166 BOTANICAL GAZETTE [AUGUST 
phytol group is displaced by the ethyl group and the ethy] derivatives crystal- 
lize out. With methyl alcohol the crystals are the methyl derivatives. 
WILLSTATTER speaks of the native green pigments as phytylchlorophillids. 
On the same basis the ethyl derivatives are ethylchlorophillids. The displace- 
ment of the phytol by the ethyl group is hastened by an esterase (chloro- 
phyllase). The phytyl derivatives are amorphous, while the ethyl and methyl 
derivatives are crystalline. The constitution of the green crystals given with 
ketones, esters, and aldehydes is unknown.—W™. CROCKER. 
Silver leaf.—Gissow” reports that the peculiar disease known as “silver - 
leaf” is common on fruit trees in Canada. This disease has been recognized 
and has received distinctive names in several European countries. Its chief 
symptom, as its name indicates, is a silvery appearance of the leaves which is 
brought about by the separation of the epidermis from the palisade cells and 
the consequent filling of the resulting space with air. The wood of the diseased 
trees is browned and contains mycelium. After the death of the affected trees, 
fruit bodies of Stereum purpureum develop on the trunks and branches. This 
fungus has been shown by PERcIvAL, PICKERING, and others to be causally 
associated with the disease. The observations of these investigators are 
confirmed by Gtssow’s experiments in Canada, where in many cases he was 
able to produce the disease in 100 per cent of the inoculated trees. He also 
found that scions grafted on diseased trees soon became infected. In all 
cases the wood is infected with the mycelium of Stereum purpureum, but the 
most striking feature of the disease is the total absence of the mycelium from 
the diseased leaves. The mode in which the separation of the epidermis from 
the underlying tissue is brought about by the fungus was not determined. 
The disease appears to furnish an example of physiological effects wrought 
by the action of the mycelium on parts of the host not actually invaded. Suc 
phenomena, where the effects cannot be traced to mere mechanical injury, 
are practically unknown in the field of plant pathology.—H. HAaSSELBRING. 
Cytology of Laboulbeniales,—As a sequence to his general introductory 
account's of the cytology of the Laboulbeniales, Faut™ has published a full 
account of the special morphology of two species, Laboulbenia chaetophora 
and L. Gyrinidarum. These two forms lack antheridia; therefore the study 
of them is not complicated by the question of fertilization by spermata. 
The young procarp consists at first of the carpogonium, the trichophoric cell, 
and the trichogyne. The nucleus of the carpogonium and that of the tricho- 
Phoric cell divide, and at about the same time the wall between the two cells 

“ GUssow, H. T., Der Milchglanz der Obstbiume. Zeitschr. Pflanzenkrank. 
222385-4o1. figs. 1. pls. 2. 1912. 
Rev. in Bor. Gaz. 54:84. 1912. 
Faut, J. H., The cytology of Laboulbenia chaetophora and L. Gyrinidarum. 
Ann. Botany 26:325-355. pls. 4. 1912, 

