538 ScHREINER & SKINNER: EFFECT OF GUANIDIN ON PLANTS 
Likewise, in adding the requisite amount of potash, the cultures 
in the line P to N received none, the cultures in the next line re- 
ceived 2 c.c. each, in the third line 4 c.c. each, and so on up to 
the culture at K, which received 20 c.c. of the potash solution. 
The phosphate solution is added in the same manner, none to 
cultures in line K to N, 2 c.c. to cultures in the second line, and 
so on up to the culture at P, which received 20 c.c. 
Each bottle received, therefore, a total of 20 c.c. of one, two, 
or three of the stock solutions, depending upon whether it was 
at the apex, along the sides, or in the interior of the triangle. All 
of the cultures were then diluted up to the 250 c.c. mark. 
In this investigation, as already mentioned, the culture solu- 
tion contained 25 parts per million of the guanidin carbonate. 
The amount of this carbonate to be added to each culture bottle of 
250 c.c. was, therefore, 6.25 milligrams. Of the 250 c.c., 20 C.Cc. 
were already contained in the bottles in the form of the fertilizer 
salt solution. Therefore the solution with which the fertilizer 
salt solution in the bottles was to be diluted consisted of 6.25 
milligrams of the compound dissolved in 230 c.c. of pure water or 
27.17 milligrams per liter. A sufficient quantity of this strength 
of solution was prepared to fill the 66 bottles. 
As a means of comparing the cultures grown in these solutions 
containing the guanidin, it was necessary to put up cultures pre- 
pared in exactly the same way, except that pure water was used 
In all of this work physiologically pure water was used. This 
was prepared by shaking ordinary distilled water with a highly 
absorptive carbon black, as described in earlier publications,* which 
removes from the water any injurious property it may possess 
The culture solutions were now ready to receive the plants, 
which were thereafter grown in a greenhouse under suitable 
conditions. 
In this work it was necessary to have a large 
several hundred, and sometimes thousands of uni 
i. e. seedlings of the same age and equal development and genera 
Vitality. 
The manner of growing the seedlings and the method of 
inserting them in the above culture solutions were as follows: 
number, often 
form pean 
jae wig F ive 
* Livingston, B. E., et al. Further studies on the properties of unproductt 
soils. U.S. Dept. Agr. Bur. Soils Bull. 36. 1907. 
