1913] CURRENT LITERATURE 257 
pollen from stamens of all lengths develops readily on the stigmas of all —— 
of pistil, provided the stigmas are of the well eee sort. From this 
knoblike haustorial outgrowth which extends into the tissue of the integument. 
—LeEsTER W. SHARP. 
Crown-gall.—In their account of the crown-gall of plants, Situ, 
Brown, and Townsenp® described the occurrence of secondary galls origi- 
nating at some distance from primary galls which had been produced by direct 
infection, and suggested that the secondary galls arose in some way from 
€ primary galls, although the mode of origin was not clear at that time. 
This problem has now been solved by a histological study of the crown-gall by 
MITH, Brown, and McCuttocu.® They find that the secondary galls arise 
from strands of tissue which originate from the primary galls and make their 
way along the stem or leaf, usually in the region of the primary wood. The 
tumor strand apparently does not absorb the cells in its path, but makes its 
way by crushing and flattening them. Secondary galls arise at various points 
along the tumor strand. cross-section of a secondary gall developing in the 
leaf from a strand arising from a primary gall in the stem shows a stem structure 
with the woody elements greatly developed and regularly arranged like the 
secondary wood of a stem. If, however, a primary gall develops in the leaf as 
a result of direct inoculation, its structure is irregular. The tissue consists of 
an enormous development of parenchyma intermixed with irregular masses of 
tracheids. There is no distinct differentiation of parts as in the secondary galls 
arising from stem galls. The similarity which has been formerly pointed out 
between these plant galls and animal tumors leads the writers to consider the 
crown-gall apart from all other plant diseases, and to place it in the category 
of true tumors.—H. HASsELBRING. 
* Rev. Bor. Gaz. 52:75. 191t. 
* SmitH, Erwin F., Brown, NEtueE E., and McCuttocs, Lucia, The structure 
and development of crown gall; a plant cancer. Bur. Pl. Ind. Bull. 255. pp. 60. 
Sigs. 2. pls. 109. Igt2. 
