sia a 5 
1905] LIVINGSTON—TRANSPIRATION AND GROWTH 179 
Water cultures were grown in black bottles of about 50°° capacity, 
the seedlings’ being first germinated in sand and then placed in cork 
stoppers in the manner described by the authors just referred to. 
Transpiration was taken by weighing, and the solutions were changed 
every few days. Otherwise, these were grown under the same con- 
ditions as were the basket cultures. Four wheat seedlings were 
grown in a bottle. 
At the end of an experiment the series was photographed, the 
tops were removed by cutting just above the seeds, the leaf surface 
was determined, and also the weight of tops and leaves. The deter- 
mination of leaf surface was made in the following way, which is a 
modification of that used by previous writers.? A plate of glass was 
coated with dextrin mucilage and the latter allowed to become nearly 
dry. On this was gummed the wheat leaves side by side, with their 
edges in contact so far as possible. When the mucilage had become 
thoroughly dry, but before the leaves had dried appreciably, a photo- 
graphic print of the leaf outline was made by direct contact. For 
this the developing paper called “velox” was used; after being 
developed, fixed, and washed the sheets were squeegeed and dried on 
ferrotype plates, face down, thus giving perfectly smooth, hard sur- 
faces. The white area of a print so prepared is equal to the area of 
one side of the leaves whose surface is to be determined. This area 
was measured by one of two methods, which were found to agree 
accurately: (1) it was measured directly by means of a planimeter; 
(2) its area was obtained indirectly by cutting around its margins 
with scissors and then weighing the white portion as well as the 
whole sheet. The area of the entire sheet having been first obtained 
from its dimensions, the required area of the white portion is easily 
obtained from the known quantities by calculation, assuming that 
the paper is uniform. The two weights were both obtained at the 
same time after cutting out the white portion, in order to avoid any 
errors due to changes in the moisture content of the paper. The 
uniformity of the latter was tested as follows: four rectangular — 
of velox paper were developed, fixed, washed, and dried as in the 
actual determination of leaf area. From each of these was deter- 
? BuRGERSTEIN, A., Die Transpiration der Pflanzen. Jena. 1904 Pp. 24, 
et seq., and the references there made. 
