444 THE BIOLOGICAL BASIS OF INDIVIDUALITY 



of different tissues or substances, or even of apparently the same kind of tissues 

 at different localities within the same individual? Do the organismal differen- 

 tials cause variations in the hormones and the tissues in which they originate 

 or in the recipient tissues? As the following analysis will show, as a rule the 

 specificity in the reactions in these cases seems to reside in the recipient tissues 

 rather than in the morphogenic agents.. This conclusion is in accordance with 

 what is known as to the lack of organismal differentials in hormones in the 

 large majority of cases and their presence in the tissues, in which latter, 

 therefore, the individuality of the organism predominantly resides. 



A simple specificity of the first type exists, for instance, in the structure 

 of the different parts of the uterine cervix and in the graded interaction of 

 this organ with two kinds of hormones. We shall return, here, somewhat more 

 fully to this condition, to which we have already referred in a different con- 

 nection in a preceding chapter. 



In the genital tract of the female guinea pig there exists a graded change in 

 structure in the direction from the vagina through the different portions of 

 the cervix to the uterus, and correspondingly, there can be demonstrated 

 experimentally a graded responsiveness of these tissues to the two ovarian 

 hormones, the follicular hormone and the corpus luteum hormone. The grada- 

 tion in the action of the lutein substance is in an opposite direction to that of 

 the follicular hormone. Thus in the system consisting of vagina, cervix and 

 uterus, the response to the follicular hormone is strongest in the vagina and 

 shows a graded decrease in the various portions of the cervix. It has still a 

 definite effect of its own in the uterus, but one that is different from the 

 effect observed in vagina and cervix. Through increasing the amount of 

 follicular hormone the reaction in the middle portion of the cervix, which 

 normally is much less responsive to this substance than the vagina, can be 

 made more distinct; but the same quantity of hormone exerts, then, a still 

 stronger stimulating effect on the vagina. In general, the greater the amount of 

 hormone which is allowed to act, the greater the proportional response of the 

 various tissues, this response being always relatively greater in the vagina 

 than higher up, and decreasing the more the nearer the tissue is to the uterus. 

 The reverse relation is noted in the case of the lutein hormone. This exerts a 

 very strong effect on the uterus, which extends only to the directly adjoining 

 part of the cervix, while in the vagina and presumably also in the lower 

 portion of the cervix it exerts mainly an antagonistic and inhibiting influence 

 on the follicular hormone, thus favoring a resting condition in these organs, 

 which otherwise would be stimulated by the latter substance. The most in- 

 teresting feature in this connection is the graded character of these reactions. 

 Apparently we have to deal with a graded difference in the state of sensitiza- 

 tion of these tissues, which either leads to the binding of a graded amount of 

 hormone by the various tissues and thus to a gradation of the reactions, or 

 causes a difference in the responsiveness of the tissues after they have com- 

 binca with the same amount of hormone. In this case there is thus a specificity 

 in the interactions of adjoining tissues in the same organism with two hor- 

 mones and a corresponding specificity in the structure of these tissues. We 



