440 Dandeno — Relation of Mass Action to Toxicity. 



point, but it is necessary to be so, considering some work which 

 has been done along a similar line. For example, True* 

 states, referring to H 2 S0 4 : " And since it splits off two II ions 

 from every molecule, it would have in chemically equivalent 

 quantities twice the number of H ions found in HC1." The 

 author just referred to evidently had an erroneous view as to 

 what chemical equivalent quantities meant, although he had 

 previous to this published some papers (one of which has 

 already been referred to) on a similar character of work. 

 Hence it maybe seen that care, both in preparing and in 

 naming solutions, is very desirable. 



The solutions used in the following experiments were 

 selected because they represent the chief types, — acid, base, 

 and toxic salt. The carbonate and the bicarbonate were used 

 in order to see how physiological reactions might harmonize 

 with the theory of electrolytic dissociation. Carbonic acid pre- 

 sented a peculiar aspect of the question, inasmuch as it is an 

 acid which is said to dissociate, and yet it produces almost no 

 toxic effect at the highest concentration obtainable. 



The method of marking and of measuring the radicles, and 

 the test applied to decide the question of death, were accord- 

 ing to the method of Loew 6 , namely, that of a growth in 

 water after having been submitted to the solution test. If 

 growth took place in the solution, and then in water, the 

 radicle *was considered living ; but if no growth took place in 

 water — after the twenty-four hours in the solution — the radicle 

 was considered dead. For measuring the growth of the pea 

 and the corn, a mark was made on the glass vial on one or 

 both sides ; then sighting through in line with the root tip, 

 measurement could thus be made very accurately, and cer- 

 tainly very conveniently. In the case of the lupine, a mark 

 was made with india ink at, or a little below, the junction 

 between the root and stem ; and this mark kept above the solu- 

 tion. Measurement was made from this mark to the end of 

 the root tip and recorded. 



An attempt was made to follow the method of marking 

 adopted by Heald, and Kahlenberg and True, but it was found 

 too clumsy for the purpose, mainly for the reason that the 

 india ink would " run " so as to leave the mark upon the root 

 broad and indefinite, and in some cases the mark was entirely 

 lost when the portion of the radicle on which the mark was 

 made was in the solution. 



The seedlings used were Zea mais (common field corn, yel- 

 low dent variety), Pisum sativum (small field pea) and Lupinus 

 alous (white lupine). These were selected chiefly because they 

 were convenient for the purpose ; and also because other inves- 



* This Journal, vol. ix, March, 1900, p. 184. 



