20 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 dining-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 ~LQth. 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 



