316 REPORT OF THE BOTANICAL DEPARTMENT OF THE 
A. Gautier*® had previously shown that arsenic is normally 
present in animal bodies, especially in epidermal structures. 
His findings have also been verified from the biological stand- 
point by M. Segale,?® who determined the presence of arsenic 
in animal tissues by means of reactions induced by Penicil- 
lium brevicaule when transferred to autolized tissue. 
Now, in view of these citations and since Headden’s de- 
scriptions and plates so closely resemble the ordinary cases 
of Crown-rot, affecting trees alike in both sprayed and wn- 
sprayed orchards, and since some old orchards in this State 
(which have been sprayed with arsenic ever since spraying 
was invented) often have only Crown-rot scars dating back 
six to fourteen years, and look thrifty now, we either must 
conclude that we have two very similar diseases due to two 
different causes, or that there was an unwarranted conclu- 
sion drawn, regarding the relation of the arsenic found, to 
the injury of the trees. The latter seems more plausible, for 
herbaceous plants about the bases of the affected trees grow 
abundantly and normally. It would seem that high winds 
and low temperatures of Colorado may account for the crown 
and root-injured trees described by Headden, even though 
arsenic was found in them. 
LOW TEMPERATURES. 
The majority of writers on Crown-rot seem to agree that 
it is caused by low temperatures in connection with certain 
other factors. From the literature reviewed, it seems quite 
evident that a certain combination of factors causes injury 
mostly to underground parts, and that other combinations 
affect mainly the aerial parts. It appears likely that the 
time relation, of a severe cold period, to a certain vegetative 
* Arsenik kommt normaler Weise im thiersichen Organismus vor und 
ist besonders in den ektodermalen Organen localisirt. Ztschr. physiol. 
Chem., 36: 391-97. 1902. 
* Untersuchungen iiber das Vorhandensein von Arsen in den normalen 
Geweben vermittelst der biologischen Methode. Ztschr. physiol, Chem., 42: 
175-80. 1904. 
