652 RECORD OF CURRENT RESEARCHES RELATING TO 



The perfectly mature ovum before fecundation presents the aspect 

 of a sphere of granular protoplasm with a central and perfectly 

 uniform nucleus showing not the slightest trace of a nucleolus. The 

 hundreds of granules into which the nucleolus has been divided have 

 been dissolved in the protoplasm of the nucleus. 



Proportion of Water in the Medusae.* — Dr. Ki-ukenberg has 

 already shown that a large specimen of Hldzostoma Cuvieri contained 

 95* 392 per cent, of water, with 1 • 608 of organic and 3 • of inorganic 

 substances. In order to test the statement of Mobius that Aurelia 

 aurita from the Bay of Kiel had been found on analysis to contain 

 99*82 per cent, of water— a proportion leaving the solid materials at 

 only Jg- of the amount determined in a Triest specimen — a single 

 specimen of the same species was analyzed, and also two other Aurelice 

 together. The result showed the solid matters to exist in the pro- 

 portion of from 4 '21 to 4' 66 jier cent., the water in that of from 

 95 '34 to 95*79. Chrysaora hyoscella gives between 95*75 and 

 96*3 per cent, of water, and from 3*7 to 4*25 of solid bodies. Pro- 

 bably most other Medusae agree with those selected in these points, 

 so that no marine animal exists having the large proportion of 99*8 

 per cent, of water as a constituent of its tissues. 



A Fresh-water Hydroid Medusa. — One of the most startling 

 zoological discoveries of recent years was made in June last in the 

 warm-water tank in which the Victoria regia is grown at the gardens 

 of the Eoyal Botanical Society, London. The water (which has a 

 temperature of 85° to 90° F.) was found by Mr. Sowerby to be 

 literally swarming with little Medusfe of a new genus, about ^ inch 

 in transverse diameter. No true fresh-water Medusa has hitherto 

 been known, the one living in the discharging canal of the Cette 

 salt-works t being the most recent case of the discovery of a species 

 not actually inhabiting the sea. 



The Medusae were examined by Professor Allman, and subsequently 

 by Professor Lankester, and were described by the former under the 

 name of Limyiocodium victoria (Xifivrj, a pond, and kojSwj/, a bell) in a 

 paper read at the meeting of the Linnean Society on Jime 17, and by 

 the latter as Craspedacustes Sowerhii (in allusion to the relation of its 

 otocysts to its velum) at the Eoyal Society on the same day. 



From Professor Allman's paper J we extract the following : — 



The Medusae are very energetic in their movements, swimming 

 with the characteristic systole and diastole of their umbrella, and in 

 the warm-water tank were apparently in the very conditions which 

 contributed most completely to their well-being. 



The umhreUa varies much in form with its state of contraction, 

 passing from a somewhat conical shape with depressed summit through 

 figiu-es more or less hemispherical to that of a shallow cup or even of 

 a nearly flat disk. Its outer surface is covered by an epithelium 

 composed of flattened hexagonal cells with distinct and brilliant 

 nucleus. 



* ' Zool. Auzcig.,' iii. (1880) p. 306. t See tliis Journal, ii. (1879) p. 582. 



j 'Nature; xxi.(li-80) p. 178. 



