308 M. Dutrochet on the Origin of Mouldvness. 



air, become, by that alone, a filament of mould, and then as- 

 sumed an opacity which it had not so long as it continued an 

 aquatic filament. It is thus demonstrated that the aquatic fila- 

 mentous vegetables, now under review, are the thallus growth- 

 stalks of mouldiness. These thalluses, when they are entirely 

 under the water, grow indefinitely in this state. Their deve- 

 lopment is commonly radiated towards the commencement, but 

 frequently it advances in a way that is wholly irregular, so that 

 it truly produces a kind of felt, by the crossings of the filaments. 

 These filaments are sometimes provided with articulations, but 

 more frequently they have none. 



The moulds which I have seen produced from the aquatic 

 thallus now under consideration, have all appeared to me to be- 

 long to the genera described by Persoon under the names of 

 Monilia and of Botrytis. I have observed that all the thallus, 

 whose filaments have joints like the Confervae, give origin to the 

 monilia, whose aerial filaments are also furnished with articula- 

 tions. It is, without doubt, to a thallus of this kind that the 

 observation of M. Amici refers, concerning the alleged conferva 

 which he saw grow in the sap of the vine. All the monilia, 

 however, are not thalluses with jointed filaments ; when the 

 filaments of these monilian thalluses are destitute of joints, the 

 aerial filaments of these microscopic vegetables are equally des- 

 titute of them. As to the filaments of the Botrytis thallus, they 

 are never articulated. 



But one important question still remains for solution ; viz. 

 What are the qualities which a liquid must possess, ere it will 

 develope the thallus of mould ?* I have previously remarked, 

 that water holding a small quantity of albumen in solution never 

 produces these thalluses. From this fact I started, to discover 

 what chemical qualities it was necessary to give to this same 

 liquid, to make it produce the thallus of mouldiness. In these 

 experiments I used only distilled water, that I might be the 

 more certain of the results. I dissolved a drop of the most 

 liquid portion of the albumen of a new laid egg in an ounce of 



• The term mould is here employed in the sense given to it by Bulliard, 

 that is to say, in the usual sense. Persoon has divided the genus mould 

 (A/wcor) of Bulliard into many genera, retaining the name mould to one of 

 them alone. '* 



