68 



MICROSCOPIC HISTORY OF THE VIXEGAR-PLAXT. 



Fig. 6 represents the plant as obtained from a rotten Turnip. 

 "PENICILLTUM, Link. — Microscopic, cobweb-like or niothery flocculenfc 

 masses, producing simple globose spores, disposed in 

 patches about the pencil-shaped ends of septate 

 fertile threads. 



P. glaucum, Grev. — (The Vinegar-plant,) my- 

 celium forming a close, tough, crust-like, or 

 leathery web; branches entangled and bifid; spores 

 verdigris green. Habitat — on decaying bodies, 

 and in fluids in a state of acetification." 



Fig. 7 is a drawing of a PenicilUum, which I take 

 to be P. (jiaucum, found in a quantity of stale paste. 

 On reading the above descriptions, and comparing 

 with them and the sketches of the plants indi- 

 cated, that of the Vinegar-plant, Fig. 4, it will be no difficult task to point 

 out its generic position. The genus Mncor, though Lindley says that it is 

 -. frequently the cause of fluids becoming ^mothery, 



is not the parent of the Vinegar-plant, as no 

 indication of a membranaceous sac for the spores 

 could be traced. Neither can we lay it to the 

 credit of the geiuis Aspergillus, the roA^s of spores 

 forming a brush-like head are sufficient to exempt 

 it; though it is plain that the plant found in the 

 succinate of ammonia by Dr. Pereira, is a perfect 

 Aspcrgilhis. In the genvis PenicilUum, we find 

 that the stipes, instead of coming to an abrupt 

 head terminated by a mass of spores as in the 

 two former genei'a, branches out in the form of 

 a tree, and on these branches the spores are de- 

 posited in clusters. This branching pi'ecludes the 

 possibility of a determinable form of head: accor- 

 ding as the angle of the branches is greater or smaller, and as the spores 

 are thickly or sparingly deposited on them, so will it approach to the 

 rounded or oblong form. This may in some measure account for the difference 

 observed in the form of the masses in Fig. 4. Again, the circumstance in 

 which a plant is placed may influence the form of its branches. We know 

 that a tree will increase most on the side next the stream. In the case of 

 the Vinegar-plant the fact of the very abundance of nutriment, may have 

 caused a lengthening and attenuation of the branches, in the same manner 

 as the quantity of nourishment, aqueous and aerial, supplied to the Elms in 

 the Crystal Palace, gave them an unwonted vigour. 



I then look upon the clavate mass of spores in Fig. 4 as the nearest 

 approach to perfect fructification yet observed in the Vinegar-plant, and as being 

 identical with, or at least very similar to^ the PenicilUum glaucum, Fig. 7; 



