522 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
Microbes in the Arctic Regions.* — Dr. Levin, after a few remarks 
dealing with the exceptionally hygienic conditions of the Arctic regions, 
proceeds to a record of his own experiences. Air was taken from twenty 
different localities in the Arctic zone. In these samples only a few 
moulds were found. In 78 samples of sea-water, taken from the surface, 
bacteria were found in every case, but the numbers were very small ; 
about one bacterium to each ccm. Eighty samples of water, taken from 
glaciers, snow, streams, ice, and melted snow, all gave evidence of the 
presence of bacteria, but the quantity was very small. Samples taken 
from deep-sea soundings showed a greater number of bacteria than on 
the surface. Three different kinds are mentioned, but minute particulars 
are not given. 
The last series of experiments, or rather experiences, relate to 
observations made on the intestines and intestinal contents of animals 
inhabiting the Arctic regions, such as white bear, seal, shark, eider- 
duck, penguin, guli, guillemot, sea-urchin, anemone, shrimp, &e. In 
most cases the intestinal contents were found to be absolutely sterile. 
In one white bear and in two seals, a single species of bacterium, pro- 
bably Bacillus coli communis , was detected. The rest of the Yertebrata 
were unaffected, but in the lower marine animals bacteria were almost 
invariably present. 
The importance of these observations is certainly great, as they hear 
directly on the question whether bacteria are indispensable to nutrition. 
Several distinguished observers (Pasteur, Nencki, Nuttall, Thierfelder) 
have shown that digestion can be accomplished without the intervention 
of bacteria ; while others f give good reasons for holding that bacteria are 
practically a most important factor in the digestive process. 
Pigment-formation of Fluorescing Bacteria. :f — According to Herr 
K. Wolf, the green pigment of fluorescing bacteria is an accidental pro- 
duct, that is to say, it only occurs when the conditions of nutrition are 
extremely favourable to bacteria. They may thrive and develop well 
in many media, but without forming pigment. The production of pig- 
ment is of necessity associated with three factors, phosphoric acid salts, 
easily decomposable ammonia compounds, and free oxygen. If one of 
these three factors be absent, or even insufficient, pigment does not 
appear. Bacillus fluorescens liquefaciens and B. pyocyaneus thrive toler- 
ably well, the bacteria which do not liquefy gelatin fare badly, when 
oxygen is excluded. All those that produce no ammonia produce no 
pigment. The brown hue of the cultures on boiled potato, on potato- 
gelatin, boiled white of egg, and in anaerobic cultures, does not depend 
on pigment formation but, as in the case of the Lacteria of the coli 
group, is possibly to be explained by the arrangement of the micro- 
organisms. Fluorescing bacteria thrive on hen’s egg under aerobic 
conditions. During the aerobic growth of fluorescing bacteria, oxygen 
is copiously absorbed and carbonic acid given off. Under similar con- 
ditions fluorescing bacteria produce a very considerable quantity of 
ammonia. 
* Ann. Inst. Pasteur, xiii. (1899) pp. 558-67. 
f Cf. this Journal, ante, p. 197. 
'% Dresden, 1 897, 36 pp. See Bot. Centralbl., lxxviii. (1899) p. 133. Cf. this 
Journal, ante , p. 315. 
