195 
augite and hornblende, even when minutely diffused through 
a rock. 
The following are the titles of the works referred to: 
Untersuchungen tiber die Mikroskopische Zusammensetzung 
und Structur der Basalt-Gesteine. Von Dr. F. Zirkel. 
(Bonn, 1870.) 
Mikromineralogische Mittheilungen. Von Dr. F. Zirkel. 
Pp. 801. (‘ Neues Jahrbuch fiir Mineralogie,’ 1870.) 
Sur les Crystallites, études crystallogeniques. Par H. Vogel- 
sang. (‘ Archives Néerlandaises,’ 1870.) 
Kritische Mikroskopisch-mineralogische Studien. Von H. 
Fischer. (Freiburg.) 
Mikroskopische Unterscheidung der Mineralien aus der 
Augit, Amphibole und Biotit-gruppe. Von G. Tscher- 
mak. (Proceedings of the Vienna Academy of Sciences, 
1869.) 
Spontaneous Generation—The controversies on this subject 
have not ceased. Professor Frankland has repeated for him- 
self the experiments which he formerly carried on for Dr. 
Bastian, on the supposed development of organisms in saline 
solutions within closed tubes, but “ taking additional and 
much more stringent precautions against the subsequent 
admission of atmospheric germs into the tubes.” 
For this purpose four tubes of hard Bohemian glass were 
about half filled with a solution of carbonate of ammonia and 
phosphate of soda in distilled water. No care was taken to 
exclude living germs from these ingredients. These tubes 
were carefully exhausted by the Sprengel air-pump and 
hermetically sealed, and then exposed for four hours to a 
temperature varying from 155° to 160° C. in a Papin’s diges- 
ter. When cool the tubes were removed from the digester 
and immediately plunged, two of them into colourless con- 
centrated oil of vitriol, and the remaining two into a nearly 
colourless saturated solution of carbolic acid in water. These 
precautions were taken in order to avoid the possible admis- 
sion of atmospheric germs through invisible cracks in the 
glass ; such cracks, entirely invisible to the naked eye, being 
sometimes known to exist. On examining the tubes when 
they came out of the digester, it was evident that their inte- 
rior walls had become corroded by the enclosed liquid. 
The cylinders containing the immersed tubes were now 
maintained at a temperature from 60° to 75° F., and were 
exposed to bright diffused daylight, and sometimes to sun- 
light, for more than five months. The liquid in all the tubes 
became more or less turbid, and in some cases a small quan- 
tity of a light floceulent precipitate subsided to the bottom. 
