homologous Alternation of Generations in Plants. 353 
upon was subsequently accepted by Alexander Braun 1 : but his 
views, which will now be considered afresh, were as regards 
the majority of European botanists completely overshadowed 
by the authoritative dictum of Sachs : while we recognise the 
great merits of the Text-book which ensured to it a cosmo- 
politan circulation, it is nevertheless to be remarked that the 
almost dogmatic attitude, which the author adopted with 
regard to alternation of generations, has prevented the spread 
of Celakovsky’s views in quarters where their merits should 
have ensured acceptance. 
Putting on one side the subject of ‘ alternation of shoots ’ 
to which Celakovsky devoted much attention, and which is 
suitably referred to by Sachs 2 as a phenomenon of minor 
importance, we recognise as the great contribution which 
Celakovsky made to this subject, that he drew a broad dis- 
tinction between antithetic alternation , and homologous alter - 
nation 3 . The former term he applied to that alternation 
which is seen in the archegoniate series : he clearly recognised 
that in the archegoniate series the sexual was pre-existent 
from the point of view of descent, and called it the ‘ Protophyt/ 
while the neutral he styled the ‘ Antiphyt ’ : it is unnecessary 
for us to adopt these terms, as the words gametophyte and 
sporophyte are suitable and firmly established. The term 
homologous alternation was applied by Celakovsky to that 
type of alternation which, though a much less clearly defined 
phenomenon, commonly occurs in the Thallophytes, and the 
term implies the basis of distinction between this and antithetic 
alternation 4 : it consists in a differentiation inter se of homo- 
1 Sitz. d. k. Akad. zu Berlin, 1876, pp. 289, &c. 
2 Text-book, 2nd Eng. Ed. p. 228, last paragraph. 3 1 . c., p. 30. 
4 There will doubtless be found some botanists who will object to these phe- 
nomena being included in the term alternation ; I think however that it is desirable 
that they should be, for two reasons : first, because the original use of the term as 
applied to animals covered and indeed referred chiefly to such phenomena as 
these, the antithetic alternation finding no counterpart at all in the animal king- 
dom : — this has been pointed out by A. Braun ( 1 . c., p. 296) ; and secondly, becai.se 
I think it is desirable, even at the risk of less simplicity of classification, to accen- 
tuate the difference between the antithetic alternation, and those phenomena in the 
lower plants and in animals, to which the term alternation was first applied by 
Steenstrup. Botanists are apt to lose sight of the original use of the term altema- 
A a 2 
