A JOURNEY IN BRAZIL. 
provided for voyagers on the great deep than are to be 
found on this magnificent ship. The state-rooms large and 
commodious, parlor and diniug-hall well ventilated, cool, and 
cheerful, the decks long and broad enough to give a chance 
for extensive " constitutionals " to everybody who can stand 
upright for two minutes together, the attendance punctual 
and admirable in every respect ; in short, nothing is left to 
be desired except a little more stable footing. 
April ~10th. - -A rough sea to-day, notwithstanding which 
we had our lecture as usual, though I must say, that, owing 
to the lurching of the ship, the lecturer pitched about more 
than was consistent with the dignity of science. Mr. Agas- 
siz returned to the subject of embryology, urging upon his 
assistants the importance of collecting materials for this 
object as a means of obtaining an insight into the deeper 
relations between animals. 
" Heretofore classification has been arbitrary, inasmuch 
as it has rested mainly upon the interpretation given to 
structural differences by various observers, who did not 
measure the character and value of these differences by 
any natural standard. I believe that we have a more 
certain guide in these matters than opinion or the indi- 
vidual estimate of any observer, however keen his insight 
into structural differences. The true principle of classifica- 
tion exists in Nature herself, and we have only to decipher 
it. If this conviction be correct, the next question is, 
How can we make this principle a practical one in our 
laboratories, an active stimulus in our investigations ? Is it 
susceptible of positive demonstration in material facts ? Is 
there any method to be adopted as a correct guide, if we 
set aside the idea of originating systems of classification 
of our own, and seek only to read that already written in 
