LIVING MATTER 



of a millimetre in their largest diameter. Muscle fibres, indeed, 

 both plain and striated, may measure more than a decimetre, and 

 the nerve processes of the ganglion cells more than a metre. Still 

 the amount of living matter contained within a cell is always, 

 comparatively speaking, very small. In a bird's egg, which is a 

 single colossal cell, the active, living protoplasm consists only of one 

 very delicate layer, the whole of the rest being inactive yolk, which 

 is destined to feed the germ during its embryonic development. 



III. Both in animal and in plant cells, protoplasm has the 

 same common properties : it appears as a semi-fluid, almost 

 always colourless substance, with no apparent morphological 

 structure, although it contains a variable quantity of small 

 punctiform gran- 

 ules ; it is readily 

 permeable by water, 

 which swells it up 

 without dissolving- 

 it ; impenetrable as ~rnc * 



a rule to colouring 



FIG. 6. Epithelial cell from intestine of insect larva. (Carney.) 

 me, cell membrane ; j>e, cell protoplasm in form of net- 

 work with granulations; mn, nuclear membrane; pn, 

 nuclear protoplasm with a-chromatic, reticulated substance ; 

 bn, skein of chromatic substance in centre of nucleus. 



matters during life, 

 it stains readily after 

 death. When at 

 rest it has an alka- 

 line reaction, which 

 may become neutral 

 or even acid during 

 activity. The hya- 

 line, non-granulated 

 protoplasm often 

 forms in the cell a 

 more or less dense 

 external layer,known 

 as ectoplasm or hyaloplasm, to distinguish it from the internal 

 granular portion that surrounds the nucleus, the so-called endo- 

 plasm or granuloplasm (Fig. 1). 



Under the high power of the microscope, this apparently 

 homogeneous protoplasm shows a very complicated structure. 

 Reniak (1844) and M. Schultze (1871) affirmed that there was a 

 fine fibrillar structure in the protoplasm of the ganglion cells of 

 the nervous system, a theory subsequently extended to epithelial, 

 glandular, and other cells. Froniman (1865) and Heitzmann 

 (187->) modified this statement, and assumed a finely reticulated 

 structure, in which the granules would be the nodal points of the 

 protoplasmic network. Carnoy (1883), while admitting the theory 

 of a reticulum, affirmed that the granulation represented not the 

 network but the fluid contained in its meshes, to which he gave 

 the name of enchylema (Fig. 6). Finally, Biitschli (1892) showed 



VOL. I c 



