AUTHOR'S ABSTRACT OF THIS PAPER ISSUED 
BY THE BIBLIOGRAPHIC SERVICE, JUNE 21 
A STUDY ON THE CHROMOSOMES IN THE SPER- 
MATOGENESIS OF THE STONEFLY, PERLA IMMAR- 
GINATA SAY, WITH SPECIAL REFERENCE TO THE 
QUESTION OF SYNAPSIS 
WARO NAKAHARA 
Department of Histology and Embryology, Cornell University, Ithaca, New York. 
THREE PLATES (FIFTY-ONE FIGURES) 
CONTENTS 
Introduction oss. srits ocd ask ee AGT SRR Mae oer crate oes Me en izist 509 
“1RGYA VITO LLORAS OS NEES Bete POOR MIE AIS tt dos CaRL an Cee nt ANS © hens clomiotes 510 
NUL EON es trad che RSE CE ¢ TAOS 4 pote manera Wate cie ese ee ale aees 510 
rHDral CONSIGEERUIONS 2 oot iG fee eitie ce Se fet ette sce bern ree bbe o ttem ete He 513 
Pairing of chromosomes and the probability of synapsis................ 513 
BUGEMESLEC: MGUECS. Of SV MAUSIO GY. boon. oic's:- Sapa etyag by gcc Paes Noein she tad aaes 515 
MOREE oR MITEIEEE DR Wits eae ed NA oe Sos Sed hcvocaneBORgnp) WIPE eres Se al cha, Shae eG 518 
ie ret LOMIALKS Cea ata te Skee Re ket Ce Fee ace ote meee ad eae 519 
ageraruncwered aia %, sahsds EER e ee. AEC Recher Reis eh 2 as ea 520 
INTRODUCTION 
The need of accurate knowledge of the chromosomes, and 
especially their behavior in the maturation divisions, can hardly 
be overemphasized. The chromosome theory of inheritance, so 
beautiful a unification of biological knowledge as it is, cannot be 
fully established until the true nature of synapsis and other 
phenomena involved in the course of maturation divisions are 
satisfactorily understood. 
The present contribution to the study of the chromosomes 
is based on my observations on the spermatogenesis of the 
stonefly, Perla immarginata Say (Plecoptera). The fact that, 
notwithstanding recent cytological activity, the order Plecoptera 
has not been made a subject for chromosome study led me to 
make some preliminary observations on a few species of this 
group of insects during the fall of 1916. Perla immarginata, 
509 
