230 



THE AMERICAN MONTHLY 



[December, 



Diatoms and How to Collect 

 Them.* 



The diatoms or bacillaria are 

 small and single celled microscopic 

 plants, belonging to the class of 

 kryptogams. Their color is due to a 

 peculiar coloring matter, diatomin. 

 When living, the plants are colored 

 greenish-brown or brown. The walls 

 are composed of silica, and resist de- 

 composition after the plant has died. 

 To this circumstance is due the ori- 

 gin of infusorial earths, and you well 

 know what colossal deposits are 

 found in different localities, and 

 what a large share these little organ- 

 isms have had in the formation of the 

 surface of the earth. The walls are 

 composed of two parts, w^hich fit one 

 in another, like the cover of a paper 

 box, forming the two principal sides, 

 which show the beautiful markings 

 of the diatoms. 



The belts (hoops) of the diatoms 

 are smooth or striped and otherwise 

 marked, and if you boil them with 

 strong acids they will come off; so that 

 the two principal sides will be isola- 

 ted. If you want to make a prepar- 

 ation you alw^ays have to remove 

 the belts, which costs sometimes a 

 great deal of trouble. 



Small as these forms are, their dif- 

 ference in size is sometimes enor- 

 mous. As regards the larger forms 

 you will, in some cases, be able to 

 observe them with the eye as small 

 white spots ; the smallest, however, 

 are only visible when in large num- 

 bers, heaped together. 



The diatoms are distributed in 

 both fresh and salt water. The first 

 are, as a rule, small, single forms ; 

 the latter, however, large and di- 

 versiform. 



I will give you some information 

 about collecting them. The marine 

 species are partly attached and partly 

 free forms. You have to take a 



* Translated by Mr. Brunno MuUer. It shou'd be 

 stated that this article is a translation of a f^imiliar, 

 private letter of Mr. Carl Muller, an experienced 

 collector and preparer in Germany, to his brother, 

 who, at the editor's request, has translated it for th^ 

 Journal, 



spoon and a walking-cane to which 

 to fasten the spoon, some well corked 

 glass bottles, and some pieces ot 

 blotting-paper. The locality w^here 

 to collect will be a brackish swamp, 

 or parts of the sea-shore within the 

 ebb and flood tide. The free-living 

 forms you will find on the alg^ that 

 float in the water, and the browner 

 these algas look the more certainly • 

 you may expect to find diatoms upon 

 them. Stones lying in the water and 

 covered with a slimy substance will 

 also yield diatoms. If you take 

 these algse and press them carefully 

 you can keep them in the blotting- 

 paper. 



The mud on the ground will yield 

 a great quantity of diatoms, but 

 where the ground is sandy or stony 

 you need not look for them, except 

 where the ground has a slimy touch. 



Take the surface of the mud away 

 one inch thick with the spoon and 

 put it in the bottles. When you get 

 home put the mud on a plate and 

 let it dry. In spring or autumn, 

 when the diatoms are copulating, you 

 will be able to ob.sei"ve them. The 

 mud then will change in color to 

 brown or yellow. In this mud some 

 air-bubbles will be formed by the di- 

 atoms, which tear the tender, thin 

 skin, and will float on the surface of 

 the water. You then only need to 

 catch these flakes, or take up the 

 mud with the spoon. This is im- 

 mensely rich material and is com- 

 posed only of diatoms. 



I have discovered a new system of 

 obtaining specimens from poor ma- 

 terial. Take the material and dilute 

 it well with water in a bowl, and let 

 it stand about a quarter of an hour. 

 The mud must be well stirred in the 

 water so that it looks like muddy 

 water. Let it stand and rest again. 

 The heavy mineral particles will sink 

 down. After a quarter of an hour 

 the water will be clear again, but on 

 the top all vegetable particles will 

 float. If you have a small, fine 

 sieve, pour the water through and all 

 the rough parts will remain in the 



