248 
the same way, in tomato, potato, petunia, 
phytolacea, violet and other plants. (2) 
The disease may be reduced by repotting 
or transplanting a plant in active growth, 
thus stimulating a rapid root development. 
New leaves that form at this time often 
come diseased. Leaves that form at the 
time of the development of the flowers also 
often come diseased, as do also rapidly de- 
veloping suckers. The pathological changes 
are the same in these cases as when the 
disease is produced by cutting back. (3) 
The disease may be produced by injecting 
the sterile juice of diseased plants into the 
growing bud or by pouring it on the roots. 
Perioxidase obtained from healthy or dis- 
eased plants and injected into the bud or 
poured on the roots may also cause the dis- 
ease. The author concludes as follows: 
“The evidence which I have cgollected, 
taken along with that obtained by other 
workers, especially Mayer and Beijerinck, 
is therefore very strongly in favor of the 
infectious nature of the trouble under cer- 
tain conditions. The matter can not, how- 
ever, be considered as settled. So far as 
the evidence at hand goes, it appears that 
in growing cells there is possibly a definite 
relation between active oxidizing power, 
through the medium of oxidizing enzymes, 
and the availability of reserve food to the 
growing cells. It appears that this balance 
between the oxidizing enzymes and the 
availability of reserve foods can be broken 
by removing, on the one hand, the supply of 
reserve foods, in any way during growth, 
in which case the enzyme content of the 
cell is increased from two to four times the 
normal activity. This removal of reserve 
food may be either the result of diversion 
to other parts of the plant or of direct re- 
moval, as in the case of cutting back or of 
sucking insects, and possibly also can be 
brought about by other conditions not at 
present understood. On the other hand, 
the most remarkable thing is that the in- 
SCIENCE. 
(N.S. Von XIII. No. 320. 
troduction of the enzyme in question (peri- 
oxidase) sets up the same series of path- 
ological changes as is brought about by the 
removal of reserve food, namely, the in- 
crease of the normal enzyme of the cell, and 
the decrease of availability of reserve foods. 
When this pathological condition is reached 
it is very difficult for the plant to correct 
the trouble. The perioxidase probably 
moves from one part of the plant to an- 
other, though how much of the general 
spread of the disease in the plant is due to 
such movement has not been determined. 
The evidence of the communicability of 
this disease is quite as strong, if not 
stronger, than that upon which rests the 
belief in the communicability of ordinary 
‘variegation through grafting on healthy 
plants. The two groups of diseases are 
at least very closely related and are prob- 
ably simply different phases of the same 
malady. Possibly peach yellows and the 
California vine disease belong here also 
and are to be similarly explained. Die- 
back of the orange may also belong here. 
The paper was illustrated by two colored- 
plates and four half-tones, and will be 
printed as a bulletin of the U. 8. Depart- 
ment of Agriculture. 
Report of the Committee appointed to consider 
Methods of securing Improvements in Re- 
views of Current Botanical Literature: Pre- 
sented by the Chairman, Prorrssor W. 
G. Fartow, Harvard University. 
This report has already been referred to, 
and a further account of it will be found 
in a later number of this Journal. 
The Cause of the Red-brown Color in certain 
Cyanophyceae: Dr. G. T. Moors, Dart- 
mouth College. 
The various theories which have at- 
tempted to explain the cause of the red- 
brown color in Anabaena, Glloiotrichia, Oscil- 
latoria an other so-called ‘blue-green algae,’ 
were discussed. It was shown that this 
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