154 SCIENCE PROGRESS 



diseases generally must be classified as parasitic or those of 

 microbic origin, such as tuberculosis, cholera and plague, and 

 non-parasitic or those arising from disorders of metabolism — as, 

 for instance, gout, heart-disease, tumour, etc., it will be con- 

 venient similarly to proceed in our discussion of them, that is, 

 we will first consider the progress of medical science in relation 

 to parasitic diseases, and subsequently its position in relation to 

 the remainder. 



Just as modern biology is based on the Origin of Species, so 

 the foundation of our knowledge of the parasitic or microbic 

 diseases, so far as it is scientific and not mere empiricism, was 

 laid deep and true, a veritable Yggdrasil for strength, by the 

 investigations of M. Pasteur. Prior to his revolutionary dis- 

 coveries, the vague theories current ascribed their etiology to 

 morbid poisons — note the tautology— in the air, to decaying 

 vegetable matter, to ferments floating about promiscuously, and 

 so forth. The supporters of the germ theory of disease, before 

 the increasing body of facts proved too strong for their op- 

 ponents, encountered a strenuous opposition from the more 

 " conservative " element of the medical profession; they had in 

 fact to fight a kind of Quatre Bras against the doctors before 

 aligning themselves for their Waterloo against the microbes. 

 All such controversies, however bitter and envenomed at the 

 time, are fortunately now a thing of the past and possess merely 

 that historic interest which still enchains our attention when 

 reading of the discoveries of a Galileo, the enunciation of 

 Newton's laws, or the gradual acceptance of the atomic 

 theory. 



In the brief period — scarce a third of a century — since 

 M. Pasteur's discoveries marvellous progress has been made. 

 Though we stand as yet only as it were in the early morning 

 of discoveries touching the etiology of the parasitic diseases, 

 their prophylaxis and cure, the sun of science shines brightly 

 above the horizon and all the air is radiant with hope. In spite 

 of the opposition of such fanatics as anti-vaccinationists — soon, 

 let us hope, to be as extinct as the Fifth Monarchy men — and in 

 spite of official discouragement and of a lamentable exiguity of 

 funds, very noteworthy results have already been achieved. In 

 malaria, perhaps, estimated both in its annual death-roll — some 

 1,300,000 in India alone — and in the chronic ill-health it inflicts 

 on the involuntary hosts of Plasmodium malarice, the most 



