58 BOTANICAL GAZETTE [ JANUARY 
the convex side. Kohl says he found constantly that the pro- 
toplasm in the cells of the convex side pulled away from the 
cell wall sooner than in the cells of the concave side. If there _ 
is a real contradiction here it is not so much between Kohl’s 
observations and the greater permeability of the protoplasm in 
the concave cells as between the two series of observations 
made by Kohl himself, one showing tl at plasmolysis gives a 
plus curve at first, and the other that the convex cells plasmo- 
lyze sooner. There appears to me a possibility however, that 
makes the contradiction only apparent and not real. MacDou- 
gal found in tendrils which were plasmolyzed, then fixed and cut 
into thin sections, that the protoplasm of the cells on the convex 
side was pulled completely away from the wall, while in the 
outer rows on the concave side it was barely separated from the 
wall. Nevertheless the tendril, when plasmolyzed, had increased 
its curvature and MacDougal believes he has shown that the 
protoplasm becomes more permeable in the cells of the concave 
side. The explanation seems to me to be that the protoplasm — 
becomes more permeable not only for water, but also for the — 
plasmolyzing solution. Hence the protoplasm in the ceils of @ 
the concave side allows the KNO, to pass inward to a greater — 
or less degree, while that in the cells of the convex side resists : 
penetration by the plasmolyzing soluticn, and on the convex : 
side the protoplasm is forced away from the walls sooner and 
more completely than on the concave side. Some observations 
of my own seem to show that the protoplasm in the parenchyma — 
of Vicia faba roots can become permeable to KNO,. In — 
numerous sections the protoplasm in the cortical parenchyma 
was not contracted from the walls even ina 10 per cent. solu: 
tion, though the cells had completely lost their turgidity Iwas 
not able to see any difference in the pulling away from the wall : | 
of the protoplasm in the cases which showed that phenomeno?, : 
even when Kohl’s method was used. My observations on that | 
point were not extensive, however. Different observers have 
‘Teported quite different results as to the plasmolysis of cells A q 
of the convex and concave sides, and the point probably needs 4 
