36 



§ X. MINUTE MICROSCOPIC ORGANISMS. 



It is very desirable to procure specimens, from many localities, 

 of the various forms of microscopic animals and plants, not only 

 on account of their intrinsic interest, but for their relation to im- 

 portant general questions in physical and natural science. These 

 will almost always be found to occur in the following localities : — 



1. In all light-colored clays or earths, as found in peat bogs, 

 meadows, soils, &c., particularly when these are remarkably light. 



2. In the mud from the bottom of lakes and pools. A small 

 handful of this mud or of the confervoid vegetation on the bottom, 

 if dried without squeezing, will retain the Diatomacese and Des- 

 midiese. 



3. In the mud (dried) from the bottom and along the margins 

 of streams in any locality. The muds from brackish and from 

 fresh waters will differ in their contents. 



4. In soil from the banks of streams. The surface and subsoils 

 should both be collected. 



5. In the soundings brought up from the bottom of the sea or 

 lakes. These should be collected from the greatest possible depths. 

 If an armature be used to the lead, it should be of soap rather 

 than fatty matter, as being more readily removed from the organ- 

 isms. The mud which adheres to anchors, to rocks, &c., below 

 /«/^^-water-mark, as well as below low-vi&i^v, should also be care- 

 fully gathered. 



6. In bunches of damp moss from rocks, roofs of houses, trees, 

 about pumps, &c. 



T. In the deposits in the gutters and spouting of roofs of houses- 



8. In the dust which at sea collects upon the sails or deck of 

 vessels. When not in sufficient quantity to be scraped oft', enough 

 may be obtained for examination by rubbing a piece of soft clean 

 paper over the surface affected. 



Specimens of all these substances should be gathered, and, when 

 moist, dried without squeezing. The quantity may vary from a few 

 grains to an ounce, depending on the mode of transportation to be 

 adopted. Ei'ery specimen, as collected, shoidd have the date, lo- 

 cality, depth below the surface, collector, SfC, marked immediately 

 upon the envelop. 



It is also desirable to collect filterings from river, brackish, and 



