LINNEAN SOCIETY OF LONDON. 25 



wlio care more about the natural-history studies of Linnaeus than 

 the doubtful medical lore of bis day. He classified fevers under 

 two classes — the Exanthematici, subdivided into Contagiori and 

 Sporadici ; and the Critici, including coutinued, intermittent, 

 and remittent fevers. In a brief view on the Theory of Physic, 

 Linnaeus supposes the circulating fluids to be capable of being 

 vitiated by principles which he considers as putrid ferments. 

 The exanthematic class he considers to be excited by some ex- 

 ternal causes which are called contagion, and which he hypothe- 

 tically asserts to be Animalcnla. At the present day we say 

 Bacteria. 



As might be expected, Linnaeus had some original ideas about 

 Geology. He writes : — " The globe which was covered with 

 water has dried insensibly : the continents have appeared, and 

 the seas have been restricted within their basins. The traces of 

 a slow and successive retreat of the ocean are seen everywhere : 

 tlie traces of the universal deluge are not apparent anywhere. 

 Water, the earth, and its salts are the only ' principles ' which 

 have contributed to the formation of animals and vegetables. 

 These, after a more or less short life, are reduced into an 

 earthy substance proper for the formation of new organisms, 

 which perish in their turn." He notices the layers of different 

 kinds of rock, the presence of fossils and petrifactions, and con- 

 siders that water alone acted, and not fire. 



Lamarck, the founder of Philosophical Zoology, came before 

 the scientific world, in the first instance, as a botanist. Like 

 many naturalists of his century, he studied nature in preference 

 to disease after having passed the portals of the medical pro- 

 fession. His love of anatomy, however, never ceased, and bore 

 great fruit in subsequent years ; but in .the first instance he 

 studied plants, and became ^^I'actically acquainted with those of 

 large districts in France. He passed some ten years working 

 patiently at his 'Flore Francaise,' and gradually elaborated a 

 classification which was the result of much consideration. 



Many years had elapsed since the artificial method of Lin- 

 naeus bad been founded, and in the meanwhile the natural system 

 of the Jussieus had been used and apjreciated. Lamarck very 

 properly considered the first method of great use in finding out 

 the name of a plant, and gave the last its true value as a 

 scientific clas^^ification, which alone could serve as a fixed base for 

 any anatomical and physiological investigations. He considered 

 that the natural method placed a plant or animal in the midst of 

 those tvith tvhicJi it had tlte greatest niimher of important structural 

 resemllances, and that the artificial system isolated and distin- 

 guished a form from all otiiers. He saw clearly that the natural 

 method must be true, and that it must be founded upon the 

 nature and structure of the most important organs without con- 

 sidering whether they were to be readily observed and recognized. 



Giving both methods their due, he utilized them. In the 



