28 THE AMERICAN MONTHLY [Jan., 



Diatomacesp. In this lie has been followed by Grrunow, 

 Heiberg, Sclmman, Cleve, and Suringar. Dr. Pfitzer, 

 however, maintains that the name Bacillariacea^ should 

 be substituted, the genus Bacillaria having been estab- 

 lished by Sinclair in 1788; whereas the genus Diatoma 

 was established by De Candolle in 1805; and some of the 

 older writers on the subject have used this designation. 

 It may be deemed inconvenient now to abandon the 

 name of the group which has been so generally adopted 

 by recent writers, but, on technical grounds. Dr. Pfitzer's 

 view is undoubtedly correct and we chose the right on 

 technical grounds to designate them the Bacillariacea?, 

 and they shall because they must be so designated. 



Now what is known as a group or family of Bacilla- 

 riacege ? Let us go back to Aristotle as the father of 

 Natural History. He classified animals, for animals were 

 capable of classification. Vegetables, rocks and earth 

 were of small moment then. They did not think, move, 

 and have their being it was thought. He first attempted 

 the scientific division of the animal world. His outlines 

 are rude of course but this acute observer admitted but 

 two great sections of animals ; The highest creatures 

 possessing blood (i. e. red blood), which corresponds to 

 the Vertebrata of modern authors, and animals provided 

 with a colorless fluid instead of blood, and correspond- 

 ing to the Invertebrata of more recent zoologists. Pass 

 we now to consider the naturalists as they must be con- 

 sidered and John Ray or Wray (as he wrote his name 

 till 1670), was born in 1628, and he is remarkable as be- 

 ing the first to define species although he did classify 

 animals and plants. His definition of species rested un- 

 til it was overthrown by the researches of Darwin in 

 1857. In 1766, came Linnaeus and he classified animals 

 and plants with a positiveness not thought of before. 

 He defined species as something positive and readily 

 to be distinguished and ranked families also as a group 



