in the Hemiptera, where they have been described by Wilson and 
Montgomery. 
A glance at the above classification will show that among insects 
the first type of monosome (A 1) is characteristic of the Orthoptera, 
although it occurs in a few instances in the Hemiptera and Coleoptera. 
In the Orthoptera it has been found in all the forms investigated with 
the exception of Syrbula, Stenopelmatus, and Periplaneta. In Syrbula, 
one of the Acrididae, Montgomery (:05) found that the allosome of 
the spermatocytes is represented in the spermatogonia by two elements 
of equal size and is therefore a diplosome. During the early growth 
period the diplosomes become joined end to end to form a rod: shaped 
element, which retains its compact structure and during the prophase 
of the first division becomes bent into a V. It divides reductionally 
in the first division and equationally in the second. ‘These results of 
Montgomery’s need confirmation, since all other observers who have 
traced the history of the allosome in the Orthoptera have found that 
it is unpaired in the spermatogonia and does not divide during the 
first division. Montgomery’s Figure 33 is suggestive of an interpreta- 
tion different from his, in that it shows a chromosome attached by 
mantle fibers to only one spindle pole, a condition that I have found to 
be realized in all the forms I have studied. Montgomery, however, 
believed that later this element divides. To quote: —‘‘In a number of 
cases after nine of the chromosomes were arranged in the equator and 
some of these were beginning to divide (Fig. 33) one (y) had not yet 
taken up that position but lay nearer one spindle pole than the other. 
This was the case e. g. with four cells in exactly the same stage lying 
in the same section of one testicular follicle, and in all of these the 
isolated chromosome was of the same size and form, straight, and 
appearing to consist of two closely apposed arms. It may bé that this 
is the heterochromosome, with which it agrees in general form and size, 
but this could not be definitely determined; ultimately it takes a 
position in the equator and divides with the others.” 
In Stenopelmatus Miss Stevens (:05") has found that a conspicuous 
element, colored deeply with chromatin stains, appears in the early 
spermatocyte but is not represented in the spermatogonia. This 
peculiar element “first appears attached to an end of the spireme in 
the growth stage of the young spermatocytes, where it is much smaller ~ 
than in later growth stages. It gradually increases in size, is a con- 
spicuous element in the first maturation spindle, goes into one of each 
pair of spermatocytes of the second order, and then degenerates during 
