358 The Microscope. 



Though not admitting the absolutely alphabetical sequence 

 attained by cards, this system is in some respects even more prac- 

 tical than that for small collections, say up to three or four 

 thousand slides. It is easier to see and compare numerous items 

 when collated upon a page than when stacked away in cards. Thus 

 fifty or sixty entries of hairs or of crystals can be reviewed and 

 compared, and a half-dozen selected for some purpose, much better 

 by glancing over a page than by leafing over that number of 

 separate cards; Avhile the graphic effect of the page is of percep- 

 tible use in keeping one's mind constantly familiar with the extent 

 and character of his collection. The cards are theoretically better, 

 and in very large collections practically better for finding any 

 specified slide that one knows he wants; but are not better, nor even 

 as good, for assisting him to decide what he wants among many, 



Troy, N. Y. 



CRYSTALLINE FORMATIONS OF LARD AND OTHER 



FATS. 



PLATE VII. 



BY DK. THOMAS TAYLOR. 



Lj^IGURES 1 and 3. Respectively, primary and secondary crys 

 -■" tals of loon fat. xllO. 



Figures 2 and 8. Primary and secondary ciystals of musk-rat 

 fat. The primary (No. 2) are always very small, measuring about 

 three one -thousandths of an inch in diameter. 



Figure 4. Crystals of oleo. xl40 diameters. (Extract of 

 beef- fat.) 



Figure 5. Crystals of common lard by plain light. x400. 



Figure 6. Secondary crystals of butter. xllO. 



Figure 7. Crystals of beef fat. xl40. 



Figure 9. Crystals of deer-fat. xl40. 



Figure 10. Lard by plain light. xl40. 



Figure 11. Ciystals of the solid fat of cotton-seed oil. xllO. 



Figure 12. Neutral lard crystals, miniature. xl40. 



IT. S. Agricultural Department, Washington, D, C. 



