10 



— after a most careful inquiry into their past histories — that 

 no less than 8-37 per cent, of the men (788 in number) who 

 had been in England and France only, were carriers of E. histo- 

 lytica. Amoebic diseases were not known to be more prevalent, 

 in normal circumstances, in Northern France than in Great 

 Britain ; and moreover, it was fairly certain that by far the 

 greater number of the dysentery cases occurring on the French 

 front were bacillary — not amoebic. Consequently, unless infection 

 with E. histolytica had spread through our armies from > the 

 associated colonial troops — and had spread with remarkable 

 rapidity, and without concomitant clinical manifestations — it 

 seemed certain that carriers of the parasite must be far com- 

 moner than had hitherto been supposed in the native population 

 of Great Britain, of France, or of both countries. 



The only way to arrive at the truth of the matter was obvious. 

 The civilians — the normal resident population — would have to be 

 subjected to examination in the same way as the military 

 patients. In this way alone could the findings from the latter 

 class be properly interpreted. But this was not easily done. It 

 was difficult to obtain samples of faeces from a large number of 

 persons who had never been abroad; and yet such material was 

 obviously necessary for this investigation. Anybody who had 

 been out of Britain would have to be excluded ; for it would be 

 impossible, if protozoa of any sort were found in his stools, to 

 ascertain whether the infection had been acquired at home or 

 during his sojourn in foreign parts : and this meant that a very 

 careful inquiry would have to be made into the history of every 

 case that was to be included in our ' British ' series. Then again, 

 it was obviously necessary to examine as large a number of the 

 ' British ' population as possible, since a small sample might give 

 a wrong idea of the real conditions. And finally there was the 

 difficulty of obtaining workers for the undertaking. The investi- 

 gation, if it were to be of any value, would have to be made by 

 competent workers, whose findings could be trusted : and the 

 men and women whom I had trained for this purpose, and upon 

 whose diagnoses reliance could be placed, could ill be spared 

 from the hospitals where they were then employed in the 

 examination of military patients. Their work for the Army 

 naturally took precedence of all other work. 



I made several attempts to carry out investigations of this sort 

 myself, but owing to preoccupation with other more urgent 

 duties the results which I obtained were insignificant. But I 

 endeavoured to. impress upon all the workers whom I trained 

 from time to time for the War Office the importance of conduct- 

 ing inquiries into this problem ; and I urged them all to seize 

 every opportunity of obtaining the information needed. For 

 various reasons the majority of these workers were unable to 

 devote their attention to the matter; but one group of them, 

 acting upon my suggestions, ultimately succeeded in obtaining 

 data of the greatest interest. I refer, of course, to the workers at 

 the Liverpool School of Tropical Medicine, whose results have 



