36 BIOLOGY. [BOOK i. 



Finally, these anatomical elements float more or less directly 

 in living liquids, which are called blastemas. For instance, the 

 freshwater polypus, celebrated on account of the curious experi- 

 ments of regeneration to which it has given occasion, is solely 

 composed of corpuscles living, spherical, of cells swimming in an 

 intercellular liquid, which is a blastema. This is also the texture 

 of certain infusoria, for example, of the Paramsecia, and likewise 

 of a number of plants. 



Besides in plants, and especially in superior animals, exist 

 systems of canals serving for the circulation of liquids as 

 living as the figurate anatomical elements. These liquids, which, 

 like the blastemas, to distinguish them from which there has 

 been a wrong attempt, are both receptacles of disassimilated 

 products and reservoirs of assimilable products, have been called 

 plasmatic liquids, or plasmas. 



We have successively to describe living substance under the 

 two general forms which it assumes, namely, the histological form 

 and the blastematic and plasmatic form. 



1. Of the Figurate Elements in General. 



The science of the figurate elements of living bodies, whose 

 real origin only remounts to the end of the last century, has 

 long borne the name of General Anatomy. It was not till 1819 

 that Mayer published a treatise of General Anatomy under the 

 title of Treatise on Histology, and a New Division of the Body 

 of Man. The word Histology has had eager acceptance, no 

 doubt because it is derived from the Greek, and it is now in 

 general use. 



The first elementary histological form which organised matter 

 assumes is the cellular form. "We must understand by cell a 

 microscopical corpuscle, having a sort of independence, an indi- 

 vidual life, assimilating and disassimilating on its own account. 

 The cell has generally a form more or less spherical. It is consti- 

 tuted by a substance more or less soft. When it is complete it 



