68 ADAPTATION AND DISEASE 



acquired immunity, the inheritance not merely of conditions 

 of defect, but of positive acquirements. 



Here we come to the boundary of the territory already 

 acquired, unless, indeed, during the last three years of war, quiet 

 workers in the United States, whose observations I have been 

 unable to follow, have carried the demonstration yet further. 

 Years ago 1 1 pointed out the need to distinguish in this relation- 

 ship between extrinsic and intrinsic influences upon the germ 

 cells. Toxines are instances of the first order — introduced 

 from without they act upon the germ cells at the same time as 

 they influence the tissue cells in general. As examples of the 

 intrinsic and indirect, I instanced the effect of influences from 

 without telling upon the function of one or other organ and so 

 disturbing general metabolism that either the absence of normal 

 metabolites or presence of abnormal metabolites circulating in 

 the blood might bring about alteration in the constitution of the 

 germinal biophores, with resulting alteration in the constitution of 

 the offspring. In this way, I pointed out, gouty and rheumatoid 

 states and defect and excess of internal secretions may tell upon 

 the germ cells. It is thus that we best explain the development 

 of diatheses. I pointed out in 1912 2 that " if the cells of particu- 

 lar organs are highly susceptible to hormones and other active 

 principles of the secretions of other organs, is it not likely that 

 the parent germ plasm, the cell matter which by its active 

 growth is capable of giving origin to all these organs and tissues, 

 should likewise be susceptible to their action, and influenced by 

 their excess or deficiency ? Nay, should we not expect that 

 bodies of this nature, developed by the cells in their activity, 

 should act with greater ease upon the living substance of the 

 germ cells than extraneous drugs are likely to act ? As a matter 

 of fact, alterations in such glands as the thyroid, the pituitary, 

 the adrenal cortex, the pineal, are found to have a profound 

 influence upon the sexual function/' 3 Influences acting upon 

 these organs of internal secretion, and conditions acquired by 

 these organs, may well so modify them that the offspring in 



1 On the Inheritance of Acquired Conditions, 1901, reprinted as Chapter II. 

 of Part II. of this volume. Article " Inheritance and Disease " in Modern 

 Medicine by Sir William Osier and T. McCrae, vol. i., 1907, p. 109. See 

 also Principles of Pathology, vol. i. 2nd edit., 1910, p. 199. 



2 " A Study in Eugenics," The Lancet, 1912, ii. (Nov. 2). 



3 I had laid this down in 1901. (Consult Chapter I. of Part II.) 



