80 DIATOMS. 



because it is little, for many of the most interesting 

 species are very minute and the most useful of all — 

 ampbipleura pellucida — owes its value to the extreme 

 delicacy of its markings, while the entire value is very 

 small. A favorite collecting place of mine is at the 

 upper or northern end of Morgan Lake. 



When the wind is from the south a scum is blown ashore 

 there v^hich is full of diatoms, but unfortunately the 

 number of species is not great although we may some- 

 times gather them by the ounce. The principal forms are 

 stauroneis phoenicenteron and navicula cuspidata, both 

 of which are found also in the river. Indeed I can recall 

 at this time only two sjjecies found in the ponds and 

 streams near here which I have failed to find in the river. 



The best time to collect diatoms is in the spring and 

 fall, especially in the spring. 



The outfit is simple and inexpensive and. consists of a 

 tin pail, a number of wide-mouthed bottles, a magnify- 

 ing glass and a long-handled spoon. If we visit a pond 

 we first look out for dirty brown scums on the surface of 

 the water. These are often blown by the wind so that 

 they are massed on the surface within easy reach of the 

 shore. They are skimmed off by the spoon and put into 

 a bottle, if found to contain diatoms by examination with 

 the hand-glass. These scums, nasty and unpromising as 

 they look, are often masses of pure diatoms, and by a 

 very little cleaning make excellent slides. Then we fish 

 out some of the water weeds and squeeze them out into 

 the pail. The common myriophyllum, which grows 

 abundantly in almost every pond, is usually a perfect 

 museum of plant and animal life. Its peculiar foliage 

 affords protection and support to innumerable small 

 creatures, including desmids and diatoms. We then let 

 the water squeezed from the weeds settle for a half hour, 

 and pouring off all but about an inch put the remaining 

 portion in a bottle, then the pail is washed out. Or if 



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