ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
203 
former authors. Okamura and the present author both supposed that 
these plantlets were the product of germinating carpospores, but further 
observation disproved this. In February and March P. leucosticta was 
found growing richly on the concrete block, and early in April fronds 
bearing mature carpospores were placed under observation. The 
liberated carpospores sank to the bottom of the glass vessel and began 
to germinate at the beginning of the second week after the liberation. 
A protonema-like growth was developed which became elongated, and 
branched sporangia were formed by the transformation of the terminal 
cell of a branch, or of an intermediate cell of the principal filament ; 
the gametes were of two kinds, large and small. Both moved actively 
in water, but flagella were actually observed in the macrogametes only. 
The whole process took about five weeks. The discovery of hetero- 
gametes in Porphyra gives rise to further problems as to the position of 
Bangiacese, and to the need of following the germination of carpospores 
in Euflorideae. Certain points of difference were apparent between the 
single-celled sporelings of autumn and the rounded carpospores liberated 
from mature fronds in spring, which may possibly be evidences of their 
different origins. The various stages of development described are 
well figured. E. S. Gf. 
Cytological Studies on Porphyra tenera Kjellm. I. — M. Ishikawa 
( Bot . Mag. Tokyo , 1921, 35, 206-18, 1 ph, figs, in text). This alga, 
the “ asakusanori ” of commerce, is much cultivated for food purposes 
in Japan. Material was collected in Tokyo Bay, November to March, 
1920 and 1921, and treated according to methods described. An account 
is given of the vegetative cell and its division, the spermatium, carpo- 
gonium and carpospore ; and stages of division of zygote and antheri- 
dium are figured. Under phylogenetic observation it is pointed out 
that the nucleus of Porphyra may be regarded as a kind of incipient 
nucleus, though it differs in some respects from the highly organized 
type in the nucleus of Cyanophyceae. The method of nuclear division 
has a close resemblance to that of Synechocystis aquatilis , in having three 
chromatic filaments and primitive mitosis ; and this affinity with 
Cyanophycese is further increased by the possession of phycocyanin and 
phycoerythrin which is recorded in 'certain species of Cyanophyceae. 
They differ, however, in the presence of a stellate chromatophore and 
sexual reproduction in Porphyra. A connecting link is found in 
Porphyridium cruentum , which has a stellate chromatophore, but no 
sexual reproduction. Porphyra is also allied to Florideae by the posses- 
sion of sexual cells, and of a chromatophore containing phycoerythrin. 
It shows a close relationship to the lower Nemalionales in the presence 
of a pyrenoid and in the absence of alternation of generations. But it 
differs from Floridese in producing carpospores directly from the carpo- 
gonium, in the presence of a kind of incipient nucleus, and in the 
absence of protoplasmic continuity. A table is given showing the 
distribution of phycoerythrin and phycocyanin in Cyanophycem and 
Bhodophycese. Ulva differs from Porphyra in having a highly diffe- 
rentiated nucleus, and a chromatophore of a different type from that of 
Bangiales ; also in the reproductive organs. In Bangia fuscopurpurea 
