There appears to be so little uniformity as to the presence of the heterochromosomes, even in insects, and in their behavior when present, that further discussion of their probable function must be deferred until the spermatogenesis of many more forms has been carefully worked out.
Bryn Mawr College, May 15, 1905.
BIBLIOGRAPHY.
Baumgartner, W. J.
'04. Some new evidences for the individuality of the chromosomes. Biol. Bull., vol. 8, no. 1.
McClung, C. E.
'99. A peculiar nuclear element in the male reproductive cells of insects. Zool. Bull., vol. 2.
'00. The spermatocyte divisions of the Acrididæ. Kans. Univ. Quart., vol. 9, no. 1.