ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 619 



ground. The falling over of the plants by hundreds in the field first 

 drew attention to the presence of the disease. 



W. Nowell * writes on root-diseases due to Rosellinia in the] West 

 Indies, generally in those islands with a damp climate. R. pe/io occurs 

 on cacao, and is transmitted from several shade trees. The disease on 

 limes and coffee may be due to either R. pepo or R. bunodes. An infested 

 tree may be killed by the gradual investment of the roots, or more 

 quickly by the fungus attacking the bark around the collar. 



J. Elliot t publishes the results of his study of " soil-rot " of Batatas. 

 The disease is due to a plasmodium, and he has observed two modes of 

 infection : one by the plasmodium as a whole causing large shallow pits ; 

 the other by means of swarm-spores developed within thick-walled cysts. 

 The formation of the cyst distinguishes this plasmodium from other alUed 

 genera, accordingly the name Ci/stopora batata g. et. sp. n. is given to it. 



F. A. Wolf I records the attack of Cucurbita by the fungus Choane- 

 phora cucurbitarum. It has done great damage, causing a bHght of the 

 flowers and a rot of the fruits. The sporangia, chlamydospore, and 

 zygospore stages of the fungus have been produced in artificial cultures. 

 The fungus is widely spread in America. 



A disease of Nymplisea in the United States has been found by F. 

 V. Rand § to be due to Helicosporium nymphearuyn sp. n., which causes 

 olive-black spots on the leaves. It gains entrance by the stomata, and 

 the myceUum ramifies in the intercellular spaces and between the 

 cells. The contents of the cells become coagulated and the nuclei and 

 chlorophyll bodies disintegrate. Spraying with Bordeaux mixture was 

 beneficial. 



Rene Maire j] has described some diseases of trees in North Africa. 

 On Arbutus Unedo he discovered a new fungus, Exobasidium Unedonis, 

 which gives rise to witch's-brooms. The fungus attacks the leaves and 

 the young shoots. Associated with Exobasidium he found Glmosporium 

 conviva sp. n. on the twigs and leaves, where it forms white pustules, and 

 Phoma Arbriti, which appears on the shoots killed by the Exobasidium. 

 A new Phragmidium on Rosa semperviveiis covers the leaves with 

 yellow pustules and the branches with black ulcerations. It is common 

 in Algiers. 



A disease of potatoes called "black-leg" IF or "black-stem" rot is due 

 to the presence of Bacillus phytoiphthora. It appears quite early in the 



* W.I. Bull. Barbados, xvi. (1916) pp. 31-71 (figs. 1-12). See also Bull. Agric. 

 Intell. Rome, viii. (1917) pp. 940-1. 



t Science, xliv. (1917) pp. 709-10. See also Bull. Agric. Intell. Rome, viii. 

 (1917) pp. 943. 



X Journ. Agric. Research, Washington, vii. (1917) pp. 319-27 (pis. 85-87). See 

 also Bull. Agric. Intell. Rome, viii. (1917) p. 944. 



§ Journ. Agric. Research, Washington, viii. (1917) pp. 219-32 (4 pis.). See also 

 Bull. Agric. Intell. Rome, viii. (1917) pp. 945-6. 



II BuU. Stat. Rech. Forest, Nord Afrique, 1. (1916) pp. 121-30 (1 pi. and 4 figs.). 



1 Journ. Board Agric, xxiv. (1917) pp. 653-6;(l fig.). 



2 T 2 



