Q4 
of the soluble modification, probably formed from the insoluble. This 
increase is larger in the sweating process. 
6. This enzym is the most durable of those in the tobacco leaf under 
ordinary. circumstances, since it occurs in tobacco even over 6 years 
old, in which no trace of other enzyms, not even of the peroxidase, can 
be found. 
7. It is certainly an important factor in the heating up of the tobacco 
pile, as recent experiments with fermenting tobacco have shown. 
The general occurrence of this enzym in plant as well as in animal 
cells suffices to indicate a highly important physiological réle. It is 
probably intimately connected with the process of respiration. ‘The 
following two hypotheses as to its function appear the most probable 
to the writer: . 
1. Since many oxidative processes lead to the formation of hydrogen 
peroxide as a by-product, it is important that such a poisonous 
by-product be at once destroyed when accidentally formed in the cells 
in the course of the respiratory oxidations. 
2, This enzym may have the .office of loosening affinities in fatty 
acids and sugar in order not to tax the chemical energy of the proto- - 
plasm itself too heavily when these compounds are consumed for the 
purpose of respiration. 
REMARKS ON THE MOSAIC DISEASE OF THE TOBACCO PLANT. 
The mosaic disease, in the Southern States called “frenching” and 
in the Northern States ‘calico,” ‘‘brindie,” and *‘mongrel” disease, is 
of special pathological interest. I*or a discussion of the causes, theories, 
and scientific investigations on the development of this disease the 
reader is referred to a special and extensive bulletin by Albert F. 
Woods, of this Division, which will make its appearance at no dis- 
tant date. In this place will be mentioned chiefly a number of 
observations made by several planters. 
The disease is easily recognized by the contrast of the dark-green 
regions, mostly near the veins, and the light-green regions of the 
lamina. The former, being better nourished on account of containing 
inore chlorophyll than the latter, grow faster. This causes the leaves 
to curl and assume a wavy shape, like corrugated iron, rendering the 
leaves worthless for wrappers. Highly diseased leaves have to be 
entirely discarded. The disease sometimes affects as much as 10 per 
cent of the plants of an entire field. At times it attacks only a few 
leaves of a plant, and at other times the entire plant is affected. 
Broad-leaf tobaceo is asserted to be more liable to the disease than 
Habana seed tobacco. The annual damage thus done in the United 
States is estimated to be more than a million dollars. 
Various causes seem to create a tendency to the disease. Some act 
in the seed bed, some depend upon the mode of planting in the field, 
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