THE TYPE SPECIES. 25 



made, though the material may possibly form the oucleus of a real 

 monograph later. 



In the examination of the early literature of this genus the author 

 is greatly indebted to l>r. C. I.. Shear, of the Bureau of Plan! Indus- 

 try of this Department, for the use of hooks and for much careful 

 cooperation in examining and discussing the subject of types and 

 descriptions. 



THE TYPE SPECIES. 



Link'- 1 in his "Observationes," published in 1809, established the 

 genus Penicittium to include the common green molds having a 

 penicillate type of conidial fructification- a conidiophore branching 

 more or [ess complexly at its apex, such branches becoming or being 

 tipped by cells, each of which produces a chain of conidia. The w hole 

 produces a brush-like appearance, the chains of conidia serving as the 

 hairs or bristles of the brush. This generic name has been universally 

 accepted t<> include in a form genus all species reproducing themselves 

 indefinitely by such conidial fructifications. However doubtful we 

 may be as to the forms originally examined, there is no question that 

 we know the general type of structure which Link intended in his 

 description of the genus. 



Under the genus PancUlbuii, Link placed three species. The first 

 specie- listed was P. glaucum, but the description given is equally 

 applicable to many different forms. This was noted as frequent in 

 decaying bodies and said to be most closely related to P. expansum 

 (the third species listed), of which he suggests his material may have 

 been but undeveloped specimens. 



The second species, P. cand'uhuit, is described as producing round 

 colonies, with mycelium and spores white, upon decaying fungi and 

 herbs. Although many authors have used this name for material 

 from differenl sources, and Morini 16 has described an ascigerous form 

 under this name, there has been no means of determining what form 

 I ink had in mind u hen writing his description. Many forms will pro- 

 duce white mycelium and spores under special conditions, while but 

 • me of those examined has been shown to do this under all conditions, 

 and this one is so specialized in its habit as to be excluded by Link's 

 statement of habitat from the application of this name. Numerous 

 authors have suggested that the /'. "candidum" forms are probably 

 colonies of species, colorless under special condil ions, but green under 

 other cultural conditions. 



The third species, P. expansum, is slightly better described, while 

 it- habitat is primarily given as rotten fruit, although the author has 

 manifestly extended his use of the name to forms growing upon other 

 substrata which he believed to be identical with the fungi grown upon 

 decaying fruit. 



