264 Miscellaneous. 
This Crenothrix has been noticed in several localities, especially 
Halle, Breslau, and Berlin, and has been carefully studied by Pro- 
fessors F. Cohn, O. Brefeld, and W. Zopf. To the observations of 
those eminent botanists we have only to add that the microgonidia, 
formed in the swollen extremities of the tubes of Crenothrix by 
transverse division of the bacillar joints constituting those extremi- 
ties, are animated during some time with an active motion, due to 
the existence of a flagellum. The latter is visible only with the 
highest magnifying power (Hartnack immersion objective no. 12). 
The gonidia afterwards give birth to an irregular form (Meris- 
mopeedia), which is soon transformed into a mass of Zooglee similar 
to a Palmella, and finally into regularly cylindrical tubes of various 
lengths. 
The causes which have brought about the exaggerated develop- 
ment of Crenothriv in the Emmerin waters are evidently manifold. 
The soil was prepared by industrial dejections, especially those from 
distilleries, which discharge nitrates in abundance into the water- 
bearing stratum, at certain places very near the surface. The sources 
are, moreover, in the vicinity of swamps and ponds, like those of 
Tegel in the environs of Berlin. 
Last winter having been relatively dry, the water-level was 
lowered about 5 metres. The rains of the spring and the beginning 
of the summer suddenly raised it, and carried with them the vege- 
table productions or the animals which had been developed in the 
humid earth. 
While at Lille the Crenothrivz was thus brought in abundance into 
the Emmerin reservoirs and the water-pipes, several wells at Tour- 
coing furnished balls of a fine Oligocheete worm (Phreoryctes Menkea- 
nus), till then unknown in France. 
Lastly, a portion of the aqueduct is dug in the aquiferous chalk ; 
and it was thought needless to arch over that part ; moreover, inlets 
have been pierced in order to increase by drainage-water the supply 
furnished by the springs. Every time that the flow of the water is 
made more rapid, in that part of the aquiferous layer a veritable 
aspiration is produced, which carries into the aqueduct the spores 
and filaments of the Crenothrix, which a slower and more complete 
filtration would have retained in the soil. 
To remedy this scourge, we at first advised to do away with the 
latter source of contamination, against which it is comparatively 
easy to guard. But we believe that this palliation would be insuffi- 
cient while the channels are sown with the innumerable spores of 
the Schizomycete. We shall doubtless be obliged to have recourse 
to filters of sand, similar to those recommended at Berlin by Zopf 
and Brefeld. 
Towns establishing new systems of canals of potable water will 
do well, in order to avoid the Crenothrix, to take the sources in 
the deep strata, to avoid waters containing salts of protoxide of 
iron (necessary to the vegetation of this Schizomycete), and to pre- 
fer to subterranean waters the more aerated waters of lakes remote 
from all industrial establishments.— Comptes Rendus de V Académie 
des Sciences, July 31, 1882, t. xev. pp. 247-249. 
