TO PHYSIOLOGY AND PATHOLOGY. 29 



motion of the body on which the fungus grows. Good nutrition, and perfect 

 health and strength increase the capacity for infection ; and thus, in a colony of 

 silk worms, the finest and largest are always the most affected by the disease. 



[PARASITES IN ANIMALS AND PIANTS. 



Similar parasites have been observed on diseased fish, in infusoria, and in hen's 

 eggs ; and it is clear that these observations confirm a series of facts regarding the 

 animal organism which often occur in the vegetable world, proving that disease and 

 death are frequently induced by parasites, which live exclusively upon the constit- 

 uent parts of other bodies ; as yet, however, no connection has been drawn 

 between these facts and the origin and propagation of miasmatic contagious diseases ; 

 and if it be allowable to designate a fungus, or its spores, by the term contagion, it 

 is clear since the size of the fungus makes no difference in our mode of consi- 

 dering it that some sources of contagion attain to a length of six or eight inches, 

 this being the size of the fungus, Sphceria Roberta, which developes itself in the 

 body of the New Zealand grub, and occasions its death. 



FALSE VIEWS OF THE CAUSES OF PUTREFACTION ARE THE 

 FOUNDATION OF THE PARASITE THEORY. 



A view of the cause of fermentation and putrefaction, which is thoroughly false 

 in its principles, has hitherto served as the main support of the parasite theory. 

 Its adherents regard putrefaction as a decomposition of organic beings, by infusoria 

 and fungi, and every putrefying body as a sort of rampart of infusoria, or a 

 plantation of fungi ; and thus, according to this view, wherever organic bodies 

 pass into putrefaction to any extent, the whole atmosphere must be filled with the 

 germs of contagion, and become the cause of disease. 



FUNGI AND INFUSORIA DO NOT OCCASION PUTREFACTION. 



It has not escaped the advocates of the parasite theory, that a close connection 

 exists between putrefaction, contagion, and miasma ; although they avoid entering 

 upon an explanation of the mode of comprehending the connection of these 

 phenomena, and their mutual dependence upon each other. This connection would 

 be established, if it were proved that infusoria or fungi, induced putrefaction or 

 fermentation ; that by them and their process of digestion and respiration, sugar is 

 resolved into equal volumes of carbonic acid gas, and vapour of alcohol ; and that 

 the following conversions are brought about, viz., urea into carbonate of ammonia ; 

 salicin into sugar and saligenin ; sulphate of protoxide of iron into sulphuret of 

 calcium ; sulphate of soda into sulphuret of sodium ; blue indigo into white indigo ; 

 starch into sugar ; sugur into lactic acid ; amygdalin into prussic acid, bitter oil of 

 almonds, and sugar. 



The following remarks will show how thoroughly untenable are these views. 



OPPOSITION BETWEEN PUTREFACTION AND THE PROCESS OF LIFE. 



The constituents of \egetable and animal structures have arisen under the 

 dominion of nn active muse of change in the form and properties of organisms; 

 and this is vital force, which decides the direction of attraction, and opposes the 

 force of cohesion, heat, ;md electricity, destroying the influence of every cause 

 that hinders the association of atoms in combinations of a higher order without the 



