140 



THE POPULAR SCIENCE MONTHLY. 



the faradaic current, and vigorous feeding — 

 to which the appetite was found ready to 

 respond. Dr. Playfair attributes the chief 

 value of the treatment to the fact that it ap- 

 peals not to one only but to many influ- 

 ces of a curative character. The "Louis- 

 ville Medical News," reviewing the cases, 

 believes that the imagination is the most 

 prominent agent in effecting the cures, and 

 is ready to class them with " faith-cures." 



Phosphorescence in Plants. — M. Cri6 re- 

 marks, in a communication to the French 

 Academy of Sciences, that " it is known that 

 the flowers of phanerogams are capable un- 

 der certain circumstances of producing phos- 

 phorescent light. The phenomenon has been 

 verified, especially of the nasturtium and the 

 marigold. Some years ago I myself saw 

 phosphorescent lights emitted in stormy 

 weather from the flowers of the Tropoelum 

 majus, cultivated in a garden. The emission 

 is especially noticeable in the mushrooms 

 The agaric of the olive, which grows in 

 Provence, at the foot of the olive-trees, is 

 distinguished for its white, quiet, uniform 

 light, which resembles that of phosphorus 

 dissolved in oil." Several other species of 

 luminous agaric are known, but the property 

 is not limited to that genus. The Rhizo- 

 morpha, or the vegetative apparatus of a 

 considerable number of mushrooms, are also 

 phosphorescent. These cryptogams, which 

 are common in mines, give a light by which 

 miners can see their hands. The luminous 

 threads of Rhizomorpha subterranea are 

 easy to perceive in the Pontpean mine, near 

 Eennes. Luminous filaments of a rhizomor- 

 pha have been observed in branches of the 

 elder. The Xylaria polymorpJiay collected 

 from old stalks in a garden, has been seen 

 to emit a feeble white glow, like that of 

 phosphorus in the air. 



Professor Vlrchow on Humboldt.— A 



monument to William and Alexander von 

 Humboldt was unveiled at the University 

 of Berlin on the 28th of May. Professor 

 Virchow delivered an address on the occa- 

 sion, in which he spoke in the highest terms 

 of the character and value of the work of the 

 two brothers. " We older men," he said, 

 " who have learned personally from Alex- 

 ander von Humboldt, and have in part 



worked with him, feel our strength renewed 

 when we see how the memory of the time of 

 the new birth of our people is perpetuated to 

 posterity in the many monuments of our city. 

 One who walks through our streets will dis- 

 cover that Goethe and Schiller, Stein and 

 the Humboldts, Bliicher and Schwarnhorst, 

 did not casually live side by side, but that a 

 recognizable connection prevailed in their 

 development, and wove their works together 

 to a single end. Every German will look 

 with pride upon the men who have risen 

 from out of the midst of the people to the 

 highest places of honor, because they 

 wakened and unfettered the noblest forces 

 of the nation. Especially could our aca- 

 demic youth, who have these models before 

 their eyes every day, learn from the history 

 of such men what recompense genuine 

 work can gain. Humboldt, who completed 

 the ' Cosmos ' in extreme age, and who wrote 

 in the last year of his life, ' For thirty years 

 I have had no rest, except at night,' was at 

 one time a sickly lad, whose teacher in the 

 first years of his childhood doubted whether 

 he would ever manifest any more than the 

 most ordinary mental faculties. He, whose 

 youth fell in an age when hardly anything 

 but speculative wisdom, poetic invention and 

 dogmatic tradition were held in honor, had, 

 in his incessant struggles in nearly all the 

 domains of natural science, brought into 

 avail that stronger objective method of 

 thought, comprehensive in its grasp, which 

 has since become the pride and the common 

 estate of the learned of modern times. 

 When he at last, like the world-sages of 

 antiquity, united in himself all the knowl. 

 edge of his time on natural subjects, and 

 with it the comprehension of its historic 

 growth, it was not the knowledge of a com- 

 piler that he displayed, but the fruit of long 

 special work in each single field. He served 

 in the ranks as a national economist and 

 as a miner, as an astronomer and as a 

 physicist, as a chemist and as a geologist, 

 as an anatomist and as an experimenter in 

 vegetable and animal physiology. He was 

 the first scientific traveler who independent- 

 ly studied all the natural and political condi- 

 tions of the countries visited by himself. 

 Political and physical geography, the study 

 of terrestrial magnetism, plant -geography, 

 and ethnography, grew under his care to be 



