348 Bower —On antithetic as distinct from 
remains — perhaps in order to simplify matters — to regard as 
homologous and truly comparable all such similar forms and 
phases as have not been actually demonstrated to be diverse 
in origin or nature. So with the study of alternation of 
generations ; this term, the very sound of which has an 
insidious attractiveness, has been commonly used in a very 
extended sense, and applied with little discrimination to the 
succession of phases of life of different organisms, whether these 
be truly similar to, or dissimilar from, one another ; and thus 
there has grown up the idea that an alternation of generations 
is due to some quality inherent in many organisms, and 
especially in plants, which leads them to pass through certain 
definite phases in the progress of their individual life. Such 
a view was at least implied by Sachs when he said 1 that the 
doctrine of alternation has the object of reducing to one 
scheme the main phases of life of all plants which bear sexual 
organs ; such an object involves the presumption of a much 
greater uniformity of organic nature than can be justified by 
known facts. We must rather be prepared to find and to 
recognise in our classification of such phenomena various 
results of the impress of different external conditions upon 
diverse organisms, and avoid, rather than press forward, the 
reduction of phases of life of all organisms which show 
sexuality to one rigid scheme. 
I am convinced that a merely formal comparison of different 
organisms, or of their successive stages one with another, will 
not suffice for the solution of the question as to the real nature 
of alternation. In order to gain a true conception of the mean- 
ing of alternation as a wide-spread biological phenomenon, the 
question should be approached from the physiological rather 
than the purely morphological point of view, while the con- 
clusions thus arrived at are to be checked in accordance with 
what is known of phylogeny 2 . 
1 Lehrbuch, 4th ed. p. 234. 
2 It will be unnecessary to quote and compare the diverse views of different 
writers on the subject of alternation : it will rather be my object to state briefly my 
own opinion, comparing it incidentally with those of others, where strong divergence 
exists. 
