372 Royal Society : — 



PEOCEEDINGS OF LEARNED SOCIETIES. 



ROYAL SOCIETY. 



March 30, 1871.— General Sir Edward Sabine, K.C.B., President, 

 in the Chair. 



" Experiments in Pangenesis, by Breeding from Rabbits of a pure 

 variety, into whose circulation blood taken from other varieties had 

 previously been largely transfused." By Francis Galton, F.R.S. 



Darwin's provisional theory of Pangenesis claims our belief on the 

 ground that it is the only theory which explains, by a single law, 

 the numerous phenomena allied to simple reproduction, such as 

 reversion, growth, and repair of injuries. On the other hand, its 

 postulates are hypothetical and large, so that few naturalists seem 

 willing to grant them. To myself, as a student of Heredity, it 

 seemed of pressing importance that these postulates should be tested. 



If their truth could be established, the influence of Pangenesis 

 on the study of heredity would be immense ; if otherwise the ne- 

 gative conclusion would still be a positive gain. 



It is necessary that I should briefly recapitulate the cardinal points 

 of Mr. Darwin's theory. They are (1) that each of the myriad cells 

 in every living body is, to a great extent, an indepeiulent organism ; 

 (2) that before it is developed, and in all stages of its development, 

 it throws "gemmules" into the circulation, which live there and 

 breed, each truly to its kind, by the jjrocess of self-division, and 

 that, consequently, they swarm in the blood, in large numbers of 

 each variety, and circulate freely with it ; (3) that the sexual ele- 

 ments consist of organized grou})S of these gemmules; (4) that the 

 development of certain of the gemmules in the offspring depends on 

 their consecutive union, through their natural aftinities, each attach- 

 ing itself to its predecessor in a regular order of growth ; (5) that gem- 

 mules of innumerable varieties may be transmitted for an enormous 

 number of generations without being developed into cells, but always 

 ready to become so, as shown by the almost insuperable tendency 

 to feral reversion, in domesticated animals. 



It follows from this, and from the general tenor of Mr. Darwin's 

 reasoning and illustrations, that two animals, to outward appearance 

 of the same pure variety, one of which has mongrel ancestry and the 

 other has not, differ solely in the constitution of their blood, so far as 

 concerns those points on which outward appearance depends. The 

 one has none but gemmules of the pure variety circulating in his veins, 

 and will breed true to his kind ; the other, although only the jniie va- 

 riety of skin-gemmules haj)pens to have been developed in his own 

 skin, has abundance of mongrel gennnules in his blood, and will be 

 apt to breed mongrels. It also follows from this that the main 

 stream of heredity must flow in a far smaller volume from the 

 developed parental cells, of which there is only one of each variety, 

 than from the free gemmules circulating witii the blood, of which 

 there is a large number of eacii variety. If a })arental developed cell 



