90 Hypothesis of Structure of Germ Substance 



of different species. But this demonstration has not 

 been afforded in a single instance of animal grafting. 



There are indeed examples of transfusion of blood 

 which do not succeed when they are made from one 

 animal to another of different species, whereas they do 

 succeed perfectly between animals of the same species. 

 There are the experiments of Bert upon the successful 

 transplantation of a fragment of the tail of a mouse 

 into the subcutaneous tissue at another part of the body 

 of the same individual or of another individual of the 

 same or a related species, as Mus decumanus and Mus 

 rattus, whereas such a transplantation is not successful 

 between species farther removed, such as Mus rattus 

 and Mus silvaticus. There are the experiments of Oilier 

 and Schmitt on the transplantation of fragments of 

 bony tissue, which were successful in transplantations 

 from one part to another of the same individual or to 

 another individual of the same species, but failed be- 

 tween individuals of different species. 60 



But all these experiments indicate only that there is 

 more affinity between the parts of the same tissue or of 

 similar tissues when they belong to individuals of the 

 same species or of related species than when they are 

 taken from individuals of different species. They do 

 not prove at all that there is more affinity between parts 

 of different tissues, which come from the same individual 

 or from individuals of the same species, than between 

 parts of the same tissue taken irom different species. 



On the other hand Joest's experiments have demon- 

 strated the possibility of true heteroplastic grafts in the 

 annelids, in which it is easy to obtain transplantations 



60 Oscar Hertwig: Die Zclle und die Gewebe. II, P. 248. 



