124 



AGRICULTURAL CHEMISTRY. 



In the former of these cases, the free acid 

 present in the stomach destroys the action 

 of the poison, the .chemical properties of 

 which are opposed to it ; whilst in the latter 

 it strengthens, or at ail events does not offer 

 any impediment to poisonous action. 

 , Microscopical examination has detected 

 peculiar bodies resembling the globules of 

 the blood in malignant' putrefying pus, in 

 the matter of vaccine, &c. The presence 

 of tnese bodies has given weight to the 

 opinion, that contagion proceeds from the 

 developement of a diseased organic life ; 

 and these formations have been regarded as 

 the living seeds of disease. 



This view, which is not adapted to dis- 

 cussion, has led those philosophers who are 

 accustomed to search for explanations of 

 phenomena in forms, to consider the yeast 

 produced by the fermentation of beer as pos- 

 sessed of life. They have imagined it to 

 be composed of animals or plants, which 

 nourish themselves from the sugar in which 

 they are placed, and at the same time yield 

 alcohol and carbonic acid as excrementitious 

 matters.* 



It would perhaps appear wonderful if 

 bodies, possessing a crystalline structure and 

 geometrical figure, were formed during the 

 processes of fermentation and putrefaction 

 from the organic substances .and tissues of 

 organs. We know, on the contrary, that 

 the complete dissolution into organic com- 

 pounds is preceded by a series of trans- 

 formations, in which the organic structures 

 gradually resign their forms. 



Blood, in a state of decomposition, may 

 appear to the eye unchanged ; and when we 

 recognise the globules of blood in a liquid 

 contagious matter, the utmost that we can 

 thence infer is, that those globules have 

 taken no part in the process of decomposi- 

 tion. All the phosphate of lime may be 

 removed from bones, leaving them trans- 

 parent and flexible like leather, without the 

 form of the bones being in the smallest de- 

 gree lost Again, bones may be burned 

 until they be quite white, and consist merely 

 of a skeleton of phosphate of lime, but they 

 will still possess their original form. In the 

 same way processes of decomposition in 

 the blood may affect individual constitu- 

 ents only of that fluid, which will become 

 destroyed and disappear, whilst its other 

 parts will maintain the original form. 



Several kinds of contagion are propagated 

 through the air: so that, according to the 

 view already mentioned, we must ascribe 

 life to a gas, that is, to an aeriform body. 



A I the supposed proofs of the vitality of 

 contagions are merely ideas and figurative 

 representations, fitted to render the pheno- 

 mena more easy of apprehension by our 

 senses, without explaining them. These 

 figurative expressions, with which we are 

 BO willingly and easily satisfied in all 



* Annalen der Pharmacie, Band xxix. S. 93 

 ttnd 100. 



sciences, are the foes of all inquiries into the 

 mysteries of nature ; they are like the fata 

 morgana, which show us deceitful views of 

 seas, fertile fields, and luscious fruits, but 

 leave us languishing when we have most 

 need of what they promise. 



It is certain that the action of contagions 

 is the result of a peculiar influence depend- 

 ent on chemical forces, and in no way con- 

 nected with the vital principle. This in- 

 fluence is destroyed by chemical actions, 

 and manifests itself wherever it is not sub- 

 dued by some antagonist power. Its exist- 

 ence is recognised in a connected series of 

 changes and transformations,, in which it 

 causes all substances capable of undergoing 

 similar changes to participate. 



An animal substance in the act of decom- 

 position, or a substance generated from the 

 component parts of a living body by disease, 

 communicates its own condition to all parts 

 of the system capable of entering into the 

 same state, if no cause exist in these parts 

 by which the change is counteracted or de- 

 stroyed. 



Disease is excited by contagion. 



The transformations produced by the dis- 

 ease assume a series of forms. 



In order to obtain a clear conception of 

 these transformations, we may consider the 

 changes which substances, more simply 

 composed than the living body, suffer from 

 the influence of similar causes. When pu- 

 trefying blood or yeast in the act of trans- 

 formation is placed in contact with a solu- 

 tion of sugar, the elements of the latter 

 substance are transposed, so as to form al- 

 cohol and carbonic acid. 



A piece of the rennet-stomach of a calf 

 in a state of decomposition occasions the 

 elements of sugar to assume a different ar- 

 rangement. The sugar is converted into 

 lactic acid without the addition or loss of 

 any element. (1 atom of sugar of grapes 

 C1'2 H12 O12 yields two atoms of lactic 

 acid=2 (C6 H6/O6.) 



When the juice of onions or of beet- root 

 is made to ferment at high temperatures, 

 lactic acid, mannite, and gum are formed. 

 Thus, according to the different states of the 

 transposition of the elements of the exciting 

 body, the elements of the sugar arrange 

 themselves in different manners, that is, dif- 

 ferent products are formed. 



The immediate contact of the decompos- 

 ing substance with the sugar is the cause 

 by which its particles are made to .assume 

 new forms and natures. The removal of 

 that substance occasions the cessation of the 

 decomposition of the sugar, so that should 

 its transformation be completed before the 

 sugar, the latter can suffer no further 

 change. 



In none of these processes of decomposi- 

 tion is the exciting body reproduced; for 

 the conditions necessary tc its reproduction 

 do not exist in the elements of the sugar. 



Just as yeast, putrefying flesh, and the 

 stomach of a calf in a state of decompcsi 



