LAMARCK’S THEORY OF EVOLUTION 265 
supposition for this: I call to witness all observing 
naturalists. 
“Not only many genera, but entire orders, and 
some classes even, already present us with portions 
almost complete of the state of things which I have 
just indicated. 
“‘ However, when in this case we have arranged the 
species in series, and they are all well placed accord- 
ing to their natural relations, if you select one of them, 
and it results in making a leap (saut pardessus) over 
to several others, you take another one of them a 
little less remote; these two species, placed in com- 
parison, will then present the greatest differences 
from each other. It is thus that we had begun to 
regard most of the productions of nature which occur 
at our door. Then the generic and specific distinc- 
tions were very easy to establish. But now that our 
collections are very much richer, if you follow the 
series that I have cited above, from the species that 
you first chose up to that which you took in the sec- 
ond place, and which is very different from the first, 
you have passed from shade to shade without having 
remarked any differences worth noticing. 
““T ask what experienced zodélogist or botanist is 
there who has not thoroughly realized that which I 
have just explained to you? 
“Or how can one study, or how can one be able 
to determine in a thorough way the species, among 
the multitude of known polyps of all orders of radi- 
ates, worms, and especially of insects, where the 
simple genera of Papilio, Phalena, Noctua, Tinea, 
Musca, Ichneumon, Curculio, Capricorn, Scarabzeus, 
Cetonia, etc., etc., already contain so many closely 
allied species which shade into each other, are almost 
confounded one with another? What a host of 
molluscan shells exist in every country and in all seas 
which elude our means of distinction, and exhaust 
our resources in this respect! Ascend to the fishes, 
