53 



1919 a) lound 19 infections in all the cases (2,137, excluding 

 asylum patients) which they examined ; a percentage of only 

 about 0-9. The other workers, whose reports are printed here, 

 found altogether 74 cases in 1,009 examined, or 7-3 per cent. 

 Even when allowance is made for the fact that the first series 

 was examined only once per case, and the second more frequently 

 in some instances, the discrepancy in these findings is consider- 

 able. Miss Mackinnon (1918) found 1 infection in 34 'British' 

 cases at Southampton ; and Baylis (1919) records only 0-25 per 

 cent, in his series of 400 naval cases. The highest figure re- 

 corded in any British series is 23-2 per cent., found by Matthews 

 and Smith (1919 a) in 207 patients in a lunatic asylum. 



The figures generally — of which the foregoing are a sample — 

 show such variations that I am in much doubt as to their signi- 

 ficance. I have estimated roughly (p. 42) that the total 

 findings indicate that some 6 to 9 per cent, of the British popu- 

 lation may harbour this flagellate : but I am not disposed to 

 attach much importance to these figures. The only certain 

 conclusion that emerges from the findings generally is that 

 Chilomastix is apparently less common in British residents than 

 in soldiers who have seen service abroad. In such persons I have 

 invariably found a higher rate of infection. 



The first British cases of infection with Chilomastix were re- 

 corded ^ by Yorke, Carter, Mackinnon, Matthews, and Smith 

 (1917). Nothing else regarding this organism seems worthy of 

 special comment here. 



(8) Tricho7nonas honiinis. — Up to the present this flagellate 

 has been reported in one series of British cases only — the asylum 

 patients examined by Smith (1919) at Eainhill. He found 

 altogether six infected out of a total of 504 examined. Of the 

 members of this series 34 had been abroad : but it appears that 

 at least one of the patients who had never left England (Case 

 J. Ho.) was infected with Trichomonas. Whether the other 

 infected cases were ' British ' or not is not stated. 



In the other series examined by Smith and Matthews, and by 

 the later workers along similar lines, there is not a single case of 

 Trichomonas infection reported. None was found by any worker 

 for the War Office Committee, and none by Baylis (1919) in his 

 navalcases, nor by Miss Mackinnon (1918) in her series of ' British ' 

 soldiers. It thus seems clear that the flagellate occurs in persons 

 who have never left Britain, though it is uncommon; and at 

 present there are no figures which permit of even an approximate 

 estimate of its frequency. 



Trichomonas hominis can, as a rule, be found only in soft or 

 liquid stools, and its cysts are at present unknown. Consequently 

 it is not surprising that it has not been found in a large number 

 of healthy persons with normally formed stools. Its apparent 

 absence cannot, therefore, be taken to prove that it is as uncommon 

 as the findings might at first sight seem to indicate. 



' Eeoorded under the name Tetramitus. 



