Aug. 5, 1918 
Anatomy of the Potato Plant 
223 
paper treating of the physiology of the potato plant in detail and in all 
aspects. The gross morphology, the anatomy of the organs and tissues, 
as well as the development of the leaf, are given careful consideration. 
However, valuable as is this paper, the author tells us nothing definite 
of the ontogeny of the vascular system or of the relative amount and 
relations of the different elements of the phloem and xylem. Moreover, 
since this work was written, our conception of the origin of the stele and 
of its relation to the leaf traces has undergone a radical change, so that, 
so far as histology is concerned, the work is out of harmony with present 
ideas. This deficiency in DeVries’s work and the absolute lack of other 
reliable study make an investigation of the anatomy of the potato plant 
imperative, the more so since the recent studies of potato diseases require 
a clear conception of normal structures as a background for the investi¬ 
gation of the changes brought about by pathological conditions. With 
the purpose of meeting this need, the present study was undertaken. 
Here an attempt is made to clear up the points left in doubt by earlier 
workers. In addition new facts are given which may make possible a 
decision between the divergent views of present experimenters who have 
been working on the physiological importance of pathological changes. 
Several potato diseases have been studied with reference to such changes 
but of special interest and importance at the present time is the leafroll 
disease, which is causing a serious loss both in this country and in 
Europe. A discussion of these divergent views, together with new in¬ 
vestigations on the subject of the leafroll disease, will be given in a later 
paper; the present contribution is concerned with the anatomy of the 
normal plant. 
MATERIAL AND METHODS OF EXPERIMENTATION 
The material for study was obtained both from plants grown in the 
greenhouse and in the disease garden of the Department of Plant Pathol¬ 
ogy of Cornell University. The Irish Cobbler variety furnished the 
material for investigation; other varieties, such as Early Rose, New 
York Rural, and Green Mountain were used for comparative study. 
Several fixing fluids were used, including those of Flemming; but the best 
results were obtained by the common chromacetic-acid fixer, 1 per cent 
chromic acid and 1 per cent acetic acid. The usual methods of dehy¬ 
drating and embedding in paraffin were employed. Leaf sections were 
cut 5 m thick, stem sections 7 to 12 ^ thick, and stained with Haidenhain’s 
iron alum hematoxylin and safranin. 
GROSS MORPHOLOGY 
Solanum tuberosum L. is an annual herbaceous dicotyledon, a member 
of the Solanaceae. In habit it is more or less spreading, but grows to a 
height of 2 to 5 feet. This habit form is constant, though selection, 
culture, and breeding have often brought about so great a variety of 
