Makch 11, 1904.] 



SCIENCE. 



421 



electricity was withdrawn from a plant 

 growth was retarded. These earlier experi- 

 "ments were conducted by surrounding 

 plants with wire cages, thus screening them, 

 as it were, from atmospheric electricity. A 

 series of experiments were made for the 

 purpose of ascertaining whether any rela- 

 tionship existed between the growth of out- 

 door plants and the differences in atmos- 

 pheric electrical potential as obtained by 

 frequent measurements of the plants, and 

 by the aid of a Thompson self-recording 

 electrometer. These experiments were not, 

 however, for various reasons, very satisfac- 

 tory. 



Subsequent experiments were, therefore, 

 conducted in a large glass case which was 

 charged to various potentials, and for this 

 purpose potted tomato plants, about three 

 inches high, corn seedlings and molds, 

 such as Mucor and Phycomyces, were em- 

 ployed. Potentials varying from 100 to 

 2,000 volts were made use of; the latter 

 appeared to act disastrously in many cases. 

 Small tomato plants responded most favor- 

 ably under a potential of about 50 volts, 

 which is not far from the optimum for 

 tomato plants of this size. Mucor and 

 Phycomyces responded most favorably to 

 lower potentials, and the effects of high 

 potentials were particularly disastrous to 

 them. The latent period had a duration 

 of from fifteen to twenty-five minutes. 



The experiments with various seeds 

 showed that germination was greatly ac- 

 celerated, although in the case of old seeds 

 there was no evidence that electrical stimu- 

 lation resuscitated life. 



The most essential facts brought out were 

 that there exists a minimum, optimum and 

 maximum potential corresponding with the 

 nature, size and degree of development of 

 the plants, and that when plants are grown 

 under conditions in which the influence of 

 atmospheric electricity is eliminated, they 

 exhibit a marked response to electrical 



stimuli. The potential which induced this 

 response is within the range of that usually 

 found in nature. There is every reason to 

 believe that electricity acts as a stimulus to 

 plants in nature, and undoubtedly has 

 much to do with their development and 

 configuration. 



The Effect of the Presence of Insoluble 

 Substances on the Toxic Action of 

 Poisons: Dr. Eodney H. True and Mr. 

 C. S. Oglevee, Department of Agricul- 

 ture. 



During the summer of 1903, at the Ma- 

 rine Biological Laboratory at Woods Hole, 

 Mass., the authors undertook a study of the 

 effect of insoluble substances on the poison- 

 ous action of solutions of electrolytes and 

 non-electrolytes. A modifying action has 

 been observed by Nageli in the case of 

 algffi, and it is a common observation that 

 poisonous solutions applied to said cultures 

 are not as effective as in even more dilute 

 water cultures. In the experiments here 

 summarized, mercuric chlorid, silver nitrate 

 and copper sulphate have received attention 

 as representative electrolytes; and phenol, 

 resoreinol and thymol as representative 

 non-electrolytes. Carefully prepared sand, 

 filter paper and paraffine were used as in- 

 soluble bodies. The test reaction was the 

 growth rate of the primary root of Lupinus 

 alhiis seedlings, made during a period of 

 twenty-four hours of exposure to the solu- 

 tions in question. The toxic substances 

 were made up in strong stock solutions 

 which in these experiments were diluted to 

 concentrations sufficiently toxic to exert a 

 marked effect on the growth of the plants. 

 In the ease of the heavy metals above men- 

 tioned, a decided acceleration in growth was 

 seen to accompany the presence of the in- 

 soluble substances in the solution. No such 

 acceleration followed the introduction of 

 the insoluble substances into the check cul- 



