64 THE PROTOZOA 



discussion of these forms, it may be stated that Rhizopoda, Flagellidia, 

 Ciliata, and Sporozoa may be found in the various cavities and canals 

 in man and the other vertebrates, where they usually give little or no 

 trouble. 



One form, however, Amoeba colt (Fig. 31, A), has been long in dispute as the reputed 

 cause of dysentery. If it is the specific cause of this disease, the animal occupies an 

 interesting position amongst the intercellular parasites ; for, so far as known, none 

 other of this kind of protozoan parasites exerts a deleterious effect upon the intestinal 

 epithelia. Nor is it proven that Amoeba colt does this in the case of dysentery, 

 although a belief to that effect is widespread. Briefly reviewing the history of this 

 belief, it appears that Lambl (^o) 1 was the first to observe Amceba in the human 

 intestine, although Losch ('75), who named it, was the first to consider it in 

 connection with dysentery. Many subsequent observers (Kartulis, Mannaberg, 

 Cohn, etc.) found Amoeba coli in the faeces of dysentery patients, Kartulis ('89) 

 amongst others stating that he found them in no less than five hundred cases. The 

 belief received a setback, however, by the observations of Cunningham ('81), Grassi 

 ('82), and Calendruccio (^90), who found Amceba coli in the intestine of sound and 

 healthy men as well as in dysenteric patients, while still other observers maintained 

 the entire absence of such an enteric organism. Councilman ('91), in a work which 

 is certainly as reliable as any that has been undertaken upon this subject, partially 

 harmonized these views by showing that there are at least three forms of dysentery, 

 of which one, at least, is characterized by certain definite symptoms and by the 

 presence of Amoeba coli, although it was not demonstrated that the rhizopod was the 

 cause. The entire matter received impartial and critical treatment by Laveran ('93) 

 in France and by Schuberg ('93) in Germany, and both came to the conclusion that 

 the cause of dysentery was not yet known, the former basing his opinion largely 

 upon the absence of Amoeba in all but one of ten cases, the latter upon numerous 

 experiments and observations upon normal and diseased individuals. Schuberg not 

 only found that Amoeba coli is present in normal men, but also found that there is no 

 specific difference in the various intestinal Amoeba which have been described by 

 various observers as living freely in the intestine in the same way as the commensal 

 ciliates and flagellates also found there and generally believed to be harmless. He 

 pertinently says : " If the flagellates are harmless, it is certainly not impossible that 

 Amoeba is also. The increased number of Amoeba in dysenteric patients is not 

 necessarily evidence that they are the cause of this disease." 2 Both he and Laveran 

 expressed the view that all experiments which had been made up to that time had 

 not excluded the possibility of other causes, e.g. bacteria. That dysentery is due to 

 some specific cause had been early demonstrated by experiment, but in none of these 

 experiments had it been possible to isolate the Protozoa from bacteria which invari- 

 ably accompany them. The reverse experiment is, however, possible, and it is 

 singular that it has not been made more frequently. Among the first to exclude 

 the Protozoa were Celli and Fiocca ('95), who obtained cases of dysentery by inject- 

 ing cats with material from faeces in which the Protozoa had been killed by heat ; 

 the same result was also obtained by injecting material in which both Amoeba and 

 bacteria were absent, the cause evidently being in the poison of the sterilized matter 

 and not in Amceba coli. They concluded that the poison is the product of bacteria 

 (Bacillus coli communis, together with typhus-like bacteria and a streptococcus, 

 were suggested as possible causes). This view was supported by a number of 

 observers, amongst whom may be mentioned Gasser ('95), Cassagrandi and Bar- 

 bagello ('95), and Petridis ('98). The latter especially has shown that dysentery 

 as observed in Egypt is due to a bacillus and not to Protozoa. He found that Strep- 



l Cf. Leuckart ('79). 2 Page 701. 



