THE INTRODUCTION OF NEW SPECIES, 23 
jections exist against every theory on such a subject, 
but this is not necessarily the case. The hypothesis 
put forward in this paper depends in no degree 
upon the completeness of our knowledge of the 
‘former condition of the organic world, but takes 
what facts we have as fragments of a vast whole, 
and deduces from them something of the nature and 
proportions of that whole which we can never know 
in detail. It is founded upon isolated groups of 
facts, recognizes their isolation, and endeavours to 
deduce from them the nature of the intervening 
portions. 
Rudimentary Organs 
Another important series of facts, quite in accord- 
ance with, and even necessary deductions from, the 
law now developed, are those of rudimentary organs. 
That these really do exist, and in most cases 
have no special function in the animal ceconomy, 
is admitted by the first authorities in comparative 
anatomy. The minute limbs hidden beneath the skin . 
in many of the snake-like lizards, the anal hooks 
of the boa constrictor, the complete series of jointed 
finger-bones in the paddle of the Manatus and 
whale, are a few of the most familiar instances. In 
botany a similar class of facts has been long re- 
cognised. Abortive stamens, rudimentary floral en- 
velopes and undeveloped carpels, are of the most 
frequent occurrence. To every thoughtful naturalist 
the question must arise, What are these for? What 
have they to do with the great laws of creation? 
