250 SUSCEPTIBILITY AND IMMUNITY. 



remove progressively all the material necessary for the development of the 

 parasite." 



In discussing this theory, in a paper published in the American 

 Journal of the Medical Sciences (April, 1881), the writer says: 



"Let us see where this hypothesis leads us. In the first place, we must 

 have a material of small-pox, and a material of measles, and a material of 

 scarlet fever, etc., etc. Then we must admit that each of these different 

 materials has been formed in the system and stored up for these emergencies 

 attacks of the diseases in question for we can scarcely conceive that they 

 were all packed away in the germ cell of the mother and the sperm cell of 

 the father of each susceptible individual. If, then, these peculiar materials 

 have been formed and stored up during the development of the individual, 

 how are we to account for the fact that no new production takes place after 

 an attack of any one of the diseases in question ? 



" Again, how shall we account for the fact that the amount of material 

 which would nourish the small-pox germ, to the extent of producing a case 

 of confluent small-pox, may be exhausted by the action of the attenuated 

 virus (germ) introduced by vaccination ? Pasteur's comparison of a fowl 

 protected by inoculation with the microbe of fowl cholera, with a culture 

 fluid in which the growth of a particular organism has exhausted the pabu- 

 lum necessary for the development of additional organisms of the same kind, 

 does not seem to me to be a just one, as in the latter case we have a limited 

 supply of nutriment, while in the former we have new supplies constantly 

 provided of the material food from which the whole body, including the 

 hypothetical substance essential to the development of the disease germ, was 

 built up prior to the attack. Besides this we have a constant provision for 

 the elimination of effete and useless products. 



" This hypothesis, then, requires the formation in the human body, and 

 the retention up to a certain time, of a variety of materials which, so far as 

 we can see, serve no purpose except to nourish the germs of various specific 

 diseases, and which, having served this purpose, are not again formed in the 

 same system, subjected to similar external conditions, and supplied with the 

 same kind of nutriment." 



It is unnecessary to discuss this hypothesis any further, inasmuch 

 as it is no longer sustained by Pasteur or his pupils, and is evidently 

 untenable. 



The Eetention Theory, proposed by Chauveau (1880), is subject to 

 similar objections. According to this view, certain products formed 

 during the development of a pathogenic microorganism in the body 

 of a susceptible animal accumulate during the attack and are subse- 

 quently retained, and, being prejudicial to the growth of the particu- 

 lar microorganism which produced them, a second infection cannot 

 occur. Support for this theory has been found by its advocates in 

 the fact that various processes of fermentation are arrested after a 

 time by the formation of substances which restrain the development 

 of the microorganisms to which they are due. But in the case of a 

 living animal the conditions are very different, and it is hard to con- 

 ceive that adventitious products of this kind could be retained for 

 years, when in the normal processes of nutrition and excretion the 

 tissues and fluids of the body are constantly undergoing change. 

 Certainly the substances which arrest ordinary processes of fermen- 



