"44 



REPRODUCTION 



transfusion of blood. They have slowly learnt that in this case hetero- 

 grafting (for we can truly call transfusion the grafting of the fluid 

 tissue blood) is not permissible, and nobody now allows sheep's blood 

 to pass into the veins of a man. But the danger to the host of repeated 

 and massive homoeo-transfusions is only beginning to be recognized 

 by the men who have the power to ' bind and to loose ' veins and arteries. 



Some normal organs, e.g., the ovary, are more readily homceografted 

 than others. Guthrie has shown that hens whose ovaries have been 

 interchanged are capable of laying eggs. When the hens were im- 

 pregnated and the eggs hatched out the colour characters of the resulting 

 offspring seemed to have been influenced, not only by the hen to which 

 the ovary originally belonged, but also by the hen to which it had been 

 transferred. 



Young have also been obtained from guinea-pigs, whose ovaries had 

 been replaced by ovaries from other guinea-pigs. Eighteen months 

 after interchange of the ovaries in two sister puppies, it was shown by 

 histological examination that the engrafted ovaries contained numerous 

 normal Graafian follicles, as well as corpora lutea. Statements are on 

 record of successful ovarian homoeografts even in women. 



Another point of great interest in connection with homoeografting 

 is that a small number of individuals of a species may constitute more 

 favourable hosts than the great majority for a tissue from another 



Fig. 486. Method of Transplantation (of both Kidneys) in Mass (after Guthrie) 

 Segments of the inferior vena cava and abdominal aorta are removed with the 

 kidneys and renal vessels, and interposed in the course of the vena cava and aorta 

 of another animal, according to the method of Carrel and Guthrie. 



individual of the same species. For instance, a rabbit's thyroid 

 cannot as a rule be successfully grafted into another rabbit, even 

 when thyroid deficiency has been caused by removal of the greater 

 part of the thyroid from the host. But if a large number of rabbits 

 are tried one will occasionally be found in which thyroid homceo- 



