AUTEOR'S ABSTRACT OF THIS PAPER ISSUED 
BY THE BIBLIOGRAPHIC SERVICE, JULY 21 
THE SEXUAL CHARACTERISTICS OF THE MEM- 
BRACID, THELIA BIMACULATA (FABR.) 
I. EXTERNAL CHANGES INDUCED BY APHELOPUS THELIAE (GAHAN) 
SIDNEY I. KORNHAUSER 
The Zoological Laboratory of Northwestern University and the Biological Laboratory 
of the Brooklyn Institute of Arts and Sciences at Cold Spring Harbor, 
Long Island 
FIFTY-FOUR TEXT FIGURES 
CONTENTS 
ee O CH GELOM, 228s. ot Senin wns tie ain cueiae <2 ames ashes Saas ate ee aghraie «eee ae 531 
2. Synopsis of previous papers on the sex of Al a BA oe Como 
3. Material and methods. . : oT iteoly Joba ay Pisaa 
4. Brief account of the life history, meet habits a holier: : 545 
5. Aphelopus theliae (Gahan), a Peat cpaseinde Omer fe shite 
history and habits.. : . 547 
6. Changes induced by Wanelonast in Mine jeolont ad nunc 6 che meee 
and appendages of Thelia.. mrt BS. SELSOG Ye eer SU An one 
7. An account of two significant asda} Sieg Sedge eS CORE een 
Se, LD EST ELTSIEE iN Bae DE RE Gee Cotes pitas sere A ee einer tte oe ey. ee Oe 2 ae 599 
Ub, QUI DIPRE TS peal eee a ARR erin teem ead ox DiI ell ng fs edly ino era 629 
1. INTRODUCTION 
In the insects and especially in the Homoptera, the supposed 
physical mechanism for sex determination is well known. Most 
of the forms show a single x-chromosome in the male diploid 
group and two x-chromosomes in the female diploid group. 
A wide difference of opinion exists as to the part these chromo- 
somes play in sex differentiation. One investigator will speak 
of them as sex determiners, another will allow that they are 
merely associated with sex, a morphological expression of the 
underlying sex and comparable only to other structural sexual 
differences. The present paper is an attempt to throw some 
light on sex determination in insects. 
531 
JOURNAL OF MORPHOLOGY, VOL. 32, NO. 3 
