MEMOIR OF LAMARCK. 33 



tending to destroy it in every Individual necessarily 

 brings on Death." He conceives that the egg^ for 

 example, contains nothing prepared for life before 

 being fecundated, and that the embryo of the chick 

 becomes susceptible of vital motion only by the 

 action of the seminal vapour ; but if we admit that 

 there exists in the universe a fluid analogous to this 

 vapour, and capable of acting upon matter placed 

 in favourable circumstances, as in the case of em- 

 bryos, we will then be able to form an idea of 

 spontaneous generations. The more simple bodies, 

 such as a monad or a polypus, are easily formed ; 

 and this being the case, it is easy to conceive how, 

 in the lapse of time, animals of more complex 

 structure should be produced, for it must be ad- 

 mitted as a fundamental law, that the production of 

 a new organ in an animal body results from any 

 new want or desire which it may experience. The 

 first effort of a being just beginning to develope 

 itself, must be to procure the means of subsistence, 

 and hence in time there came to be produced a 

 stomach or alimentary cavity. Other wants, oc- 

 casioned by circumstances, will lead to other efforts, 

 which in their turn will produce new organs. One 

 of the gasteropode molluscse, for example, may be 

 conceived to have felt the necessity, as it moved 

 along, of exploring by touch the bodies in its path 

 and to have made efforts to do so with some of the 

 anterior points of its head, which would continually 

 direct to that point masses of the nervous fluid, as 

 well as other liquids : from these reiterated affluences 

 vol. xxxi. c 



