NATURAL HISTORY MISCELLANY. 51 
three kinds or classes: Ist. “ Those Pager em of the immediate products 
of the breaking up of eruptive rocks.” “Rocks built up of the more 
or less rounded or angular debris of fice sins existing sedimentary or 
eruptive rocks.” 3d. “Rocks composed of mineral substance extracted 
from aqueous solution by crystallization, precipitation, or the action of 
organic life.” Strata of the first class are often identical in aspect and 
chemical composition, but their irregular sedimentary structure is dis- 
solved upon submitting them to the microscopical test. Very fine, com- 
pact rocks may be distinguished from crystalline rocks by the same 
means. ‘Roofing-slate, however, has a definite arrangement of the par- 
ticles in lines, which constitute the lines of weakness or the cleavage of 
the slate.” This arrangement, however, is explained by the effects of 
pressure, applied at right-angles to the structure itself, causing an elon- 
gation of some, together with a sliding I of others of the par- 
ticles 
Uski the third head we notice that the’ clays of Staffordshire, when 
altered by contact with basaltic dykes, present a structure identical with 
common stoneware made from the same clays, and show “no change in 
mineral or chemical composition, beyond the expulsion of the water 
always contained in such beds.” The foliated schists, quartzites, etc., 
show the contours of the original sand-grains, and, as Sorby has pointed 
out, the existence of ripple-drift and wave-structure 
eel 
ANSWERS TO CORRESPONDENTS. 
Tue MistLETOE.—I believe it is the common opinion of naturalists 
om the common Mistletoe of this Southern country steals the elabo- 
from the stalk which supports it. I, think it can be proved 
aa A but that it draws its portion of crude sap and elabo- 
rates it, returning a portion to the tree on which it grows. I would 
be very glad to know if I am correct in reference to the common opin- 
ion of naturalists, and will oblige you to inform me.—J. M. 
It is not the common opinion that the Mistletoe of the Southern States, 
view of proving experimentally that the Mistletoe does not take elabo- 
rated sap alone (for it very probably takes some) from its host, as they 
could not fail to be interesting. — H. M. 
Ts Masropow ns Kansas. —T send yon a photograph and dee 


