NEOPLASMS 471 
If injury and animal parasitism have any importance 
in neoplasmata then this opportunity certainly occurs 
under natural conditions. Fibiger observed gastric 
tumors in rats arising under the influence of nematodes 
while Slye and Wells report facial neoplasms in mice 
apparently arising at points of old injuries. It seems to 
me that we have no right to assume an immunity of wild 
animals, in their native environment, to tumors; the 
incidence is another matter but it may be considerable. 
It was thought possible that there might be some light 
shed upon the matter by an analysis of our sarcomatous 
and epitheliomatous tumors in wild- and captive-bom 
animals. In our second paper (6) upon this subject I 
ventured the statement that sarcomatous growths 
occurred more frequently in captive-born, epithelioma- 
tous in mid-born specimens. Greater data have not borne 
out this conclusion and information was sought as to the 
embryonal derivation of tumor-bearing tissue. Analyz- 
ing the cases in which all the factors could be obtained, it 
seems that among seven tum.ors of captive-bred animals, 
five came from the entoderm, two from the mesoderm, 
whereas in wild-bred animals, of the fifty-seven tumors, 
five came from the ectoderm, thirty-two from the 
mesoderm and fourteen from the entoderm. These 
figures do not include the parrots. The sex values have 
no significance. 
It is interesting and noteworthy, that, as in the human 
being, the majority of the tumors came from tissues aris- 
ing in the mesoderm and that the entodermic derivatives 
received the largest number of metastases ; no ectodermic 
tissues were sites of secondary tumors. The visceral 
seats of metastases are probably of little value for com- 
parison in so small a number ; the lung and liver however 
occupy the prominent places. 
Interesting as the foregoing facts may be, they do not 
shed light upon the question of breeding and degeneracy 
(6) Jour. Path, and Bact., Vol. XVII, 1912. 
