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Title: Studies in Spermatogenesis
Part II

Author: Nettie Maria Stevens

Release Date: March 7, 2010 [EBook #31546]

Language: English

Character set encoding: ASCII

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STUDIES IN SPERMATOGENESIS

PART II.

(PAGES 33-74. PLATES VIII-XV.)

A COMPARATIVE STUDY OF THE HETEROCHROMOSOMES
IN CERTAIN SPECIES OF COLEOPTERA,
HEMIPTERA AND LEPIDOPTERA, WITH
ESPECIAL REFERENCE TO

SEX DETERMINATION.

BY N. M. STEVENS

[Illustration]

WASHINGTON, D. C.:
Published by the Carnegie Institution of Washington
October, 1906

CARNEGIE INSTITUTION OF WASHINGTON

PUBLICATION NO. 36, PART II.

FROM THE PRESS OF
THE WILKENS-SHEIRY PRINTING CO.
WASHINGTON, D. C.

STUDIES IN SPERMATOGENESIS.--II.

A COMPARATIVE STUDY OF THE HETEROCHROMOSOMES IN CERTAIN SPECIES OF
COLEOPTERA, HEMIPTERA, AND LEPIDOPTERA, WITH ESPECIAL REFERENCE TO SEX
DETERMINATION.

By N. M. STEVENS.

INTRODUCTION.

In Part I of this series of papers, the spermatogenesis of five species
belonging to four different orders of insects was considered. In two
species of Orthoptera an "accessory chromosome" was found; in _Tenebrio
molitor_, one of the Coleoptera, an unequal pair of chromosomes was
described; in the other species no heterochromosomes were discovered.
The apparent bearing of the chromosome conditions in _Tenebrio molitor_
on the problem of sex determination has led to a further investigation
of the germ cells of the Coleoptera. One of the Hemiptera homoptera and
two of the Lepidoptera have also been examined for comparison with the
Coleoptera and the Hemiptera heteroptera.

METHODS.

As a result of previous experience with similar material, only two
general methods of fixing and staining have been employed: (1) Fixation
in Flemming's strong solution or Hermann's platino-aceto-osmic,