The Michoscopk. 295 



parison, I have chosen a species near the middle of the series; with 

 this we may hurriedly and easily compare others, higher and lower. 



If to a beaker of clear water a few fragments of hay be added, 

 and let stand a few days, there may be found in the infusion great 

 numbers of a small, animated speck, represented by the sketch. It 

 is somewhat egg-shaped or globular, quite soft and elastic, with two 

 similar external appendages, consisting of two long, lash-like fibres. 

 Under the lens the whole organism appears endowed with life. This 

 is attested by its free motion, sensitiveness and ability to appropriate 

 and change to voluntary activity the energy of organic food. The 

 proper tests prove that its substance is identical with that form of 

 matter everywhere associated with life, and called protoplasm. In 

 fact, this animal is little else than this remarkably complex and won- 

 derful substance now universally recognized as the physical basis of 

 life. 



This minute lump of matter, only about jq\ q of an inch in 

 diameter, is naked protoplasm; true, its outer boundary appears to 

 be somewhat denser than the portion included; still, it appears that 

 its food may be taken directly through the surface at any place; 

 there is not a food receiving orifice — a mouth. On examining the 

 globule farther, two important bodies attract our attention. First, 

 imbedded in the protoplasm, may be seen a globule of protoplasm 

 firmer than the surrounding mass; this is the nucleus. This ele- 

 ment of the protozoan body, possessed also by the histogenic cell, 

 has elicited much study and animated discussion. Almost every 

 issue of the microscopical and morphological journals bring to notice 

 accounts of new and many far-reaching discoveries regarding it in 

 relation to the career of the cell to which it belongs; second, within 

 the endoplasm may be seen a clear globule which grows until a cer- 

 tain size is attained, when a sudden collapse occurs and it disappears, 

 to again steadily form and disappear as before. The two lashes 

 which arise from the lower, anterior part of the body are extensions 

 of the body protoplasm, hence, possessing its properties of sensibility 

 and contractility. One of these flagella reaches ahead, and by its 

 repeated strokes against the water pulls the body through that 

 medium; the other is used as a director of its course, or sometimes 

 as an anchor. These few differentiated parts are all that character- 

 izes this representative of one of the great classes of one division of 

 the protozoa, viz: the flagellata, the first class of infusoria. By 

 variation of these parts and their products arise those characters 

 and differences on which are established scores of genera that are 

 simpler, and scores that are moi'e complex. 



