POISONS, CONTAGIONS, MIASMS. 



125 



tion, when introduced into solutions of 

 sugar, effect the transformation of this sub- 

 stance, without being themselves regene- 

 rated; in the same manner, miasms and 

 certain contagious matters produce diseases 

 in the human organism, by communicating 

 the state of decomposition of which they 

 themselves are the subject, to certain parts 

 of the organism, without themselves being 

 reproduced in their peculiar form and na- 

 ture during the progress of the decompo- 

 sition. 



The disease in this case is not contagious. 



Now when yeast is introduced into a 

 mixed liquid containing both sugar and glu- 

 ten, such as wort, the act of decomposition 

 of the sugar effects a change in the form and 

 mature of the gluten, which is, in conse- 

 quence, also subjected to transformation. 

 As long as some of the fermenting sugar re- 

 mains, gluten continues to be separated as 

 yeast, and this new matter in its turn ex- 

 cites fermentation in a fresh solution of 

 sugar or wort. If the sugar, however, 

 should be first decomposed, the gluten which 

 remains in solution is not converted into 

 yeast. We see, therefore, that the repro- 

 duction of the exciting body here depends 



1 . Upon the presence of that substance 

 from which it was originally formed ; 



2. Upon the presence of a compound 

 which is capable of being decomposed by 

 contact with the exciting body. 



If we express in the same terms the re- 

 production of contagious matter in conta- 

 gious diseases, since it is quite certain that 

 they must have their origin in the blood, we 

 must admit that the blood of a healthy indi- 

 vidual contains substances, by the decompo- 

 sition of which the exciting body or conta- 

 gion can be produced. It must further be 

 admitted, when contagion results, that the 

 blood contains a second constituent capable 

 of being decomposed by the exciting body. 

 It is only in consequence of the conversion 

 of the second constituent, that the original 

 exciting body can be reproduced. 



A susceptibility of contagion indicates the 

 presence of a certain quantity of this second 

 body in the blood of a healthy individual. 

 The susceptibility for the disease and its in- 

 tensity must augment according to the quan- 

 tity of that body present in the blood j and 

 in proportion to its diminution or disappear- 

 ance, the course of the disease will change. 



When a quantity, however small, of con- 

 tagious matter, that is of the exciting body, 

 is introduced into the blood of a healthy in- 

 dividual, it will be again generated in the 

 blood, just as yeast is reproduced from wort. 

 Its condition of transformation will be com- 

 municated to a constituent of the blood ; and 

 in consequence of the transformation suf- 

 fered Hy this substance, a body identical with 

 or similar to the exciting or contagious mat- 

 ter will be produced from another consti- 

 tuent substance of the blood. The quantity 

 of the exciting body newly produced must 

 constantly augment, if its Jturther trans- 



formation or decomposition proceeds more 

 slowly than that of the compound in the 

 blood, the decomposition of which it effects. 



If the transformation of the yeast gene- 

 rated in the fermentation of wort proceeded 

 with the same rapidity as that of the parti- 

 cles of the sugar contained in it, both would 

 simultaneously disappear when the ferment- 

 ation was completed. But yeast requires a 

 much longer time for decomposition than 

 sugar, so that after the latter has completely 

 disappeared, there remains a much larger 

 quantity of yeast than existed in the fluid at 

 the commencement of the fermentation, 

 yeast which is still in a state of incessant 

 progressive transformation, and therefore 

 possessed of its peculiar property. 



The state of change or decomposition 

 which affects one particle of blood, is im- 

 parted to a second, a third, and at last to all 

 the particles of blood in the whole body. 

 It is communicated in like manner to the 

 blood of another individual, to that of a 

 third person, and so on or in other words, 

 the disease is excited in them also. 



It is quite certain that a number of pecu- 

 liar substances exist in the blood of some 

 men and animals, which are absent from 

 the blood of others. 



The blood of the same individual contains, 

 in childhood and youth, variable quantities 

 of substances, which are absent from it in 

 other stages of growth. The susceptibility 

 of contagion by peculiar exciting bodies in 

 childhood, indicates a propagation and re- 

 generation of the exciting bodies, in con- 

 sequence of the transformation of certain 

 substances which are present in the blood, 

 and in the absence of which no contagion 

 could ensue. The form of a disease is 

 termed benignant, when the tranformations 

 are perfected on constituents of the body 

 which are not essential to life, without the 

 other parts taking a share in the decomposi- 

 tion ; it is termed malignant when they 

 affect essential organs. 



It cannot be supposed that the different 

 changes in the blood, by which its constitu- 

 ents are converted into fat, muscular fibre, 

 substance of the brain and nerves, bones, 

 hair, &c., and the transformation of food into 

 blood, can take place without the simulta- 

 neous formation of new compounds which 

 require to be removed from the body by the 

 organs of excretion. 



In an adult these excretions do not vary 

 much either in their nature or quantity. 

 The food taken is not employed in increasing 

 the size of the body, but merely for the pur- 

 pose of replacing any substances which may 

 be consumed by the various actions in the 

 organism ; every motion, every manifesta- 

 tion of organic properties, and every organic 

 action being attended by a change in the 

 material of the body, and by the assumption 

 of a new form by its constituents.* 



* The experiments of Barruel upon the dif- 

 ferent odours emitted from blood on the addition 



