46 THE BIOLOGICAL BASIS OF INDIVIDUALITY 



days, the muscle tissue consisted chiefly of long slender fibers, with good 

 cross-striations and an increase of muscle nuclei as compared to the normal 

 number. By this time the lymphocytes, which at first were present in small 

 numbers, had almost or completely disappeared. At 28 days the muscle, except 

 for slight signs of degeneration in a few areas, appeared mature and normal 

 in almost every respect. Conditions were similar when the transplanted muscle 

 was about at the height of its development. Later on there was some invasion 

 by fibroblasts and the muscle fibers became small ; but there was still some in- 

 crease in nuclei and in connective tissue cells and lymphocytes. It was pre- 

 sumably the abnormal situation and the lack of the normal function of the 

 transplanted muscle which led to the slight pathological changes noticeable at 

 this time. 



After homoiotransplantation of striated muscle tissue there were fewer 

 regenerative growth processes in the first period and much more degeneration, 

 on account of an invasion of the transplants by lymphocytes, and, to a less 

 extent, by connective tissue at subsequent periods. Thus homoiotransplanted 

 muscle disappeared much earlier than autotransplanted muscle, no well- 

 preserved tissue being present at 50 days. This result was due to the primary 

 action of the bodyfluids of the host, which were inadequate for the homoio- 

 genous graft, which injured it and interfered with its growth processes; and 

 it was secondarily the result of the activity of the host cells, which led to 

 further and, in the end, total destruction of the muscle tissue, at a time when 

 the autogenous muscle was well preserved. The growth processes, which take 

 place in the muscle following a primary degeneration of its major portion, 

 represent less true regenerative processes than those of compensatory hyper- 

 trophy, consisting in an increase in sarcoplasm and a multiplication of nuclei. 



While in the autotransplanted muscle a nuclear proliferation was seen as 

 early as four days after transplantation, it was lacking at this time in the 

 homoiotransplanted muscle. In the latter there appeared at six days a slight 

 lymphocytic reaction and there were also fewer muscle fibers and a smaller 

 number of well developed nuclei in the homoiotransplants. At ten days the 

 lymphocytic reaction increased in intensity, some muscle fibers degenerated, 

 but other muscle fibers remained and underwent still a slight proliferation of 

 nuclei. There was thus, in the early periods after transplantation, a balancing 

 between growth processes and degenerative processes. Later, the invasion of 

 the muscle by lymphocytes and its destruction increased. At 32 days there was 

 an intense lymphocytic reaction, which more or less completely took the place 

 of the muscle transplant. However, there were a few small nucleated muscle 

 spindles or fibers with cross-striation. The invasion of lymphocytes continued 

 to increase and at the same time connective tissue cells of the host participated 

 in the process of destruction of the graft. At 50 days, only a few remnants of 

 muscle tissue were found, and at 70 days there was a maximum of lymphocytic 

 reaction coinciding with a minimum in the preservation of the muscle tissue. 

 At 118 days, no muscle tissue was seen; its place had been taken by lympho- 

 cytes, connective tissue and a few small blood vessels. 



Hence, while the type of growth processes that occur in the muscle grafts is 



