AN EXTRA DYAD AND EXTRA TETRAD IN CAMNULA 383 
in the first spermatocytes twelve elements are always present, it 
seems justifiable to regard twenty-three and twelve as the funda- 
mental numbers for the male germ cells of this genus. 
Since, nevertheless, numerical variations in the organization 
of the chromosome complex occur within the individual in the 
species pellucida, it is impossible to state, without having made 
systematic counts in every cyst containing mitotic figures, what 
the conditions are in any given animal. All possible chromosome 
counts can be made, for instance, in the cells of nine consecutive 
first spermatocyte cysts of individual 2525 (table 3) before dis- 
covering any variation, and yet the number of elements in the 
cells of this generation varies from twelve to thirteen. Further- 
more, the valence of the thirteenth element varies: in some cysts 
it ig a dyad, in others a tetrad. Again, in individual 2526 counts 
were made in every cyst and follicle in which metaphase figures 
occurred without discovering any variation. But an examination 
of some first spermatocyte prophases showed the chromosome 
count to be inconstant. 
The fundamental diploid or spermatogonial metaphase com- 
plex in Camnula consists, then, of twenty-three dyads; and the 
haploid or first spermatocyte complex of eleven tetrads and one 
dyad, the accessory. - There are the usual two classes of second 
spermatocytes with respectively eleven and twelve dyads. 
I have observed nothing unusual about these chromosomes. 
They have terminal fiber attachments and consequently are of 
the Hippiscus (McClung, 714) or telomitic (Carothers, ’17) type. 
Their form and behavior have been fully discussed by McClung 
(14), Wenrich (16), Carothers (17), and others. 
Plate 2, illustrating the complexes of individual 954.1, and 
plate 5, illustrating those of no. 2482, will serve to represent the 
fundamental chromosomal organization for the various germ-cell 
generations in the camnulan testis. 
Individual 954.1 was collected on Oreas Island, Puget Sound, 
Washington, in 1909. Nothing unusual was found in the germ 
cells of this animal except the element labeled C in figure 15 
(pl. 2). This element has been identified tentatively as the 
chromatoid body. It was observed in only three or four meta- 
JOURNAL OF MORPHOLOGY, VOL. 34, NO. 2 
