RECENT ADVANCES IN ZOOLOGY. 285 
on itself. Nor is this all; the ventral system needs no support, the 
dorsal, lying above the cavity of the body, needs to be supported ; 
in all ‘ Vertebrates’ this support primarily consists of a solid un- 
jointed rod-—the dorsal rod or notochord; such a notochord was 
found by Kowalevsky to be developed also in the Ascidians. 
Two results, then, were arrived at, and, as you do not all 
know the works of Kowalevsky, I may add—what would be quite 
unnecessary in a less general company—that the distinguished 
Russian’s statements have been found by other naturalists to be 
exactly and perfectly correct. These results were— 
1. That a notochord was not confined to ‘ Vertebrates’; and 
2. That the central nervous system of Tunicates was formed 
in just the same way as in ‘ Vertebrates.’ 
You may be sure that these results of Kowalevsky were not at 
first accepted ; to use the words of Prof. Kupffer, who wrote with 
the honest bluntness of Prince Bismarck’s countrymen, they did 
not ‘seem to be generally taken as trustworthy”; the Professor 
owns that he himself was sceptical, but his scepticism was of the 
kind which a countryman greater still than Prince Bismarck had 
ealled an “active scepticism,” or which, as Goethe explains, has 
for its sole object that of conquering itself. To this important 
and thoroughly scientific duty Kupffer devoted himself in 1869, 
and his testimony and the weight of Prof. Haeckel’s opinion began 
_ to work a revolution in Systematic Zoology, which has not yet 
expended its influence. 
The value of a discovery in science is not to be guaged merely 
by the additions which it makes to knowledge; science, as Plato 
long ago taught, consists not in the passive perception of facts, 
but in the reasoning upon them; or, to use the words of Berkely, 
with regard to that Greek philosopher, the man of science is the 
greater the more “ fine hints sparkle and shine throughout his 
writings.” 
Now, what are the kind of considerations that arise when we 
reconsider the ‘ Vertebrata’ by the light of Kowalevsky’s dis- 
covery; first of all this, that among the ‘ Vertebrata’ there is 
one remarkable form—the Lancelet (Amphioxus)—in which the 
central nervous system is a hollow tube, and in which this tube 
is supported by-a notochord, but is never protected by cartila- 
ginous or bony rings developed around it. In other words, 
the zoologist comes to the conclusion that he has outdone 
