194 SECTIONAL ADDRESSES. 
to the four-nucleate phase (the completion of meiosis), are really macro- 
and micro-sporangia respectively ; and that the gametophyte stages are 
limited to the few succeeding nuclear divisions, resulting in the formation 
of oospheres and sperms. Church, however, combats this view most 
vigorously.2 According to him: ‘to talk of alternation of generations 
is mere academic futility. There is only one soma, or one generation, so 
there is nothing to alternate. To attempt to construct an idea of two 
generations to bolster up an academic conception of ‘‘gametophyte” and 
‘* sporophyte ” borrowed from land flora is nonsense.’ 
Elsewhere Church advances cogent arguments in support of his view ; 
and his comparison of the efficiency of the reproductive arrangements in 
Fucoids with those in animals is interesting and persuasive. When he 
asks us to concentrate our attention on Meiosis as the most important 
fact in the racial history, we shall most probably all agree with him. 
When, however, he bids botanists ‘ scrap ’ the ‘ alternation of generations ” 
superstition, many will demur. Some of his opponents point out that in 
vigorous cultures of Laminaria the spore may give rise to an egg after 
only one nuclear division—the one in the embryospore. This brings it 
very close to what they claim happens in Fucus. Another point, though 
small, and perhaps of no great significance, is interesting. In its supposed 
sporangial condition the Fucus ‘oogonium’ is unilocular, like other 
Pheophycean sporangia, but in its gametangial condition it is multi- 
locular.2* Another consideration that weighs with the opposing school 
is that throughout the greater part of the group ‘alternation’ is an 
acknowledged fact, and that in the ascending series it shows a consistent 
progression towards greater strictness, with increasing reduction of the 
gametophyte phase. The theory has been so useful in unifying the 
phenomena presented by the different groups of the Brown Seaweeds that 
many Algologists will be reluctant to relinquish it without stronger reasons 
being adduced. 
Svedelius,™ in a discussion of the biological importance of alternation 
of generations, maintains that the case of Laminaria invalidates the theory 
of Bower and Wettstein that the gametophyte generation is an adaptation 
to a land habitat, for the same phenomenon obtains in the marine series 
Dictyota—Laminaria—Fucus. After pointing out the importance of the 
reducing division in the sorting of chromosomes, and the consequent 
increase of variability, and in the initiation of new types, he suggests that 
the establishment of a diploid sporophyte would be advantageous to the 
race; for by postponing the reduction divisions the plant is given the 
chance to effect many reduction divisions, and so many more fundamental 
combinations of chromosomes. Through this the genesis of higher types 
is made possible. It may be pointed out that as far as the evolutionary 
principles above mentioned are concerned, it is perfectly immaterial 
whether we follow Church in calling Fucus a gametophyte, or agree with 
other botanists in regarding it as a sporophyte. 
In spite of their great interest, problems relating to the Physiology 
and Ecology of the Pheophycee can only be touched upon—the space at 
our disposal does not allow of more. 
2 Jour. Bot., 1924-25. 
?3 Farmer and Williams, Phil. Trans., 190 B, 1898. 
4 Ber. d. deutsch. bot. Ges., 39, and Svensk. Bot. Tidske, 1918-19. 
