366 FUNGI 



The species of FAirotium are saprophytes, and are found inhabiting 

 decaying plants, fruits, &c., and forming in such situations a loose 

 mycele of delicate thin-walled cells. The common mould formerly 

 called Aspergillus glaucus (Link) is the acrospore stage of Eurotium 

 herbariorum (Link), and was believed to he an independent form before 

 de Barv discovered the pleomorphism of this fungus and identified it 

 with the sporocarp stage (Eurotium). 



3. Pexicillium (Link). — The sporocarp of Penicillium takes its- 

 origin in the winding; round each other once or twice of two lateral 

 branches of mycelial hyph^e. These are so like each other that it is im- 

 possible, from the observations made on them, to say which is male and 

 which female — a question on which the ultimate development throws no 

 light, since it is uncertain whether the ascogenous hyphse proceed from 

 either or from both, and moreover, besides being alike in formation, they 

 are equal in activity. Neither has any observation been made of the 

 conjugation of these presumptive sexual elements— though their position 

 towards each other signifies a sexual union. Together with the out- 

 growths from these of numerous short ascogenous hyphce, there arises 

 from the neighbouring hyph^ of the mycele a dense growth which com- 

 pletelv envelops the presumptive carpogone and becomes interlaced 

 with the ascogenous hyphse proceeding from it — these being at first 

 thicker hyphse than those of the envelope-tissue. However, with the 

 growth of the whole body, the cells of the envelope increase considerably 

 in volume, especially the central mass, and acquire thickened pitted cell- 

 walls, while the layers nearer the circumference form themselves into an 

 outer wall the cells of which have yellowish-brown membranes. The 

 whole has a pseudo-parenchymatous appearance. The originally outer- 

 most cells are cast off, owing to their taking no part -in the growth. 

 V\'hile this development of the envelope has been going forward, the 

 ascogenous hyphas have been pushing in between the interstices of the 

 cells, and sharing in the process of thickening of the cell-membranes. 

 At this stage of the history of the sporocarp a period of rest intervenes 

 lasting about six or seven weeks. This past, the ascogenous hyphss 

 begin anew their growth in vigorous fashion, and, branching copiously at 

 the expense of the cells of the envelope, ultimately produce at the ends 

 of the branches short thick twisted terminal branches, which bear 

 serially strings of asci containing each eight ascospores. So far is this 

 process carried that finally not only is the whole interior envelope-tissue 

 used up. but the asci themselves disappear, leaving enclosed by the outer 

 wall only a dense mass of ascospores. De Bary compares the exist- 

 ence here of two forms of ascogenous hyphas — viz. the relatively slender 

 form which traverses and uses up the envelope-tissue, and the short 



