M. Dutrochet on tlie Origin of' Mouldincss, 31 1 



according to the opinion of M. Dumas, it forms with the albu- 

 men a kind of compounded neutral — an albuminate of soda. I 

 here repeat, that the free condition of an acid or an alkali in 

 solution in the water, containing an organic substance, is abso- 

 lutely necessary for the determining of the growth of tlie thallus 

 of mould. The quantity of diese chemical agents necessary for 

 the production of the effect, cannot be determined as it respects 

 its minimum, for this, in reality, appears to be inappreciable; 

 it can, however, be determined as to its maximum. It is well 

 known that no living being can exist in a liquid which is 

 too acid or too alkaline. I have found that the thalluses of 

 mould are produced in albuminous water,, to each half ounce of 

 which a drop of the concentrated sulphuric, nitric, and muriatic 

 acid?^! is added. : Tliis. is bearly the maximum of the- acidity 

 which allows the production and the growth of the thallusv As 

 to the maximum when the alkalies are concerned, it appears to 

 me it has. been reached \vhen the liquid contains an hundredth 

 part by weight of caustic soda, or potash. 5 ua 'tu\ .^v^wi^i/.. 

 When a neutral salt is added to the albuminous water, it does 

 not promote the appearance of the thallus- I make this state- 

 ment as the result of a great number of experiments. 



When I made my first experiments upon the thalluses of 

 mould, I was ignorant of their nature ; and witnessing these 

 filamentous infusores vegetables appearing constantly in the al- 

 buminous water, rendered slightly acid or alkaline, and never 

 appearing in the pure albuminous water, I was tempted to think 

 that this living vegetable being was the product of spontaneous 

 generation, as M. Amici had done, as before stated. It ap- 

 peared to me probable that the invisible germs of the filamentous 

 vegetable were created by a chemical action of the acid or alkali 

 upon the organic matter dissolved in the water, and that they 

 then developed themselves in virtue of the vital action which 

 would have been the necessary attribute of that compound 

 chemico-organic moUculairey or of that germ. Such were the 

 ideas that led me astray, previous to my having discovered that 

 these filamentous infusores vegetables were the thallus of mould. 

 Before this discovery, all that had the appearance of the mar- 

 vellous disappeared, viz. the appearance, in certain liquids, of 

 hese infusores vegetables, which, as it would seem, I could 



