APPENDIX 



COLLECTION AND PREPARATION OF DIATOMS 



It is assumed that every student of the Diatomacese has a general knowledge of the 

 collection, preparation, mounting and examination of material. For the novice, however, 

 the following methods, used by the author for many years, may be of service. 



Collection of Fresh-water Material. The yellow film on the inside of aquaria always 

 contains small species. Stems of water-plants near the shores of ponds and the submerged 

 roots, the brownish coating of rocks in streams and water-falls, fountains, and water-troughs, 

 are prolific. At all times of the year, some diatoms may be found in a thin layer upon the 

 mud of rivers or creeks. In the spring, brown patches of mud, filled with bubbles, floating 

 near the shore in ponds, or coming down with the current in rivers, are rich in various forms. 

 Within the limits assigned to our district, I have made collections in the following locali- 

 ties: Schuylkill River, including the region near Fairmount Dam, several reservoirs and 

 the water-supply; the Wissahickon and Fairmount Park, Darby, Crum and Ridley Creeks, 

 the Neshaminy and the Brandy wine; meadow pools and rivulets near the city; the upper 

 Delaware, the Water Gap and numerous cascades northward; the Shawangunk Mountains 

 and the Poconos; many parts of New Jersey along the coast; the Pine Barren region, the 

 Hammonton, Atsion and Kirkwood Ponds and the swamps near Atco. 



In the collection of fresh-water material, it is well to be provided with a number of 

 small bottles. Take a handful of the water-plants or algse, and squeeze the material into 

 the bottles, or, lacking a bottle, wrap it in paper. With a small forceps it is possible to 

 detach minute quantities of a pure gathering which may not need further preparation be- 

 yond burning to a red heat on the cover-glass before mounting. A malacca cane, with 

 extending rod to which may be screwed a bottle, net, spoon or hook, is useful on a long 

 trip. If it is impossible to separate the thin film of diatoms from the mud in the bed of 

 streams, dip up the surface mud with one bottle, allow to settle a few minutes, then pour 

 off the supernatant liquid, which will be comparatively free from sand, into another 

 bottle. It must be confessed, however, that the mud in streams near Philadelphia contains 

 a large quantity of fine mica which, in some instances, it is impossible to remove. 



Collection of Marine Material. Shell scrapings, the stomachs of fish, marine algse, 

 especially the brown and red algae, the hulls of vessels, mud from anchors and dredgings, 

 are all sources which may prove valuable. In the sand ripples, after the tide recedes, a 

 yellowish-brown deposit will be noticed. This should be taken up carefully with a spoon 

 and placed in a bottle; the sand will settle at once and a very pure gathering will be held 

 in suspension in the water. Such collections may be made along the entire coast of New 

 Jersey on sunny days in summer. In salt meadows near Absecon and Hackensack, large 

 quantities of diatoms, including Pleurosigma, may be obtained hi the yellow scum floating 

 on the surface. 



The Blue Clay Deposit. The blue clay occurs as a pre- or post-glacial deposit in the 

 bed of the ancient Delaware River, and, at depths varying usually from fifteen to forty 

 feet below the surface, has been obtained from artesian wells at Pavonia, Pensauken and 

 Gloucester, N. J., also at Port Penn on the Delaware, and especially from the dredgings 



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