74 



SCIENCE-GOSSIP. 



(thread-like hairs) already named are of great 

 interest, and worthy of attentive study. Let us 

 try to understand it. Looking now at one of those 

 globes under slight pressure so as to keep it in one 

 place, and with a high magnifying power we see 

 that the entire surface of the little sphere is covered 

 with a network of cells, each cell being a hexagon 

 (produced by pressure) and each one is attached to 

 its neighbour by a very fine thread which runs 

 across from cell to cell. The whole membrane of 

 the globe is thus seen to be so many distinct cells 

 held together by this thread-like attachment. As 

 the globe grows and expands these threads are 

 stretched to their utmost limit, and finally a breach 

 is made in the outer membrane, and the now 

 matured inside globes make their escape, and begin 

 an independent existence, repeating in their life- 

 history that of the parent form. But no account 

 that was ever spoken or printed can adequately 

 convey to the mind the exquisite beauty and grace- 

 ful motion of these pure green and transparent 

 spheres. They are sometimes found in great 

 abundance in rather shallow ponds and ditches 

 and are always objects of keen interest to the 

 beholder, especially when it is considered that all 

 these wonderful things take place in an organism 

 so small that the keenest vision can barely see it as 

 a tiny speck, unless assisted by the microscope." 

 Before leaving the subject of this wonderful little 

 plant, you ask what is it that gives it the power of 

 perpetually moving and revolving ? This remark- 

 able power of movement is given it by countless 

 pairs of thread-like hairs, or cilia that are studded 

 all over its surface. As long as the rolling-globe 

 lives these hairs are in a continual state of agita- 

 tion, how or why the wisest Fellow of the Royal 

 Society is unable to tell us, but the motion of these 

 minute hairs give rotary movement to the organism 

 which revolves in the water with so much of beauty 

 and grace that the observer is startled as delighted 

 the first time he perceives it in the wonder-revealing 

 tube of the miscroscope. 



There was in our school-days, a certain big book 

 with black boards and red edges, called " Smith's 

 Classical Dictionary," and in that work is given an 

 old Greek story which tells that there was a famous 

 monster called Hydra that lived in a swamp near 

 Lake Lerna in Argos, that it was so fierce and 

 destructive that it laid desolate all the country 

 in its neighbourhood, and whenever one of its 

 numerous heads was cut off, two new ones grew 

 on in its place, and one of the famed twelve labours 

 of Hercules was to fight and to destroy the 

 monster. No doubt the modern Hydra to which 

 we are now going to introduce you, obtained its 

 name from this old classic myth, and when its life- 

 history first became known to scientific men, it 

 created quite as much wonderment and excitement 

 in the scientific world, as that of the fabled mon- 



ster Hydra could have done amongst the Greeks. 

 There is to this very day in the museum at Naples, 

 a fine marble statue of Hercules. He is represented 

 in the act of engaging the Hydra in mortal combat, 

 and the nine-headed monster has leaped upon him 

 with all its force. This creation in the enduring 

 marble is suggestive of the creature now under our 

 consideration. The difference between the story of 

 the Greek poet about his Hydra, and the modern 

 man of science about his Hydra, is that the latter 

 has a history tenfold more wonderful, more 

 interesting, and more full of instruction, with 

 the added charm that every word of it is true. 

 Just to think of it, that there is, at this very hour, 

 in an Epping Forest pond, a Hydra with a real life- 

 history more remarkable, a creature that does 

 things more astounding than ever entered the heart 

 of a Greek poet to imagine. Having dipped our 

 little glass vessel, we succeed in securing a specimen 

 of this wonderful animal, or polyp, as it is more 

 accurate to term it. We hold this most remarkable 

 of " pond lodgers " up against the light, and take a 

 good look at him. The creature we happen to have 

 taken captive is the variety called the Green Hydra, 

 Hydra viridis is the name in the text-books. There 

 are nine "business ends" to our captive Hydra, 

 just like the Hydra in the Neapolitan marble of 

 Hercules; each of these "business ends" are 

 hollow tubes, and are " furnished with poisonous 

 stinging-organs, which spring out with astonishing 

 quickness the instant of contact with its prey, 

 killing the smaller at once, and so benumbing the 

 larger that they become quite helpless, and can be 

 devoured at leisure." The absolutely true things 

 observed and recorded of our Hydra, are more like 

 a page out of Baron Munchausen than a record of 

 sober fact from a science paper — but are matter of 

 common knowledge to every student of minute life. 

 " You can take our Hydra and cut off his head, and 

 engraft it firmly and effectively on another whom 

 you have beheaded, and you may exchange heads 

 one Hydra with another. You can cut him up into 

 forty or fifty pieces, and each piece will become a 

 completely-formed and perfect Hydra. You can 

 take a fine lancet, and cut him lengthwise, from 

 head to base, and you will have a double-headed 

 Hydra, and you can reverse the process, and have 

 him single-headed with a double body. The crea- 

 ture may even be turned inside out, and its powers 

 of adaptation are so great that it will continue 

 to live and enjoy itself." The most ardent anti- 

 vivisectionist may keep his mind easy, as the polyp 

 suffers little, if at all, by these operations, for when 

 his body has been cut in two lengthwise, as in 

 a well-known drawing in " Contes Drolatiques," by 

 Gustave Dore, the arms belonging to each side 

 seize their prey as usual, and Hydra viridis goes on 

 living his life as if nothing worth mentioning had 

 happened. (To be concluded next month.) 



