NATURAL HISTORY OF THE DIATOMACEjE. 42 1 



been frightened away from a field of inquiry which was beset with 

 so many difficulties at the outset. Under these circumstances it is 

 hoped that the present sketch will recommend itself for perusal to every 

 one interested in natural history, and at the same time introduce to many 

 unacquainted with them an extremely attractive group of wonderfully 

 constituted and beautifully sculptured beings. Those wishing to follow 

 the subject up more thoroughly will find, in the works of Kiitzing, Smith, 

 Rabenborst, Ralfs, and others,— a list of which will be given hereafter — 

 ample opportunities for making themselves acquainted with what is 

 known concerning the diatomacese. 



The Diatomacea?, or, as they have come to be familiarly termed by 

 those more or less acquainted with them, the Diatoms, have been so 

 named from a genus called Diatoma, which received its name at a time 

 when it was considered to be an animal, and was placed in a group to 

 which a celebrated German naturalist, named Ehrenberg, gave the dis- 

 tinctive title of Polygastrica, or, polygastric animalcules, or, minute 

 animals possessing many stomachs. The name Diatoma had been 

 bestowed upon the organism in question from two Greek words, dia, 

 through, and tcmuo, to cut asunder, on account of its appearing as a 

 number of minute, oblong boxes, attached, corner to corner, in such a 

 manner as to form a zig-zag chain, and looking as if the chain had been 

 formed from a ribbon-like band, partially broken across at intervals. 

 After a while, when it came to be known that the group to which the 

 name of polygastrica had been given was made up of many totally dis- 

 tinct groups, — some animals, some plants, and some neither one nor the 

 other, but merely broken pieces of animals, plants, or minerals, — different 

 forms were, one after the other, or, in some cases, many together, 

 removed from this heterogeneous assemblage. Some, it was found, could 

 be placed in divisions already known, but others had to be made into 

 classes by themselves, and these newly constituted groups had to have 

 bestowed upon them, as a natural consequence, appellations by means 

 of which they might be distinguished and known. The Diatomaccce was 

 one of these apparently natural groups, and as all the forms, it was found, 

 grew after a manner the same as the organism upon which the name of 

 Diatoma had been bestowed, that is to say, by a partial or total splitting 

 across, the distinctive name of Diatomaccce was given to them, and they 



