Prof. Agassiz on the Origin of Species. 151 
has been ascertained, and that history is recorded in the life of individu- 
als through successive generations. The same kind of argument might 
be adduced from every existing species, and with still greater force by a 
reference to those species already known to the ancients. 
Let it not be objected that the individuals of successive generations 
have presented marked differences among themselves; for these differen- 
ces, with all the monstrosities that may have occurred, during these 
countless generations, have passed away with the individuals, as individ- 
ual peculiarities, and the specific characteristics alone have been preserved, 
together with all that distinguishes the genus, the family, the order, the 
; ‘Class, and the branch to which the individual belonged. Moreover all this 
lias been maintained through a succession of repeated changes, amounting 
in each individual to the whole range of transformations, through which an 
individual passes, from the time it is individualized as an egg, to the time 
It is itself capable of reproducing its kind, and, perhaps, with all the 
intervening phases of an unequal production of males and females, of 
sterile individuals, of dwarfs, of giants, ete., ete., during which there were 
millions of chances for a deviation from the type. Does this not prove 
ae ae ee. 
nee, species, genera, families, orders, classes, and branches of the animal 
kingdom exist only as categories of thought in the Supreme Intelligence, 
U . 
number 
18 derived from a primary one, remain connected to fori - 
uniti Ww 
that kind of independence resulting from an individualization 
ct of a single egg. e have derivative individuals 
aMong the Nudibranchiate Mollusks, whose eggs produce singly, by a 
lete se i i 
4 similar phenomenon among those Acalephs the young of which 
stoma) ends in producing, by transverse division (Strobila), a 
t of Independent free Medusze (Ephyre ; e have it also among 
lds which produce free Meduse. Next, we must distinguish 
~ Sty individuality, which is inherent to those individuals arising as 
