48 SEVENTH REPORT. 



THE TOXIC ACTION OF COPPER SULPHATE UPON CERTAIN 

 ALGAE IN THE PRESENCE OF FOREIGN SUBSTANCES. 



ELLEN B. BACH. 



The toxic action of copper sulpliate upon certain of the algae is pre- 

 sented at some length by -Moore and Kellerman in a paper entitled "A 

 Method of Destroying or Preventing the Growth of Algae and Certain 

 Pathogenic Bacteria in Water Supplies'" ( U. S. Department of Agri- 

 culture Bulletin No. (14, 1904). It is there stated that a dilution'of 

 one to one million in all cases would be sufficient to prevent the growth 

 of a polluting algal form in a body of water. Such a dilution would 

 be about n-lUuOOU, wliere ^'n'' stands for the gram equivalent per liter 

 of solution, and the denominator represents the concentration of the 

 solution. If this strength would kill filamentous algae and leave un- 

 harmed higher algae (as Chara), or other aquatic plants, it would be 

 a useful method of keeping aquaria clear. 



An aquarium jar of about six liters capacity contained a luxuriant 

 growth of Chara, wliicli had recently become almost completely covered 

 with filamentous algal forms. Strings of the algae also hung from the 

 surface of the water and the sides of the jar. On the bottom of the 

 jar was a thin layer of ordinary garden soil. A normal solution of 

 copper sulphate was made, and sufficient of it added to the water in 

 the jar to make the resulting solution nearly n-100000. This strength 

 would be greater than that given by Moore and Kellerman, yet the 

 algae, as well as the Chara, lived and flourished. Evidently something 

 was present that absorbed some of the copper, and so rendered the 

 solution less toxic. Dandeno ])roves (Am. Journ. of Sc, Vol. XVII, 

 June, 4904, p. 437) that '"non-chemical bodies retard very materially the 

 activitj' of the solute in bringing about death to the radicle of seed- 

 lings." Sand was used as one of the non-chemicals. In the same paper 

 he also shows that "the quantity of the solution has an important 

 bearing upon its jjower to affect the radicles."' If these two points are 

 true in the case of seedlings, why would they not hold for algae in 

 toxic solutions? Experiments were set up for investigation along these 

 two lines. 



At first both Chara and filamentous algae were used, separately and 

 together. It was found that a Chara stem 20 cm. or more in length 

 would live in a definite quantity of copper sulphate solution in which 

 a stem half as long would die in twenty-four hours or less. The same 

 was true of the smaller algae. A large mass of filaments would live 

 where a smaller number would die within a short time. When Chara 

 and the lower forms were put together into a solution strong enough 

 to kill Chara alone within a known time, the algae would die and the 

 Chara live. Varying the quantity of the solution had a similar eifect. 

 A known amount of the plant tissue that would live in 20 cc. of the 

 copper sulphate solution, would die in a short time in 200 cc. of the 

 same strength. As yet no very accurate data has been obtained upon 



