10S THE POPULAR SCIENCE MONTHLY. 



direction, with the raollusks, but he still had nearly all to learn, or, to 

 speak more accurately, nearly all to create, in that uninvestigated 

 world in which Linnaeus had failed to introduce the methodical ar- 

 rangement which he had been so successful in introducing among the 

 higher animals. After devoting a year to preliminary studies, La- 

 marck began his lectures in the Museum in the spring of 1794 ; he 

 immediately instituted the great division of animals into vertebrates 

 and invertebrates, which has become fixed in science. Adhering to 

 the Linn scan division of the vertebrates into mammalia, birds, reptiles, 

 and fishes, he divided the invertebrates into mollusks, insects, worms, 

 echinoderms, and polyps. In 1799 he separated the order of crusta- 

 ceans from the insects with which it had been confounded ; in 1800 

 he separated the arachnids from the insects ; in 1802 he set off the 

 annelids as a subdivision of the worms, and the radiates as separable 

 from the polyps. Time has confirmed the justice of his division, which 

 depends in every respect upon the organization of the animals. This 

 is the rational method, incorporated in science by Cuvier, Lamarck, 

 and Geoffroy Saint-Hilaire. 



As our sketch has so far dealt only with Lamarck's achievements in 

 natural history, we pass with a simple mention a few works in which 

 he treated of physics and chemistry ; mistakes of a good intention, 

 which attempted to establish truths that rest exclusively on experi- 

 ment, by reasoning alone, or to resuscitate old theories like that of 

 phlogiston. These efforts did not even receive the honor of a contra- 

 diction ; they did not deserve it ; and they should serve as a warn- 

 ing to all those who would write upon any science without being 

 acquainted with it, and without having had practical experience in it. 



The generalizations of Lamarck in geology and meteorology, sci- 

 ences which at the time he wrote had hardly come into existence, were 

 mistaken in another sense. They were premature. Every science 

 must begin with the knowledge of facts and phenomena. When these 

 are numerous enough, a partial generalization is possible ; as they in- 

 crease, the basis grows broader ; but systems which can justly claim to 

 be absolute and definitive can never be, for they presuppose that all 

 the phenomena and facts are known, a condition which will be impos- 

 sible as long as man lives. In the beginning of this century geology 

 did not exist, and little was known of the matters of which it treats ; 

 but systems were created that included the whole earth. Lamarck 

 elaborated his system in 1802 ; and twenty-three years afterward the 

 clear mind of Cuvier succumbed to the prevailing tendency, and he 

 published his treatise on the revolutions of the globe. It was La- 

 marck's merit that he perceived that there were no revolutions in 

 geology, and that the slow manifestations of force through hundreds 

 of thousands of years far better explained the wonderful changes of 

 which our planet has been the scene than violent disturbance could do. 

 " To nature," he said, " time is nothing : it is no obstacle. Nature 



