1872.] 



Mr. F. Gal ton on Blood-relationship. 



401 



elements : we do not mend matters in the least, but we gratuitously add 

 confusion to our ignorance, by dealing with hereditary facts on the plan 

 of ordinary pedigrees — namely, from the persons of the parents to those 

 of their offspring. 



It will be observed that, owing to the clearer idea'we have now obtained 

 of the meaning of kinship and of the consecutive phases of the chain of 

 life, the various causes of individual variation can be easily and surely 

 sorted into their proper places. I will mention a few of them, merely as 

 examples. 



Previous to the segregation of the embryonic elements, if the structureless 

 ones be diverse without any strongly preponderating element, it is impossible 

 to foresee the character of the embryo, just as it is impossible to foresee 

 the character of a handful chosen from an urn containing a mixed assem- 

 blage of variously coloured balls ; but if they be not diverse, then the 

 embryonic elements will be a true sample of the structureless ones, the 

 conditions of purity of blood are fulfilled, and the offspring will resemble 

 its parents. 



We also see, in the process by which the embryonic elements are ob- 

 tained, how the curious phenomenon may occur of inheritance occasionally 

 skipping alternate generations. The more that has been removed from 

 the structureless group for the supply of the embryonic (which, as we have 

 seen, is a nearly sterile destination) the less remains for the <f residue," 

 too little, it may be, to assert itself by that, the only prolific, line of 

 transmission. In the supposed case it would recuperate itself during the 

 succeeding generation, where the elements in question will have remained 

 wholly latent, owing to their insignificance in the structureless stage of 

 that generation, which would be sufficient to secure any portion of it from 

 selection for the embryonic form. 



Again, it is in the process of selection of elements, both latent and 

 patent, from the adult parents for the structureless stage of the next gene- 

 ration, where I suppose the curious and unknown conditions usually to occur 

 through which a change in the habits of life, after the adult age has been 

 reached, is apt to produce sterility. I may be permitted to remark, hypo- 

 thetical^, that this view appears to be corroborated by the fact that many 

 grains of pollen or many spermatozoa are required to fertilize each ovum, 

 because, as it would seem, each separate one does not contain a sufficiently 

 complete representation of the primary elements to supply the needs of an 

 individual life, and that it is only by the accumulation of several separate 

 consignments (so to speak) of the representative elements that the necessary 

 variety is ensured. I argue from this that there is a tendency to a large 

 individual variation in the constituents of each grain of pollen, or sperma- 

 tozoon, and, by analogy, that there is a similar though smaller tendency 

 in each ovum ; also that changes in the habits of life may increase this 

 variation to a degree that involves sterility. 



