tort] CURRENT LITERATURE 75 
fact that eggs of apogamous forms may produce staminate as well as ovulate 
plants does not affect the problem, since such eggs are diploid, and the sex 
tendencies have not yet been separated. The case is similar to that of budding. 
A cytological study was made in Melandrium rubrum, Cannabis sativa, 
and Mercurialis annua, but at present no cytological features have been 
recognized which seem to have any bearing upon the problem of the separation 
of the sexes. In Melandrium rubrum one chromosome is constantly larger 
than the others, as was noted during the reduction divisions and in vegetative 
cells, but it could not be connected with sex differentiation. 
The problem is unusually large and difficult, and the present paper suggests 
many points of attack.—CHARLES J. CHAMBERLAIN. 
Crown gall.—The most noteworthy contribution recently made to plant 
pathology is the bulletin on crown gall of plants by Smiru, Brown, and Town- 
SEND.%3 This disease, on account of its wide distribution and the conspicuous 
nature of the deformations to which it owes its name, has long attracted the 
attention both of practical horticulturists and plant pathologists. Yet, with 
the exception of the work of some Italian investigators, little has been done to 
work out the etiology of the disease. From general observations it has been 
believed that the disease is communicable, and one investigator (CAVARA 
isolated an organism from a gall of the European grape and established a 
strong probability that it was the causal organism of that particular gall. 
The nature of the outgrowths known as crown gall and occurring on a great 
many different kinds of plants, the cause of their occurrence, and the relation 
of the crown galls of different plants to each other, have remained among the 
most obscure problems in the whole field of plant pathology. The results of 
investigations on these problems are reported in the present bulletin 
e work begins with a short historical sketch of the more feito 
investigations on the crown gall, special emphasis being laid on the work of 
Italian investigators who first ascribed the disease to bacteria. This is followed 
by an account of the isolation of the causal organism, and the evidence showing 
that the crown gall of various plants is due to bacterial organisms; and that 
these belong either to a single species or to closely related species or strains, 
each of which can be inoculated into many species of plants. The morphology 
crown gall and some animal tumors is discussed. is similarity is emphasized 
by the occurrence of metastases in infected plants. The last part of the 
bulletin relates to the practical aspects of the subject, together with a statement 
of the plants infected and their distribution. The evidence given in the first 
part is supported by 36 excellent plates. 
3 Suit, E. F., Brown, NELLIE A., TownsEnD, C. O., Crown gall of plants; its 
cause and remedy. Bur. Pl. Ind. Bull. 213: pp. 200. pis. 36. figs. 3. 1911. 
