General Science. 
409 
HELMINTHOLOGY. 
50. Earth-worms multiply by Eggs. — M. Julius Leo, of 
Berlin, has confirmed, by new observations, what Swammer- 
dam has already said on the subject of earth-worms, namely, 
that they multiply by eggs, which are found in spring, and 
which allow not only the inclosed young animal to be seen, 
but also the circulation of its blood. These observations have 
been confirmed, (Isis, 1820, vol. iv. p. 886.) by M. Rudolphi, 
according to whom, what some modern naturalists have found 
in the body of earth-worms, and which they have taken for the 
living young of these worms, is nothing else than an intestinal 
worm improperly named Ascaris lumbrici , which he refers to 
the genus Vibrio , and which he has found not only in the 
worms themselves, but also in their eggs. 
IV. GENERAL SCIENCE. 
51. Probable origin of certain Salt-springs.— Mr Amos 
Eaton has observed, that the water-limestone which forms the 
roof over the floor of the salt-springs, when exposed in a damp 
cellar, for two or three weeks, shoots out crystals of common 
salt, sufficient to cover its whole surface. Hence, he concludes, 
that the salt springs may have had their origin from water 
percolating through this stratum of limestone, and that there 
may be many other kinds of rocks, besides the water-limestone, 
which contain the elements of common salt. — Professor Silliman’s 
Journal, vol. vi. p. 242. 
This theory of salt-springs is a very probable one, were it not 
equally probable that the water-limestone may have derived its 
salt from the same cause as the springs, or even from the springs 
themselves . 
52. Method of Cutting Steel by Soft Iron. — Mr Barnes 
of Cornwall in America, having occasion to repair a cross- 
cut saw, recollected "of having heard that the Shakers some- 
times made use of what he called a buzz to cut iron. He there- 
fore made a circular plate of soft sheet-iron, fixed an axis to it, 
and put it in his lathe, which gave it a very rapid rotatory mo- 
tion. He then applied to it when in motion a common file to 
make it perfectly round and smooth, but the file was cut in two 
