19 iq] current literature 311 



will be welcomed by plant pathologists, especially those who are interested in 

 tropical plant diseases. In the introduction the author states that the losses 

 due to fungi are at least 10 per cent. He also states that "certain articles on 

 phytopathology in the tropics give an entirely wrong impression of the number 

 and destructiveness of the diseases." In the Malayan regions, at least so far 

 as the PhUippfties are concerned, there are represented all groups of fungi that 

 are present in the temperate regions. Extremely destructive diseases are 

 produced by some of each group. It is very evident from this and other works 

 that the diseases follow the host plants very closely. Agricultural plants, 

 especially vegetables and truck crops that are very widely distributed, are 

 attacked by the same pathogens, whether grown in the tropical or temperate 

 zones. The coffee industry was at one time wiped out by a fungus, the cacao 

 loss is about 50 per cent, and the rice losses are very heavy. The author lists 

 60 hosts of which about one-half are grown to a greater or less degree within the 

 bounds of the United States, especially in the southern states or Pacific Coast 

 states. There are a total of 339 diseases listed, many of which are found within 

 the United States. The author gives brief but accurate descriptions of the 

 symptoms, the causal organisms, and statements concerning the control 

 measures. Ten pages are devoted to the discussion of spray mixtures and 

 methods of control. — Mel T. Cook. 



Root-nodules. — Miss Spratt' has investigated the formation of root- 

 nodules by Bacillus radicicola. The plants producing nodules when infected 

 are sharply differentiated into 2 classes, legumes and non-legumes. In the 

 Leguminosae the cortical cells respond to the stimulus, resulting in the nodule. 

 In other plants the penetration of the bacteria into root-hairs and cortex 

 induces no morphological change until a young lateral root is infected during 

 its passage through the cortex, and as a consequence becomes swollen and forms 

 the nodule. In other words, the root-tubercles of non-leguminous plants are 

 modified lateral roots, while those of the legumes are exogenous in origin. A 

 contrast in the structure of the 2 types of nodule is evident. In leguminous 

 nodules the bacteroidal tissue is central, and the vascular system consists of 

 a number of peripheral strands; while in the non-leguminous nodules the 

 stele is central, retaining its connection with the root cylinder and growing 

 point. In making a comparative study of the nodules of Leguminosae, Miss 

 Spratt recognizes 4 types, based chiefly upon the distribution of meristem, 

 bacteroidal tissue, and vascular tissue, and these types are definite enough to 

 characterize various groups of Leguminosae. 



The author concludes that "the form of the nodule depends primarily on 

 the nature of the environment of the host, which influences the cell-sap and con- 

 sequently the behavior of the bacteria after they have entered, and secondarily 

 on the anatomical peculiarities of the particular plant."— J. M. C. 



^ Spratt, Ethel R., A comparative account of the root-nodules of the Legumi- 

 nosae. Ann. Botany 33:189-199. pi. 13. figs. 5. 1919. 



