a das ee 
; The Serimetre.—Pseudomorphism and Pseudomorphosis. 273 
@’ Acclimatation, where he will find, besides this memoir, other reports, 
as that of Guérin Mannaville concerning the important subject of silk 
uring the sojourn of Castellani in China he learned the important 
fact that in that country no species of silkworm is reared in the open 
success of experiments undertaken in the early part of the year 1859. 
The Bombyx Cynthia feeds upon the leaf of the Aylanthus glandulosa. 
The Serimetre—We cannot leave the subject of silk without men- 
tioning the interesting machine invented by Froment for the purpose of 
determining the relative tenacity and elasticity of different kinds of silk. 
Ist. 
ght necessary to break it. 2d. The elasticity, by the elongation it 
el 
upon the tenacity of silk, for example, the cocoons raised in _Avignon 
Save a tenacity of 12, while cocoons of the same species raised at Paris 
gave only 8. 
: 2d. It appears that the male cocoons furnish silk finer and more tena- 
cious than that of the female cocoons. s for an equal length the 
wognt of the male cocoons being represented by - - - 11°28 
at of the female cocoons was - —- - i ae 
ain a mean of 200 experiments gave for male cocoons a 
te - - - - - - 10-63 
nacity - - 
For female cocoons the tenacity was . - ; - 
By reason of the small difference between these numbers the results are 
for the present offered with some degree of doubt, but the Société d’Ac- 
tation has taken measures for removing these doubts. The Serzco- 
rection of Persoz, from whose report we have taken them. oa 
Pseudomorphism and Pseudomorphosis.—Metamorphism, considered 
rals to minerals or to rocks. The first—the metamorphism of mine 
‘ib Thas been made, by A. Delesse the subject of profound study, 
Witch he has distinguished by the name of pseudomorphism. When a 
ow rphism, The substance ‘to which a mineral 
ts its form may vary; it may even be of an organic nature, for a 
