REMOVAL OF INHERITED TENDENCIES. 441 



constitutes the diathesis must have preexisted to each of the diseases 

 named, even though it was in no manner obvious to the most careful 

 observer ? 



Acute, chronic, diathetic, or incubative disease may therefore be 

 regarded as merely expressing the various gradations of morbid pro- 

 cesses, from the very rapid to the very slow, from the very severe 

 to the very mild, and from the most readily perceived to the imper- 

 ceptible. 



As acute diseases are only compatible with life for short periods, 

 they are rarely transmitted ; in fact, they are excluded from the list 

 of diseases properly inheritable. The open chronic forms of disease, 

 such as scrofula and syphilis, are not unfrequently handed down to the 

 offspring, but far oftener is the heritage of the diathetic grade. This 

 is better tolerated, or more compatible with the continuance of the life 

 in the blood than the open chronic forms which quite commonly ren- 

 der the procreative act abortive. 



Before bringing our subject to its practical bearings, it seems ne- 

 cessary that the reader should divest his mind of any vestiges of the 

 glamour of superstition which has so long been around the reproduc- 

 tive process. Darwin succeeds in this with admirable directness by 

 putting reproduction simply as a process of growth. Two cells with 

 somewhat diverse qualities commingle and by gradual accretion de- 

 velop individual peculiarities. The new self- multiplying stream of 

 blood sometimes appears as if derived in unequal proportions from the 

 two progenitors. This may, however, be supposed to arise from an- 

 other cause, a temporary or permanent prepotency of the gemnules of 

 one parent over those of the other, which gives them greater activity 

 and power of fission. Be this as it may, every new blood-stream is 

 but a continuation of two older, wonderfully compressed at the junc- 

 tion. The preexistent forms and forces are only slightly modified by 

 mixture, and by the influence of some variable conditions. In all the 

 general outlines of qualities it is the same blood, exhibiting the same 

 tendencies near or remote to good or to evil, to health or to disease. 

 If there has been a slow struggle often so subtile as to be at times 

 occult in the parental organism between the tendency to the main- 

 tenance of a permanent type and some morbid predisposition the 

 same is almost certain to be carried on in the blood of the child. The 

 leading causes of any divergence from the continuation of the struggle 

 consist in the crossing of blood, and in the application of modifying 

 conditions when impressibility is at its acme, as from germinal coales- 

 cence to adolescence. 



With the foregoing facts and deductions in mind, and ranging them 

 around what Dr. Farr terms the great hygienic problem how to free 

 the people from hereditary disease the solution does not appear as 

 hopeless and difficult as has been supposed. On the side of release is 

 the great conservative principle of reversion ; on the side of continued 



