239 
Pteridophytes. Are they vestigial? 
afterthought, a mode of propagation taken up by already 
existent vegetative parts. There is, however, a comparative 
obstacle to this view : for spore-production is a characteristic 
of the simplest sporophytes : and if the plants of the past in 
any degree resembled the plants of the present, spore-produc- 
tion must have been, even on an homologous theory, an early 
event in evolutionary history. But to those who hold the 
antithetic theory of alternation, that the sporophyte is the 
result of amplification of the zygote, and that spore-production 
was its first end, and was, just as it is now seen to be, a con- 
stantly recurring feature throughout descent 1 , a recapitulation 
theory is plainly inconsistent with their view 2 . For ex hypo- 
thesis in the simplest cases the spore-production preceded the 
vegetative development of the sporophyte, though in develop- 
ment of the individual, in the more advanced cases, the 
vegetative system precedes the spore-production. 
The question of priority in the history of descent of sporo- 
phylls and vegetative leaves cannot then be settled summarily 
by the statement that the latter appear first in the ontogeny 3 : 
neither can it be decided by any detailed comparison of the 
two leaf-forms as regards individual development 4 : an hypo- 
thesis that the foliage leaf is a sterilized sporophyll is based 
just as much upon the fact of the similarity of development of 
the two leaf-forms, as the converse view that the sporophyll is 
an altered foliage leaf. Nor will the record of an infinity of 
intermediate forms, half sterile and half fertile 5 , nor the proof 
that experimentally the sporophyll can be converted into 
a foliage leaf 6 , carry us any further than to show the intimate 
relations of the two. These facts do not touch the question 
of phylogenetic priority. 
1 See Bower, Presidential address to Sec. K, Brit. Assn. Report, 1898, p. 1031. 
2 This was fully pointed out by me in the Annals, vol. vi, p. 372. 
3 Goebel, Science Progress, 1895, p. 120. 
4 Gluck, Flora, 1895, Heft 2, p. 383. 
5 Gluck, loc. cit., p. 384. 
6 Goebel, Annals of Botany, vol. vi, p. 359 ; also Ber. d. Deutsch. Bot. Ges., 
1887. Atkinson (Bot. Gaz., vol. xxii, p. 220) made similar experiments, and 
from similar results finds the converse view to be still tenable. 
