Chapter II 



Exchange of Tissues Between Different 

 Varieties or Races (Subspecies) 



The reactions against heterogenous transplants, on the whole, are 

 sharply denned and distinct from those against homoiogenous trans- 

 plants ; a transition to the latter is seen, however, in the grafts from 

 Peromyscus to mice of strain C57. If we pass from transplantations of tis- 

 sues between different species to transplantations between different varieties, 

 races or subspecies, the results are different ; these correspond to severe 

 homoiogenous reactions. Such experiments were carried out with Gray 

 Norway rats and two mutant races derived from them, mutant albino and 

 Curly Coat ; these mutations were discovered and their bearers propagated 

 by Helen Dean King, at the Wistar Institute in Philadelphia. Five series of 

 transplantations were made, each one representing a different type. I. Autog- 

 enous transplantation of thyroid and cartilage and adjoining tissues in Gray 

 Norway rats; II. Syngenesiotransplantation between brothers and sisters in 

 Gray Norway and the two mutant races; III. Intrarace transplantations be- 

 tween not nearly related individuals in each one of these three races; IV. 

 Interrace transplantations from one of these races to another; V. Exchange 

 of tissues between these three races and tame albino and hooded rats. Exam- 

 ination took place at 9, 12, 16 and 20 days following transplantation ; however, 

 at 20 days the number of experiments available for grading was not as large 

 as at 16 days. 



In the grading of the reactions in these experiments, the second set of 

 grades was used. In autogenous transplantations in the Gray Norway rat 

 the grade was 6. The average grades in the other experiments, together with 

 the range of variations, are shown in table 1. The highest and lowest grades 

 in each case represent the separate grades for thyroid only, because these 

 grades are sharper than those for cartilage transplants. 



From these results we may draw the following conclusions: (1) After 

 autogenous transplantation in the wild Gray Norway rat, an injurious reac- 



TABLE I 



. „ ^ Range of t , _ Range of „„ ^ Range of 



12 Days X1 16 Days ,, 20 Days , r 



Variation Variation Variation 



Series II 4.42 5.5-3.4 3.3 5.2-2.3 2.05 3.6-1 



Series III 3.15 5.5-1 2.55 4.8-1 2.20 3.9-1 



Series IV 2.60 4.3-1 2.15 3.5-1 1.80 3.8-1 



Series V 2.30 4.2-1 2. 3-1 2.15 3-1 



131 



