264 THE VEGETABLE WORLD. 
The Movtps were long supposed to have a very simple organi- 
sation, because they had been imperfectly observed. Even in our 
days they are very imperfectly known. It is now known, how- 
ever, that some of them are endowed with multiplied reproductive 
apparata. The Mucors, which are the commonest of the Moulds, 
- grow on organic substances in a state of decompo- 
sition, forming large catonous tufts, with vesicles 
full of greenish spores on the summit of long 
slender pedicels (Fig. 332). It has only re- 
cently been :ascertained that the genera which 
had been -named respectively Aspergillus and 
Eurotium are only two different and successive 
modes of fructification; Aspergillus being the 
— fructificationof the young, Eurotium that of the 
Fig. 332.—Mosses. adult state. 
The parasite which proved so destructive to the potato belongs 
to the family of fungi now under consideration ; and here also we 
note two modes of fructification ; one, namely, in which the spores 
are born naked at the extremity of the filaments, while in the 
other the spores are contained in certain voluminous vesicles. 
In a recent memoir, M. de Bary, professor in the University of 
Fribourg in the Brisgau, has directed attention to the very curious 
phenomena attending the germination of the naked spores, and ag 
may be useful to present a resumé of these interesting researches. 
The spores, or rather the so-called naked spores of the potato 
parasite, of the Peronospera, present us with three distinct modes 
of germination. In the first process germination is indicated by 
the emission of simple or ramified filaments, which possess the 
power of penetrating the tissues of the potato by piercing the 
walls of its superficial cells. The second form of germination 18 
characterised by the formation of a secondary spore, from the 
summit of ‘which issues a simple tube, which in due course attains 
the length of two or three times its greatest diameter, expanding 
like a vesicle at the extremity. When all the plastic contents of 
the spore are enclosed in this terminal vesicle, it is isolated from the 
Jilamentous germ by a partition, and thus constitutes a distinct cell. 
But this spore of the second order is a phenomenon of rare occur 
rence, and of secondary importance only, according to M. de Bary: 
