166 LAMARCK, HIS 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. 
“Tt 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 (amceba), volvoces, monads, etc. 
“This digestive canal is,” he says—proceeding with 
his @ priort 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 
