514 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
irregularly shaped cell. The upper cell divides rapidly, and gives rise 
to the young gonimoblast, which branches copiously and horizontally 
in all directions among the cells of the thallus. Tlie spores are developed 
from terminal cells of erect gonimoblast filaments, these filaments extend- 
ing round the whole hemispherical external frond. The tetrasporanges 
are formed from one of the ordinary distal cells of a peripheral layer. 
The author proposes to erect the genus into a distinct family of the 
Gigartinaceae, Harveyelleae, distinguished by the gonimoblast branching 
freely among the thallus cells beneath the peripheral layer. 
Fertilisation of Sphseroplea.* — Herr H. Klebalm regards the two 
varieties of Sphaeroplea annulina, vars. Braunii and crassisepta, as con- 
stituting distinct species ; they differ in the width of the vegetative 
cells and the size of the oospheres ; in the nature of the septa ; in the 
number of nuclei and pyre no ids in the rings of the vegetative cells ; in 
the divisions of the antherids and oospheres ; in the changes of the rings 
in the antherids ; and in the mode of breaking up of the protoplasm, and 
the position of the oosphere in the oogone. The following are the most 
important results of a fresh investigation of the mode of impregnation. 
Cell-division takes place karyokinetically. The nuclei of the anthero- 
zoids result from repeated karyokinesis of the nucleus of the antherid ; 
the nuclei of the oospheres are derived from those of the oogone without 
apparent change. The oospheres of the variety Braunii usually contain 
more than one nucleus, both before and after impregnation ; even in the 
ripe oosperm there appears to be more than one. The oospheres of the 
variety crassisepta, on the other hand, contain only one nucleus. The 
impregnation of the oosphere, even when it contains several nuclei, is 
effected by a single antherozoid. In S. Braunii the nucleus of the 
antherozoid fuses with one of the nuclei of the oosphere, which is 
indistinguishable beforehand from the other nuclei. 
Fucus Hybrids.f — Mr. J. LI. Williams has obtained a new hybrid 
in the Fucaceae, — between Ascophyllum nodosum $ and Fucus vesicu- 
losus 9 • No corresponding impregnation could be obtained between 
F. v esiculosus £ and A . nodosum 9 • 
Sexuality of the Tilopteridese.J — M. C. Sauvageau gives more de- 
tailed reasons for withdrawing Ectocarpus pusillus from that genus, and 
placing it in the new genus Acinetospora, which, together with Haplo- 
spora and Tilopteris , makes up the Tilopteridese. The so-called “ mono- 
spores ” display the usual characteristic of vegetative organs of propa- 
gation in their very great variability in size ; they germinate with remark- 
able facility. Ectocarpus crinitus must probably be transferred to this 
family along with E. pusillus. The Tilopteridese may be defined as Phaeo- 
sporeae with endogenous propagules. Acinetospora is monosiphonous ; 
Tilopteris and Haplospora are polysiphonous, at least at their base. 
Auxospores of Diatoms. § — Herr G. Karsten distinguishes four types 
in the mode of formation of the auxospores of diatoms : — In the first 
type only a single mother-cell takes part in the formation of the auxo- 
* ‘Die Befruchtung v. Sph&roplea annulina 1899 (1 pi.). See Bot. Centralbl., 
lxxviii. (1899) p. 362. t Ann. of Bot., xiii. (1899) pp. 187-8. 
X Journ. de Bot. (Morot), xiii. (1899) pp. 107-27 (5 figs.). Cf. this Journal, 1898, 
p. 566. § Ann. Jard. Bot. Buitenzorg, 1898, 2 me Suppl., pp. 47-51. 
