LY, 
Remarks on the Latest Form of the Development Theory. | 
Br FRANCIS BOWEN, 
ALFORD PROFESSOR OF NATURAL RELIGION, MORAL PHILOSOPHY » AND CIVIL POLITY 
IN HARVARD COLLEGE. 
(Communicated March 27, April 10, and May 1, 1860.) 
Ir is a familiar truth in paleontology, that the various races or species of animal 
and vegetable life which now tenant the earth, or have formerly tenanted it, did not 
originate all at once, but have been introduced at different and widely separated epochs. 
Those of which the remains are entombed in the earlier fossiliferous strata are now all, 
or nearly all, extinct; only a very few among the Invertebrates have living represent- 
atives at the present day. And ag the process of extinction was not sudden or sweep- 
ing, but gradual and protracted, so the new species appeared in succession, after long 
intervals of time, to fill the vacant places. “It appears," to adopt Sir C. Lyell's lan- 
guage, “ that from the remotest periods there has been ever a coming in of new organic 
forms, and an extinction of those which pre-existed on the earth ; some species having 
endured for a longer, others for a shorter time ; while none have ever reappeared after 
once dying out.” The species which are now in existence belong, geologically speak- 
ing, to comparatively recent times; indeed, none of the p orders among them are 
found in a fossil state at all. 
= Only two theories are possible as to the origin of all the species which have thus 
been successively introduced upon the earth. The one refers the beginning of each to 
a special act of creative power. The work of creation, upon this view, was not begun 
and ended at one time, but has been frequently renewed and extended, no period being 
without some manifestations of it in the appearance of new forms of life. This doc- 
trine rests upon the fact, confirmed by all observation, that, in the ordinary process of 
reproduction, each species gives birth only to those of its own kind. It is contrary to 
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