246 The Philippine Journal of Science 1918 



mind, however, in connection with the powers shown by Enta- 

 moeba and Balantidium to penetrate deep into the tissues of the 

 intestine that the close apposition of portions of the colon to 

 the surface of the liver make it possible that the liver may 

 become involved as a result of the direct migration of the para- 

 sites through the tissues, a contingency that has been in the 

 minds of certain pathologists for some time. The possibility 

 of the conveyance of the parasites through the lymph channels 

 must not be entirely overlooked. The likelihood of retrograde 

 infection through the bile ducts is rather remote, although it 

 is conceivable. Stress has been laid by some of the workers 

 on the presence, more or less frequently, of Balantidium in the 

 blood vessels and the lymph spaces, and Bowman (3) and 

 Walker (49) both report the presence of Balantidium in the lymph 

 glands of the mesentery. 



Walker states his firm conviction that Balantidium will pass 

 through the healthy epithelium. This process, he says, is not 

 accompanied by necrosis or ulceration of the epithelium ; it con- 

 sists of the pushing aside or at the most a rupture of the 

 epithelium. In every case, he says, entrance is through the 

 epithelium and in no case within the tubules. Once within the 

 tissues, the presence of the parasites is certainly associated with 

 necrosis. Walker adds that the lesions and cellular reactions 

 produced in the early stage before being complicated by secondary 

 bacterial invasion are characteristic and are distinguishable from 

 those due to bacterial infection. 



In experimental work performed on monkeys, Walked' found 

 the epithelium intact "except for mechanical injury dae to en- 

 trance of the balantidia or to minute haemorrhages, but no 

 exudate or ulcerations." He also concludes that lesions in the 

 intestinal epithelium from bacterial infection or other causes 

 are not only not necessary for the entrance of the Balantidium 

 into the tissues, but that in none of the monkeys in which such 

 lesions existed have the balantidia taken advantage of them to 

 enter the tissues. 



Manlove(28) cites two cases of balantidial dysentery in man, 

 in support of Walker's contention that Balantidium may produce 

 "abscesses" in the intestine that are sterile except for the 

 presence of the protozoon. Walker mentions the fact that the 

 Balantidium found in the pig, which he holds to be identical 

 with that infesting man, seldom if ever penetrates the tissue of 

 the pig intestine. On this point I can speak from experience, 

 for I have found Balantidium in sections of the pig intestine 



