January 20, 1922] 



SCIENCE 



73 



natural product on a water bath until it is 

 hard, but not brittle, when cool. Then dissolve 

 in a menstruum such as chloroform or xylol. 

 After balsam is applied to the slide allow to 

 stand over-night and then finish by placing 

 cover glass over the sections, using gentle heat 

 to render the balsam fluid. This mounting 

 medium will then be found to be hard enough 

 to withstand any pressure applied- on the cover 

 glass by careless students. 



It is advisable to prepare this balsam one- 

 self, unless it can be procured from a reliable 

 firm which uses the above method of prepara- 

 tion. 



George H. Needham 

 College op Pharmacy, 



XJniveesity or Washington, 

 Seattle, Wash. 



THE HISTORY OF SCIENCE 

 Relative to your recent articles on the his- 

 tory of science and its present position in 

 American colleges, you might be interested to 

 know that efforts are being made to adapt 

 the history of science as a cultural course for 

 engineering students. I taught such a course 

 in the college of engineering of the University 

 of Colorado, and now am teaching it in the 

 college of engineering of New York Univer- 

 sity. 



Philip B. McDonald 

 December 27, 1921. 



AMEBOID BODIES ASSOCIATED WITH 

 HIPPEASTRUM MOSAIC 



In a recent publication ' the writer described 

 and pictured certain bodies in the cells of corn 

 plants suffering from mosaic disease. Since 

 the bodies are confined to diseased portions of 

 the plant, it was suggested that they might 

 be of etiological significance. 



Those who are working on the mosaic disease 

 problem will be interested to know that similar 

 bodies have now been found in the light green 

 portions of mosaic leaves of Hippedstrum 

 equestre Herb. This plant belongs in the 

 Amaryllidaceae and is not closely related to 

 corn. Its leaves which are thick and soft are 

 well suited for cytological studies. The mosaic 



1 Bui. Exp. Sta. H. S. P. A. 3:44-58 (1921) 



pattern shown by Hippedstrum is quite dif- 

 ferent from that of corn. The intracellular 

 bodies associated with this disease will be de- 

 scribed in detail in a future paper. 



L. 0. KUNKEL 



Experiment Station of the Hawaiian Sttgae 

 Planters ' Association, 



Honolulu, T. H. 



THE TUNING FORK. 



In Science for November 11, I cited briefly 

 some inadequate references to the actions of a 

 tuning fork to justify the preservation of mat- 

 ter that was very old; there was no reason to 

 name the wi'iters for these references were 

 minor parts of their papers. But in Science 

 for December 16, one of the writers, Mr. 

 Young, comes to the front, as if I had made 

 a personal attack on him, and defends his 

 former expressions, but qualifies them, still 

 leaving the subject in a very confused state. 

 He quotes his former dynamically unsound 

 "statement that the fork has only a single 

 note at the base" and now adds the indefinite 

 remark, "This of course is only an approxi- 

 mation"; it is noteworthy that he does not 

 attempt to state what he thinks is the truth. 



In his final paragraph he attributes to Pro- 

 fessor Watson an "alternative explanation" 

 which is only a corollary of Chladnis' old ac- 

 cepted theory; but pi'obably the professor of 

 physics would not use over his own signature 

 such an inexact expression as the "center of 

 mass tends to rise" or "lower," or leave it 

 doubtful whether "center of mass" always re- 

 lates to the same point. 



Chaeles K. "Wead 



QUOTATIONS 



"KEY" CHEMICALS 



Lord Crewe and Lord Haldane argued last 

 week for the release of scientific apparatus 

 and chemicals from the restrictions imposed 

 by the safeguarding of industries act and the 

 reparation act. Scientific research and the 

 teaching of scientific students, they alleged, 

 were seriously impeded because of the delay 

 and difficulty in importing certain chemicals 

 and apparatus from Germany. The stronger 



