336 IMPORTANCE OF THINGS MINUTE. 



tude of the universe. We are more perplexed in attempting 

 to comprehend ^he organization of the minutest Infusoria,* 



* Ehrenberg has ascertained tliatthe Infusoria, which have hcrtofore been 

 considered as scarcely organized, have an internal structure resembling that 

 of the higher animals. He has discovered in them muscles, intestines, teeth, 

 different kinds of glands, eyes, nerves, and male and female organs of repro- 

 duction. He finds that some are born alive, others produced by eggs, and 

 some multiplied by spontaneous divisions of their bodies into two or more 

 distinct animals. Their powers of reproduction are so great, that from one 

 individual (Hydatina senta) a million were produced in ten days; on the 

 eleventh day four millions, and on the twelfth sixteen millions. The most 

 astonishing result of his observations is, that the size of the smallest colour- 

 ed spots on the body of Monas Termo, (the diameter of which is only g- J^ ,5- 

 of a line) is 4.,_ of a line, and that the thickness of the skin of the sto- 



4.8T5T50 !!■ ,■ mi • 



mach may be calculated at from ___i^^^ to __ ,, J -^^-^^ of a line. This 

 skin must also have vessels of a still smaller size, the dimensions of which 

 are too minute to be ascertained. Abhandlungen der Academie der Wissen- 

 schaften zu Berlin, 1831. 



Ehrenberg has described and figured more than 500 species of these 

 Animalcules; many of them are limited to a certain number of vegetable 

 infusions ; a few are found in almost every infusion. Many vegetables pro- 

 duce several species, some of which are propagated more readily than others 

 in each particular infusion. The familiar case of the rapid appearance and 

 propagation of animalcules in pepper water will suffice to illustrate the 

 rest. 



In the London and Edin. Phil. Mag. Aug. 1, 1836, p. 158, there is an 

 extract of a letter sent by M. Alexander Brongniart from Berlin to the 

 Royal Academy of Sciences of Paris, announcing that Ehrenberg has 

 also discovered the silicified remains of Infusoria in the stone called Tri- 

 poli (Polierschiefer of Werner,) a substance which has been supposed to 

 be formed from sediments of fine volcanic ashes in quiet waters. These 

 petrified Infusoria from a large proportion of the substance of this kind 

 of stone from four different localities, on which Ehrenberg has made his 

 observations ; they were probably living in the waters, at the time when 

 they became charged with the volcanic dust, in which the Tripoli ori- 

 ginated. It is added in this notice that the slimy Iron ore of certain 

 marshes is loaded witii Infusoria, of the genus Gallionella. — L'lnstitut, 

 No. 166. 



These most curious observations throw important light on the obscure 

 and long-disputed question of equivocal generation; the well-known fact 

 that animalcules of definite cliaracters appear in infusions of vegetable 

 and animal matter, even when prepared with distilled water, receives a 



