THE MIcROSCOPE. 349 
so small that they are not noticed on the surface—Ralph S. Tarr, 
an Popular Science Monthly. 
In the Farhandlinger I Videnskabs-selskabet I Christiania for 
1887, Prof. G. O, Sars describes an interesting method of trans- 
mitting microscopic creatures, especially from great distances, 
with a detailed account of the success of his experiments. 
On the 14th of March a quantity of mud was gathered from a 
fresh water lake in the northern part of Australia. This was 
dried and sent to Christiania, where it was received on the 29th 
of October, in masses so hard and stony that they were broken 
with difficulty. The weather was so cold that experiments were 
not begun until the last of May, the mud and its contents hay- 
ing been in a dried condition for more than a year. It was 
finally placed in an aquarium consisting of a large cylindrical 
glass vessel, where a great number of the various orders of the 
Entomostraca were hatched out from the “ winter eggs ” dormant 
in the gathering, and in many cases studied throughout several 
successive generations. Prof. Sars’ method of obtaining a sup- 
ply of these minute forms from a distant part of the world is a 
suggestive one, and in the hands of others may be followed with 
as successful results. 
Assuming that the specific cause of diphtheria is the Klebs- 
Loeffler Bacillus or some other bacterium, clinical and epidemi- 
ological observations, irrespective of the help from the bacteri- 
ologists, have shown that the specific micro-organism is endowed 
with a persistent vitality. Infected clothing and infected rooms 
haye many times been known to retain and communicate the 
infection months or years after they were infected. It is there- 
fore entirely safe to assume that the bacillus of diphtheria, dried 
and wafted abroad in the open air, free, or clinging to filament- 
ous particles, may retain its viability for some time. These 
germs may be carried a long distance by the wind, but all the par- 
_ticulate contents of the atmosphere, of course, have a tendency by 
virtue of their high specific gravity, as compared with that of air, 
to fall to the ground again. When in process of ventilating infect- 
ed rooms, the infection-laden air is poured out, it is so immensely 
diluted in the great ocean of external air that, practically, we 
may consider its harm-producing abilities as annihilated ; yet it 
is conceivable that a stray bacillus among the millions may, in 
the subsequent process of aerial sedimentation, find a human 
