THE POPULAR SCIENCE MONTHLY. 



capable of growth, by bending in differ- 

 ent directions — phenomena familiar to vege- 

 table physiologists. But two years ago 

 other phenomena were observed, which did 

 not appear to belong to any of the known 

 categories. Elfving found that pieces of 

 iron and, to a less- degree, of zinc or alu- 

 minium, as well as different organic sub- 

 stances, such as sealing-wax, rosin, etc., at- 

 tracted the growing sporangium-bearing fila- 

 ments of a mold {Phycomyces nitens). All 

 other metals Elfving found inactive, but the 

 filaments of the mold itself showed a mutual 

 repulsion. This movement, however, Prof. 

 Errera considered wholly due to the hygro- 

 scopic condition of the stimulatory substance. 

 The sensibility of phycomyces, he observed, 

 was in fact so great that it might be used as 

 a reagent to test tbe existence of hydroscopic 

 power, which he illustrated in the case of 

 camphor, the hydroscopic condition of which, 

 after one experiment, was proved by careful 

 weighing, although it was unknown to chem- 

 ists. All the experiments succeeded in a 

 saturated atmosphere, showing that hydro- 

 tropism was not due, as generally believed, 

 to difference in the hygrometric state of the 

 air. To sum up, concluded the author, the 

 apparently mysterious action of iron on 

 phycomyces was nothing but a matter of 

 hydrotropism, and hydrotropism itself, nega- 

 tive or positive, was the bending of a vege- 

 table organ toward the points, not where 

 it would find a minimum or maximum of 

 moisture, but where it would transpire most 

 or least. 



Disappearance of Wild Plants. — The re- 

 port of the committee of the British Asso- 

 ciation on the disappearance of wild plants 

 from their native habitats mentioned fifty 

 of the less common wild plants of the west 

 of Scotland which had been greatly reduced 

 in number in recent years from natural and 

 other causes. The natural causes were due 

 to agriculture, drainage, industry, and the 

 growth of towns and villages, and seemed to be 

 outside of the scope of protective measures. 

 In many cases disappearance is attributable to 

 the removal of specimens by collectors for 

 the formation of herbariums, and of plants 

 with showy flowers and ferns for sale. 

 Herbariums are essential to the study of 

 botany, but the committee thought their 



multiplication might be made unnecessary 

 by the formation of local collections for ref- 

 erence. Collections for sale might be pre- 

 vented by the intervention of proprietors. 

 But it was difficult to suggest any course of 

 prohibitive measures. In the discussion the 

 too specific designation of places where 

 choice plants can be found was deprecated 

 as making access to them too easy to un- 

 scrupulous searchers. A resolution was 

 passed on the preservation of birds and eggs ; 

 and Canon Tristram, speaking to it, put in a 

 plea for the preservation of birds of prey, 

 pointing to the mice-plague in Dumfries and 

 Lanark shires as a result of destroying the 

 balance of Nature by wholesale killing of 

 such birds. 



Prize Essays on Alcohol. — The American 

 Medical Temperance Association, through 

 the kindness of J. H. Kellogg, M. D., of 

 Battle Creek, Mich., offers the following 

 prizes : 



1. One hundred dollars for the best essay 

 On the Physical Action of Alcohol, based on 

 Original Research and Experiment. 



2. One hundred dollars for the best essay 

 On the Non- Alcoholic Treatment of Disease. 



These essays must be sent to the secre- 

 tary of the committee, Dr. Crothers, Hart- 

 ford, Conn., on or before May 1, 1893. They 

 should be in type-writing, with the author's 

 name in a sealed envelope, with motto to 

 distinguish it. The report of the committee 

 will be announced at the annual meeting at 

 Milwaukee, Wis., in June, 1893, and the suc- 

 cessful essays read. These essays will be the 

 property of the Association, and will be pub- 

 lished at the discretion of the committee. 

 All essays are to be scientific, and without 

 restrictions as to length, and limited to physi- 

 cians of this country. Address all inquiries 

 to T. D. Crothers, M. D., secretary of com- 

 mittee, Hartford, Conn. 



Devolution of the Little Toe. —The 

 thumb and great toe of men are two-jointed, 

 while the other fingers and toes are three- 

 jointed. But it has been observed, in the 

 examinations of skeletons, that the little toe 

 is occasionally two-jointed ; the middle and 

 terminal phalanges having been so united 

 that they can hardly be distinguished. This 

 variation occurs in about thirty-six per cent 



