COLLECTIXO DIATOMS. 20 



to the drawing of Species the original designs have in the same way 

 been made at 900 diameters, and have been reduced by phototype to 

 400 diameters in order to diminish the expense and so render the work 

 available for a very large number of observers. The figures of this 

 work will therefore often be improved by the use of a magnifying glass. 



4. Collecting Diatoms. 

 A. Collecting Inland. 



Diatoms are to be found distributed everywhere ; whatever water- 

 course may be explored our researches are almost certain to be rewarded ; 

 the smallest ditch, the smallest pool, provided the water is not stagnant, 

 contains diatoms in greater or less numbers. Moreover they accumulate 

 in prodigious manner. It is by reason of this fact that at different times 

 I have found the bottom of the immense harbour basin of Blankenberge 

 entirely covered over with a thick deposit of diatoms, principally 

 consisting of Pleurosigvui. 



When starting in search of diatoms, certain necessary collecting instru- 

 ments and appropriate vessels to contain the gatherings must naturally 

 be got ready. The following is a list of the articles which a diatomist may 

 take with advantage on his excursions : 



The principal article is a leather bag fitted with a strap; this is 

 carried over the shoulder and under the arm. The bag should con- 

 tain a sufficient number of pockets to carry a dozen wide necked bottles of 

 say 20Z. capacity, a smaller leather case containing six large phials with wide 

 necks, holding about 1 oz. a piece, each phial fitting into a pocket ; in 

 the country this case is carried in the pocket of the overcoat. 



Next comes a box containing some small tubes and a camel's hair pencil 

 for painting off pure gatherings, or avoiding the inconvenience of bringing 

 home a larger quantity of material. 



In addition to the bottles and the tubes, some pieces of gutta-percha 

 paper or waterproof macintosh cloth, nine inches square, are very useful 

 to wrap up algae, masses of confervae, and other diatom-yielding plants ; 

 these are made up into bundles, after slightly pressing out part of the 

 water. These bundles are kept from unfolding by an elastic ring, and 

 are put at once into the bag. For scraping the surface of mud, such 

 as alluvia, the sides of jetties, &c, the writer uses a copper spoon with 

 a screw clamp to fasten to the end of a walking-stick when used. On 

 one side of the neck of the spoon is rivetted a small knife blade, 

 which forms a convenient means of cutting away portions of aquatic 

 plants covered with diatoms and lifting them out of the water. 



