398 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1914. 
The search among the brown alge for parallels to the chromosome 
history of the cormophytes has been much more successful. The 
first case made out, that of Fucus, by Farmer and Williams (1896) 
and by Strasburger (1897) seemed, it is true, not very illuminating. 
They found the reduction occurring in the first divisions of what 
seemed clearly to be the egg- and sperm-producing organs, a point 
where it occurs in no other green plant. This case of Fucus, you will 
remember, is the one used by Scott (1896) to point a moral, when 
voicing the generally felt criticism of those botanists who proposed 
‘‘making the number of chromosomes the criterion by which the two 
generations are to be distinguished.” Scott says: 
T venture to think it premature to rush into inductive reasoning from imperfectly 
established premises. The case of Fucus in which the Fucus plant is shown to have the 
full number of chromosomes goes dead against the idea that the sexual generation (and 
who could calla Fucus plant anything but sexual) necessarily has the reduced number 
of chromosomes. This fact is indeed a rebuff to deductive morphology. 
When, however, Strasburger (1906) and Yamanouchi (1909) 
followed out the logical trend of the chromosome evidence unre- 
servedly, this life history of Fucus became more readily comparable 
with that of the cormophytes, and with those of certain brown and 
red alge that had in the meantime been elucidated by Willams and 
Yamanouchi. From this point of view, elaborated most completely 
by Yamanouchi, the Fucus plant with its 2X number of chromosomes 
is a sporophyte, and the reproductive organs arising in its concep- 
tacles are sporangia comparable with those of aseed plant. After the 
reduction, which occurs at the normal point, at sporogenesis, each of 
the four megaspores, without escaping, gives rise to a gametophyte 
of two fertile cells or eggs. Each of the four microspores in turn 
forms a gametophyte, or X generation, of but sixteen cells, each of 
which is fertile and forms a spermatozoid. It is interesting to note 
here the similarity which has been pointed out by Strasburger and 
by Chamberlain of the chromosome cycle of Fucus to that of ani- 
mals. In the latter, from the plant cytologist’s point of view, the 
sexual generation has become reduced to the four haploid nuclei 
formed at spermatogenesis and oogenesis, and the so-called ovary 
and spermary are really spore-producing organs of the 2X or asexual 
generation. 
In the brown seaweed Dictyota the discovery of the chromosome 
cycle revealed, for the first time in any thallophyte, an alternation 
that seemed clearly comparable with that of the cormophytes in this 
respect. Williams (1904) was able to show that the morphologically 
similar, mature plants of Dictyota dichotoma differ not only in that 
some produce spores only and others male or female reproductive 
cells only, but also that the nuclei of the former have twice as many 
chromosomes as those of the sexual plants. He found also that 
