M. Dutrochet ati the Origin of Mouldiness. 307 



them also appear adhering to the sides of the glasses containing 

 the liquid in which they grow. Soon after their first appearance, 

 we observe their filaments radiating as from a common centre ; 

 at a later period, their ramifications cross and intersect each 

 other, and in every sense form a sort of felt. When the liquid 

 in which these infusores vegetables grow ha& but little depth, 

 and wh^n -consequently they rapidly attain to the surface of the 

 liquid, we perceive they are soon covered in the free air, with a 

 kind of white effervescence, which, examined in the microscope, 

 is found to be entirely composed of mould of the minutest di- 

 mensions, but composed of different varieties. 



It was important to know if these moulds were parasite ve- 

 getables, accidentally implanted upon the filamentous infusores 

 vegetables which filled the water, and occupied its surface ; or 

 whether these same moulds were the production, in the air, of 

 these aquatic vegetables. To satisfy myself on this point, I 

 put small portions of these aquatic vegetables into small me- 

 nisca, that is to say, small glasses of the same shape as watch 

 glasses, not above four or six lines in diameter, and very flat. 

 Seizing one of the small menisca with common pincers, 1 plunged 

 it into the water which contained in suspension the small portions 

 of the filamentous vegetables above alluded to, and by this means 

 I got hold of them without in any degree inj uring them ; they 

 remained in the meniscus with the very small quantity of water 

 which it could contain. I then placed this meniscus under a 

 small glass bell, shut close by water, above which the meniscus 

 was elevated, by being placed on a small support. The fila- 

 mentous vegetable thus placed on the surface of the water, and 

 in a very humid atmosphere, was constantly covered with mould, 

 at the end of three or four days ; and it thus became easy for 

 me to transport them under the microscope without injuring 

 them. 



fi- In this manner 1 have completely satisfied myself that mouldi- 

 ness is the growth in air of the aquatic filamentous vegetables, 

 which we are now considering. I have seen, in the most distinct 

 way, the aerial filaments of the mould springing from the stalks 

 of the aquatic filamentous vegetable ; sometimes by a production 

 from the side, and sometimes by the sprouting out of the extre- 

 mity of one of these aquatic filaments, which, in coming into the 



