Tas 
1906] BREAZEALE—EFFECT OF SOLIDS UPON GROWTH 55 
of fixing the seedlings practically prevents water loss, except through 
the transpiration of the plants. The work of Lrvincston? indicates 
that total loss by transpiration for a period of two or three weeks 
furnishes a fair criterion for comparison of the growth of different 
cultures of wheat grown in this manner. The transpiration figures 
are used in this way in the experiments here given. The work was 
carried on in a greenhouse with a temperature of 15 to 25° C. 
For Experiments I to III a soil extract from poor Leonardtown 
loam, collected near Leonardtown, Md., was used. It was prepared 
by stirring the soil for three minutes with water in amount equal to 
twice its air dry weight, allowing it to stand twenty minutes, and then 
filtering through a clean Pasteur-Chamberland filter tube, in the man- 
ner described by WHITNEY and CAMERON.5 
In Experiment I the solids used were calcium carbonate, tri- 
calcium phosphate, ferric hydrate and aluminum hydrate. Ferric 
hydrate was prepared by precipitation from the chlorid with ammonia, 
followed by thorough washing with hot water. It was transferred 
moist to the culture media. Aluminum hydrate was prepared in a 
similar way from the sulfate. Data for this and the three following 
experiments are given in Table J. The percentage increase in transpi- 
ration for each solid is computed by considering the transpiration 
from the untreated extract as unity. 
All of the solids accelerated growth, as is shown by the transpira- 
tion figures. But in the case of the ferric hydrate the root growth 
was accelerated to a much greater extent than that of the tops. The 
roots of the culture with this substance were much longer than those 
of the other cultures. It is evident here that root growth was acceler- 
ated without a corresponding increase in transpiraticn. 
Experiment II comprised, besides calcium carbonate and ferric 
hydrate, carbon black (prepared from burning petroleum, and 
thoroughly washed), magnesium carbonate, and barium carbonate. 
The small amounts of water transpired are due to cloudy weather. 
The plants of this series are shown in fig. 1, the numbers in the 
figure corresponding to the culture numbers given in parentheses 
4 Lrvincston, B. E., Relation of transpiration to growthin wheat. Bort. GAZETTE 
40:178~-195. 1905. 
s Witney, M., and Cameron, F. K., The chemistry of the soil as related to 
crop production. U.S. Dept. Agric., Bureau of Soils, Bull. 22:16 ff. 1903. 
