MAGNITUDE AND MINUTENESS. 



to be in reality the effect of certain ciliated organs attached to 

 the head of the animal, to which it imparts a rapid conical 

 motion. It appears, that it has the power of drawing in these 

 appendages, and when it does so, it changes its form from the 

 oblong shape represented in the figure, to that of a roundish 

 globule. 



This creature possesses another property still more astonishing : 

 when withdrawn from the liquid element which is his proper 

 habitation, it is reduced to a grain of dust, so minute as to be 

 visible only by the microscope. In this state it can be kept for 

 long intervals of time, apparently deprived of all life. When, 

 however, it is again immersed in water, it recovers all its original 

 force, and resumes its habits. The most eminent observers have 

 affirmed, that they have submitted the same individual rotifer, 

 several times successively, to these alternations of life and 

 temporary death. 



The microscopic researches of Ehrenberg have disclosed most 

 surprising examples of the minuteness of which organised matter 

 is susceptible. He has shown that many species of infusoria 

 exist which are so small that millions of them collected into one 

 mass would not exceed the bulk of a grain of sand, and a thousand 

 might swim side by side through the eye of a needle. 



The shells of these creatures are found to exist fossilised in the 

 strata of the earth in quantities so great as almost to exceed the 

 limits of credibility. 



By microscopic measurement it has been ascertained that 

 in the slate found at Bilin, in Bohemia, which consists almost 

 entirely of these shells, a cubic inch contains 41000,000000; and 

 as a cubic inch weighs 220 grains, it follows that one hundred 

 and eighty six millions of these shells must go to a grain, 

 each of which would consequently weigh the 186,000000th part 

 of a grain. 



. All these phenomena lead to the conclusion that these creatures 

 must be supplied with an organisation corresponding in beauty 

 with those of the larger species. 



In figs. 4 and 5, page 1 93, are represented some of the fossil 

 animalcules found in the tripoli of Bilin, magnified in a great 

 proportion. 



22. A thread of spider's web, four miles long, weighs little 

 more than a grain. Every one is familiar with the fact that the 

 spider spins a thread by which its own weight hangs. It has been 

 ascertained that this thread consists of 6000 filaments ! 



23. One of the most obvious means of producing a high degree 

 of subdivision is by dissolving in a large measure of water a 

 small portion of the substance to be divided. 



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