ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
453 
Economical Product from Seaweeds.* — Herr A. Kreftling describes 
the production from the Fucaceae of a non-nitrogenous substance which 
he calls “ tangic acid ” ( Tangsaure). It appears to be related to the 
carbohydrates, although its empirical formula C 13 H 20 O l4 does not indi- 
cate this. It is not dissolved by any medium with which it does not 
form a chemical combination. The alkali-salts are strongly viscid, and 
form a substance well adapted for gumming paper and other materials. 
The broad-leaved Laminarise are especially applicable for the manufac- 
ture of this substance. 
Polymorphy of Cutleria multifida.j — Mr. A. IT. Church confirms 
the current statement of the genetic connection of Cutleria and Aglao- 
zonia , the former being a sexual, the latter a non- sexual condition. 
There is no doubt that the oospheres of Cutleria develope partheno- 
genetically, and this development takes place in the latter part of the 
summer. There seems to be no difference whatever between the mode 
of germination of the sexually and that of the parthenogenetically pro- 
duced spores. Under certain conditions the zoospores of Aglaozonia 
give rise to what may be called a protonematoid stage of Cutleria. The 
polymorphy of Cutleria multifida has nothing in common with a true 
alternation of generations. In the opinion of the author the phenomena 
point to a gradual loss of sexual function rather than to an imperfectly 
differentiated or incipient sexuality. 
Conjugatse.f — Messrs. W. and G. W. West maintain their classsifica- 
tion of the Conjugatae into three families, the Zygnemaceae, Temno- 
gametaceae, § and Desmidiaceae, including the Mesocarpeae as a sub-family 
in the Zygnemaceae. Many of the Desmidiaceae exhibit a tendency for 
the separate cells to unite into filaments. The authors state that in all 
the Conjngatae, the individual is surrounded by a definite mucilaginous 
envelope, though the thickness and substance of this envelope vary 
greatly. Contrary to the assertion of Ewart, they state that these algae 
can resist a very losv temperature, although the formation of zygosperms 
is prevented. Direct sunlight greatly promotes their growth as long 
as they remain in normal conditions; a bright light being apparently 
necessary for the process of conjugation. 
The Zygnemaceae are made up of the Mesocarpeae, Pyxisporeae, and 
Zygnemeae. The Mesocarpeae are composed of two genera only, Mou- 
geotia (including Mesocarpus , Crater ospermum , Plagiospermum, and 
Staurospermum ) ; the Pyxisporeae of the single genus Pyxispora ; the 
Zygnemeae of Zygnema , PI eurodiscus, Spirogyra, Sirogonium, and Debarya. 
Cross-conjugation — i.e. conjugation in both directions — is almost un- 
known in the Zygnemeae. The occurrence of lateral conjugation implies 
that the sexual differentiation is sometimes manifested, not in the entire 
filament, but in the different cells of the same filament. The forma- 
tion of parthenospores without conjugation is not uncommon in the 
Zygnemeae ; these non-sexually produced spores are aplanospores. The 
authors think that the Mesocarpeae have probably been developed along 
a different line of descent from the rest of the Conjugatae. 
* Chemische Industrie, 1897. See Bot. Centralbl., 1898, Beih., p. 519. 
t Ann. of Bot., xii. (1898) pp. 74-109 (3 pis.). 
X Tom. cit., pp. 29-58 (2 pis.). § Of. this Journal, 1897, p. 317. 
