CHAPER VI 



FACTORS INTERFERING 

 WITH GENES 



1 . Hormones 



The pattern of proteins in protoplasm is generally determined by 

 genes, but there are many evidences showing that factors other than 

 genes can also play an important role in the determination of the 

 pattern. Hormones appear to be substances which are produced by 

 organisms for the purpose to interfere with the gene action. 



Insects will generally change in a remarkable way their shapes 

 and functions during their developmental process, that is, they undergo 

 metomorphosis. Such metamorphosis may be caused by the rapid 

 development of the structural change in the protoplam protein. In 

 other words, metamorphosis may be a result of a rapid change in 

 "crystal shape" of the protoplasm; and the "crystal shape" may be 

 altered by the change in the structure of the component substance. 

 On the other hand, it is generally accepted that hormones are involved 

 in metamorphosis. The removal from insects of endocrine glands, 

 such as prothracic gland and corpora allata, can induce profound 

 effects in the feature of matamorphosis. This fact strongly suggests 

 that hormones may be able to change the structure of protoplasm 

 proteins. 



Such effects of hormones upon the "crystal shape" of protoplasm 

 can generally be observed in animals. As is well known when fed 

 thyroid gland, the metamorphosis of tadpoles is accelerated and pigmy 

 frogs will result, whilst when fed thymus, the metamorphosis is 

 delayed to make giant tadpoles. Likewise in man disorders in endo- 

 crine secretion lead to abnormal shapes and functions. It may be 

 concluded, therefore, that hormones are factors capable of strikingly 

 interfering with the action of genes. The effect of hormones on the 

 "crystal shape" of protoplasm seems to be of extremely high physio- 

 logical significance; organisms can establish their normal development 

 and achieve various functions owing to this effect of hormones. 



As we have seen above, enzyme systems are directed by genes, 

 whereas it is believed that hormones constitute an important set of 



