LIFE-HISTORY OF PENICILLIUM. 859 
The conidia lose their power of germinating in from one and 
a half to one and three quarter years. 
The life-history of Penicillium may thus be shortly summed 
up :—From a spore of the second (asexual) generation, that 
is, from an ascospore (or a conidia-spore), there is developed 
a large mycelium which bears the reproductive organs, the 
carpogonia, and antheridia, and is the first or sexual gene- 
ration. After fertilization the second generation begins and 
is a sexually produced but asexual plant. ‘The destruc- 
tion of the first generation does not immediately take place, 
but at first the second generation remains in direct con- 
nection with it and is nourished by it. It is at the same 
time surrounded by a nutrient tissue, which is formed from 
the sterile hyphe, and is later separated from the mother- 
plant in the form of a sclerotium (sporocarp) which may be 
compared physiologically to a seed. After a longer or shorter 
period of rest the second generation grows, living as a para- 
site on the nutrient tissue belonging to the first generation, 
and forms an asexual plant which develops asci and asco- 
spores. From each spore of this second asexual genera- 
tion there proceeds, as we have seen, the first or sexual gene- 
ration. 
The conidia are not directly connected with the altera- 
tion of generations, and represent only a mode of asexual 
reproduction. In Penicillium the alternation of generations 
consists only of two stages. The first or sexual genera- 
tion is large and capable of producing asexual spores, the 
conidia, which resemble the gemme of the Liverworts and 
Mosses. ‘The second or asexual generation is small and 
lives as a parasite on the nutrient tissue which surrounds 
it. The formation of the ascospores shows that Penicillium 
must be placed in the great group of the Ascomycetes, and 
there can be little doubt that, from the striking resemblance 
of the minute structure of the sclerotia of Penicillium to 
that of the Truffle,! the former must be placed close to the 
Tuberacee. : 
See Sachs’s ‘Textbook of Botany,’ p. 255. Some figures and a rather 
poor account of the structure will be found in the ‘ Popular Science Review ’ 
for 1862. 
