87 
To those who still doubt the compound nature of the lichen 
thallus this explanation of the origin and function of the outer 
gonidia of the podetium must seem extremely doubtful. For in 
this case not only is there a symbiosis between fungus and alga, 
according to the generally received notion of symbiosis, namely, 
where the parasite which is unable to get its own living lays hold 
of a host of suitable nature to supply its needs, and unites itself 
so closely to it as to become an integral part of it, but a second 
union occurs. Later on in the life of the plant, the fungus hy- 
phe, following their own manner of development, governed pos- 
sibly by tendencies inherited from ancestors to whom the alge 
were not a necessity, develop into an organ by such a manner of 
growth that it is impossible for them to carry with them their lit- 
tle supporters. This organ has an important function, that of 
furnishing spores to provide for the continuance of the species. 
Nature, ever ready with resources, now provides the little alge 
from without, which in their turn seek out the plant requiring 
assistance, unite themselves to it, and “live forever afterward in 
peace and harmony.” After all, this is no more wonderful than 
other processes which are held as well authenticated facts. 
53, G, 
Fontinalacees—Monographie des. J. Cardot. (Mem. Soc. Sci. 
Cherbourg, xxviii. 1 52 pages, 1892). 
This work makes an epoch in the history of mosses, as the 
author claims for it the honor of being only the third monograph | 
of a family of Bryophyta. Every type but one has been seen, 
and all the larger collections and exsiccate have been gains 
The result is very satisfactory. Six genera are recognized, 0 
which three, Fontinalis, Brachelyma and Dichelyma, are North 
American. Thirty-three species of Fontinalis with twenty-one 
in North America, adds ten to the number included in Lesquer- 
€ux and James’ Manual. The species are ranked in four ie 
according to their importance—F. antipyretica, Ff, iden . 
disticha, F. Nove- Anglia, F. hypnoides, F. microdonta, F- re é oa 
moides and F. filiformis taking first rank, whereas es . . 
New species rank third and fourth, 7. maritima, F. i oe 
©. Howellit, F. chrysophylla, F. Delamaret, B. mollis, F. sh oti, 
F. involuta, F. tenella, F. Duriai, F- flaccida and F. Langlotsi 
