BLOOD VESSEL ANASTOMOSIS 169 



rule. Difficulties arise in the latter two, at the place of junction between the 

 vessels of donor and host because of tissue and bodyfluid incompatibility, and 

 thrombi often develop, but even without such thrombi, other than autogenous 

 tissues are injured and ultimately succumb. This applies also to homoio- and 

 heterotransplanted organs, which apparently regress relatively soon after 

 transplantation. There is some difference of opinion as to the length of 

 time during which transplanted pieces of arteries can remain alive, but this 

 seems to be a point of less importance. Certain connective tissue structures 

 may live presumably longer than the more sensitive constituents of these 

 transplants. 



From a theoretical point of view, these transplantations by blood vessel 

 anastomosis are of special interest, because they make possible a separation 

 of the effects of the bodyfluids on transplanted tissues from those of the 

 host cells. The latter effects are, in all probability, as far as the incomplete 

 reports on the results of microscopical examination make an evaluation of 

 this factor possible, either entirely lacking or very slight under the given 

 conditions of experimentation. It is essentially the injurious action of body- 

 fluids, carrying disharmonious individuality and species differentials from 

 the host to the grafted tissues, which accomplishes the destruction of 

 homoiogenous and heterogenous tissues and organs. However, those investi- 

 gators who express an opinion as to the cause of the lack of success of 

 homoio- and heterotransplantations, as, for instance, Borst and Lexer, stress 

 two specific factors. In the first place, it is assumed that the homoiogenous 

 and heterogenous transplants cannot make use of the specific foodstuffs of 

 the host and, therefore, after using up their own reserve material, they 

 starve, and that secondly, cytolysins or related immune substances develop 

 as a result of processes of immunization taking place in the host. Even 

 Borst, who emphasizes the biochemical differences between host and trans- 

 plant as the primary cause of the state of athrepsia and immunization, has 

 in mind specificities inherent in various organs and tissues, which require 

 not only the adequate nourishment but also the normal function of these 

 structures in order to overcome adverse conditions. Biochemical differences, 

 in the way he applies this term, refer largely to or include the tissue 

 differentials. This concept differs therefore from that which holds the 

 differences in individuality and organismal differentials as primarily re- 

 sponsible for the changes characteristic of the various types of transplantation. 



Transplantation by pedicled flaps. It is especially in skin transplantation 

 that pedicled flaps are used. This method of grafting tissue resembles trans- 

 plantation by blood vessel anastomosis, in so far as the transplant has, from 

 the beginning, a satisfactory blood supply, reaching it in this instance through 

 the vessels of the pedicle, which originate in the donor of the skin graft. 

 Secondarily, the skin flap makes connection with the vessels of the host, from 

 whom it then also receives blood. Thus its own blood vessels carry to the 

 transplant substances bearing autogenous individuality differentials, while 

 the blood vessels coming from the host carry to it substances bearing strange 

 individuality differentials. The pedicle-flap mode of transplantation, there- 

 fore, differs from that by blood vessel anastomosis, which has just been 



