240 BOTANICAL GAZETTE [SEPTEMBER 
Cecidology.—Among the most important of the foreign contributions 
is a paper by Karny,” in which the author describes a large number of gall- 
ing Thysaneura, including a number of new species. However, the empha- 
sis is placed upon the animal rather than the plant side of the subject. 
A-most excellent paper by Houarp* on the galls of French West Africa 
gives descriptions of 51 new species of gall-makers on 29 species of host plants. 
The author describes both insect and cecidia and in most cases gives illustra- 
tions of the cecidia. The grouping is with reference to the plants, a practice 
which is apparently growing in favor with the students of cecidology. 
Root nodules are the subject of two papers. Miss Spratt discusses the 
root nodules on the Podocarpineae which are caused by Pseudomonas radicicola. 
These nodules are modified lateral roots. The organism penetrates the root- 
hairs and then the cortex, and the stimulus is in the meristimatic tissue, but 
there is no differentiation of the meristimatic zone in the cortical tissue such as 
is found in the nodules of other non-legumes. The organism produces a 
zooglea in the cells which stimulates the nuclei of the host and causes them 
to divide amitotically. In the spring the cells immediately below the endo- 
dermis at the apex of the nodular stele become meristematic and produce new 
cortical cells in the interior of the old nodes. The other paper on root nodules 
is by Borromiry,3 who finds the nodules on the yrica Gale are also modified 
lateral roots. ‘These nodules are also caused by P. radicicola and each mature 
nodule shows four zones: (a) the apical meristem, (b) the infected thread 
area, (c) the bacterial zone, (d) the basal zone in which the cells contain oil 
rops. The bacteria eventually disappear and the basal zone is replaced by 
the other zones. 
is BEssEy’s4 study of the nematode root knots. This disease is caused by 
. + and was probably indigenous in some 
agin region of the Old World from which it has been distributed throughout 
that about 480 species and varieties of plants, including nearly all the larger 
f The life cycle is four weeks or more, 
dependent on the temperature of the soil. The author gives a good discussion 
af 7 Karny, K, Gallenbewohnende Thysanopteren aus Java. Marcellia 11: 115-1609. 
2. 
* Hovarp, C., Les galles de PAfrique occidentale francaise (V. Cecidies nou- 
velles). Marcellia II:176-209. 1912. 
22 
om pete ETHEL XOSE, The formation and physiological significance of root 
me in the Podocarpineae, Ann. Botany 26:803-813. 1912. 
ss Borromiey, W.B., The root nodules of Myrica Gale. Ann. Botany 26:111-117- 
a4 _ 
wes Bessey, E. A., The root knot and its control. U.S. Bur. Pl. Industry, Bull. 217- 

