CHEMICAL SCIENCE. 231 



the improvements in that instrument, the subject of the development, 

 growth, and offices of the fungi has received much attention. They 

 compose, with the algae and lichens, the class of thallogens (Lindley), 

 the alga existing in water, the other two in air only. A fungus is a 

 cellular flowerless plant, fructifying solely by spores, by which it is 

 propagated, and the methods of attachment of which are singularly 

 various and beautiful. The fungi differ from the lichens and algae, in 

 deriving their nourishment from the substances on which they grow, 

 instead of from the media in which they live. They contain a larger 

 quantity of nitrogen in their constitution than vegetables in general 

 do, and the substance called " fungine " has a near resemblance to 

 animal matter. Their spores are inconceivably numerous and minute, 

 and are diffused very widely, developing themselves wherever they find 

 organic matter in a fit state. The principal conditions required for 

 their growth are moisture, heat, and the presence of oxygen and elec- 

 tricity. No decomposition or development of fungi takes place in dry 

 organic matter ; a fact illustrated by the high state of preservation in 

 which timber has been found after the lapse of centuries, as well as by 

 the condition of mummy-cases, bandages, &c., kept dry in the hot cli- 

 mate of Egypt. Decay will not take place in a temperature below that 

 of the freezing point of water, nor without oxygen, by excluding which, 

 as contained in the air, meat and vegetables may be kept fresh and 

 sweet for many years. 



The action which takes place when moist vegetable substances are 

 exposed to oxygen is that of slow r combustion (" eremacausis "), the 

 oxygen uniting with the wood and liberating a volume of carbonic acid 

 equal to itself, and another portion combining with the hydrogen of 

 the wood to form water. Decomposition takes place on contact with a 

 body already undergoing the same change, in the same manner that 

 yeast causes fermentation. Animal matter enters into combination 

 with oxygen in precisely the same way as vegetable matter ; but as, in 

 addition to carbon and hydrogen, it contains nitrogen, the products of 

 the eremacausis are more numerous, being carbon and nitrate of ammo- 

 nia, carburetted and sulphuretted hydrogen, and water ; and these am- 

 moniacal salts greatly favor the growth of fungi. Now paper consists 

 essentially of woody fibre, having animal matter as size on its surface. 

 The first microscopic symptom of decay in paper is irregularity of sur- 

 face, with a slight change of color, indicating the commencement cf 

 the process just noticed, during which, in addition to carbonic acid, cer- 

 tain organic acids are formed, as crenic and ulmic acids, which, if the 

 paper has been stained by a coloring matter, will form spots of red on 

 the surface. Spots of the same kind are similarly formed on leather 

 colored during its manufacture. Provided the fungi have not taken 

 root, the color can be restored by ammonia or any alkali. The same 

 process of decay goes on in parchment as in paper, only with more ra- 

 pidity, from the presence of nitrogen in its composition. When this 

 decay has begun to take place, fungi are produced, the most common 

 species being PeniciUum g/aucum. They insinuate themselves between 

 the fibre, causing a freer admission of air, and consequently hasten the 

 decay. The substances most successfully used as preventives of decay 



