270 THE AMERICAN MONTHLY [Sept, 



1000 grms. ; ferro-cyanide of potassium, 100 grms. Mix 

 solutions (1) and (2). They form a precipitate of inso- 

 luble blue. Pour on a filter and wash until the liquid 

 runs blue below the filter. Dry, scrape off the precipi- 

 tate and keep for use. 



For an injection, make a saturated aqueous solution 

 .... Soak 10 grammes of gelatine in distilled water 

 for 20 minutes, then remove it from the water, and melt 

 it in a water-bath. In a water-bath heat 200 grammes 

 of the blue solution, and when this and the gelatine are 

 at the same temperature, pour the blue into the gelatine, 

 and stir with a glass rod. A precipitate is formed, but 

 dissolved as the heat increases. The solution is perfect 

 when the glass rod shows no blue grains on its surface. 

 Filter through flannel and keep the temperature at 40° 

 C. until ready to use. If any remains after the injection 

 is made, a little thymol should be added, otherwise the 

 gelatine will liquefy in a few days and the material be 

 destroyed. 



{To he continued). 



Notes on the Habitat of Diatoms. 



By R. D. NEVINS, 



BLAINE, WASH. 



The collector may think himself fortunate if he finds 

 any locality or discovers any habit of growth of these 

 lovely things which will enable him to secure them 

 specifically separate or nearly so and already cleaned by 

 processes of nature. 



I will give some notes of what have been to me lucky 

 "finds," hoping to provoke from others reports of similar 

 good fortune. 



Zostera marina and another species which we have on 

 Puget sound, Z. oregana, have been to me treasures in 

 this respect. The plant is found everywhere floating its 



