Dandeno — Relation of Mass Action to Toxicity. 441 



tigators had worked with the same kind of seedlings, render- 

 ing comparison of results possible. Seedlings were prepared 

 in the usual way, and were used when the radicle was of a 

 suitable length. However, none was used whose radicle was 

 less than 12 mm in length. 



For the test in regard to physical affinity, a pure sand was 

 obtained from ground quartz. This was thoroughly washed, 

 first in strong HC1, then in water, and lastly in distilled water 

 several times. Two grades were secured, fine and coarse. The 

 particles of the fine sand were of such a size that the volume 

 of one grain was '0655 cbmm , and a grain of the coarse sand 

 •22 cbmm . The surface area of the fine sand is to the surface 

 area of the coarse sand, therefore, as 3 : 2, in a given mass of 

 sand. From this it is not to be inferred that all the grains 

 were exactly of the same size. The measurements given are 

 an approximation towards an average. A further test was 

 made to see how great the volume of air space would be in 

 the one as compared with that of the other. The following 

 was the result of careful experiments : In a total volume 

 of 15*6 CC , there was, in the case of the fine sand, 5*6 CC of 

 air and 10 cc of sand. Of the coarse sand, in a volume of 

 15*6 CC , there were 6*0 CC of air. Both were tested as nearly as 

 possible under the same conditions of packing. Several tests 

 gave the same result. It thus appears that the coarse sand 

 contained a little more air space than did the 1me, — actually 

 38*4 as against 35*9 per cent, in proportion to total mass of 

 sand and water. 



The volume of sand used per seedling was 12 cc , and 8 CC , 

 in the case of both kinds of sand. As no difference was 

 observed in regard to growth whether the quantity was 12 cc 

 or 8 CC , no mention is made in the records. 



Some of the experiments seemed to show that the shape of 

 the vessel in which liquid tests were made had a perceptible 

 influence upon the power of the seedling to resist the toxic 

 action of the solution, resulting possibly from inequality of dif- 

 fusion. But in all tests recorded in this paper, the vessels 

 were homeopathic vials of uniform proportions for all the sizes 

 (from 25 cc to l cc capacity). 



For corroborative tests, the seedlings were germinated in cal- 

 cium chloride tubes, the " seed " remaining in the bulb and the 

 radicle growing down through the small end. Manipulation 

 was thus very convenient, and the minimum of damage done 

 the seedling in the process of transfer and of marking. This 

 test was made only with seedlings whose radicles had pene- 

 trated beyond the end of the tube. 



The different tests used by the various investigators to decide 

 death renders it extremely difficult to make comparisons. The 



