- 516 Chronicles of Science. [ July, 
We read in ‘ Cosmos’ a letter from M. Duchesne Thoureau relating 
to a pattern taken from a large tapis, entirely due to the work of a 
group of spiders in a state of captivity. He expresses his belief that 
it is quite possible to produce by the aid of such auxiliaries, and with- 
out expense, soft and warm carpets, to arrive at which results it would 
only be necessary to dispose of a number of working spiders, and 
over a space proportionate to the magnitude of the work desired. 
From the works of Oersted, Grube J. Miller, &c., it appears that 
the genus Autolytus presents the peculiarity so rare among Aurelids of 
a striking polymorphism, the males being so different from the females, 
that the two sexes have been described as belonging to distinct 
genera. There exists also in each species a third form, namely, the 
asexual form, which produces the sexual individuals, by gemmation 
at its posterior extremity, the alternation of generations in these 
worms being thus well established. M. A. Agassiz has found in the 
harbour of Boston, the Autolytus of which the males were described by 
Oersted in 1848, from Greenland, under the name of Polybostrichus 
setosus. He has, likewise, observed in the same locality, another 
species, to which he has given the name of Autolytus cornutus, a species 
which appears to be nearly related to the European species, A. 
Heligolandie. The differences between the individuals of the two 
sexes are of the same nature as in the European species. ‘The females, 
at the moment of their detachment from the organic individuals, 
possess no ovigerous sac, but it is soon formed, and the ova deposited 
in its interior. The embryos are rapidly developed, and their escape 
from the sac appears to cause the death of the female, for M. Agassiz 
has never met with females after their embryos have escaped. The 
embryos at the moment of issuing from the sac have a triangular out- 
line, their body diminishing rapidly towards the posterior externity. 
The frequency with which the minute parasitic worm, Trichina 
spiralis, has been found of late in the muscles and intestines of the pig, 
and the fatal and serious results which have attended the consumption 
of flesh so contaminated, has spread a panic throughout Germany, and 
a committee has been appointed by the Berlin Medical Society, con- 
sisting of Virchow, Remak, Gurlt, and others, to examine into and report 
upon the subject. Thus far the disease has not been met with in any 
animal that is a vegetable feeder; but Dr. Langenbeck says, that 
trichine have been found in extraordinary numbers in earthworms 
last year—as many as 500 or 600 having been observed in a worm of 
middling size—and these worms form part of the food of those animals 
which swine devour when left at liberty. He advises that the swine 
should be always fed in styes, and debarred access to localities where 
worms are numerous. 
It is seldom that a natural object proves so complete a puzzle to 
the initiated as one which has recently been brought to ight. It is an 
elongated semicylindrical body, whitish, and rough like shagreen, 
length about two feet. It was purchased by the Rev. H. H. Higgins 
of a dealer in London, for the Liverpool Museum, where, struck by 
its remarkable and anomalous character, he showed it to Dr. Gray, 
who took it to London. It has been examined by Milne-Edwards, and 
