452 PROTOPLASM 



Some interesting experimental results are obtained from the 

 toxic effects of salts on protoplasm, particularly in reference to 

 protoplasmic streaming. Trace elements are highly toxic in 

 slightly higher than normal concentrations and may stimulate 

 protoplasm to an excessive rate of activity. A trace of copper or 

 weak concentrations of barium and strontium chloride will 

 arouse Elodea leaf cells to an excessively high rate of streaming. 



The appearance of unexpected applications of purely theoreti- 

 cal discoveries which prove to be of considerable economical 

 value is the rule in science. Such a one is the use to which 

 Nageli's discovery of the "oligodynamic" effect of copper has 

 been put. Cress growers found their cress dying from some 

 unknown cause, which proved to be smothering by the green 

 alga Spirogyra. The investigator in charge, recalling Nageli's 

 classical experiment, added copper in the concentration of 

 1 : 50,000,000 parts. The Spirogyra was destroyed, the cress 

 unharmed, and the cost negligible. Pathogenic bacteria in 

 drinking water and mosquito larvae in stagnant water may be 

 killed in a similar way. 



It is evident that salts play an important role in life. But how 

 important? Do they determine not only the state of our health 

 but perhaps also what we are? One of the most fundamental 

 concepts in biology is the relative stability of protoplasm. Pro- 

 toplasm is thought of as being a very stable substance, unalter- 

 able in its ultimate nature and course of development, yet C. R. 

 Stockard has produced changes in fish development, such as 

 double monsters, and J. Loeb brought on the parthenogenic 

 development of an egg {i.e., without fertilization) simply by a 

 change in the salt content of the surrounding solution. How 

 much of us, then, is what it is because of our particular kind of 

 protoplasm, and how much because of our external or internal 

 salt environment? 



