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previously been largely transferred. The results were the same as if no 
bleeding had taken place at all. Hence Captain Galton cries out against 
the doctrine of pangenesis. But it seems to us perfectly clear that no other 
result would have been expected, even by a Darwinian disciple, from Mr. 
Galton’s experiments. We fail to see the force of his reasoning. 
The Process of Silicification of Animals . — On June 2 a paper was read 
before the 'Geologists’ Association by Mr. M. H. Johnson, F.G.S., on the 
above subject, and it contained some interesting facts. The author pointed 
out how a crop of sponges invested with their gelatinous flesh or sarcode, 
and living at the bottom of a deep ocean, were suddenly buried in a thick 
stratum of white mud, consisting of the minute shells of Foraminiferce, that 
they then died, and while in the process of decomposition this interchange 
of materials took place — the nascent carbonic acid parting with its carbon 
in exchange for the silicon of the silicate of soda which sea-water is*known 
to contain. At the close of the paper, the author produced a tadpole, upon 
which he had experimented, and which he had that afternoon subjected 
for two hours and a half to the action of nitric acid, without its undergoing 
any alteration, the inference being irresistible that the animal had become 
invested with a film of silica of sufficient thickness to protect it from the 
acid 5 another tadpole that had not undergone the same preparation having 
been converted into a brown cloud by immersion in the acid for the same 
time. 
j Development of Isotoma Walkeri . — In the second volume of u Memoirs ” 
which the Peabody Academy has just published, there appears a most valu- 
able paper by Mr. A. S. Packard, jun., on the above subject. Speaking 
of the head, the author says, that it is so entirely different from what it is 
in the adult, that certain points demand our attention. It is evident that at 
this period the development of the insect has gone on in all important 
particulars much as in other insects, especially the Neuropterous Mystacides 
as described by Zaddach. The head is longer vertically than horizontally, 
the frontal or clypeal region is broad, and greater in extent than the epi- 
cranio- occipital region. The antennae are inserted high up on the head, 
next the ocelli, falling down over the clypeal region. The clypeus, how- 
ever, is merged with the epicranium, and the usual suture between them 
does not appear distinctly in after life, though its place is seen, in the elabo- 
rate figures which accompany the paper, to be indicated by a slight indenta- 
tion. The labrum is distinctly defined by a well-marked suture, and forms 
a squarish knob-like protuberance, and in size is quite large compared to 
the clypeus. From this time begins the process of degradation, when the 
insect assumes its Thysanurous characters, which consist in an approach to 
the form of the Myriapodous head, the front or clypeal region being re- 
duced to a minimum, and the antennae and eyes brought in closer proximity 
to the mouth than in any other insects. That other most essential Thy- 
sanurous characteristic, the spring, is now fully formed. It arises as a 
thick tubercle from the sternite of the penultimate segment of the abdo- 
men, and subdivides into a pair of two-jointed finger-shaped prolongations. 
The tip of the abdomen is deeply bilobate, the median line of the body 
being deeply impressed. 
Australian Silk. — The Acclimatisation Society of Sydney have received 
