ACALEPH.E.— THE MKDUS.E. 



functions tlie Acalejilue perform. Tlie fact, he says, 

 admits of easy illustration, both in the Beroes and in 

 the Meduiia;. On one occasion he took a dead Cydippe, 

 and, placing it on a glass, exposed it in the snn. As 

 the moisture evaporated, the dilTerent parts appeared 

 to be confusedly painted on the glass ; and when it had 

 become perfectly dry, a touch removed the only vestiges 

 of what had been eo lately a graceful and ain'mated 

 being. With regard to the Medusse, Mr. Patterson 

 relates an anecdote communicated to him by the late 

 eminent zoologist. Professor E. Forbes. He had been 

 delivering some zoological lectures in a seaport town 

 in Scotland, in the course of which he had reverted to 

 some of the most remarkable points in the economy of 

 the Acalepha?. After the lecture, a farmer who had 

 been present came forward, and inquired if he had 

 understood him correctly as liaving stated that the 

 MedusK contained so liitle of solid material that they 

 might be regarded as little else than a mass of animated 

 sea-water? On being answered in the affirmative, he 

 remarked that it would have saved him many a pound 

 had he known that sooner; for he had been in the 

 liabit of employing his men and horses in carting away 

 large quantities of jelly-fish from the shore, and using 

 them as manure on his farm ; and he now believed 

 they could have been of little more real use than an 

 equal weight of sea- water. Assuming that so much as 

 one Ion weight of Medusa recently thrown on the beach 

 had been carted away in one load, it will be found 

 that, according to the experiments of Professor Owen, 

 the entire quantity of solid material would be only 

 ahoui four j^ojinds of avoirdupois weight — an amount of 

 solid material which, if comjiressed, the farmer might 

 with ease have carried borne in one of his coat pockets. 



The appearance of the Medusa; as they float in the 

 clear waters near a rocky coast is very fairy-like and 

 attractive. Some are uncoloured, and translucent as 

 crystal ; others shine and gleam with beautiful rose 

 hues or azure tints; others are of a rich purple, 

 emerald, ultramarine, or dark warm brown ; and others 

 again seem to coruscate and glow with all the colours 

 of Iris ! 



In certain species only tlie central parts are coloured, 

 exhibiting the most brilliant reds and yellows, the 

 intensest blues or violets, while all the rest is purely 

 limpid ; in others again the central mass seems invested 

 in a thin diaphanous veil, like the evanescent soap- 

 bubble blown by playful children. 



In moving through the water the Medusfe keep their 

 convex part in advance, and in a slightly oblique direc- 

 tion. If lightly touched while swimming, they contract 

 their tentacles, fold np their mushroom-like discs, and 

 sink into the sea. Like Ehrenberg, M. Kolliker thought 

 he could discover visual and auditory organs in an 

 Oceania, and Gegenbauer supposed he had detected 

 tliem in other genera, such as RIdzostoma and Pclar/ia. 

 The eyes consist, it is said, of certain small, hemi- 

 spherical, coloured particles, in which are deposited 

 small crystalline globules, whose free parts are com- 

 pletely undefended. The ears are seated close to the 

 optical organs; they are small vesicles filled with liquid, 

 the eyes having neither pupil nor cornea, and the ears 

 without opening or arch. 



The most interesting particular connected with the 

 economy of the Acaleph:e i? their mode of reproduction. 

 At one period of the year they are loaded with festoons 

 of the liveliest colours, which, on examination, prove to 

 be wholly composed of very minute eggs. These, in 

 some cases, develop themselves while attached to the 

 parent bodies, and are only thrown off when they reach 

 maturity. In other cases no resemblance is apparent 

 between the mother and her offspring. They are 

 elongated like worms, and broad at the extremity : 

 these are " microscopic leeches," whose scarcely per- 

 ceptible vibratile cilia enable them to dart to and fro 

 with extreme agility. After a while they progress into 

 Polypes, and are provided with eight tentacles. This 

 preparatory kind of animal seems to exercise the repro- 

 ductive faculty by means of certain buds or tubercles 

 which appear on the surface of the body, and also by 

 occasional filaments, so that, as in the case of the 

 corals, a single individual becomes the founder of a 

 numerous colony. This Polype undergoes a still more 

 remarkable metamorphosis. It attains a complicated 

 organization and an articulate body, which seems to 

 consist of a dozen bodies piled one upon another "like 

 the jars of a voltaic pile." The upper disc, which is 

 convex, separates itself from the aggregate mass by a 

 violent effort, becomes free, and develops into a minute 

 star-like Medusa : every disc, or in other words, every 

 individual, in like manner secures its freedom and an 

 independent existence in its turn. 



Gosse, whose researches in reference to the Acalepb.-e 

 form a very valuable contribution to the natural history 

 of the Zoophytes, divides them into three great divisions. 



1. Discophora, whose form is that of a circular disc, 

 more or less convex and mushroom-shaped, and which 

 moves Iiy an alternate contraction and dilatation of 

 the disc. 



2. Ctcnvphora, whose body is cylindrical, and whose 

 movements are effected by means of many parallel rows 

 of cilia set on the surface in longitudinal order ; and — 



3. Siphonojihora, with an irregularly-shaped body, 

 having no digestive cavity, but organs of suction, and 

 moving either by means of certain air-vessels, or by 

 means of a contractile air reservoir. 



The Discophora are again sub-divided into — A, 

 Gymnopthalmata, having the optical apparatus un- 

 covered or wholly wanting, a large central digestive 

 cavity, and simple or branched circulating vessels, 

 which strike off to the margin ; and, B, Stcganojih- 

 thalmata, in which the eye-specks are defended by 

 membranous hoods, or lobed coverings, and circu- 

 lating vessels eo ramified as to form a labyrinthine 

 network. 



Of tlie GymnopJithalmata we have an admirable 

 example in ^Equorea violacea (Milne-Edwards), whose 

 disc may be compared to a crystal saucer reversed, 

 and fringed all round the edge with short, slender, 

 thread-like tentacula of a delicate violet colour. Its 

 circulating vessels, eight in number, are quite simple, 

 and the ovaries are placed upon them. The peduncle 

 is wide, and expands into several broad and long 

 fringed lobes. 



The Stegannphthalmain include the Medusads 

 proper, whose umbrella-shaped disc is furnished with 



