FUNGI. 323 
also been discovered in some of the white rusts and 
parasitic moulds. In bunt it has been ascertained 
that an alternation of generations takes place ; 
while in the higher fungi curious instances of con- 
jugation, like that which occurs in fresh-water 
alge, are on record. The mode of growing 
agarics from the spores, however, is still involved 
in obscurity. No one can say whether the stem 
and cap rise at once from the mycelium without 
any sexual process, or whether the spore of the 
mushroom produces a prothallus similar to that 
of ferns, on which sperm and germ cells are de- 
veloped, giving birth by their union to the full- 
formed plant. We cannot by any known method 
grow domesticated mushrooms from. spores ; and 
in a wild state the myriads of spores that fall to 
the ground where they grow, may yield next 
season not a single specimen. They behave like 
unimpregnated germs orova. The conditions that 
are needed to make them fertile are unknown. 
Indeed, the physiological relations of the various 
seemingly reproductive structures which I have 
described are as yet quite obscure, and present a 
field for most interesting observation and research. 
But it is worthy of remark that in the lowest 
cryptogams the mode of reproduction far more 
closely resembles that of the highest animals than 
what we see in flowering plants, And the curious 
