168 THE AMERICAN MONTHLY [June, 



3, which is adapted from classical figures of the older 

 German and French histologists. 



In non-injected sections of the kidney, many of the 

 facts just described can be shown, but not so readily. 

 The same criteria as those mentioned in the study of the 

 alimentary mucous tissues for the detection of arterioles 

 and capillaries can be applied and the relation of these to 

 the parts of the tubule studied out and thus the descrip- 

 tion and figures can be verified. Of the connective 

 tissues nothing extended need be said. The outer cap- 

 sule is a membrane of white-fibrous tissue, and between 

 the tubules there are fine strands of areolar tissue. These 

 do not form a system of optical importance and are visi- 

 ble only as fine threads or wavy lines. 



Biological Laboratory of Hamline University. 

 May 17, 1894. 



How to Find Diatomaceous Earth, 



By WM. a. terry. 



bristol, conn. , 



One of the most obvious places to look over for dia- 

 tomaceous earth is the bank of a railroad cutting. 

 Where such cutting has gone through a deposit it forms 

 an ideal opportunity for examination, as each stratum 

 can be separately explored with ease, and the whole 

 deposit thoroughly studied. The lines of stratification 

 are generally obvious in a fresh cutting — in all cases 

 originally horizontal. A fresh-water deposit will show 

 the overlying black stratum of muck or peat, and under 

 this the characteristic ash-colored layer containing the 

 diatoms. 



Where a railroad embankment crosses a marsh or a 

 body of water, the soft deposit is frequently forced up 

 on each side, rising above the water to the height of 

 several feet ; by digging down from the a})ex of these 

 elevations, a diatomaceous deposit can almost always be 



