Fungi. — Pathologie. - - Bryophyten. 027 



reach of the microscope, and similar in their nature to those 

 which bring about the essential differences between species and 

 varieties themselves". G. Massee and A. D. Cotton (Kew). 



Woods, Albert F., Observations on the Mosaic Disease 

 of Tobacco. (Bulletin No. 18. Bureau of Plant Industry, 

 U. S. Department of Agriculture. May 1902. 24 pp. b pl.) 



A brief review is given of the work of previous investi- 

 gations of the mosaic disease by A dolph Mayer, Beijerinck 

 and Koning in Europe, and by Sturgis and the author in 

 America. As a result of his more extended study of this 

 trouble, a detailed account of which is given, the author con- 

 cludes that the disease is not due to parasites of any kind, but 

 is the result of defective nutrition of the young dividing and 

 rapidly growing cells, due to a lack of elaborated nitrogenous 

 reserve food, accompanied by an abnormal increase in activity 

 of oxidizing enzyms in the diseased cells, since both oxidase and 

 peroxidase accompanied by a zymogen were found present. 

 The unusual activity of these enzyms prevents the proper 

 elaboration of reserve food, so that a plant once diseased seldom 

 recovers. By the decay of the roots, leaves, and stems of both 

 healthy and diseased plants, the enzyms are liberated and remain 

 active in the soil. They are very soluble in water and appear 

 to pass readily through plant membranes. If young plants take 

 them up in sufficient quantity to reach the terminal bud, they 

 become diseased in the characteristic way. 



The disease is easily produced artificially by cutting back 

 the plant, and was caused in this way not only in tobacco 

 plants, but also in tomato, potato, petunia, pokeweed, English 

 violet, and other plants. It greatly resembles the disease of the 

 mulberry in Japan, known as mulberry dwarf, which Japanese 

 investigators assert to be due to the excessive cutting back of 

 the trees to cause them to produce a new growth of branches 

 and tender leaves for the silkworm. A pathological condition 

 of the same nature is produced by sucking insects and mites 

 in the young growth of carnations and other plants. 



Means of prevention of the disease under field conditions 

 remain undetermined. Suggestions based on the results of the 

 investigation are given which may lead to the discovery of 

 remedial measures. Hedgcock. 



Geheeb, Adalbert, Zur Aufklärung einiger exotischer 

 Laubmoose, welche als „species novae" in die 

 Litteratur Eingang fanden, jedoch auf bereits be- 

 kannte Arten zurückzuführen sind. (Beihefte zum 

 Botanischen Centralblatt. Band XIII. Heft 1. p. 105—111. 

 1902.) 

 Nach Vergleichung von Originalexemplaren und durch 



mehrfache Belehrung von Seiten der Herren V. F. B rother us 



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