224 REVIEWS. 
«That ‘Natural Selection’ is incompetent to account for the’ 
= stages of useful structures 
t it does not harmonize with the co-existence of closely 
similar ee of diverse ori 
there are grounds for thinking that specific differences 
may be developed suddenly instead of gradually. 
“That the opinion that species have definite though very differ- 
ent limits to their variability is still tenable. 
“ That certain fossil ana forms are absent which might 
have been expected to be p 
si Sit some facts of erap Na distribution supplement other 
difficultie 
i That itie objection drawn from the physiological difference be- 
om ‘species’ and ‘races’ still exists unrefuted. 
« That there are many remarkable phenomena in organic forms 
upon which ‘ Natural Selection’ throws no light whatever, but the 
explanations of which, if they could be attained, might throw light 
upon specific origination 
“ Besides these objections to the sufficiency of ‘Natural Selec- 
tion’ others may be brought sy the hypothesis of ‘ Pangene- 
sis,’ which, aper aing as it does to explain great difficulties 
seems to do so by presenting pee not less great — almost to be 
the ition of obscurum per obscurius.” 
These theses are the subjects of successive chapters in which 
they are maintained and defended with much acumen, and with 
many references to facts, easily comprehended by the general 
reader, but on which we have not room to dwell. In Chapter IV.on . 
“« Minute and Gradual Modifications,” he réfers to the conception of 
Mr. Galton in his work on ‘‘ Hereditary Genius” that ‘‘ new spe- 
cies have from time to time manifested themselves with sudden- 
ness, and by modifications appearing at once (as great in degree 
as are those which separate Hipparion from Equus) the species 
remaining stable in the intervals of such modifications: by stable 
being meant that their variations only extend for a certain degree 
in various directions, like oscillations in a stable equilibrium.’ ied 
Mr. Mivart gives among other examples of this sudden varia- 
tion, the cases of young oysters, ‘‘ which were taken from the 
shores of England and placed in the Mediterranean, and at once 
altered their mode of growth and formed prominent diverging rays, 
like those of the proper Mediterranean oyster; as also the twenty- 
nine kinds of American trees, all differing from their nearest 
capri views were previously entertained by Messrs. Cope and Hyatt, as will be 
seen farthe 
