130 THE AMERICAN NATURALIST [Vol. LVI 



cies of the germ. They are what they are somatically 

 because of the special restrictions or excitations of their 

 particular situation in the organism. But if these highly 

 specialized tissue-cells can be so stimulated as to form an 

 entirely different type of tissue, may not such stimulative 

 influences invade even the germ-cell with modifying ef- 

 fects! 



Lastly, there are the endocrinal secretions to be reck- 

 oned with. Since they are at present popular subjects 

 of research and are constantly being alluded to and dis- 

 cussed in the biological literature of the day, I need not 

 review the field. It is evident that in them we have cir- 

 culating through the body a series of powerful substances 

 capable of producing profound effects in any or all parts 

 of the body. Through them, apparently, various organs 

 effect reciprocal stimulations and the tissue-complexes of 

 the entire body are maintained in a state of general 

 physiological equilibrium. Both clinical and experi- 

 mental evidence reveals that hypertrophy or atrophy of 

 an endocrine gland may be followed by marked altera- 

 tions of structure or function in one or more regions of 

 the body. Thus the cretinism or the myxoedematous 

 condition which results from removal of the thyroid or 

 arrest in its function, or the symptoms resembling 

 exophthalmic goiter following hyperthyroidism are famil- 

 iar examples. The remarkable overgrowth of the bones 

 of the extremities and head knowm as acromegaly— mor- 

 bid giantism— associated with enlargement of the pitui- 

 tary body is another. Also the relations of the gonads to 

 the secondary sexual characters are well known, as is that 

 of the fetus to the normal hypertrophy of the mammary 

 glands in pregnancy. 



Since hypertrophy or atrophy of an endocrine may pro- 

 duce deep-seated permanent changes in various tissues 

 of an organism, I would again point out the possibility 

 that the germinal homologues of the proteins of such 

 tissues, if such there be, might likewise be permanently 

 modified, and that if for some reason there came a con- 

 stant inherited increase or diminution of an endocrine 



