1890.] Recent Literature, 933 
all the Loni forms of microbes, and shows that these microorganisms 
-— different powers of receiving stains according to their ages, 
f he be correct in the foregoing statements, many genera will be 
bun away with. It is very interesting to follow his experiments show- 
ing the growth and development of one form into another, noting his 
methods of detecting the cells, etc., which methods show much labor 
and careful manipulation. 
In treating of the typhoid germ he claims that it is not chromogenic. 
The work shows a marked difference in the various forms of the Bac- 
terium balbianii (found in marine alge), and the Micrococcus prodigiosus 
and the Bacillus violaceus, and follows them through the filamentous, 
dissociated, entangled, and zoogleeic forms ; it shows that they can live 
in air and may resist 100° C., that they assume an orange color on the 
surface of certain solid media, and that they undergo endogenous spore 
formation. It also shows that the Bacterium osteophilium is mostly 
found in macerated human bone surrounded with yellow fat, and that 
this also undergoes endogenous spore formation. He shows an evolu- 
tion cycle, divided into the filamentous, dissociated, entangled, and 
zoogleeic states. These different states correspond to a morphological 
grouping, and are due to the nutritive media, temperature, pressure, 
amount of oxygen, etc. Consequently, many morphological forms 
represent the same species. The zooglceic state merely represents a 
state of preservation. As has been said, the forms cannot determine 
the genera ; and as we do not know at present the principal genera, we 
must not attempt to classify them 
It will be seen that Billet is kigi in the right direction to reduce 
bacteriology to an exact science.—S. G. Dixon. 
Corals and Coral Islands. By James D. Dana.— About a 
half-century ago two exploring expeditions were almost simultaneously 
circumnavigating the globe; one under the command of Captain 
(afterwards Admiral) Fitzroy of the English Navy, the other under the 
command of Lieutenant (afterwards Admiral) Wilkes of the United 
States Navy. These two expeditions are chiefly memorable for the 
aaa of two brilliant young naturalists by whom respectively they were 
companied. In the English expedition went a recent graduate of 
Cambridge, Charles Darwin, whose dust now rests in Westminster Ab- 
bey near to that of Sir Isaac Newton, and whose discovery of natural 
selection—the law of gravitation of organic nature—makes his name 
an epoch-making one in science since that of Newton. In the 
American expedition went a recent graduate of Yale, who still lives, 
full of years and honors, his eye not dim and his natural force not 
abated, facile princeps of American geologists, James D. Dana. Among 
