l66 LAMARCK, BIS LIFE AND WORK 



dimensions of the parts contained, when, as the result 

 of the organic movement which it enjoys, it will be 

 subjected to successive changes and losses of its 

 substance. 



" It will then be obliged to take nourishment not 

 only to obtain any development whatever, but also to 

 preserve its individual existence, because it is neces- 

 sary that it repair its losses under penalty of its 

 destruction. 



" But as the individual in question has not yet any 

 special organ for nutrition, it therefore absorbs by the 

 pores of its internal surface the substance adapted for 

 its nourishment. Thus the first mode of taking food 

 in a living body so simple can be no other than by 

 absorption or a sort of suction, which is accomplished 

 by the pores of its outer surface. 



" This is not all ; up to the present time the animal- 

 ized corpuscle we are considering is still only a primi- 

 tive animalcule because it as yet has no special organ. 

 Let us see then how nature will come to furnish it with 

 any primitive special organ, and what will be the organ 

 that nature will form before any others, and which in 

 the simplest animal is the only one constantly found ; 

 this is the alimentary canal, the principal organ of 

 digestion common to all except colpodes, vibrios, 

 proteus (amoeba), volvoces, monads, etc. 



" This digestive canal is," he says — proceeding with 

 his k priori morphology — " a little different from that 

 of this day, produced by contractions of the body, 

 which are stronger in one part of the body than in 

 another, until a little crease is produced on the sur- 

 face of the body. This furrow or crease will receive 

 the food. Insensibly this little furrow by the habit 

 of being filled, and by the so frequent use of its 

 pores, will gradually increase in depth ; it will 

 soon assume the form of a pouch or of a tubular 

 cavity with porous walls, a blind sac, or with but 

 a single opening. Behold the primitive alimentary 



