CONFORMITY TO TYPE 255 



if transfusion of blood were practised and then should 

 influence the germinal cells of the animal into which 

 they were introduced. To determine this point, Galton 

 " largely transfused the blood of an alien species of rab- 

 bit into the blood vessels of male and female silver-gray 

 rabbits, from which he afterwards bred." " He repeated 

 this process for three generations and found not the 

 slightest sign of any deterioration in the silver-gray 

 breed." Having been criticised by Darwin for the 

 manner in which the experiments were performed, he 

 subsequently repeated them with improved apparatus 

 and on an equally large scale for two more generations, 

 but without differing results. 



Galton therefore devised a new theory of heredity 

 the theory of the stirp based upon the theory of pan- 

 genesis, but differing from it in certain essentials. 



The term "stirp," from the Latin stirpes, a root, 

 " is used to express the sum total of the germs, gemmules, 

 or whatever they may be called, which are to be found, 

 according to every theory of organic units, in the newly 

 fertilized ovum." 



The theory is postulated in four parts, thus: " 1. Each 

 of the enormous number of quasi-independent units of 

 which the body consists has a separate origin or germ. 

 2. The stirp contains a host of germs, much greater in 

 number and variety than the organic units of the bodily 

 structure that is about to be derived from them, so that 

 comparatively few individuals out of the host of germs 

 achieve development. 3. The undeveloped germs retain 

 their vitality that they may propagate themselves while 

 still in the latent state and contribute to form the stirps 

 of the offspring. 4. Organization wholly depends upon 

 the mutual affinities and repulsions of the separate 

 germs: first in their earliest stirpal stage and subse- 

 quently during all the processes of development." 



" It is thus seen that the stirp itself contains all of the 

 essential units, to which few are added that some must 

 circulate and be added to those in the stirp is granted, 

 and they explain the rare cases in which zebra marks 



