Pflanzenkrankheiten. 205 



tophthova previously described by him as causing the "Black Thread" 

 disease of Hevea stems and fruits in Burma. Comparing the 

 Symptoms of the disease with those of "Canker", due to Phytoph- 

 tiiora Faberi, he concludes that this disease is not the same as 

 "Canker" of Cacao and Hevea, but is identical with "Bark Rot" or 

 "Decay of renewing bark", first recorded by Petch in Ceylon. 

 The causative Phytophthora is remarkable for the formation of a 

 stromatoid body of loose cells beneath the cuticle of the host. From 

 this stromalike body the sporangiophores arise. The author sug- 

 gests a comparison of this structure with the sorus of Cystopus. 

 Details as to the behaviour of the fungus in culture are given, 



E. M. Wakefield (Kew). 



Grossenbachep, J. G., Some neglected phases ofphyto- 

 pathology. (Phytopathology. V. p. 155—162. 1915.) 

 The paper is a plea for reforming American phytopathological 

 researches, inasmuch these researches are generally too much 

 studies about microorganisms and far too little studies about 

 diseased plants. Phytopathology has been too much concerned 

 with the morphology and physiology of the microorganisms asso- 

 ciated more or less constantly with many diseases of cultivated 

 plants, to permit continuous and thoroughgoing studies of the 

 seasonal and life history of the tissues first affected by the early 

 stages of diseases. This has tended to discourage investigations 

 into the conditions that precede such visible derangements in 

 plants. This one-sided development of phytopathology has been 

 since a longtime marked in the United States, and much less in 

 Europe. The writer illustrates his discussions with an exposure 

 of European work, as Sorauer's Handbuch in its different editions, 

 Quanjers researches about leafroll in potatoes, and as an 

 American example of this new line of research, his own studies 

 about bark diseases in fruit trees. M. J. Sirks (Wageningen). 



Hubert, E. E., A new Macrophoma on galls of Populus tricho 

 carpa. (Phytopathology. V. p. 182—185. 1915.) 

 Very noticeable galls occurring on Populus tnchocarpa Torr. 

 and Gr. were at first supposed to be caused by an insect, Saperda 

 populnea L., but showed upon examination, no evidence of insect 

 origin. Thin transverse sections of the galls taken from older twigs 

 of an infected tree, and stained with eosin, disclosed iarge sub- 

 carbonous pycnidia in great numbers embedded in the cortex. 

 Examinations of old galls have revealed nothing but the pycnidial 

 stage. The fungus was determined by Dr. Shear to be a new 

 species of the genus Macrophoma viz. M. tumefaciens Shear n. sp. 

 Description is given in English. Cross inoculations and culture 

 experiments have not yet resulted in definite facts. The galls appear 

 almost invariably at the point where^the twigs and branches fork. 

 Those occurring at the base of young twigs have a tendency to 

 cause that portion of the twig, in advance of the gall, to become 

 dwarfed and finally to die. These growths become injurious to 

 young trees in the near vicinity of an old infected tree. It is un- 

 certain, but reasonable to suppose, that the hypertrophy is caused 

 by the hyphae of the fungus. M, J. Sirks. (Wageningen). 



