1894.] MICROSCOPICAL JOURNAL. 29 



of things below kingdoms of which plants were. Thus 

 plants were a kingdom and animals were a kingdom and 

 rocks were a kingdom. Thus as plants or vegetables 

 were a kingdom, they were divided into fiowerless and 

 flowering plants, and fiowerless plants were divided into 

 other divisions until we come to algap or water plants 

 without flowers, and these are divided into families of 

 which one covers the plants in question, the Bacillariacea'. 

 These in their turn are divided into genera and the gen- 

 era into species. So the Bacillariacew are a family of al- 

 gae, or water plants without evident flowers. That is to 

 say that was the place they bore in the plan of nature 

 but DOW they are Protista or organisms which are mid- 

 way between vegetables and animals. For Hackel, a Ger- 

 man Naturalist, must be claimed the credit for placing 

 them there and I am disposed to place them there also. 

 They mostly have shells composed of Siliceous rock- 

 like earth so that they can be preserved almost indefi- 

 nitely and their shells are known as Diatoms and are 

 found in the carboniferous and triassic periods. But 

 more commonly in the Tertiary and constitute the Infu- 

 sorial Earths of Richmond, Ya., and Santa 3Ionica, Cal., 

 besides many other points on the surface of the globe. 

 Being very small and finely marked they came to be used 

 as test objects for microscopic lenses so that one of them, 

 Pleurosigma angulata is widely known. Their natural 

 history and how they occur and their place in geology 

 along with how to get and preserve them will be told 

 hereafter. 



EDITORIAL. 



Stone Uncferthe Microscope. — It is often held that the 

 best method of determining the probable dural)ility of a build- 

 ing stone is to study its surface, or thin transparent slices, un- 

 der a microscope. This method of study in rrcent years has 



