PROGRESS OF MICROSCOPICAL SCIENCE. 
had examined a cornea at this stage, we should have said without 
hesitation, Here is an instance of abundant " proliferation " or germi- 
nation of tissue ; the cornea corpuscles have given birth in situ to a 
progeny much more numerous than themselves. At that time the 
modes of preparation in use were very imperfect and unsatisfactory, 
so that a great deal that is now clear was necessarily left to con- 
jecture. Appearances were seen under the microscope which sug- 
gested endogenous multiplication of cells, and there was no reason 
for doubting that these appearances corresponded to the reality. Now 
we are in a somewhat different position. Cohnheim's discovery of the 
chloride of gold method (to which others nearly as valuable have 
since been added) has placed both supporters and opponents of germi- 
nation in a far better position than before. The result has been 
unquestionably unfavourable to the continued admission of the doc- 
trine of the textnral origin of pus. For the position of matters is 
such that the attentive study of the preparation carries to the mind 
the conviction, in spite of previously conceived opinions, that the 
relation of the adventitious corpuscles, with which the tissue of the 
inflamed cornea is beset, to the normal elements, is one of juxtaposition 
merely, the convincing fact being that, even in those parts of the 
cornea where the immigrant corpuscles are most numerous, the proper 
cornea corpuscles are still seen to present their normal aspect and 
distribution. 
Structure of the Genus Brisinga. — M. G. O. Sars, the celebrated 
Norwegian naturalist, has published a memoir on the anatomy of this 
genus, founded on an examination of a new species, B. coronata. In this 
valuable memoir, which is illustrated by seven excellent plates, 
Professor Sars has given a detailed description of the anatomy, phy- 
siology, and development of the genus Brisinga, perhaps the most 
1 remarkable form of star-fish hitherto discovered. The author also 
discusses, at considerable length, its relations to other star-fishes, 
recent and fossil, as well as to Echinoderms in general, and the rela- 
tion of Echinoderms to the Annelids. He regards Brisinga as the 
most generalized form of star-fish, and consequently of Echinoderms, 
and supposes it to be one of the little-modified survivors of a primitive 
type from which the other forms of Echinoderms have descended. 
It has affinities to the most ancient fossil star-fishes of the PalaBOzoic 
rocks (Protaster, &c.). The existence of a genuine vascular system, dis- 
tinct from the general perivisceral cavity and its extensions, is denied 
both in. the case of this genus and of other star-fishes. The , author 
also states that there is no anal orifice, although there is, as in other 
star-fishes, a dorsal gland, with a narrow duct opening on the dorsal 
surface, and he suggests that this duct has in other star-fishes been 
mistaken for an intestine, and its outlet for an anus, the existence of 
which, in any star-fish, he doubts. Professor Sars adopts the view, 
previously advanced by Duvernoy, Huxley, and Haeckel, that an 
Echinoderm is a cluster (or " comus ") composed of several articu- 
lated zooids (" persons ") united by their anterior ends. 
Development of Unfecundated Ovules of the Frog. — Several 
observers have noted the occasional partial development of ovules 
