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PHYSIOLOGY: MURPHY AND MORTON 
seemed of importance from these observations to study the lymphocytes 
in animals immune to transplanted cancers. 
There are two types of this so-called immunity; the natural, possessed 
normally by a certain variable proportion of animals inoculated; and the 
induced variety, obtained by a previous treatment of the animal with an 
injection of homologous living tissues. We have studied the circulating 
lymphocytes in these two types of immunity and for comparison in sus- 
ceptible mice with growing tumors. 
In the mice with induced immunity the circulating l)nnphocytes 
show no change either in actual numbers or relative proportion to the 
other white cells during the ten days which must elapse between the im- 
munizing tissue injection and the cancer inoculation. Within twenty- 
four hours after the cancer graft is introduced, however, there is a sharp 
rise in the number of these cells amounting to an average increase for 
the group of 100% above the former level. This increase continues 
with slight variations for something over 50 days, with a maximum aver- 
age for the series of between 200 and 300% above the normal. The 
other white cells of the blood retain their normal level. 
The natural immune animals, those which without treatment were 
able to overcome the cancer graft, showed a similar response on the part 
of the lymphocyte to that seen in the preceding group. The period of 
increase, however, is not evident for several days or a week after inocu- 
lation and the average maximum is not so high, being between 100 and 
200% above the normal. Like the first group, there is slight, if any 
change in the actual numbers of the otlier white cells of the blood. 
Animals in which the cancer graft resulted in a take, showed no such 
lymphoid response as did the immune animals. A composit curve of 
the white cells plotted for a number of such animals showed a slight 
tendency on the part of the lymphocyte to increase during the first two 
weeks, but this was followed by a gradual decline in number as the can- 
cer increased in size. The polymorphonuclear cells during this period 
showed an actual increase in numbers. 
In order to ascertain the importance of the lymphoid reaction in the 
immunity process, we have destroyed the major portion of the lymphoid 
tissue in mice having one of the two types of immunity. This was done 
by giving the animal several small exposures to X-ray, previously esti- 
mated to be sufficient for the purpose. In the induced immunity the 
X-ray was given between the time of the immunizing tissue injection and 
the cancer inoculation. This treatment resulted in the complete de- 
struction of the immunity and the inoculated cancers grew more readily 
than in the normal animals. 
