A COMPARATIVE STUDY OF THE CHROMOSOMES 

 OF LACHNOSTERNA (COLEOPTERA). 



E. L. SHAFFER, 

 DEPARTMENT OF BIOLOGY, PRINCETON UNIVERSITY. 



A. INTRODUCTION. 



The studies presented here were begun in the spring of 1916 at 

 Princeton University and were continued until the spring of 1917. 

 Most of the material used was collected at Cold Spring Harbor 

 during the summer of 1916. l The studies were discontinued in 

 the summer of 1917 owing to the war. On returning to Princeton 

 last spring, it was thought advisable to assemble the observations 

 previously made despite the fact that they did not represent as 

 complete a study as had been intended. 



I wish to express my sincere thanks to Professor E. G. Conklin 

 for much valuable assistance and encouragement. 



B. MATERIALS AND PLAN OF STUDY. 



It was originally intended to make a detailed study of the 

 process of synapsis as well as a comparative study of the chro- 

 mosomes of four selected species of May beetles, genus Lach- 

 nosterna. While the material was not entirely favorable for these 

 purposes, some interesting facts were brought to light. 



The four scarab beetles of the genus Lachnosterna which were 

 selected for study were the species delata, fusca, gracilis and 

 tristis. Besides these, for comparative purposes, two other 

 scarab beetles were .studied, Pelidonota pimctata and Cotalpa 

 lanigera. The form most studied was L. delata and since the 

 other forms showed no essential differences from delata, the latter 

 will be used as the basis of description in the present paper. 



Comparatively little detailed study of spermatogenesis in the 

 Coleoptera has been done. The work of Miss Stevens ('05, '06), 



1 The writer wishes to express his thanks to the Brooklyn Institute of Arts anP 

 Sciences for the privileges of a research fellowship at the Laboratory of the Institute 

 at Cold Spring Harbor, L. L, during the summer of 1916. 



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