NUCLEATED CORPUSCLES. 



17 



dicate, without much definition, the varieties of albuminoid 

 substance found in the growing stages of the living elements 

 of texture, and in the lowest forms of life. 



The generalization has been long known, and may be 

 safely made, that the phenomena of life are never exhibited 

 without the presence of albuminoid substance. 



The simplest form of living element in both animal and 

 vegetable texture, or at least one of the simplest forms, and 

 the most important, is the nucleated corpuscle, which is 

 remarkable not only for the remarkable part which it plays, 

 but for its resemblance to some of the simplest kinds of 

 animals, the genus Amoeba. 



Fig. 2. SPECIES OF AMCEBA.. After Pritchard. 



7. Amoeba is the name of a family of animals which are 

 microscopically minute, and inhabit both salt and fresh water. 

 They consist of a mass of protoplasm unlimited by any 

 envelope, containing granules, arid usually a clear, rounded, 

 firmer body, the nucleus, with a still denser speck in its 

 interior, the nucleolus. This mass of protoplasm moves 

 about by throwing out temporary processes in different direc- 

 tions, and changing its form by virtue of its contractility. 

 In fact, the powers of assimilation, reproduction, irritability, 

 and contractility, appear all to be present in one common 

 mass. There are other families in which such a mass as 

 constitutes the amceba is surrounded by a membranous cover- 

 ing or a hard shell. 



8. The Nucleated Corpuscles found in the ^textures of the 

 higher animals present many varieties of appearance, but in 

 their young and active condition they have this much resem- 

 blance to amceba, that they present a mass of protoplasm with 

 one or more nuclei, which may contain nucleoli. Some are 

 surrounded with a membranous envelope, others have none, 

 and with regard to a great number of them it is extremely 

 difficult to say whether they have a membrane round them 



14 B 



