358 SYSTEM OF INSECTS. 
either concatenated like a chain, or placed separately at 
small intervals from each other. It may run either in a 
right line, or deviate from it in various ways. It appears 
to be the opinion of most modern Physiologists, that the 
series of affinities in nature is a concatenated or con- 
tinuous series; and that though an Azatus is here and 
there observable, this has been caused either by the an- 
nihilation of some original group or species in conse- 
quence of some great convulsion of nature, or that the 
objects required to fill it up are still in existence but 
have not yet been discovered?: and this opinion is found- 
ed on a dictum of Linné, Natura...saltus non facit®. If 
this dictum be liberally interpreted, according to the 
evident meaning of the word saltus, few will be disposed 
to object to it; since both observation and analogy com- 
bine to prove that there must be a regular approxima- 
tion of things to each other in the works of God; and 
that could we see the whole according to his original 
plan, we should find no violent interval to break up that 
approximation: but if it be contended, that in this plan 
there is no difference in the juxtaposition of the nearest 
groups or individuals, and never any interval between 
them, I think we are going further than either observa- 
tion or analogy will warrant. Were this really and 
strictly the case, it seems to follow that every group or 
individual species must on one side borrow half its cha- 
racters from the preceding group or species, and on the 
other impart half to the succeeding*. But one of the 
2 'W. S. MacLeay in Linn. Trans. xiv. 54. 
> Linn, Syst. Nat. i. 11. © Qu. Whether every real 
species or group has not some one or more peculiar characters which 
it neither deriyes from its predecessor nor imparts to its successor in 
a series ? 
