198 THE AMERICAN MONTHLY [Jul 



"Zoology." — The current issue of the "Journal of the 

 Linnean Society" contains, among other articles of inter- 

 est to the microscopist, a contribution by Mr. H. Wagner 

 on "The Eye Spot and Flagellum of Euglena viridis," and 

 a paper by Mr. H. M. Bernard on "The Structure of 

 Porites." 



Making Diamonds. — Among the impurities that have 

 been detected in calcium carbide are microscopic diamonds. 

 These gems are so exceedingly small as to be of no com- 

 mercial value, but they accentuate the fact that carbon in 

 the crystalline condition can be produced artificially, and 

 give reason for the assumption that some day it will be 

 possible to produce diamonds of a size sufficient to be 

 marketable. 



Microtome.-— A Cambridge Instrument Company is in- 

 troducing an improved model of their well-known rocking 

 microtome. Among the advantages that they claim for the 

 new form is the possibility of cutting sections to any re- 

 quired degree of*thinnes8 without the risk of the sections 

 either varying in thickness or of being torn on the up- 

 ward movement of the object. 



Structure of Epidermis. — In man and mammals, L. 

 Ranvier has recognized seven distinct layers, which are 

 described to the Royal Microscopical Society as stratum 

 germinativum, filamentosum, granulosum, intermedium, 

 lucidum, corneum, and disjunctum, in the order of their 

 development. The limits are well defined, each layer hav- 

 ing distinct physical characters and chemical reactions. 

 These layers arenot formed by special elements, howerer, 

 and a cell originating in stratum germinativum becomes 

 changed and passes into stratum filamentosum and so on 

 through the series. 



Structure of Metals. — Mr. J. E Stead has published 

 the results of the work that he has recently done on the 

 metals. Experience has made it easy to cut, grind, polish, 



