154 BOTANICAL GAZETTE [AUGUST 
tubes and bast fibers becomes distorted and irregular. The cambium ring also 
is broken and irregular from the fact that uniform differentiation into phloem and 
xylem no longer occurs. In the wood the medullary rays undergo transformation 
as in the phloem, becoming irregular masses of parenchymatous storage tissue. 
he wood is also considerably enlarged. : 
In G. juniperinum the changes are similar but less marked, the greatest 
changes in the medullary rays being near the periphery. The sieve tubes are 
mostly suppressed and the xylem is somewhat reduced. In the leaves the chief 
change induced by this fungus is the transformation of the spongy parenchyma 
into palisade-like tissue. The observations of this writer agree in detail with 
the more extensive account of WOERNLE, wh llent paper on the anatomical 
changes induced by both the European and American species of Gymnospo- 
rangium is nowhere cited or referred to in the article. 
As a general result of the effects of the fungus on its host, LAMARLIERE points 
out the tendency toward “parenchymatization,” i. e., a tendency of the cells 
to remain in their more undifferentiated form, a phenomenon from which he 
draws a parallel to tuber formation—H. HAssELBRING. 
Dioecism among Mucorales.—In continuation of his studies of dioecism 
among the Mucorales, BLAKESLEE?® has recently investigated the extent to which 
differentiation of sex occurs in the spores from germ-sporangia obtained from zyg0- 
spores. The principal results contained in the paper are as follows. The germ- 
sporangia of the | pecies Sporodinia grandis and Mucor I (undescribed) 
contain but a single kind of spores, which produce mycelia again capable of form- 
ing zygospores. With the heterothallic species the case is different. Here spores 
in the germ-sporangium may be either all (+) or all (—), or (+) and (—) may 
be mixed. Of the species tested, Mucor mucedo produces all (+) or all os 
spores in its germ-sporangia, showing that a segregation of sex takes place at 
some period previous to the formation of spores. In Phycom-yces nilens, howevet, 
(+) and (—) spores are mixed in the same germ-sporangium, together with 
others that show a tendency to produce a homothallic strain. The mycelia of 
the homothallic strain are characterized by the production of irregular contorted 
growths to-which the writer gives the name. pseudophores. The production of 
sporangia on these mycelia is very limited. The spores from them show a Segre” 
gation into (+) and (—), and others reproducing the homothallic strain. 
The reading of this paper is made somewhat difficult partly through lack of 
clearness in style, which is as essential in scientific exposition as is accuracy i 
investigation, and partly through the loose use of terms introduced by the author 
himself. The terms heterothallic and homothallic as used in the earlier papers 
on zygospore-formation apply to the condition of sexual differentiation of 
individuals within a species, strain, or form, being equivalent to dioecious a 
monoecious. While it is possible to speak of a heterothallic species or TA : 
ah ioe ae ucorineae. Annales 
Py Rs | 
16 BLAKESLEE, A. F., Zygospore germinations in the M 
Mycol. 4: 1-28. 1906. 
