author's abstract of this paper issued 

 by the bibliographic service, may 4 



THE EFFECTS OF THE DUCTLESS GLANDS ON THE 

 DEVELOPMENT OF THE FLESH FLIES 



B. W. KUNKEL 



From the Department of Biology, Lafayette College, Easton, Pa. 



The effects on enibryoiiic development of the ductless glands 

 have not as yet been very widely studied, and our knowledge of 

 their action is extremely meager. As practically all the experi- 

 ments on the developing embryo have been m ade on vertebrates, 

 it seemed desirable to determine if possible how some of the 

 invertebrates react to these glands in which no organ comparable 

 to a ductless gland has, so far as I know, been demonstrated. 



In addition to the work of Gudernatsch on frogs and rats, 

 recently Northrop has experimented on Drosophila and found 

 that although the larvae of this fly do not develop normally on a 

 sterile paste made by grinding fresh thyroid and thymus with 

 glass, the larvae develop quite normally when bacteria are present 

 in the cultures. Aside from these studies just mentioned, the 

 only other animals which have been used have been Paramecium 

 by Nowikoff, Shumway, and Budington and Harvey who also 

 used Stylonichia. 



In view^ of the suppression of growth and acceleration of differ- 

 entiation which has been observed in the tadpole by Gudernatsch, 

 it seemed especially desirable to test the effects of thyroid gland 

 on an animal in which the processes of growth and differentiation 

 are more or less completely separated, as is the case in the 

 insects which have a complete metamorphosis. The flesh flies 

 seemed to lend themselves to this purpose most perfectly because 

 of their abundance and the ease of rearing them as well as because 

 the larvae consume the ductless glands with avidity and thrive 

 on them. 



The flesh flies which I found visiting exposed meat during the 

 summer months are: Lucilia caesar, L. sericata, Calliphora 

 erythrocephala, and a species of Sarcophaga, probably sarracena. 



255 



