PJiOFESSOR OF INVERTEBRATE ZOOLOGY 39 



engaged in foreign wars, the philosophers preserved in 

 some degree, at least, the traditional calm of their pro- 

 fession, and passed their days and nights in absorptio'n 

 in matters biological and physical. In 1801 appeared 

 his Systime des Animaux sans Vertebres, preceded by 

 the opening discourse of his lectures on the lower 

 animals, in which his views on the origin of species 

 were first propounded. During the years 1 793-1798, 

 or for a period of six years, he published nothing 

 on zoology, and during this time only one paper 

 appeared, in 1798, on the influence of the moon on 

 the earth's atmosphere. But as his memoirs on fire 

 and on sound were published in 1798, it is evident 

 that his leisure hours during this period, when not 

 engaged in museum work and the preparation of his 

 lectures, were devoted to meditations on physical and 

 meteorological subjects, and most probably it was 

 towards the end of this period that he brooded over 

 and conceived his views on organic evolution. 



It appears that he was led, in the first place, to 

 conchological studies through his warm friendship 

 for a fellow naturalist, and this is one of many 

 proofs of his affectionate, generous nature. The 

 touching story is told by ^tienne Geoffroy St. 

 Hilaire.* 



" It was impossible to assign him a professorship of 

 botany. M. de Lamarck, then fortyrnine years old, 

 accepted this change in his scientific studies to take 

 charge of that which everybody had neglected ; be- 

 cause it was, indeed, a heavy load, this branch of 

 natural history, where, with so varied relations, every- 



* Fragments Biographiqucs, p. 213. 



