E. B. MAINS 
of natural humus can be used by a number of plants when in a carbon- 
dioxide-free atmosphere. J. Laurent (1897, 1898, 1904) investigated 
this subject thoroughly for corn. He found that glucose, invert sugar, 
sucrose, soluble starch, and starch can be taken up by corn through 
its roots and utilized in a carbon-dioxide-free atmosphere and to a 
somewhat less degree in a normal atmosphere in the dark.^ 
In the second case, cut pieces of leaf were floated upon various 
carbohydrate solutions. A number of workers have shown that por- 
tions of plants may utilize sugar from solutions in which they were 
placed. Boehm (1883) showed that cut pieces of leaf of Phaseolus 
multiflorus upon solutions of cane sugar and glucose form starch in the 
dark. E. Laurent (1886) has shown that etiolated potato sprouts 
placed in the dark with their cut ends in a 10 percent cane-sugar solu- 
tion grow for more than five months and form starch. A. Meyer, 
according to Acton (1889), found that shoots, when supplied with 
dextrose, glycerine, sucrose, and inulin, can form starch. A number 
of other authors have carried out similar experiments with like results. 
Carbohydrates Supplied to Seedlings 
In order to grow plants in carbohydrate nutritive solutions, it is 
necessary to have both the plants and solutions as nearly sterile as 
possible or the solution will be quickly filled with the growth of a 
number of saprophytic fungi. The only feasible way to obtain sterile 
seedlings is to sterilize the seed. A number of methods have been 
used by different workers for sterilizing seeds, but almost all of these 
methods have been found inefficient in some particular by other 
workers. 
Ward {i()02d) used "various antiseptics" and also heated the seeds 
to 60-70° C. for the purpose of sterilizing brome seeds. These were 
then placed in sterile petri-dishes to germinate. Laurent (1897, 1904) 
used .2 percent HgCl2 solution for to 3 hours for corn. J. K. 
Wilson (191 5) has recently reported good results for a number of seeds 
from the use of a solution of chlorine obtained from bleaching powder. 
A number of other antiseptics have been used, such as H2 SO4, CUSO4, 
H2O2, phenol, HNO3, etc., none of which have been found generally 
or uniformly successful. Of these H2SO4, HgCU, and the calcium 
hypdchlorite method of Wilson were tried by myself. 
2 Since the above was written Kundson (1916) has also shown that maize is 
able to take up through its roots dextrose, laevulose, maltose, and sucrose from 
their 2 percent solutions with an increase in growth and dry weight. 
