ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
69 
both among one another and with the adjacent cells ; and this is also 
the case with the cells of the stalk. The thin “ lamina ” constitutes 
the assimilating tissue of the “leaf”; while the “veins” have a con- 
ducting function comparable to that of the veins in the leaves of 
flowering jDlauts. The “ stalk ” serves also as a reservoir for food- 
material. 
Development of the Fucaceae.*— Dr. F. Oltmanns has followed out 
the development from the oosperm of a number of species belonging 
to the Fucacem. The species specially investigated and described in 
great detail are : — several species of Fucus, especially F. vesiculosus, 
Pelvetia caniciilata, Ascophyllum nodosum and allied sp., Halidrys 
siliquosa, H. osmundacea^ Cystosira sp., Sargassum linifolium, S. varians, 
Himanthalia lorea, and Durvillsea Harveyi. The thallus of all the 
species examined presents, at a definite period of their develojiment, a 
club-shaped form with three-sided apical cell, agreeing in all essential 
points. Its further development may be classified under five heads, 
viz. : — (1) Durville.® ; thallus a large stalked and variously divided 
and leaf-like structure bearing the conceptacles on the entire surface or 
on the margin, Durvillaea, Ecklonia (?), Sarcopliycus (?) ; (2) Lori- 
FORMES ; young plant radiar, afterwards assuming a bilateral form ; 
shoot branching dichotomously, with a three-sided apical cell; con- 
ceptacles wanting only on the lower, much smaller part of the plant; 
oogone with only one oosphere, Himanthalia ; (3) Fuce® ; young plant 
radiar, very soon passing into bilateral or dorsiventral ; shoots with 
four-sided apical cell ; branching dichotomous or monoj^odial ; concep- 
tacles only on the slightly modified apices of the primary or lateral 
shoots ; oogones with 2-8 oospheres ; Fucus, Pelvetia, Ascophyllum ; 
(4) Cystostre® ; the plant either maintains its radiar structure, or 
forms bilateral branches ; three-sided apical cell permanent ; branching 
monopodial ; conceptacles on slightly modified apices of branches, or on 
special branches ; oogone with one oosj^here ; Halidrys, Pycnophycus, 
Cystosira, &c. ; (5) Sargasse®, bilateral or radiar structure with three- 
sided apical cell; the branches form at the base one or more leaf-like 
branches, which give the plant a peculiar habit ; conceptacles on 
special branches ; oogone with one oosphere ; Sargassum, Turhinaria, 
Carpophyllum, &c. 
With regard to the number of oosperms in an oogone, the author 
found the niunber of original nuclei to be always eight ; and those which 
do not develoj)e into oospheres are still to be clearly detected at the 
period of maturity. His observations on the actual mode of impregua- 
tion closely correspond to those of Thuret. 
Conferva and Microspora.f — After a resume of the observations 
hitherto made on the various species of Confervacese by different 
algologists. Prof. G. v. Lagerheim gives a careful diagnosis of these two 
genera and of all their known species. In Microspora the chloroplasts 
have the form of branched bands containing starch ; in Conferva of small 
discs which do not contain starch ; in other words, the products of 
Haenlein u. Luerssen’s Bibliotli. Bot., Heft 14, 1889, 100 pp. and 15 pis. • 
and SB. K. Preuss. Akad. Wiss., xxx, (1889) pp. 585-99 (1 pi.). ’ 
t Flora, Ixxii. (1889) pp. 179-210 (2 pis.). Cf. this Journal, 1888, p. 94. 
