310 BOTANICAL GAZETTE . [NOVEMBER 
buckwheat, that K-ions are osmotically more potent than any 
other ions in his nutrient solutions. Some erratic cultures in my 
series seem to support his statements, but no generalization can 
be made from them. Of interest, also, in this connection are 
the recent researches of Yasuda.*? Working with infusoria, he 
finds that these organisms are able to adjust themselves to solu- 
tions of quite high concentration, and that, in general, the limit 
to their power of adjustment seems to be osmotically about the 
same, no matter what salts are used. In other words, the limit 
is apparently one of osmotic pressure. It is probable that many 
of the so-called chemical or nutritive effects of dissolved sub- 
stances upon the plant organism may turn out, upon further inves 
tigation, to be wholly or in part osmotic. 
In a weak solution vegetative growth is very much more 
rapid than in a strong one This may be due to the fact that in 
a strong solution the water content of the protoplasm is reduced 
in amount below the limit for optimum lability. When the plant 
grows fastest and best, it is in the filamentous form. In 
weak solution, where activity seems to be ata maximum, the 
ions of the electrolytes, which are essential for metabolism, are 
not plentiful. This may suggest how the cylindrical form of 
cell with its increased surface™* may be advantageous. A : “ 
rate, we may be sure that the greater surface of the cylinder 
puts the plant into better condition for exchange of mate 
with its surrounding medium. On the other hand, the ca 
concentrated solution not only withholds water from the a 
but presents a demand upon them for water. The cell me 
. ‘“ s the 
this in part by offering as small a surface as possible yee 
solution. In this case, although the requisite ions may be p sf 
water in the” 
ent, and even in the right number, the scarcity of fount 
«picket einiger Z 
* YASUDA, ATSUSHI: Studien iiber die Anpassungsfahigkeit reread 1900. 
an concentrirte Lésungen. Jour. Coll. Sci. Imp. Univ. Tokyo 13 101-14 so sae 
*In a cylinder, the lateral surface is greater than that of a yee 2.727 
volume, as long as the ratio of the length to the diameter equals . ait js often 4 
In typical filament cells of this alga the ratio of the diameters 1S 3, gre filament cell 
and even greater. It is seldom less than 2.8. Thus it is shown _ alls alone, tha! 
offers more surface to the surrounding medium through its lateral w 
does the palmella cell of equal volume. 
