246 Hints to Beginners with the Microscope. 



They are composed individually of thread-like filaments, made 

 up of cells or microscopic segments, filled with vegetable 

 granules ; every microscopic cell as it becomes mature divides 

 into two young ones, and those thus formed divide again, and 

 thus from hour to hour this process of division is repeated. 



We are all familiar enough with the prodigious results ob- 

 tained by continually doubling the product of any given 

 number even as many times as there are nails in a horse's 

 shoe or squares upon a chess-board, and know that by this 

 process we soon arrive at arithmetical expressions far beyond 

 what our minds can appreciate — millions and billions, and 

 other numbers which it is easier to talk about than to com- 

 prehend — and yet how inadequate are sums like these to 

 express the increase of the progeny of the confervas, during a 

 single day, by this process of spontaneous fissure ! 



These confervas, moreover, have another mode of reproduc- 

 ing themselves which is even still more prolific and more 

 wonderful. The cells of which they consist are individually 

 capable of forming progeny in their interior from which similar 

 growths are developed. When a portion of one of these organ- 

 isms is examined under the microscope, its cells may at certain 

 periods be observed to contain numerous spherical granulations 

 which, as they approach maturity, become pear-shaped, and 

 provided at one extremity with a little rostrum or beak, their 

 body is filled with a green material (en clochrome) , and the}" 

 generally exhibit a minute red spot, once described as an eye, 

 but now recognised to be a globule of oil. As these germs 

 become perfected they may be seen moving restlessly about in 

 the interior of the cells in which they were formed, striking the 

 walls of their prison with their little beaks, as though anxious 

 to get free. At length the walls of the cell become ruptured and 

 its liberated contents escape into the surrounding water, through 

 which they speedily begin to move hither and thither with 

 astonishing rapidity — now progressing in a straight line, now 

 wheeling round and round, and, anon, lowering their beaks 

 they begin to oscillate upon them like peg-tops waggling just 

 before they tumble down. Sometimes they stop altogether and 

 again resume their curious and eccentric movements. After 

 two or three hours of such exercise, their motion becomes 

 much retarded, and at length, after faint struggles, entirely 

 ceases, and the little zoospores lie as though they were dead ; 

 the vital principle, however, is still active within them, they 

 soon may be seen to expand in their dimensions, to become 

 partitioned off internally, and finally to send off two or more 

 rootlets by which they become attached and stationary. Strange 

 transition, from the roving life of an animal to the fixed con- 

 dition of a plant ! 



