ZOOLOGY AND BOTANY* MICROSCOPY* ETC. 
569 
sented characteristic features in the species of the plankton-flora peculiar 
to themselves. 
Movements of Diatoms.* — Mr. W. M. Kozlowski reviews the various 
theories which have been proposed to account for the movements of dia- 
toms, and sums up in favour of the efficient cause being assimilation. 
The chief ground of this conclusion is the dependence of the movements 
on the intensity, the colour, and the direction of the light. The author 
doubts whether the periodicity of tbe movements occurs in nature ; it 
may be the result of the artificial disposition of the light in the 
Microscope. 
Galiionella.f— Prof. W. Migula has had the opportunity of examin- 
ing the structure and development of the rare organism Gallionella ferru- 
ginea, found occasionally in water containing iron. He rejects the 
conclusions previously drawn as to its systematic position, whether 
among the Diatomaceae or the Confervaceae, and assigns it a place in 
the Cyanophyceae, between Leptotlirix and Spirulina. It has two dis- 
tinct forms. In one the threads are extremely fine, simple, yellowish, 
unsegmented, and irregularly coiled, about 1 p in diameter ; the other 
form has threads of about twice the thickness, which are distinctly 
segmented. These latter are seen, under a high magnification, to be ar- 
ranged in a double coil. The author does not believe in any genetic 
connection with Leptothrix ochracea. 
Re sting- Spores in a Calothrix.J — In a new species of Calothrix 
from the Sandwich Islands, C. sandwicense sp. n., Herr W. Schmidle finds 
resting-spores, resembling those described by Gomont in C. stagnalis. 
They occur in the cell immediately behind the basal heterocyst, one 
only in each cell. 
£. ScMzomycetes. 
Myxobacteriacea8.§ — Mr. R. Thaxter dissents from Zukal’s view |j 
that the Myxobacteriacece (Myxobotrysaceae) are Mycetozoa, and also 
throws doubt on several points in that writer’s account of the develop- 
ment of the organisms observed by him. Thaxter adheres to his former 
view that the Myxobacteriacese are Schizomycetes. Further details are 
given with regard to the germination of the spores and other points in 
the life-history of the group, and the following new species are described : 
— Chondromyces cipiculatus, on antelope-dung ; G. gracilipes, on rabbit- 
dung ; Myxococcus stipitatus, on dung of sheep, pig, &c. ; M. cirrltosus, 
on grouse-dung ; M. cruentus , on cow-dung. The author’s genus Myxo- 
bacter is sunk in Schroeter’s earlier Cystobacter. 
Evolution of Oxygen from Coloured Bacteria.^ — The experiments 
made by Dr. A. J. Ewart show that “ a number of coloured bacteria 
possess the power, under appropriate conditions, of evolving oxygen in 
greater or less amount. In certain of these the oxygen evolved appears 
to be occluded oxygen absorbed from the air by the pigment-substance 
* Bot. Gazette, xxiv. (1897) pp. 39-46. 
t Ber. Deutscli. Bot. Gesell., xv. (1897) pp. 321-7 (1 ph). 
+ Flora, lxxxiv. (1897) Erganzbd., pp. 170-3 (3 figs.). 
§ Bot. Gazette, xxiii. (1897) pp. 395-411 (2 pis.). Cf. this Journal, 1893, p. 370. 
|] Cf. this Journal, ante, p. 154. 
t Journ. Linn. Soc. (Bot.), xxxiii. (1897) pp. 123-55. 
2 R 2 
