50 SEVENTH REPORT. 



Clear CUSO4 Solution, Distilled water, dies in about n-12480. 



Sand in dish " " " in about n-10240. 



Soil in dish " " " between n-3200 & n-2800. 



Clear CUSO4 Solution, Tap water, dies in about n- 12800. 



Sand in dish " " " between n-12674 & n-12544. 



Soil in dish " " " in less than n-3200. 



Clear Solution, River water, dies in less than n-10880. 



Soil in dish " " "in less than n-3200. 



Not much has yet been done with the river water; but it would seem 

 from the few results obtained, that copper sulphate is less toxic in 

 river water, clear solutions being compared. At this time of the year 

 the river water is not very clear, and it may be that the small particles 

 floating in it act as non-chemicals and absorb part of the copper, thus 

 lowering the death-point. 



In looking over the limited data here given, it appears that the 

 strength of the copper sulphate solution necessary to free an aquarium, 

 or body of Avater, from algae must depend upon the per cent of plant 

 life present, the amount of foreign substance (non-chemical) in the water, 

 and the kind of water. In view of these facts, might it not be, that, 

 if copper sulphate were introduced at the surface of a body of water 

 of some depth, the plants at the surface would be killed and absorb 

 sufficient of the copper to render the solution too dilute to be toxic at a 

 greater depth? And so the algae at the bottom would remain unharmed. 

 There seems still to be much room for investigation. 



Michigan Agricultural College. 



A STUDY OF THE EFFECT OF DILUTE SOLUTIONS OF 



HYDKOCHLORIC ACID UPON THE RADICLES 



OF CORN SEEDLINGS.^ 



F. A. LOEW. 



The research work done so far along the line of toxicity of dilute 

 solutions of acids and salts upon radicles of seedlings can be loosely 

 placed in four classes. True and Healed and some others did consid- 

 erable work with dilute solutions and seedlings, evidently with the idea 

 of finding biological evidence for the support of the dissociation theory 

 of acid solutions. The work of Kearney and Cameron seemed to be 

 mostly in connection with soil problems. Moore, who worked with 

 CuSO^, sought to find methods for controlling the amount of algea in 

 reservoirs and water systems. Dandeno and others studied the behavior 

 of seedlings in solutions Avhen placed under different circumstances. 

 In Europe work on similar problems has been carried on by both the 

 Germans and the French. As far as I have been able to find, no 

 attempt has been made to explain the cause of death of the radicle in 

 such extremely dilute solutions. Dandeno- suggests that death is prob 

 ably caused by chemical action upon the radicles. Upon this suggestion 

 I began my study of the effect of Hydrochloric acid upon radicles of 

 corn seedlings. 



iThis work is incomplete and should be duplicated. 

 ^American Journal of Science Vol. XVII, June 1904 



