137 
mation of a sporangium. Tims, according to Brefeld and others, Olpid- 
itun represents the final member in a degeneration which began with 
Peronosporaceae, The author’s view is just the opposite of this. He 
regards Chytridiaceae as a natural group and the simplest and earliest 
in point of time, i. e., as the starting point of the whole great series 
which ends in the Oomycetes with richly branched mycelium. 
Concerning disputed relationships he has the folloAving: The Olpid- 
iaceae have much in common with the zoosporous Monadineae, but the 
differences are still greater. One principal difference consists in the 
manner of taking food. In the Monadineae this takes place through the 
active amoeboid movements of the plasmodium by which solid sub¬ 
stances are commonly taken up. In the Myxochytridineae the amoeboid 
movements of the naked vegetative body are always feeble or wholly 
wanting, and the taking up of solid bodies does not occur. Conse¬ 
quently while the Monadineae take their food like the Myxomycetes, in 
the Myxochytridineae there is only an absorption of dissolved food as 
in the genuine fungi. In connection with this stands the extrusion of 
undigested food balls, something which, of course, does not occur in the 
Myxochytridineae. Together with the accompanying physiological dif¬ 
ferences due to the different manner of taking food, there are also im¬ 
portant purely morphological differences. In a number of zoosporous 
Monadineae (Aphelidium, Plasmodiophora) the amoeboid body breaks up 
into spores without previous formation of membrane, but in those forms 
in which a wall is previously formed the swarm spores escape from the 
cyst at indefinite places, i. e ., there is no special canal for escape. The 
contrary is true for all the Myxochytridineae except Sphaerita. Finally 
it should be emphasized that not rarely the actively amoeboid body be¬ 
comes a genuine plasmodium, through the blending of several amoebae, 
while genuine plasmodia are wanting in Myxochytridineae, with the 
possible exception of Rozella. The relationship of the Myxochytridineae 
with the Monadineae is to be recognized, but on the other side there is 
also to be noted in the described departure a step toward the fungi. It 
is especially the Holochytriaceae which show a transition into genuine 
mycelium. Forms like Myzocytium belong with the Myxochytridineae 
on account of their holocarpal development, but differ in the elongated 
vegetative body, surrounded from the first by a membrane, which, by 
its branching, takes on a mycelial character. 
Morphologically the Zygomycetes and Oomycetes can be very easily 
united to these Holochytriaceae, as a further development, with a richly 
branched, eu-carpal, mycelial vegetative body. 
The family of the Sporochy triaceae with mycelial haustoria appears to 
me to join on to the Hyphochytriaceae above. Among the Monadineae, 
Colpodella pugnax shows a similar development but is distinguished by 
the absence of mycelium and the much later following wall formation. 
Finally the family of Hyphochytriaceae which joins on to the Sporochy- 
triaceae (Polyphagus) is continued into Protomyces and the Ustilagineae. 
