INTRODUCTION TO CRYPTOGAMIC BOTANY. 2o7 



as conidia often make their appearance on such productions, 

 some cases will arise in which mature deliberation will be re- 

 quisite to arrive at a just conclusion. If these considerations 

 be not kept in view, we shall have the mycelium of Agarics 

 described as Himantia, that of Polypori as Rhizomiorpha 

 and Sporotrichum, that of Sphwria as Stereum or Botrytis, 

 and so for many similar cases. 



268. The early stages of the minute pufifballs are so ex- 

 tremely different from the full-grown plant, in consequence of 

 their gelatinous texture, creeping habit, and anastomosing 

 veins, that they have often been described under distinct 

 generic names ; and yet a single day's observation might have 

 taught the identity of the two states, however discordant they 

 may be at first sight, because the one distinctly passes into the 

 other, and that within a few hours. There is far more difficulty 

 where a plant is arrested in its growth at a certain stage, 

 having previously undergone important modifications, so as to 

 disguise its real nature. If, for instance, the numerous species 

 assigned to Sclerotium, and one or two other neighbouring 

 genera, be observed only during the season which gave them 

 birth, there are few instances in which their real nature is 

 capable of detection. In general they are compact masses of 

 cellular tissue, which have arisen from the metamorphosis of 

 an originally floccose mycelium. This is occasionally very 

 evident, as in the Sclerotia of pears and apples, where the 

 mycelium in some cases assumes the form of a Sporotrichum, 

 in others the tissues become more compact in the centre of the 

 floccose mass, while in others the mass is of less density, its 

 free tips fructify, and, instead of a Sclerotium, we have a state 

 of Penicillium which is known by the generic name of Core- 

 m^ium. Precisely the same process takes place Avith several 

 other moulds, but they are not always readily traced. This, 

 however, may be effected by causing a small portion to grow 

 under circumstances which force it to fructify, as was done by 

 myself and Mr. Hoffman, in the granular Sclerotium of onions, 

 which gave rise to a minute Mucor* Other species, resem- 



* Jouru. of Loud lloit. Soc, vol. 3, p. 91. 



