The Action of Cold and of Sunlight upon 
Aquatic Plants. 
BY 
ALFRED J. EWART, D.Sc., Ph.D., F.L.S. 
I N a recent paper by Messrs. West and West, these authors 
take exception to certain results published by me two 
years ago in my first paper upon Assimilatory Inhibition 1 . 
The objections which they make form an admirable illustra- 
tion of the mistake into which biologists and collectors 
often fall in making use, or rather misuse, of experimental 
observations made by the physiologist in the laboratory. 
The prejudice which seems to exist in certain quarters against 
the results of laboratory investigations is an extremely 
absurd and unreasonable one, for it is only by research 
of this kind that any accurate and precise knowledge of 
fundamental principles can be obtained. The conditions 
under which plants exist in nature are so variable and 
complicated that it is impossible by direct observation to 
determine precisely what are the factors engaged in pro- 
ducing any given result, especially since any marked change 
in the external conditions must necessarily affect not merely 
one, but directly or indirectly every form of vital activity 
of which the plant is capable. It is true that particular 
1 West and West, Ann. of Bot., 1896, Yol. xii, p. 33 ; Ewart, Journ. Linn. Soc. 
Bot., Vol. xxxi, 1896, p. 217. 
[Annals of Botany, Vol. XII. No. XLVXI. September, 1898.] 
