A CYTOLOGICAL STUDY OF SECRETORY PHE- 

 NOMENA IN THE SILK GLAND OF 

 IIYPHANTRIA CUNEA. 



ELIZABETH KINNEY, 

 WASHINGTON UNIVERSITY, ST. Louis. 



INTRODUCTION. 



The general anatomy and histology of the silk glands of 

 lepidopterous larvae have been carefully studied and described 

 by numerous investigators beginning with the work of Helm ('76), 

 but little purely cytological study of the cells with an aim 

 toward giving an account of the mechanism of secretion was 

 reported before the investigations of Maziarski ('n) and later 

 of Nakahara ('17). Since that time, few papers have appeared 

 based upon studies of the silk gland, with the exception of an 

 account by Yamanouchi ("22) describing a morphological study 

 of silk secretion. 



In previous investigations of silk secretion, studies have been 

 made only upon glands of caterpillars which spin a cocoon at a 

 certain period in their life history. Such study is of value in 

 observing glandular function and development during the pro- 

 gressive stages preparatory to and at the time of activity. In 

 order to best study the actual process of secretion, the optimum 

 material would naturally be found in a form which secretes 

 actively over a comparatively long period of time. 



The fall webworm, Hyphantria cunea, is ideally adapted for 

 the study of active secretion, for the caterpillars live together 

 in colonies, secreting the web continually throughout larval life 

 in the process of securing food. This form, therefore, was 

 selected for the present investigation and by the application of 

 cytological methods, an attempt has been made to determine 

 the cellular organization which is concerned with secretory 

 phenomena in the silk gland. 



Work upon this problem was for the most part carried on 

 during 1925 and 1926, at Washington University, St. Louis, 



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