1915] CURRENT LITERATURE 503 
radiculosa the primary cap cell may also add to the neck of the archegonium, 
but contributes nothing to the axial row. In this species the neck canal 
cells range from five to six. The embryo, while not different from that of 
0 
suspensor-like cell is produced. In the capsule the sterile cap is pronounced, 
and in consequence the dehiscence is by means of four longitudinal slits. The 
authors conclude that the evidence does not warrant the erection of the two 
families Aneuraceae and Blyttiaceae.—W. J. G. LAND. 
Brown oak.—Groom” has investigated the cause of what is known as 
“brown oak” or “red oak’? in Great Britain. The phenomenon consists in 
the replacement of the ordinary heart wood of Quercus Robur by a firm, richer 
toned, often reddish brown wood, which varies in tint from dull brown to 
rusty brown. It is found to be due to the influence of a fungus which lives 
exclusively in the heart wood, which it infects through wounds. “Brown 
oak’”’ usually occurs at the base of the trunk and in the adjoining root and 
extends more or less upward in the stem and downward in the root. If the 
fungus gains entrance to the upper parts of the tree, it produces in these 
regions masses of ‘brown oak.’’ The color is due to the fact that the fungus 
produces a brown substance in the individual cells which is highly resistant to 
solvents. The source of the food of the fungus was not determined, although 
there are reasons to believe that tannin is one of the sources. The identity of 
the fungus is also left in doubt. It produces conidiophores resembling those 
of Penicillium, and on certain specimens basidiocarps appear, which were 
identified as a species of M. mn eet but cultures did not establish any con- 
nection between the two phases.— a 
Morphology of Arisaem de a careful study of Arisaema 
triphyllum, and has seta iy to our knowledge of the morphology 
of the Araceae. The critical situations may be summarized as follows: There 
is a wide range in time in the development of the flowers, with a strong tendency 
to the earlier development of staminate flowers. The tapetal nuclei of the 
microsporangium are freed and “wander” among the developing microspores, 
as Duccar has described for Symplocarpus. The embryo sac is of the Lilium 
type, and a complex and permanent suspensor system is developed. The 
endosperm arises from one of the daughter cells render of the primary 
endosperm nucleus, the other daughter cell not divi The primary roots 
are diarch, while the secondary roots of seedlings oe all roots of mature 
plants are triarch to pentarch. The statement is made that the sex of ma- 
ture plants is changeable, dependent upon the amount of available water. 
17 Groom, Percy, “Brown oak” and its origin. Ann. Botany 29:393-407- I915. 
%8 Pickett, F. L., A contribution to our knowledge of Arisaema ¢triphyllum. 
Mem. Torr. Bot. Club 16:1-55. pls. 1-5. figs. 70. 1915. 
