The dust which collects at sea upon the sails or deck of ves- 

 sels can generally be scraped up with a piece of paper. When 

 the quantity is so small that it cannot be so collected, a piece of 

 damp paper may be laid on it once or twice in several places and 

 then folded up without drying. Latitude and longitude, direction 

 of wind at time of falling of dust, name of vessel and collector's 

 name should be noted. 



Recent gatherings. — Gather the marine plants adhering to 

 rocks, piers, iron or wood work ; the dirtier they look the richer 

 ^will be the harvest, as the brown coating on aquatic plants ob- 

 scuring them and submerged iron, stone, or wood work is but a 

 mass of Diatoms. Such gatherings should be dried and placed 

 in layers ; each specimen being plainly labelled with the exact 

 locality, date of collection, and collector's name. Fragments' of 

 marine plants which would be rejected by the student of Algae 

 yet yield specimens of microscopic organisms. When convenient 

 the name of the Alga should be stated. If possible it is desirable 

 to transmit specimens of Diatom-encrusted Algae put up in spirits, 

 as the species are thus preserved in a natural state ; but precau- 

 tions should be taken to tie a label, written on stiff cardboard, in 

 ink, to the neck of the bottle, for the reason above mentioned, 

 under Marine Invertebrata. Fresh-water plants clouded with 

 Diatoms may be gathered in the same way. The finer filamentous 

 species of both marine and fresh-water plants yield the best re- 

 sults, the fucoids secreting a mucus which seems repugnant to the 

 growth of many Diatoms ; yet on the stalks of Laminaria and 

 other large olive-colored Algae are found the finer red tinted spe- 

 cies which, in turn, bear upon their fronds a crowd of minute 

 vegetation. Do not clean or wash such Algae in any way, but 

 merely raise them from the water and, without squeezing, lay them 

 on paper to dry. The moss-like carpeting on submerged rocks 

 is often Diatoms alone, and it will be well to scrape the surface 

 of the stpne and remove the gathering to a bottle for preservation 

 in spirits. Fresh-water forms are often found hanging in green 

 colored festoons from the exit pipe of drains, sluices, or fountains. 



The green, brown, or fawn-colored scum that floats on the water 

 of bogs, marshes, ponds, or rivers, may be dried on paper in the 

 same way, though it is far preferable to preserve it in spirits. It 

 may be raised from the water by means of a spoon and transferred 

 to a bottle. The surface of the sea may be skimmed by means 



