344 DR. W. R. M‘NAB. 
powers were available. Micheli! was the first to do so in 
the year 1729, and he gives on Plate 91, fig. 3 of his work 
a correct representation of Penicillium, which he called 
Aspergillus albus. \t is of interest that Micheli correctly 
separates Penicillium from Aspergillus glaucus, which 1s 
easily recognised in his fig. 1; he, however, unites Peni- 
cillium with a number of other moulds in his genus Mucor. 
Linneus in his ‘Species Plantarum,’ thirty-five years later, 
described Penicillium under the name of Mucor crustaceus 
albus. In 1801 Persoon? described a fungus, which is undoubt- 
edly Penicillium, under the name of Monilia digitata. Link 
first firmly established Penicillium as a new genus of fungi, 
and he is the author of the name now in common use. He 
carefully separated Penicillium from Aspergillus, and further 
set aside the specific name crustaceum given by Linneus, 
and replaced it by glaucum. In 1829 Fries reinstated the 
Linnean specific name, and in 1846 placed Penicillium in 
the Mucedines in opposition to the Mucorint. Subsequent 
authors, as Bolton, Corda, and others, describe the fructifica- 
tion of Penicillium, but it is not till 1869 that E. Loew? 
describes the germination of the spores, the growth of the 
mycelium, and the development of the conidiiferous hyphe. 
A new impulse and direction was given to the study of the 
fungi when, in 1851, Tulasne discovered the pleomorphism of 
the reproductive organs—a subject the investigation of which 
was further prosecuted by De Bary. Penicillium, being an 
abundant and common form, became of great importance in 
the study of the supposed pleomorphism, and truly marvellous 
results followed. 
Bail, in 1856, announced that spores of Penicillium, when 
sown in mash, grow like yeast, instead of producing myce- 
lium. Hoffmann, Turpin, and Berkeley followed in the same 
direction, the latter considering that yeast was a peculiar 
condition of certain moulds, particularly Penicillium, which 
no longer produced fruit, and, further, he believed that he 
obtained Penicillium by the germination of yeast-cells. A 
little later Joly and Mousset thought they had confirmed the 
idea that Penicillium was the fruit of yeast. In 1861 Pou- 
chet stated that yeast was an incomplete plant, and really 
the spores of Aspergillus; but three years later he changes 
his opinion, and says that yeast consists of spontaneously 
generated spores, which, when they germinate, produce Peni- 
1 Micheli, ‘Nova plantarum genera juxta Tournefortii methodum dis- 
posita.’ Florentie, 1729. 
2 Persoon, ‘Synopsis Methodica Fungorum.’ 
3 Pringsheim’s ‘ Jahrbuch,’ vol. vii, p. 472. 
