1865.] Zoology and Animal Physiology. 509 



through a Nauplius-j)h&se, or, at least, a .Zoea-phase, although these 

 phases are wanting in the existing species of which we know the 

 development. Dr. Miiller, however, has discovered that the Isopoda 

 of the genus Tanais still retain the characters of incontestable Zoea. 



A new kind of dimorphism has been remarked by Miiller in the 

 males of a species of Tanais. In this species, the individuals of 

 which live together in myriads, the young males closely resemble the 

 females. But the last moult gives rise to two very distinct forms of 

 males. Some of these are furnished with enormous elongated and 

 very mobile nippers, and with antennae of as many as twelve or even 

 seventeen olfactory filaments, of which the antennae of the female do 

 not exhibit one. The others retain short and heavy pincers, very 

 similar to those of the females, but their antennae have incomparably 

 more numerous filaments than those of the first form of males. Muller 

 regards these as two varieties of males, each of which in their way 

 had been selected by peculiar and different advantages adapted to guide 

 them in the search for females, and that therefore this singular fact is 

 not inconsistent with the Darwinian hypothesis. 



A remarkable instance of gemmation in an Annelid has been ob- 

 served by M. L. Vaillant. The animal was a Syllidian from the Gulf 

 of Suez, inhabiting the cavity of a sponge. The segment which bears 

 the leaf-like processes was much broader than the rest of the body, 

 and formed a sort of cup or funnel, representing two thick lips, of 

 which the lower was smooth and simple, whilst the upper one was 

 covered with an immense number of buds placed very close together, 

 and having a very remarkable form, resembling that of some low forms 

 of Annelids allied to Nemertes or Planaria. They had a very con- 

 tractile body, nearly equal in length to that of the parent animal, flat- 

 tened and obtuse at the free extremity, where they presented two or 

 four small black eye-like spots. Towards the point of attachment the 

 body became narrowed into an elongated pedicle, and if this were 

 broken, the little creature moved freely in the water by movements of 

 the body, but no vibratile apparatus could be detected. M. Vaillant 

 says these bodies could not be parasites on account of the continuity 

 of their tissue with those of the parent animal, and he does not think 

 they can be regarded as oculiferous tentacles, because great mobility 

 of the eyes occurs only where those organs are very few in number. 



In ' Silliman's Journal ' it is stated that starfishes may be dried so 

 as to retain their natural colours almost unimpaired, by immersing 

 them in alcohol of moderate strength for about a minute, or just long 

 enough to destroy life and produce contraction of the tissues, and 

 afterwards drying them rapidly by artificial heat, which is best effected 

 by placing them upon an open cloth stretched tightly upon a frame, 

 and supported a few feet above a stove. Care should be taken not to 

 raise the heat too high, as the green shades change to red at a tem- 

 perature near that of boiling water. The same process is equally ap- 

 plicable to Echini and Crustacea. 



Dr. Child, in continuation of his experiments upon the production 

 of organisms in closed vessels, has come to the conclusion that there is 

 no doubt of the fact that bacteria can be produced in hermetically- 



