ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
227 
antlierozoids begins only after leaving the mother-colony, and the 
Endosphaerosirae, which are always smaller, and in which mature bundles 
of antherozoids are formed before their escape. Of Eudorina elegans the 
author observed both tabular and spherical daughter-colonies, but was 
unable to determine whether they were male Or non-sexual. The 
bundles of antherozoids he regards as male colonies. 
Reproduction of Hydrodictyon.* — Dr. G. Klebs gives further 
details of his experiments on the conditions which determine the pro- 
duction of zoospores or of gametes in Hydrodictyon utriculatum. The 
nutrient solution employed imparts to all cells the most active tendency 
to the production of zoospores. In the dependence of the production of 
zoospores on light, Hydrodictyon presents a marked contrast to (Edo - 
gonium and other Algae ; but recalls the similar phenomenon in the 
growth and production of cellulose in Zygnema. The presence of oxygen 
is also essential to the formation of zoospores. The power of non- 
sexiral multiplication which lies latent in every cell is dependent on the 
presence of a definite material element which the author terms the rudi- 
ment. The conditions for its perfect development are the presence 
of warmth, oxygen, organic nutrient substances, nutrient salts light, 
and fresh water. Of these the nutrient salts are the most important. 
Gametes can also be formed in all mature nets ; the determining 
factors being not internal causes but external conditions. The most 
favourable is a 5 per cent, solution of cane-sugar, with absence of 
nutrient salts ; glycerin produces the same effect ; also glucose, milk- 
sugar, mannite, and erythrite ; a moderately high temperature is also 
essential ; but the formation of gametes appears to be almost indepen- 
dent of light. 
By varying the conditions, as above indicated, one and the same net 
may be induced to form zoospores in one part, gametes in another part. 
The conditions under which one or the other tendency predominates are 
given in detail. While an interruption of growth tends to induce the 
formation of zoospores, and the suppression of the production of zoo- 
spores induces a tendency to the formation of gametes, the experiments 
afford no support to the hypothesis that the maturity of the cell is by 
itself favourable to the production of sexual elements. 
New Genus of Siphoneae.j — Prof. J. G. Agardh thus describes a 
new genus Callipsyma, belonging to the Udoteaceae : — But slightly 
encrusted, and having the filaments which compose the entire frond 
constricted into oblong joints ; those of the laminae which proceed from 
the margin of the rachis dichotomous and laterally agglutinated ; those 
of the stem slightly flexuose. 
Fungi. 
Behaviour of the lower Fungi towards inorganic nitrogen-com- 
pounds. ± — According to Herr O. Loew formic aldehyde CH 2 0 is 
poisonous to fungi and other organisms, but some of its unstable com- 
pounds are not. Only such inorganic compounds of nitrogen can supply 
* Flora, lxxiii. (1890) pp. 351-410. Cf. thi3 Journal, 1890, p. 206. 
t ‘ Till Algernas Systematik,’ Lund, 1887. p. 65. Cf. this Journal, 1887, p. 998. 
X Biol. Centralbl , x. (1890) pp. 577-91. 
Q 2 
