GIANT BAMBOOS. 
257 
over moist earth in a separate receptacle from that which 
held the plant which was under observation. Thus there 
was no record at all of changes caused by the transpiration of 
the plant itself. ‘Furthermore a glance at Sachs’ figure* 
does .not encourage a belief that his plants, if none were 
treated better than the one there shown, could have been in 
anything like-a normal condition as regards the important 
function of transpiration ;f nevertheless Sachs fully recog¬ 
nized the important effect which alterations in atmospheric 
moisture may have upon the growth of internodes, as the 
following words show : “ In the day-time, also, the difference 
of tension of the aqueous vapour in the atmosphere is usually 
greater than during the night, and transpiration is thus 
increased, and it may easily happen that turgescence during 
the day is less than at night, and growth likewise may be 
retarded thereby.’’^ But he does not appear to regard this 
as a normally recurrent phenomenon. 
J. Reinke in 1876 published a valuable paper on growth § 
in which the importance of atmospheric moisture is fully 
recognized. His observations upon the growth of J uncus and 
Scirpus, in which plants the growing region of the single 
long internode is buried in the earth, showed that in these 
cases psychrometric changes had practically no influence 
upon elongation. 
Experiments upon seedlings of Helianthus exposed to 
hourly alternations of light plus less moisture and darkness 
plus more moisture showed that moisture of the air distinctly 
favoured growth, but light had a marked effect also. 
But in making records of the growth in thickness of the 
stem of Datura stramonium, Reinke discovered a much more 
I * Luc. cit., p. 118. 
f Kraus has shown that the removal of leaves affects the period of 
alternation of the volume of water in different parts of the stem. Ueber die 
Wasservertheilung in der Pflanze, III., p. 58, 1881. 
f Loc. cit. I quote from the English Ed. of Sachs’ Lectures on the Physio* 
logy of plants translated by Marshall Ward. 
§ Untersuchungen über Wachsthum. Bot. Zeit. 1876. 
