630 REVIEWS AND BOOK NOTICES. 
they have been san mT aiming to construct, diverging lines 
meant races diverging in character, and the purpose of ‘all efforts 
at so-called natural tecciheaticn was to trace out the relationships 
between existing plants or animals. ow it is evident that he- 
reditary descent may have in different cases produced very differ- 
ent results as regards the problem of classification. In some cases 
the differentiation of characters may have been very frequent, and 
specimens of all the characters soe "er may have been transmit- 
ted to the present time. A living form will then have, as it were, 
ms fin 
resemblances. Exact and distinct SUREE will then be 
almost impossible, and the wisest course will be not to attempt 
arbitrarily to distinguish forms closely reisa in nature, but to 
allow that there exists transitional forms of every degree, to mark 
perhaps to select the most generalized form, or that which pre- 
sents the greatest number of a resemblances to others of the 
family, as the type of the w 
r. Darwin, in his most ‘itarsating work upon Orchids, points 
out that the tribe of Malaxez are distinguished from Epidendree 
by the absence of a caudicle to the pollinia, but as some of the 
_ Malaxez have a minute a cle the division really breaks down 
in the most essential point t 
‘This is a misfortune, he remarks,* ‘which every naturalis 
encounters in attempting to y a largely developed ae 
called natural group, in which, relatively to other groups, . et 
has been little extinction. In order that the naturalist — y 
enabled to give precise and clear definitions of his div ee y 
ranks of intermediate or gradational forms must have been ut gri 
swept away : if here and there a member of the intermediate a 
has escaped ee it puts an effectual bar to any absolutely 
distinct definiti have 
In other cases a particular plant or animal may aera ali 
transmitted its form from generation to generation almost U 
unsuitable to their circumstances, and may have perished re 
or later. We shall then find a particular form standing apan E 
all others, and marked by various distinct ehari Oce rly 
ally we may meet with specimens of a race which w s m y 
mmon but is now undergoing extinction, pe is p ri 
the last of its kind. Thus we may explain the occurrence k x 
ceptional forms such as are found in the Amphioxus. The 
x botanists by their want of affinity to 
perpie of pari r enes- 
of ya a plants. This doubtless indicates that their 8 
* Darwin, ‘ Fertilization of Orchids.’ p. 159. 
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