ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
829 
to these structures. So far as the author’s studies have gone ho has not 
met with an instance of the chromatin of a cell not containing iron. 
Culture of Terrestrial Algae.* — Prof. A. Borzi gives the results of 
his long experience in the cultivation of terrestrial Chlorophyceae, 
whether mixed or pure. It is essential in either case to have a con- 
trivance for the constant and regular supply of fresh water. A porous 
substratum furnishes the best results, and he finds the most convenient 
to be a white calcareous tufa known in Sicily as “ Syracuse stone ” 
(pietra di Siracusa). The light must be allowed to reach the glass 
vessel in which the algae are grown from one side only ; the side where 
the fresh water is received and the surplus water drawn off must be the 
least illuminated; the zoospores will then collect on the wall of the 
vessel and form a green layer visible to the naked eye. It is imprac- 
ticable to obtain as absolute purity in the culture of unicellular algae as 
in that of bacteria. The plan recommended by the author to obtain 
comparative purity is a purely mechanical one, — removing the organism 
to be examined by means of a capillary glass tube, placing it in a drop 
of pure water, and repeating this process many times. He strongly 
approves Beyerinck’s gelatin method f for the culture of algae. 
Re-softening dried Algse.t — Herr J. Reinke recommends eau de 
Javelle as an excellent medium for restoring dried algae to an almost 
fresh condition. Even if they are quite black, the blackening will 
disappear with prolonged maceration. 
Demonstrating Fungi in Cells.f — For demonstrating fungi within 
cells filled with plasma, Herr H. Moller advises that the fresh material 
should be treated with chloral hydrate either after the method of 
A. Meyer (5:2), or still better, in cold saturated solution. In this 
strength not only the starch but the cytoplasm are soon dissolved, 
and the process may be hastened by heating in a water-bath. It 
is necessary to constantly change the chloral hydrate, and at each 
interval wash the sections in water. By this procedure almost all the 
contents of the cell are dispersed, while the plasma of the fungi is 
unaffected, so that when stained a good picture is obtained. 
Modes of Investigating Chemical Bacteriology of Sewage. || — Sir 
H. E. Roscoe and Mr. J. Lunt have carefully recorded by means of 
photographs the microscopic and macroscopic appearances of the or- 
ganisms found in sewage ; they consider this to be of much importance, 
as bacteriological descriptions of organisms are frequently of little value 
from the want of accurate representations of the microscopic preparations 
and pure cultures. 
For the isolation of micro-organisms the methods of gelatin plate- 
culture and of dilution were used, as well as two in which spore-forming 
organisms were isolated, or anaerobic organisms were isolated and culti- 
vated. The anaerobic organisms were isolated by carrying crude sewage 
through three cultivations in pure hydrogen ; spore-forming organisms 
were isolated by heating sterile broth in which a sowing had been made 
* Neptunia, i. (1891) pp. 198-208. t Cf. this Journal, ante , p. 130. 
X Ber. Deutsch. Bot. Gesell., vii. (1890) p. 211. § Tom. cit. , p. 215. 
1| Proc. Roy. Soc. Lond., xlix. (1891) pp. 455-7. 
