1894] The Influence of Mechanical Resistance. 197 
may come far short of attaining their normal dimensions. 
As soon, however, as the development of mechanical cells be 
considered, we shall find, as will soon be pointed out, a pro- 
found effect produced by the cast. It must be indicated in 
this place that the question that has just been discussed—the 
influence of pressure on the thickening of the walls of funda- 
mental parenchyma—may not be answered for every plant by 
my experiments. In all of my plants the normal thickness 
attained by this tissue is slight and hence a small variation 
caused by the cast would be difficult to distinguish. It is 
possible that in plants in which the fundamental parenchyma 
forms thicker walls than those used in my work, the effect of 
— would be apparent in preventing the normal increase in 
thickness, It is not at all probable, however, that the oppo- 
_ site will be found true, i. e., that cells will form thicker walls 
Nite normal when pressure prevents them from attaining 
their full size. Precisely this assumption was, however, made 
by Wortmann,. ‘1 He wound the stems of seedlings with 
tine and found upon examining them after they had been in 
these bandages for several days, that the cortical cells had 
thicker walls than normal. This result, it need not be said, 
seems contradictory to all of mine obtained by the use of 
te t can, however, I believe, be reconciled. 
Soak first place, it’ makes a great difference whether the 
In the "a confined by a twine bandage or by a gypsum a 
strands ormer case the peripheral cells grow out between the 
panied b Producing considerable distortion always accom- 
cell- te @ good increase in the thickness of neighboring 
, 8: This has been demonstrated by my experiments 
communis and Phaseolus multiflorus, the latter 
the plants used by Wortmann. When these 
of pl 
sreatly thickened, 
Plants have giy 
vor. 
€xtensj 
Space 
= » One must look carefully to escape deception. 
ort : 5 —_——— 
188, oer Beitrage zur Physiologie des Wachsthums. Bot. Zeit. 47: 286. 
