OF THE DIAT05IACE.E. 13 



speaking, the cleanest specimens, by which I mean those 

 best adapted for immediate preparation, are the filamentous 

 genera of Melosira, Odontidium, Fragillaria, and Schizo- 

 nema; also certain parasitical kinds, such as Coccoueis, 

 Achnanthes, Synedra, Gomphonema, Licmophora, &c 

 which often cover the plants to which they are attached 

 to such an extent as to hide the original form 



f a /i t V h / e ^ rd 1° l he f ° SS . U Diatom ace* it'is a singular 

 fact, that although they exist in such countless quantities, 

 they are nevertheless ranged under a very small number 

 of species. J 



As in the case of the Alga> generally, the outfit required 

 for gathering Diatomace* is of the simplest kind A 

 common iron spoon, to scrape the surface of mud; a few 

 small bottles, wide-necked and cork-stoppered ; a quantity 

 of o led paper, or some similar material. With these few 

 articles the botanist may safely commence an expedition 

 m search of these minute plants. 



[The collector will often come across likely-lookin- spots 

 ymg beyond the reach of his arm; perhaps a mal of 

 weeds in the middle of a wide ditch, or a tempting hollow 

 at the base of a steep slippery bank. To meet this con- 

 tingency, he should provide himself with an ounce vial 

 broad-brimmed and wide-mouthed, and, besides, a stout 

 india-rubber ring. The bottle, when required can be 

 easily attached to the end of a walking-stick by m ans of 

 the ring (as shown in fig. 24, Plate v.), and then in- 

 serted among tufts of Alge, &c, at some distance from the 

 side of the pond or stream.— Ed.] 



