re 
a 
1897 | BRIEFER AKTICLES 53 
numerous intercellular spaces. In roots of this kind, particularly of 
ash and Gleditschia, one oftentimes finds water lenticels. While look- 
ing over a mass of such roots of Sa/ix nigra for lenticels I found some 
white structures which were taken for lenticels. At points from 5 to 
10™" from the root tips, small white protuber- 
ances occurred, sometimes as many as four on 
one root tip. The root at this point has a 
cortex particularly well supplied with inter: 
cellular spaces. Sections made through the 
white cushions presented a condition repro- 
duced in the accompanying figures. Ata the 
cortex is seen in its normal condition. Fig. 7é 
shows some of the inner cells radially elon- ; 
gated, and at one point the elongation has ents lia pide 
through root of Sa/tx nigra 
been sufficient to burst the epidermis. In 5™™ from the tip; @, nor- 
fig. 2 this condition is still more marked. mal cortex; 4, elongated 
Some of the cells have increased to many C!s 
times their normal size, leaving large spaces between them. It is 
evident that these structures have nothing in common with lenticels, 
but partake of the nature of cedemata, resembling those described by 
Atkinson for the tomato and apple." 
In those cases the cedema was ascribed to a high turgor brought 
about by too great root absorption and lowered transpiration. The 
willow, from which the affected roots were taken, stands at the edge of 
a pond and has but few of its roots 
inthe water. There had been a week 
of very warm weather, followed by 
almost freezing temperature. The 
leaves had all fallen some two weeks 
before. The roots were collected 
during the cold weather, and when 
examined the cedemata appeared to 
have been but recently formed. In 
seeking for an explanation for these 
cedemata I am inclined to ascribe 
them to causes similar to those given 
for the apple, brought about by dif- 
ferent conditions. During the week of warm weather, with a soil tem- 
* Cornell University Exp. St. Bull. no. 53, May 1893, and no. 61, Dec. 1893. 
Fic. 2, Transection through ad- 
vanced stage of a cushion 5™™ from 
