384 HISTORY OF SCIENCE. 



celebrated are the "Sy sterna Natures," 1735, "-Fundamenta Botanica" 

 1736, "Genera Plantarum" 1737, "Species Plantarum" 1762. In 

 powers of observation and classification Linnaeus has never been sur- 

 passed, and he created what may be called a new language for clearly 

 and concisely expressing the facts he perceived. 



The "Sy sterna Natures" though first published in 1735, received in 

 the successive editions which appeared during the author's lifetime 

 great additions and improvements, and only the volumes which ap- 

 peared at Stockholm under this title in 1766, 1767, and 1768 can be 

 considered as Linnaeus's completed work. 



The "Sy sterna Natures" treats of the animal, vegetable, and mineral 

 kingdoms. In the first division of animals into sub-kingdoms Linnaeus 

 bases the characters upon the internal structure, thus : 



Heart having two ventricles and two auricles. ( Viviparous . . Mammalia. 



Blood warm and red. ] Oviparous . . Birds. 



Heart having one ventricle and one auricle. ( Respiration voluntary Amphibia. 

 Blood cold and red. j Respiration by gills Fishes. 



Heart having one ventricle and no auricle. No j Having antennas . Insects, 



red blood. \ Having tentacula . Vermes. 



He gives, besides, other characters of each sub-kingdom, founded on 

 differences of the organs of respiration, of sense, of locomotion, etc. 

 At the head of each Class is given a concise description of its distin- 

 guishing characters, and this description is so worded as at the same 

 time to give us an explanation of all the terms belonging to the Class. 

 Then follows a list of all the more important writings relating to the 

 Class. After this the author lays down the characters of the Orders of 

 each Class, and then he divides the several Orders into genera, giving 

 the character of each genus. For instance, he divides the Mammalia 

 into seven Orders, distinguished chiefly by differences in the number, 

 position, or shape of the teeth. The teeth are also made, in a great 

 measure, the distinguishing marks of the divisions of the Orders of 

 Mammalia into genera. The distinctions of the Orders of Birds are 

 taken chiefly from the beak; Amphibia and Fishes are divided accord- 

 ing to certain characters of their respiratory and locomotive organs. 

 The sub-kingdom Insecta was almost without methodical arrangement 

 before the time of Linnaeus, although, of course, an immense number 

 of facts relating to the development, metamorphoses, and structure of 

 insects had already been accumulated, and the various species of in- 

 sects had been described and figured. The arrangement of Linnaeus 

 divides insects into Orders founded on the differences in the number 

 and texture of their wings. The Class of Vermes was divided by our 

 author into five Orders, founded on very various characters. 



We have just seen that Linnaeus divided the animal kingdom, first, 

 into six Classes, or sub-kingdoms; secondly, each Class into Orders; 



