tort] CURRENT LITERATURE 239 
unknown causes. The structure of the swelling is characterized by spongy 
masses of parenchyma filled with starch and interspersed with woody layers. 
An interesting myco-cecidia of the orange is described by FLORENCE 
Hepces. This cecidia is attributed to Sphaeropsis tumefaciens, nov. sp., 
which is described. The external characters of the gall are given, but the 
development and histology are omitted—MeEt T.- Cook. 
Phycomycetes.—PETERSEN gives an abbreviated English translation 
of his paper on the aquatic Phycomycetes of Denmark, which was originally 
published in Danish. The paper” is divided into three parts, the first dealing 
with the phylogeny and relationships of the Phycomycetes, the second with 
their occurrence and distribution, and the third with descriptive taxonomy. 
s to their phylogeny, the author adheres to the view that the aquatic 
Phycomycetes and their near relatives constitute a phylogenetic series. If 
they were derived from the algae at various levels, they would hardly show 
the homogeneity which runs through the aquatic forms. As to the direction 
of their evolution, he holds that the lower Phycomycetes have been derived 
from the higher forms through reduction of the plant body. This view, 
which necessitates the assumption that motile zoospores and cilia were acquired 
by the degenerating forms, meets with difficulty when the non-aquatic Pero- 
nosporales are considered. The author regards the Pythiaceae, on account 
of their probable relationship with Lagenidium, as the ancestors of Lagent 
ceae. The Peronosporales, to which the Pythiaceae belong, would pultoadl 
form a part of the reduction chain, and it would be necessary to assume that 
zoospores adapted to aquatic conditions have arisen among the aerial Pero- 
nosporaceae from conidia eminently suited for aerial] distribution. The alternate 
ypothesis that the Peronosporaceae are losing their aquatic characters in a 
dry habitat, instead of acquiring them, seems more reasonable. e chief 
argument of the author is directed against the view of FIscHER that the 
Phycomycetes are derived from the Monadineae. Here he rightly points.out, 
among other differences, that the germinating zoospore of the Phycomycetes 
leaves the spore membrane behind, while in the endophytic Monadineae the 
zoospore makes its way in its entirety into the host cell. The author rightly 
regards the Synchytriaceae as a distinct group, which represents a line of 
development different from the rest of the Chytridiales. The idea is not fully 
carried out, however, in his synopsis of the families given later. 
In the second part of the paper are given many interesting observations 
on the biology and distribution of the aquatic Phycomycetes in Denmark. 
The Saprolegniales occur frequently on fish and frog spawn, but they do not 
© HEDGES, FLORENCE, Sphaeropsis — noy. sp., the cause of the lime 
and orange knot. Phytopathology 1:63-6s. 
7 PETERSEN, H. E., An account of chk a Phycomycetes, with bio- 
logical and ——— remarks. Ann. Myc. 8:404~560. figs. 27. 1910 
over Ferskvands-Phycomyceten. Botanisk Tideskrift 29: 
t). 
jer 
345-429. he. = 1g0og (with English abstract 
