176 



THE AMERICAN MONTHLY 



[September, 



made, but from necessity. We always 

 endeavor to publish the list of exchanges, 

 but occasionally it will happen that the 

 ISfejtes and Correspondence just fill the 

 last page. The most attractive material 

 under the microscope is that containing 

 Isthmia on seaweed. This is the richest 

 ?nd cleanest collection of that diatom we 

 have seen, although it maybe very abun- 

 dant on the Pacific coast. We will else- 

 where give some hints on mounting such 

 diatoms in the most effective manner. 



— Mr. L. M. King announces the dis- 

 covery of a new deposit of diatoms near 

 Santa Rosa, Cal. In sending us a speci- 

 men he writes concerning it as follows : — 

 The material that I send is in its natural 

 state, and crops out in ledges in the hills 

 in various parts of the surrounding coun- 

 try. It varies in richness according to the 

 locality, but in some places it is almost 

 pure diatoms and as white as snow, and 

 can be mounted without any previous 

 cleaning. The earth contains many gen- 

 era which also vary with the locality, but 

 in some places the following are particu- 

 larly well represented, viz: — Cocconema, 

 Pinnularia, Navicula, Surirclla, and 

 many others. 



— We are indebted to Dr. James K. 

 Stockwell for an excellently -prepared 

 section across the tail of a mouse, pass- 

 ing through the bone, in which the dif- 

 ferent tissues are beautifully distinguished 

 by staining. 



— Dr. Van Heurck has prepared an 

 extended report on the microscopical ex- 

 hibits at the Antwerp exposition, which 

 is published in pamphlet form. Only six 

 makers were represented, Hartnack, Nii- 

 chet, Prazmowski, Reichert, Ross, and 

 Zeiss. The apparatus exhibited was 

 freely offered for examination, and the 

 tests of objectives were made by Dr. 

 Van Heurck in his own work-room, un- 

 der precisely identical conditions. We 

 cannot undertake to notice in detail a re- 

 port of this kind, which must be read entire 

 to be of value. It can doubtless easily 

 be obtained by addressing the author at 

 Antwerp. It is printed in French. 



— A new mounting medium having an 

 index of refraction of 2-4 has been pre- 

 pared by Mr. S. Meate. Ten grains of bro- 

 mine and 30 grains of sulphur are heated 

 in a test tube, and when the sulphur is 

 dissolved 13 grains of metallic arsenic in 

 powder are added, and the heating con- 

 tinued until this is dissolved. The medium 

 is easily used, as it melts on the slide 

 when gently heated, and runs like balsam. 



— The Mojtiteiir dii Praticien, edited 

 by M. Aug. Zune, at Brusselles, is a valued 

 exchange, containing articles of a practi- 

 cal and instructive character. The last 

 number contains an article on the medico- 

 legal examination of blood, which is a 

 brief review of progress in this kind of 

 work since the year 1832. Another article, 

 by the editor, treats of the examination 

 of drinking-water, chemically, microscop- 

 ically, and for hygienic purposes. The 

 subject of the action of the more impor- 

 tant chemical reagents in quantitative 

 analysis is continued. The list of reac- 

 tions given in these articles is valuable for 

 reference. 



— ' Ex-President Porter on Evolution ' 

 is the title of the opening article in the 

 September number of The Popular 

 Science Monthly. It is by Mr. W. D. Le 

 Sueur, already well known as an able 

 writer on the relations of theology and 

 evolution, and is an outspoken review, as 

 entertaining as it is effective, of Dr. Por- 

 ter's recent address before the Nineteenth 

 Century Club. 



— A correspondent sends the following 

 quotation from E. Hackel: — 



' According to the same law of divergent 

 adaptation, both eyes also frequently de- 

 velop differently. If, for example a nat- 

 uralist accustoms himself always to use 

 one eye for the microscope (it is better to 

 use the left) then that eye will acquire a 

 power different from that of the other, and 

 this division of labour is of great advan- 

 tage. The one eye will become more 

 short-sighted, and better suited for seeing 

 things near at hand, the other eye becomes, 

 on the contrary, more long-sighted, more 

 acute for looking at an object in the dis- 

 tance. If, on the other hand, the natural- 

 ist alternately uses both eyes for the mi- 

 croscope, he will not acquire the short- 

 sightedness of the one eye and the com- 

 pensatory degree of long-sight in the other, 

 which is attained by a wise distribution of 

 these different functions of sight between 

 the two eyes. Here, then, again the func- 

 tion, that is the activity, of originally 

 equally-formed organs can become diver- 

 gent by habit ; the function reacts again 

 upon the form of the organ, and thus we 

 find, after a long duration of such an in- 

 fluence, a change in the more delicate 

 parts and the relative growth of the dif- 

 ferent organs, which in the end becomes 

 apparent even in the coarser outlines.' 



— Dr. L. Heydenreich has recently dis- 

 cussed the subject of cements for mounting 

 in the Zeitschy-.filr Wiss. Mikr., and gives 



