3 14 Peirce . — On the Structure of the Hailstorm 
the central cylinder contains an axial strand of tracheids, 
a strand of cambiform cells bounding this on either side, and 
two phloems. Staining with aniline-blue and partial deco- 
lorizing will demonstrate the presence of thin callus-plates 
on the cross-walls of certain of these phloem-cells. They 
are therefore sieve-tubes. Other cells in the phloem are 
shown by their proximity to the sieve-tubes, and by their 
abundant protoplasmic contents, to be companion-cells. 
A transverse section of the host through a sufficiently old 
haustorium will show that its xylem-cells connect directly 
with the ducts of the host, and are connected by xylem- 
strands with one or two axial bundles in the stem of the 
mother-plant. The xylem of the haustorium forms an 
unbroken connection between the xylems of parasite and 
host. In the same section, after treating with aniline-blue, 
the union of the haustorial sieve-tubes with those of the 
host, and the connection of the haustorial phloem-groups 
with the phloem of one or two axial bundles in the stem 
of the mother-plant, can be clearly seen. 
A study of the origin and development of the haustoria 
of C. epithymum shows that, as Koch has said, they 
agree with those of C. epilinum. But as in C. epilinum % 
I am unable to find that the fully developed haustorium 
consists of any elements which do not come by division 
from the first two or three rows, deep in the cortex of the 
mother-plant, which give rise to the young conical haus- 
torium. The haustorium as it grows, pushes the cortex and 
epidermis before it, finally ruptures them in the centre over 
its apex, pushes them still further by its continued growth, 
and carries them for a little distance into the body of the 
host. Then they quickly die. They have no use ; they 
can neither absorb nor conduct readily ; they in no way 
add to the efficiency of the haustorium, which, by its 
bi-collateral central bundle, is well able to transfer all the 
solutions which it draws from the conducting tissues of the 
host. The haustorium of C. epithymum corresponds in origin, 
structure, and function with the other haustoria which we 
