684 Chronicles of Science. | Oct., 
rated from its proper connection, and gives rise to that wonderful piece 
of mechanism met with in the cervical region of the mammalian class. 
When the mammalian embryo is from four to six millimetres in length, 
the observations are commenced. The guinea-pig, rabbit, rat, dog, 
sheep, pig, cow, and human feetus have all been submitted to exa- 
mination by the author. At the early period when the embryo has 
this size, the cartilages of the first three or four thoracic vertebree may 
be observed situated near the middle of the notochord. They increase 
rapidly in number, both in the anterior and posterior directions, until 
the number of twenty-four is attained ; the sacral and coecygean bodies 
appear later. The vertebral bodies are separated from one another by 
regular spaces or intervals, traversed by the notochord. This, after a 
time, dilates in these interposed spaces and becomes fusiform, after- 
wards becoming flaccid and surrounded by a viscid fluid, thus giving 
rise to the intervertebral tissue. Although the vertebral cartilages are 
the first to appear in the body, yet the cartilage of the axis does not 
appear in the guinea-pig until it has attained a length of eleven milli- 
metres. This cartilage criginates in two distinct pieces, the anterior 
of which evidently belongs to the atlas. They unite to form the single 
body of the axis vertebra before ossification has commenced and whilst 
yet in a purely-cartilaginous condition. In the human feetus the unison 
takes place when the length is about fourteen millimetres. The ossi- 
fication of the two vertebree and the anomalies observed in various 
species of Mammalia are treated of at some length by M. Robin. His 
decision as to the nature of odontoid process is beyond contro- 
versy, and has established a fact for many years denied by some 
physiologists. 
M. Pouchet has lately published some observations connected with 
spontaneous fission in Infusoria. He considers this a much rarer 
phenomenon than is usually affirmed; and with regard to the Vorii- 
celle, states that during twenty years’ cbservation he has failed to 
detect a single instance of fissiparity in these animalcules. A mon- 
strosity with two bells on a single stalk has been often mistaken for 
the commencement of fission; whilst it frequently occurs that a free 
vorticellid attaches itself to the bell-shaped body of a fixed individual, 
and is another source of error. 
M. Elias Mecznikow has described, in Du Bois-Raymond’s ‘ Archiv.,’ 
a new form of the genus Spherophrya, the connection of this acineti- 
form animalcule with the Paramecia being illustrated by a series of 
very beautiful drawings. 
Professor Gulliver continues his interesting researches on Raphides. 
Should he be enabled to extend his researches sufficiently, a very im- 
portant test would be afforded to the analytical microscopist, as regards 
the adulteration of vegetable articles of commerce, 
M. N. Lieberkuhn has published some interesting observations on 
the changes occurring in Sponges after death. It appears that in, the 
species he observed, the whole sponge does not die, but parts fall away 
and decay; other portions emit prolongations, which become detached 
and remain at the bottom of the vessel in which they are kept. When 
observed under the microscope, they are seen to be provided with 
