30 COLLECTING DIATOMS. 



The only lens necessary to a diatomist when out collecting is a 

 Coddington, but the writer has found a small compound hand micro- 

 scope very useful occasionally. This, with some slips of glass, are carried 

 in a separate compartment in the leather sachel. 



For some time past we have used with advantage a small pocket 

 microscope, sold by E. Thum, of Leipzig, and which he has named an 

 Algensucher. 



This instrument is in the form of a tube, 5 or 6 centimetres (2 inches) 

 in length by 3 centimetres broad. This tube carries at the upper end 

 the magnifying apparatus, which consists of a doublet, under which 

 can be placed two glass slips sliding in a groove and held in position 

 by a spiral spring. The diatoms are placed on one of the slips and 

 can be covered over by the other. 



This little apparatus, which is very convenient, can be furnished with 

 interchangeable doublets, so as to give different magnifications varying 

 from 50 to 200 diameters. 



Now that we are equipped and ready to start, the question arises, 

 where shall we go in search of diatoms ? 



In 1872 there was published in the Lens of Chicago (') an article 

 copied from the Intellecttial Observer, ( 2 ) entitled " Where to search for 

 Diatoms." 



This article gives very valuable information to the young diatomist, 

 and we believe that we cannot do better than reproduce the greater part 

 of it : 



" A knowledge of the most likely places to look for Diatomaceas 

 is only to be gained after some experience, and it is the wish of the 

 writer to give the result of his experience in the matter, which has 

 induced him to pen these lines. In mentioning the various species 

 of Diatomaceas in connection with given habitats and localities, it may 

 be as well to say that the writer has, in most cases, found the species 

 named in such localities ; not necessarily in one particular district, but 

 at various times and in different parts of the country. 



" We will now suppose the collectors are commencing their imaginary 

 collecting tour, and, before leaving the town, let us take a stroll round 

 the docks, for here we may meet with material in places where such 

 might be the least expected. For instance, let us examine the logs of 

 Baltic or American timber as they come from the vessels. If the 



(V) The Lens (1872), i., pp. 106-116. 



( 2 ) Intellectual Observer (1872), i., pp. 190-199. 



