30 EVOLUTIONS OF ORGANIZATION. 
One often hears final causes spoken of with a 
contempt which is indeed only a revulsion from a 
style of writing which will not now find many 
admirers, in which adaptations were found by point- 
ing out what extraordinary consequences would 
follow some impossible alteration in nature, and 
final were made to do the duty of efficient causes ; 
but in the history of the vertebrate heart may be 
seen a remarkable instance of the definite evolution 
of a complex mechanism to perform a particular 
kind of work. There is no reason to doubt that 
here we have morphological evolution, and final 
cause combined; just as it is possible to imagine, 
though we may have little experience of it, a build- 
ing morphologically belonging to the Gothic order, 
yet teleologically fitted for the wants of modern 
science. 
It is a legitimate position to take up, that all the 
evolutions of nature are definite, but that the series 
of such evolutions is indefinite in number and 
kind ; that individual evolutions, like other indi- 
viduals, are finite, but form members of a larger 
total. So, in the evolutions of organization we see 
vortic units, the textural elements, receiving and 
rejecting currents of material, while they maintain 
during a finite life-time their individuality, and 
these united into larger individuals subject to the 
