18 PHYSIOLOGY 



regarded by Altmann as the elementary particles of life, and he locates in 

 them the various vital functions, the sum of which make up the life of the 

 cell. According to Altmann these granules can only arise from the division of 

 pre-existing granules, and he has formulated the phrase omne gmnulum e 

 granulo, which is a further extension of Virchow's sentence omnis cellula e 

 cellula. It is probable that a number of different kinds of structures of vary- 

 ing importance are included among Altmann's granules. In some cases they 



FIG. 4. Section of liver stained to show granules. (ALTMANN.) 



are the products of the activity of the cytoplasm and, as in secreting cells, 

 will be later on cast out with water and salts as the specific secretion. In 

 other cases they may be cell organs or plastids with the special metabolic 

 functions assigned to all granules by Altmann. In some cases no treatment 

 whatever will display the existence of granules. 



2. THE FIBRILLAR THEORY. By the employment of appropriate methods 

 of hardening, it is easy in most cells to demonstrate a network or clusters 

 of fibrils which form, so to speak, a denser part of the cell. This fibrillar 

 network has been named the ' spongioplasm ' in contra- distinction to the 

 structureless material filling its meshes known as ' hyaloplasm.' A network 

 is, however, one of the commonest pseudostructures produced in the coagu- 

 lation of an albuminous fluid by any means whatever, and it is probable 

 that in most cases the network which is seen in hardened cells is simply an 

 artefact. Sometimes a large portion of the protoplasm may take a fibrillar 

 form which can be detected even in the unstained and unfixed cell, and there 

 is no doubt that, in certain phases at any rate, the fibrillar structure of the 

 protoplasm is really present. 



3. THE ALVEOLAR THEORY OF BUTSCHLI. This theory may be looked 

 upon as corresponding morphologically to the granular theory of Altmann. 

 If we imagine a hyaline protoplasm which is continually manufacturing 

 metaplasmic products and storing them up in its protoplasm, these products 

 will be deposited as spherules gradually increasing in size, so that the proto- 



