K.—BOTANY. 193 
through the winter by the persistent bulb, are all characteristics peculiar 
to itself. 
In the Fucaceze there have been no striking discoveries, but there are 
many problems awaiting solution. A considerable amount of attention 
has been paid to the study of Sargassum and of the Sargasso Sea, but 
the accounts of both are conflicting. One writer states very definitely 
that there are no mitoses in the oogonium of Sargassum. This is now 
contradicted, and we are told that the usual eight nuclei are formed, 
although only one oosphere results. A statement that requires confirma- 
tion is that in one of the Sargassums!® two of the eight nuclei remain 
functional in the formation of the one egg, and that there is no uni- 
nucleate stage in the oosphere. If so, then the resulting embryo must 
originate from a double ovum! There comes from New South Wales?° 
an account of a parasitic Fucoid—Notheia anomala—where antheridia 
have not been found. The author conjectures that reproduction is by 
means of parthenogenetic eggs. If this is so it is important that we 
should know whether the chromosomes undergo reduction. 
Members of the Fucacee have proved useful in the investigation of 
physiological problems. It appears to the writer that much might be 
learnt from them about the intimate details of the physiological processes 
concerned in fertilisation. The unique fertilisation phenomena in 
Halidrys have already been described, but as no figures have ever been 
published lantern illustrations are now shown. Many questions suggest 
themselves: What is the nature of the stimulus imparted to the 
cytoplasm of the ovum by the cilia of the gyrating antherozoids ? What 
are the physical processes concerned in the consequent swelling of the 
oosphere ? How is sperm-entry effected ? What are the sudden chemical 
and physical changes that cause the protrusions, the emission of toxic 
substance, and the sudden formation of the investing wall??4 These 
and numerous other interesting questions demand for their solution a 
botanist who is also an expert physicist and chemist. 
The much-discussed theory of ‘alternation of generations’ is now 
being re-examined in the light of the new Pheophycean facts. The 
divergent types represented in the group are very interesting. Here we 
have Pylaiella with a fluctuating alternation, where the diploid phase 
may be several times repeated, and with a similarity of form in the two 
generations ; Cufleria, with dissimilar forms, and an alternation that is 
not strict ; Dictyota with ‘homologous’ forms and a strict alternation ; 
Laminaria with the generations as dissimilar in size and structure as any 
in the Vascular Cryptogams ; and lastly, the Fucacee, variously described 
as presenting alternation with extreme reduction of the gametophyte 
and (for the first time) retention within the sporophyte ; or as merely a 
“nuclear alternation of generations’; or, as having no alternation at all 
—the plant being a gametophyte, and thus comparable to an animal. 
The majority of botanists have accepted Strasburger’s view that 
Fucus is a sporophyte, and that the so-called oogonia and antheridia, up 
19 Tahara, Bot. Mag., Tokyo, 37, 1923. 
20 Williams, May M., Proc. Linn. Soc. N. S. Wales, 48, 1923. 
21 The whole of the life-history and cytology of Halidrys, including meiosis, gamete 
formation, fertilisation, germination, and general ecology has been worked out, and 
the results will be published at an early date. 
1925 Oo 
