IS THE INSECT METAMORPHOSIS INFLUENCED 

 BY THYROID FEEDING? 



STEFAN KOPEC, 

 GOVERNMENT INSTITUTE FOR AGRICULTURAL RESEARCH, PULAWV, POLAND.' 



(With 5 Tables.) 



The investigations on the influence of the thyroid gland on 

 the rate of metamorphosis in insects have not as yet yielded 

 any decisive results. Northrop ('17) fed larvae of Drosophila 

 on thyroid and ascertained that this gland is not adequate as 

 food for the examined animals. Kunkel ('18) who studied the 

 influence of the thyroid on the development of the fly Lucilia, 

 noticed an abbreviation of the pupal stage and a retardation of 

 growth. Abderhalden ('19) irrigated Euphorbia plants with i 

 per cent, thyroid extract and observed that the caterpillars of 

 Deilephila euphorbia fed on these plants were "zum Teil auffal- 

 lend klein." In the researches of Romeis and v. Dobkiewicz 

 ('20) the larvae of the flies Calliphora vomitoria fed on thyroid 

 gland underwent pupation later than the control specimens, 

 their weight, however, being not smaller. From his experiments 

 Kahn ('21) draws the conclusion that in Corethra plumicornis, 

 Ecdyurus forcipula and Tenebrio molitor neither the human 

 thyroid nor the preparation "Jodalbacid" have any influence 

 on the metamorphosis of their larvae. 



The discrepancy of the above results may be explained not 

 only by the heterogeneity of the material of animals and of the 

 substances used, but, at least to the same degree, by the probably 

 too scanty material in separate experiments as well as by the 

 insufficient method of the elaboration of the data recorded. 

 E.g., Abderhalden's opinion mentioned above is not supported 

 by any numerical data and can consequently not be considered 

 as decisive from the biometrical standpoint, all the more as we 

 do not know the pedigrees of the animals under examination. 



1 Paper from the Laboratory of Experimental Morphology., cf. Mem. de I'lnstitut 

 National Polonais d'Economie Rurale a Pulawy, Vol. 5, 1924, presented at print 

 September 22, 1924. 



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