NEMATODA 201 



render them fruitful Cochin-China, Tahiti, &c. Fresh ob- 

 servations are necessary to confirm the first and to fill up 

 notable gaps. The way has been brilliantly opened by the 

 English and Brazilian physicians. Let our colleagues in the 

 French colonies put their shoulders to the wheel ; they have 

 before them a vast field of study to explore." 



Since the above remarks were written I have received several 

 communications from Dr Bancroft, and also others from Drs 

 da Silva Lima, Araujo, Assis Sousa, Paterson, Hall, of Bahia 

 the two last named being English physicians in practice there. 

 I regret that I can do little more than refer to the writings of 

 these authors in the Bibliography below ; but I may observe that 

 Drs Paterson and Hall have ascertained that the proportion of 

 the population of Bahia affected by Filaria is 8~ per cent. Out 

 of 309 persons examined, 26 had haematozoa, which is, roughly, 

 one in twelve, or more strictly, 8*666 per cent. 



Amongst recent memoirs that by Sir J. Fayrer, read to the 

 Epidemiological Society on the 5th of February, 1879, deserves 

 especial attention. In regard to its significance, I have only 

 space to remark that, much as we may regret the little interest 

 shown by our hospital physicians and surgeons in this subject, 

 it is particularly gratifying to see experienced Indian officers 

 like Sir J. Fayrer, Mr Macnamara, and Dr John Murray, com- 

 ing forward both to aid and render homage to their junior 

 colleagues in Eastern parts, who are successfully labouring to 

 advance the cause of helminthology and scientific medicine. 



In concluding this subject I may observe, that one of the 

 greatest hindrances to the due recognition of the remarkable part 

 played by parasites in the production of human endemics and 

 animal epizootics arises from the circumstance that no incon- 

 siderable number of minute worms may infest a host without 

 obvious injury. This immunity proves nothing. If, for example, 

 we take the case of Trichina we find that several millions of 

 entozoa may exist in the human, or, at all events, in the animal 

 bearer, without producing any symptom of discomfort. In such 

 cases it is not possible to determine the strict limits of health 

 and disease ; nevertheless, were we to double the amount of 

 infection, the imaginary line of demarcation is at once bridged 

 over and the parasites become acknowledged as directly 

 responsible for grave symptoms which may even prove fatal to 

 the bearer. Again, the relative strength and size of the infected 

 host constitute factors that materially limit the power of the 



