134 BROOKLYN BOTANIC GARDEN MEMOIRS 
growing point where abundant food is available, or even take two years 
in regions less favorably located. The characteristically binucleated 
haustoria are of large size and are easily demonstrated. 
I have examined several stems three years old but do not find 
that the mycelium spreads out through the entire cortex and into the 
bast as described by Wornle. G. clavipes brings about less increase 
in development of wood tissue than G. biseptatum, but this may be 
due to the fact that the mycelium does not approach the cambium as 
closely. This species may develop strictly foliicolous sori in which 
case the mycelium is very limited in extent. The sorus is then not 
deep seated. Haustoria can be found in epidermal cells. 
(GYMNOSPORANGIUM TRANSFORMANS 
I have previously reported’ that two leaf-inhabiting species of Gym- 
nosporangium can be distinguished on Chamaecyparis. The account of 
the cultures in support of this statement is being published in another 
paper. For convenience I shall call one form G. transformans. Its 
aecidial form is Roestelia transformans on Aronia. Gymnosporangium 
fraternum is an appropriate name for the second leaf form which 
infects Amelanchier. The aecidium is very similar to that of Roestelia 
Botryapites; | am not prepared to prove that it is R. Botryapites. A 
cytological examination of cedar leaves infected with G. transformans 
and G. fraternum reveals further characteristics by which they may be 
distinguished. 
If we section a leaf of Chamaecyparis infected with G. transformans, 
we find that the mycelium is especially abundant in the large inter- 
cellular spaces of the spongy mesophyll and the hyphae push in be- 
tween the cells of the palisade on all sides. No hyphae are to be found 
in the epidermis. If the section includes the short vein of the leaf we 
see that hyphae are prevented in some way from entering the vascular 
tissue. There is an irregular row of large cells surrounding the vein 
of the leaf. These pericycle(?) cells do not normally form a_ per- 
fectly closed ring; it is occasionally broken by smaller supporting 
cells. In regions where the hyphae reach the large cells one can 
find, here and there, that they have been penetrated by one or two 
haustoria. Such infected cells are about one third larger than usual. 
The cytoplasm is rather dense, including considerable stored food 
and takes the gentian violet stain somewhat deeply. The nuclei 
appear to be quite normal. MHaustoria are also occasionally found in 
mesophyll and palisade cells. The cells of the mycelium are bi- 
nucleated and the nuclei stand out very clearly, especially where 
7 Dodge, B. O. Report on further cultures of Gymnosporangia. Paper read 
at the December meeting of the Botanical Society of America, New York, 1916. 
