MUCUS COEPUSCLE. 51 



new amoeba, wlucli exhibit the characteristic move- 

 ments. 



19. Mucus Corpuscle. — Every one knows that upon 

 the surface of the mucous membrane of the air- 

 passages, even in health, there is a small quantity of 

 a soft viscid matter generally termed mucus. This 

 mucus, said to be secreted by the mucous membrane, 

 contains certain oval or spherical bodies or corpuscles, 

 which are transparent and granular. From the 

 changes of form which take place hi them, it is cer- 

 tain that the matter of which they are composed is 

 almost diffluent. These corpuscles are tnucus corpu- 

 scles, but they have no cell- wall. They are separated 

 from each other by, and are embedded in, a more or 

 less transparent, viscid, tenacious substance formed 

 by the corpuscles themselves, and termed mucus. 



80. Its vital uioTeiueiits.^ — ^o lang;Tiag,*e could con- 

 vey a correct idea of the changes which may be seen 

 to take place in the form of a living mucus or pus 

 corpuscle or white blood-corpuscle ; every part of the 

 substance of the body exhibits distinct alterations 

 within a few seconds. The material which was in 

 one part may move to another part. Xot only does 

 the position of the component particles alter with 

 respect to one another, but it never remains the same. 

 There is no mere alternation of moveme^jts as in mus- 

 cular contraction. Were it possible to take hundreds 

 of photographs at the briefest intervals, no two would 

 be exactly alike, nor would they exhibit different 

 gradations of the same change ; nor is it possible to 

 represent the movements with any degTee of accuracy 

 by drawings, because the outline is changing in many 

 parts at the same moment. I have seen an entire 

 corpuscle move onwards in one definite dii'ection for 

 a distance equal to its own length or more. Pro- 

 trusions would occui' principally at one end, and the 

 general mass would gradually follow. Again, pro- 

 trusions would take place in the same direction, and 



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