330 MORPHOLOGY OF THE ASPERGILLACE^E. 



producing the characteristic colour of the growth when observed 

 in the mass. They are mostly small (about 2.5-5 A* * n longest dia- 

 meter), but in isolated instances (P. olivaceum) may grow to a 

 length of 10 p. The younger members of the long chains are 

 often appreciably smaller, of different shape, and firmly attached 

 together throughout, only becoming loosened after they have 

 grown considerably. 



The germination of Penicillium conidia, observed by E. 

 LOEW (I.), presents no special features. 



Several species are distinguished by a tendency to the forma- 

 tion of a coremium (see vol. ii., p. 22), which in some cases occurs 

 spasmodically, being apparently dependent on circumstances 

 (P. luteum, P. glaucum), whilst in oth rs it is a regular feature 

 (P. granulatum, P. daviforme) under nearly all conditions. The 

 arboriform coremia of P. luteum are noticeable on account of their 

 size (up to i cm. in height) and ornamental appearance. Those of 

 P. claviforme described by BAINIER (I.) differ from the others in 

 that handsome isaria-like clubs are formed, which initially appear 

 white, but afterwards turn green on the top from the presence of 

 conidiophores. This fungus, the surface of which remains 

 sterile, the conidia being produced solely on the clavate stroma, 

 about i cm. in height, should more properly be grouped with 

 Isaria. 



Ascospores, in the form of small, coloured globular nodules of 

 highly diversified character, have been found in four to five species. 

 In the case of P. luteum, P. aureum, P. insigne (?) they are soft- 

 skinned, with continuous development. In the last two the skin 

 is pseudoparenchyrnatous, whereas in the first one they consist of 

 hyphaB, somewhat loosely connected at first, but afterwards co- 

 herent. Tough sclerotia, forming asci after a lengthy period of 

 rest (intermittent development), are formed by P. glaucum, Bre- 

 feld, and similar though sterile forms are found in P. italicum. 

 The perithecia of P. aureum (which seems closely allied to 

 P. luteum) are said by VAN TIEGHEM (IV.) to possess a yellow 

 mycelial integument as well. MORINI (I.) reported the occur- 

 rence of perithecia in P. candidum, Link, but gave no further 

 particulars regarding the form of the conidia ; and, since pic- 

 torial representations are lacking, the question must be left 

 undecided. The same also applies to P. Wortmanni, Klocker (see 

 p. 346, vol. ii.). More detailed particulars on the progress of 

 development are scarce and also contradictory in many respects. 

 The ascospores are ellipsoidal, with the epispore tough, glabrous 

 (P. aureum), warty (P. insigne, P. Wortmanni), or thickened in 

 ridges (P. glaucum, Bref., P. luteum, Zuk.), the epispore being 

 with (P. glaucum, Bref.) or without (P. luteum, Zuk.) a longitu- 

 dinal furrow. 



Ascospores not having been detected in a large number of 

 species, the criteria of differentiation of the various species include 

 the colour of the vegetation (mostly green in all shades from bluish 



