452 ALLARD: MOSAIC DISEASE OF TOBACCO 
In 1912 Egiz (60) in Russia published a paper concerning the 
growing of tobacco in southern and middle Russia. He meniions 
briefly the more important diseases affecting the tobacco plant in 
this region, i. e., rust (Pockenkrankheit), mosaic, and other dis- 
eases. He added nothing beyond what is already known concern- 
the mosaic disease of tobacco. Egiz considered that soil and 
climatic factors of one sort or another were responsible for the 
disease, i. e., soils too moist, soft rather than hard soils, hot sun- 
shine together with great humidicy, etc. Asa means of preventing 
the occurrence and spread of the disease he recommended burning 
all diseased plants, keeping soils in the best tilth, the application 
of good quantities of lime, and the saving of seed from healthy 
plants. Egiz also mentioned another disease somewhat similar 
to mosaic in appearance which is not infectious and results from 
injuries to the roots from one cause or another. The leaves 
become marbled or variegated. 
Chapman (61), in 1913, published the results of observations 
and experimencs with the mosaic disease of tobacco and tomatoes. 
He pronounced the disease a purely physiological one, and con- 
tended that it was not of fungous or bacterial origin. He did not 
consider that a specialized virus was responsible for the occurrence 
of the disease. He regarded the theory of antagonistic enzyme 
action previously advanced by Woods as sufficient to explain the 
primary origin of the disease. Although Chapman believed that 
improper sterilization of infected seed beds actually increased the 
occurrence of mosaic in the seedlings, it is difficult to offer a 
satisfactory explanation for such results. 
Since the time of Mayer the failure to distinguish between the 
true mosaic disease and various other diseased appearances has 
led to a literature filled with confusion and contradiction. 
Throughout Europe many investigators at first regarded a spot 
disease, ‘‘ Pockenkrankheit,” asa later or final phase in the develop- 
ment of the true mosaic disease or ‘‘ Mosaikkrankheit.” Others 
have contended that these appearances represent two distinct 
diseases. Throughout France especially, various leaf-spoc diseases 
were described as the true mosaic of Mayer. Beijerinck (12) 
applies the term “‘la nielle’”’ to the true mosaic disease. Perreau 
(38) speaks of ‘‘la nielle ‘‘ ou” Mosaikkrankheit” and has in mind a 
