100 THE BIOLOGICAL BASIS OF INDIVIDUALITY 



A comparison of the results of transplantations within various inbred 

 strains. In a further extensive series of experiments we have compared, 

 in a number of closely inbred strains, the reactions against transplants, when 

 donors and hosts belonged to the same inbred strain. (1) In strain A, pieces 

 were examined from 12 to 50 days after transplantation ; the age of the hosts 

 and donors varied, as a rule, between 2 months and 7 months, but in some 

 transplantations the hosts were as old as 16 months. These differences in age 

 did not affect noticeably the results of transplantation. In the large majority 

 of cases the transplants (thyroid, parathyroid, cartilage, fat tissue, bone and 

 bone marrow, and striated muscle tissue) behaved like autogenous transplants, 

 or they at least approached this condition. But in certain instances the thyroid 

 graft was stunted or there were some mild lymphocytic infiltrations in the 

 thyroid, muscle or cartilage-fat transplants. These changes were found as 

 early as 20 days after transplantation and also after 50 days ; but when pres- 

 ent, they were mild and they corresponded to favorable syngenesio-reactions. 

 There was a marked similarity in the condition of the various tissues trans- 

 planted from the same donor into the same host — they all showed the struc- 

 ture of autogenous transplants — although, as stated, there could develop a mild 

 lymphocytic infiltration in some instances. More severe reactions were noted 

 in experiments in which the presence of polymorphonuclear leucocytes, which 

 accumulated especially inside of fibrous nodules, indicated a probable infec- 

 tion. At some distance from the center of infection an increase in lymphocytes 

 in the fat tissue and infiltrations with small vacuolated phagocytic cells could 

 be noted; but even under such conditions the injurious changes, including 

 formation of fibrous tissue, as a rule were mostly localized and did not lead to 

 a general damage of the transplants. In the majority of these, as well as of the 

 following transplantations, examination took place after 20 or 30 days, but in 

 some cases it was as late as 50 days, as it was also in other strains than A. 



In strain C3H, the results were similar to those found in strain A ; in the 

 majority of cases the pieces behaved like autogenous transplants; however, 

 there were occasionally some slight lymphocytic infiltrations, and if an infec- 

 tion had occurred, the reactions were more severe. 



In strain D, a great variability of the reactions was noted; these ranged 

 from an autogenous to a severe homoiogenous type, in which a great part of 

 the thyroid was destroyed and the remaining acini were embedded in fibrous 

 tissue. There was also some lymphocytic infiltration; in the fat tissue an in- 

 crease in fibrous tissue had taken place, and epithelioid, small vacuolated 

 phagocytic cells, together with some accumulations of lymphocytes, were pres- 

 ent. In general, there was a correspondence between the behavior of different 

 tissues taken from one donor and transplanted into the same host. In an ex- 

 periment in which four pieces of thyroid had been transplanted from two 

 donors into the same host, two of the transplants behaved like autogenous, 

 and the other two like homoiogenous transplants. Strain D is then, it seems, 

 less homozygous than strains A and C3H. 



In strain CBA the results corresponded mostly to those found in autog- 

 enous transplantations ; but in some instances there was an increase in fibrous 



