3O STEFAN KOPEC. 



offspring parthenogenetically produced by starved Daphnia was 

 smaller than control specimens. 



In contrast to the offspring of starved females the progeny of 

 similarly treated males were essentially lighter than those pro- 

 duced by control males. The unfavorable influence of starva- 

 tion of males was evidenced by increased mortality of caterpillars 

 as well as of chrysalicls, which could not be observed in the off- 

 spring of starved females. As egg size was also in this experiment 

 normal, the cause of these changes ought to be ascribed to the 

 specific influence exerted by starvation of males on their sperma- 

 tozoa. 



A great influence on the offspring of the Mammalia exerted by 

 certain substances applied to their fathers was demonstrated, 

 e.g., by experiments on the influence of alcohol made by Stockard 

 and his collaborators ('12- 'i 8) and others, by the experiments on 

 lead performed by Cole and Bachhuber ('14) and by those of 

 Guyerand Smith ('18 and '20) on a special lens dissolving serum. 

 These researches have shown a considerable susceptibility of the 

 spermatozoa to certain extrinsic specific substances. My experi- 

 ments prove that normal development of the spermatozoa may 

 also be influenced by certain natural changes of metabolism 

 caused by inanition. Histological research has shown that the 

 males which develop from starved caterpillars contain the same 

 quantities of reserve substances relatively to their diminished 

 size as control specimens; as the testicles of the moth which 

 develop in the caterpillar at the expense of these substances are 

 too small organs to play an important role in the nutritive balance 

 of the chrysalis undergoing metamorphosis, it ought to be sup- 

 posed that the influence exerted on the spermatozoa by hunger 

 metabolism consists in qualitative and not in quantitative changes 

 of the chemical constitution of the spermatozoa. In my experi- 

 ments I did not succeed in ascertaining any marked histological 

 changes in the developing "starved" testicle, neither as to the 

 evolutive rate, nor as to the structure of the sexual elements. 

 Physiological dimorphism of metabolism in the two sexes is 

 certainly the cause why starvation of females does not elicit 

 analogous unfavorable quantitative changes in the egg. 



From the above results we may infer that the decreased weight 

 of the offspring of two starved parents determined in silkworms 



