230 Scientific Intelligence. 
their various alterations in size and direction, are frequently 
many centimeters long. ey are fibrous, of vitreous luster, trans- 
lucent and of slight yellow, greenish or reddish tints, derived from 
the serpentine and oxide of iron accompanying them, H.=2%. 
Fusibility =5°5. 
5. LL Mean. O. ratio. 
SiO, 59°27 59°228 59°25 31°40 31°40 2°1 
Al,O, 2°45 2°452 2°45 1°15 
FeO 6°50 6°494 6°49 
M 1:09 1°006 1°05 0°23 $1493 1 
CaO 1-72 1°403 1°57 
Mg 28°30 28°105 28°16 11°26 
H,O undet. undet, iichate 
99°33 98°69 98°97 
This variety of tremolite [bronzite?], it will be seen from the 
analysis, is distinguished by its large percentage of ferrous oxide 
and magnesia; and the cause of this interesting peculiarity is to 
be sought for in the chemical history of the maguetite-bearing 
serpentine in which the tremolite is imbedded. 
18. Action of light on the development of the young of Frogs. 
—M. Thury took the eggs of Rana temporaria and placed them 
e 
hind legs. By the 10th of June, the former had their fore legs 
d som still black, had no 
trace of legs, and breathed almost exclusively by means of their 
u 
those of the latter still had no legs, and by the 2d of August they 
were all dead without a trace of legs having appeared. Some of 
on the 15th of July finished their metamorphosis. At the same 
time some of the former transferred to the vessel containing the 
19. Dimorphie Development and Alternation of Generation in 
. O. Sars has discovered a remarkable di- 
orhandlinger Vidensk.-Selsk., Christiania, for 1873, p. 15, and 
plate.) The rg ay BN from the ordinary summer-eggs, 48 al- 
oety described by E. P i 
e tha 
