The Project Gutenberg EBook of Studies in Spermatogenesis (Part 1 of 2), by
Nettie Maria Stevens

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Title: Studies in Spermatogenesis (Part 1 of 2)

Author: Nettie Maria Stevens

Release Date: March 7, 2010 [EBook #31545]

Language: English

Character set encoding: ASCII

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STUDIES IN SPERMATOGENESIS

WITH ESPECIAL REFERENCE TO THE

"ACCESSORY CHROMOSOME"

BY N. M. STEVENS.

[Illustration]

WASHINGTON, D. C.:
Published by the Carnegie Institution of Washington
September, 1905.

CARNEGIE INSTITUTION OF WASHINGTON

PUBLICATION No. 36

FROM THE PRESS OF
THE HENRY E. WILKENS PRINTING CO.
WASHINGTON, D. C.

STUDIES IN SPERMATOGENESIS WITH ESPECIAL REFERENCE TO THE "ACCESSORY
CHROMOSOME."

By N. M. STEVENS.

In connection with the problem of sex determination it has seemed
necessary to investigate further the so-called "accessory chromosome,"
which, according to McClung ('02), may be a sex determinant. This view
has been supported by Sutton ('02) in his work on _Brachystola magna_,
but rejected by Miss Wallace ('05) for the spider.

The forms selected for study have been taken from several groups of
insects, and are all species whose spermatogenesis has not been
previously worked out. They are (1) a California termite, _Termopsis
angusticollis_; (2) a California sand-cricket, _Stenopelmatus_; (3) the
croton-bug, _Blattella germanica_; (4) the common meal-worm, _Tenebrio
molitor_; and (5) one of the aphids, _Aphis oenotherae_.

A brief account of a chromatin element resembling the accessory
chromosome in _Sagitta_ has been added for comparison. The
spermatogenesis of each form will be described in detail, and a general
discussion of the results and their relation to the accessory chromosome
and sex determination will follow. The spermatogenesis of the aphid has
been included in another paper, but a summary of results and a few