78 THE AMERICAN MONTHLY [April, 



foot deep has yielded a large variety of forms, and the ditch which was 

 next richest was about two feet wide and had barely three inches of 

 water in it, almost nothing but ooze. Each of these spots was by the 

 side of and quite close to a small ci-eek, formed by springs a mile or so 

 further inland, which runs toward the sea-coast at Westhampton, Long 

 Island, and they were all within the radius of a mile. A fourth spot 

 was the outlet of a mill-pond, to the side of the wheel where the water 

 backed up and was quite still, and was not more than a foot or two 

 deep. The light brown ooze is almost sure to contain desmids. From 

 those four spots alone I have taken species of all the genera except Phy- 

 matodocis, Gonatozygon, Mesotcenium, and Calocylindrus ; in other 

 words, of i^ out of the 19 genera given by Wolle. This may serve to 

 show how little trouble is often required to secure a large variety for 

 study. Sphagnum has also furnished a number of specimens, but it is 

 rather an uncertain habitat, some sphagnum yielding few or none ; at 

 least that has been my experience. The rain-pools alongside the rail- 

 road tracks are also good collecting grounds. A fine gathering was 

 made by one of our Society from such a spot at Montclair Heights. 



PRESERVING AND MOUNTING. 



After gathering, if you want to keep the desmids alive, the material 

 should be put in wide beakers or flat-bottomed glass dishes about three 

 inches high filled with fresh water, and the amount of ooze in each dish 

 ought not to be more than a quarter of an inch in depth. If given suf- 

 ficient light without being exposed to the direct rays of the sun they will 

 thrive for some time. And here let me give you a hint about getting 

 clean specimens for mounting. Wolle says, " it is so difficult to separate 

 specimens from their accompanying foreign matter Lhat it is seldom 

 amateurs can mount them satisfactorily on slides, and, therefore, this 

 method is not open to recommendation." I cannot agree with him in 

 the latter statement and am sorry he made it, for it has probably deterred 

 some from trying to preserve their gatherings. I should feel much 

 poorer if I had followed his advice myself, for I have a number of slides 

 and prize them highly in spite of the foreign matter mixed with them, 

 which really interferes very little with the view of most of them. But, 

 besides, it is possible at times to get them quite clean. The desmids 

 make their way to the light and form films or tufts on the surface of the 

 ooze in the glass after it has stood a day or two, and by careful manip- 

 ulation of the pipette they can often be drawn out with hardly any 

 foreign material at all. I remember I made a gathering from a little 

 pool at Westhampton a few summers since, and after it had stood in a 

 glass jar a day or two I was surprised to find regular little green tufts 

 scattered over the ooze at the bottom, and on using the pipette was re- 

 warded by an almost perfectly clean gathering of Euastrum, a score or 

 more at a dip. Let the student then allow his gathering to settle for a 

 day or two before he transfers his desmids to the smaller bottle with 

 carbolic acid or to Stokes' fluid. If the beaker is of good size, as the 

 desmids will gather mostly at the side nearest the light, he will be able 

 to exclude a great deal of the ooze or light brown mud. It is true you 

 can't separate them from it ; but they can and will separate thetnselves 

 if you will only give them the chance. But in any case the student 

 need not be deterred from mounting because of the extraneous matter. 

 If he puts only a small amount of material in his little phial, and shakes 



