194 



HARDWICKE'S SCIENCE-GOSSIP. 



form, the habit and structure of the polypes have a 

 general uniformity. When in repose, the creature lies 

 doubled up in its cradle, and, expanded, exhibits a 

 crown of ciliated tentacles ; in the centre a mouth. 

 When extended, and the cilia in full play, the vortices 

 produced in the water attract and carry into the 

 mouth the minute particles of food. This lovely 

 microscopical sight is well displayed in the fresh- 

 water species ; but the marine forms are no less 

 interesting. The little flosculous heads peep out 

 from the opening of the cells, cautiously emerge, and 

 suddenly expand in regular order, like living blooms 

 and flowers of inconceivable delicacy. 



The individual polype, and its domicile, are, in 

 almost every instance, microscopic ; but the united 

 and accumulative efforts of these minute creatures 

 attain gigantic results, as seen in the madrepores, 

 and arborescent species, notably the reef-forming 

 corals, capable of producing even geological changes. 

 Although not quite germane to the present subject, 

 reference may be made to another species, the red 

 coral of commerce. Here the polypary, or foundation 

 of the colony, is branched like a tree, centralised 

 into a solid axis, throughout covered with a living 

 crust or "cortex;" studding the surface of this 

 fleshy substance are the innumerable polype centres, 

 appearing as minute rayed stars ; the stem is hard, 

 and, as well known, especially to ladies, an exquisite 

 ornament, as it takes a fine polish. In the Gorgonia, 

 or Sea-fans, the axis of the branches is formed of a 

 substance not clearly understood ; it appears like a 

 concreted albumen, flexible, horny. A beautiful 

 microscopic object is a transverse section through 

 one of the thicker stems. Its solidity is seen to be 

 made up of layers of calcareous deposits, imbedded 

 in some connective tissue, undulating round a centre ; 

 the dried crust, or desiccated remains of the living 

 envelope, furnishes the well-known " Spicules of 

 Gorgonia." 



These homes of the Ascidioda, when dried and 

 empty (the "deserted village" of departed polypes), 

 beautiful as they are, and exciting wonder that such 

 structural results could be potential in a creature so 

 simple and elementary, afford no idea whatever of 

 the sight presented under the microscope, with dark 

 spot illumination, of any of the class in a living 

 condition, protruding and unfolding a coronal of 

 supremely beautiful tentacles, which when disturbed 

 are instantly gathered into a parallel band, and 

 sucked into the recesses of their cradles ; but when 

 dead, and the tenant disappeared, a domicile of 

 such rare beauty is worth a .place in the cabinet, 

 especially as the configuration of the cells is an 

 element in classification. Any of these forms, 

 after soaking in fresh water (to remove saline 

 incrustations) and carefully dried, may be easily 

 "mounted" as opaque objects, and good reflected 

 light reveals all the salient points, as seen in the 

 picture. 



The pith and terseness of purely scientific words 

 are well exemplified in the description of species 

 Dr. Johnston gives in " British Zoophytes." Our 

 younger readers should cultivate the art of word- 

 painting, A fair lesson might be to describe a glass 

 tumbler in precise language. Many works of purely 

 technical character abound in fine and graphic de- 

 scription : often the accuracy of phraseology demanded 

 by science touches the poetical, even the humorous. 

 The works of the late Edward Forbes, the most genial 

 of naturalists, reveal many instances of curiously 

 quaint and elegant description. 



The Polyzoa may be secured as permanent objects, 

 with the polypes extruded, /;? situ. Such marine 

 forms as Sertularia or the Corynidse may be arranged 

 in a cell, in their native fluid, under a covering glass ; 

 when fully expanded, and in vigorous action, pure 

 alcohol from the tip of a sable pencil is allowed to 

 run under the cover. It immediately kills the creature, 

 and, although not successful in every case, generally 

 they are paralysed and die before retraction ; the cell 

 is then closed with the ordinary cements — for experi- 

 ment, the fresh-water polyzoon Lophopus is always 

 available, and easily managed ; it takes to alcohol 

 very kindly. A group of three or four should be 

 arranged in a ring of glass under cover ; and when the 

 horse-shoe tentacles are fully expanded, the stimulant 

 is cautiously admitted, and generally a fair and 

 permanent preparation secured. 



Crouch End. 



GOSSIP ON CURRENT TOPICS. 



MANY and loud are the complaints concerning 

 the condition of the lower Thames. All 

 who can see beyond the present moment must be 

 thankful to the hot dry weather for its friendly de- 

 monstration of the dirty truth. So long as the poison 

 remains hidden we may go on converting our rivers 

 into sewers, by the barbarous practice of throwing 

 into them the material demanded for the restoration 

 of the fertility of the soil ; a practice which, if general 

 and continued long enough, would simply exterminate 

 the human race, and with them all the rest of the higher 

 animals that live on land and cannot obtain their 

 food supplies in the form of fish and sea-weeds. The 

 agricultural desolation of England would have been 

 practically effected ere this but for our importation of 

 guano and other foreign manure. I am sorry to find 

 that Dr. Andrew Wilson, in his valuable magazine 

 "Health," says, "The only clear solution of the 

 question seems to be in the direction of the free and 

 absolute conveyance of all sewage in closed aque- 

 ducts or sewers to the sea." Such an expedient is 

 only a device for hiding the evil. For my own part, I 

 prefer that this and all other consequences of human 

 sin, whether sins of commission or sins of omission, 



