TRANSPLANTATIONS 45 



nective tissue and lymphocytes set in at about the same time, and in the same 

 host the relative degree of the lymphocytic reaction was in many cases the 

 same in various tissues, despite the fact that cartilage and fat tissue give off a 

 smaller amount of homoiogenous substance than do thyroid and kidney. Al- 

 though it seems that lymph vessels grow more actively into the thyroid than 

 into fat tissue, it is not probable that this explains the difference in the degree 

 of lymphocytic reaction in these two tissues, especially in view of the observa- 

 tion that the lymph vessels which grow into the homoiogenous fat tissue are 

 less crowded with lymphocytes than are those in the thyroid gland. 



Autogenous and homoiogenous transplants of cartilage-fat tissue differ, 

 then, not only in the greater ability of the former to survive and the great 

 injury inflicted on the latter by the homoiotoxins, as well as by various kinds of 

 host cells, but also in the greater regulative power in the autogenous tissues 

 which successfully overcomes the results of injuries caused by the experimen- 

 tal procedures used. However, also homoiogenous cartilage, perichondrium 

 and fat tissue possess to some extent still a certain regulative power, as indi- 

 cated by the new formation of perichondrial cartilage around an area of 

 necrotic cartilage. In autogenous and homoiogenous transplantations condi- 

 tions are therefore very similar in rat and guinea pig. A first period of injury 

 and degeneration is followed by a second period of recovery and regeneration, 

 which affects the same tissues. There are, however, some minor differences, 

 mainly of a quantitative nature, in these two species. In the rat the regenerative 

 activity of the perichondrial cells seems to be greater than in the guinea pig; 

 but in the latter the invasion of fat tissue by connective tissue, as a rule, is 

 more extensive than in the rat. On the other hand, in the rat the lymphocytic 

 reaction may be somewhat more intense. 



We have, so far, discussed autogenous and homoiogenous transplantations 

 of thyroid, cartilage and fat tissue and associated tissues in rat and guinea 

 pig ; these were the tissues commonly used in our investigations. But in addi- 

 tion we have made use of a number of other organs or tissues ; from among 

 these we shall select striated muscle in the rat, and uterus and kidney in the 

 guinea pig, for a comparison of autogenous and homoiogenous reactions. Each 

 of these organs shows some peculiarities which are of interest in the analysis 

 of the common factors underlying the differences in the reactions against 

 autogenous and homoiogenous individuality differentials. 



7. Autogenous and homoiogenous transplantation of striated muscle 

 tissue in the rat. Elson found that after autogenous transplantation of stri- 

 ated muscle tissue, the latter remains preserved for at least six months, and 

 probably indefinitely. During the first few days the greater portion of this 

 tissue became necrotic and was invaded by polymorphonuclear leucocytes, 

 which were attracted either by the necrotic material or by some accidental 

 bacterial products ; they disappeared again after a few days. After four days 

 a proliferation of the muscle nuclei set in, and this was quite marked after six 

 days, the nuclei lying in long slender muscle spindles, many of which developed 

 cross-striations. Gradually the latter became more definite, while some of the 

 nuclei disappeared and others assumed a more peripheral situation. At fifteen 



