140 BOTANICAL GAZETTE [FEBRUARY 
erating or retarding effect of the soil upon plant growth may often be due 
primarily to a response of the roots themselves, and that the ordinarily 
observed effect upon the tops may be due to the nature of the roots rather 
than to that of the soil directly. This question deserves thorough study ; 
the results to be given here cover only a very small portion of the field. 
This work was carried on at the laboratories of the Bureau of Soils 
of the U. S. Department of Agriculture, Washington, D. C. The plant 
used was the Russian variety of wheat known as “Chul.” The plants 
were grown directly from the seed in paraffined wire baskets of the form 
described by Wuitney and Cameron.’ As these authors have already 
pointed out, such baskets possess the advantage over pots of producing a 
root system uniformly distributed throughout the soil mass, rather than 
the accumulation of roots on the inner surface of the vessel which occurs 
in the case of ordinary pots. 
The studies to be discussed in this paper were made upon the roots 
developed in the first six series described in the author’s previous publica- 
tion’ on the growth of tops, and in similar cultures. The medium used 
was a very poor soil from Takoma Park, Md., and the same soil with 
varying amounts of fermented stable manure added thereto.2 The cultures 
of any series were placed side by side in a greenhouse, the amount of 
water in all the baskets being kept practically uniform by weighing at 
intervals of one or two days and adding the amount of water which was 
found to have been lost by transpiration. It is thus seen that the different 
cultures were all subjected to the same conditions excepting those which 
depend upon the treatment of the soil. 
Series I of the paper on growth of topst° will serve as an example ; the 
results of all the series are in accurate agreement. The soils and culture 
numbers were as follows : 
Basket 8 
Number - 2 3 4 5 6 7 
Takoma | Do. Do.+ Do.+ Do.+ Do Do.+ | Do+ 
Soil Soil 5000 10,000 15,000 20,000 30,000 40,000 50,000 
p.p.m.‘f | p.p.m. p-p.m. p.p.m. p.p.m. p.p.m. p-p.m. 
untreated | manure Manure | manure manure manure manure | manure 
Sram 
7Wauirney, M. and Cameron, F. K., Investigations in soil fertility. U. 5. Dept. 
Agric., tiiean of Soils, Bull. 23. 1904 
SLIvINGSTON, B. E., Relation of sentation to growth in wheat. Bor. GAZz- 
ETTE fhe: 78-195. figs. 21. 1905. 
a description of this soil and a discussion of its properties, see LIVINGSTON, 
_E, genes ON, J. C., and Ret, F. R., Studies on the properties of a sterile soil. 
Ss. De ept. Apric., siren of Soils, Bull. 28. 190 
104 photograph of the tops and data for their — are given in that paper. 
— abbreviation p. p. m. is used to denote parts per million by weight of air 
soil. 
