PLANTS IN GLYCOCOLL SOLUTIONS 
of tomato, Eupatorium sp., and various cereals in nutrient solutions 
are omitted; also the results with plants cultivated under humid and 
arid atmospheric conditions, and, with such, the growth and stem 
elongation of which terminates with the formation of flowers and seeds. 
In the main the data correspond with the conclusions drawn from the 
experiments submitted in Tables I to IX, and show that transpiration 
is not directly correlated with and hence not a measure of growth. 
The chief results of the experiments given below may be described 
as follows: The plants grown in the glycocoll solutions show an increase 
in green weight above that of the quantity of water absorbed from the 
solution and retained within the tissues. The predominant constituent 
of this gain is in part undoubtedly the glycocoll absorbed and assimi- 
lated, and to a lesser degree due to the photosynthesis of carbohydrates. 
To what extent irregularities of growth tend to be followed by 
compensatory processes is not known. The loss in weight of plants 
indicated in Tables I and VII does not express a more or less prolonged 
rate of transpiration in excess of the rate of absorption for the same 
period. No loss of turgor and no form of wilting, temporary or per- 
manent, is here involved (2, 4, 9). The deficit is in the removal of 
reserve materials from the tissues, and is unaffected by the external 
set of atmospheric conditions under which the plants were transpiring. 
The apparently inevitable conclusion is entertained that the problem 
of the water requirement of plants and the criteria for the wilting 
coefficient, in particular the relation between the water content of 
the plant and that of the soil at the time of wilting, need to be inves- 
tigated more quantitatively than has been heretofore attempted. 
Investigations are now in progress. 
The plants in solutions 2, 3, 4 (Table IV), 5 (Table V), and 3 
(Table VII), retained their weight but changes were going on in the 
body proportions of roots. It is obvious that the constancy of the 
green weight of plants is therefore not an indication of lack of growth, 
i. e., growth increments are not the only criterion or the only measure 
of growth. No estimate can be offered as yet of the correlation be- 
tween weight and size of plant under these conditions. The suppres- 
sion of growth is not primarily attributable to energy requirements, as 
is seen in Table VII. The failure to promote growth may be due to 
the lack of variety and of a more balanced condition of materials for 
development, i. e., it may be due to the inefficiency of isolated food 
constituents, such as glycocoll, to supply material for tissue construe- 
