GENERAL HISTOLOGY. I 13 



about the same height, there is caused a cross-striation ex- 

 tending through the whole bundle. Finally, sprinkled here 

 and there between the muscle-fibrils are the muscle-cor- 

 puscles, spindle-shaped protoplasmic bodies with a nucleus, 

 the remnants of the cells, which have formed the muscu- 

 lature. 



4. Nervous Tissue. 



Function of Nervous Tissue. As the muscular tissue 

 brings about motion, so the nervous tissue serves for the 

 transmission of stimuli. It communicates the stimulations 

 of the sense-organs at the periphery to the central nervous 

 system, the seat of consciousness, and here brings about 

 perception ; further, it transmits the voluntary impulses 

 to the periphery, particularly to the musculature. By 

 the nervous system, finally, the stimuli arising in various 

 places are coordinated, thus furnishing the elements for 

 that which we call independent psychic activity. 



Elements of the Nervous Substance. Here also 

 the recipient of the stimulus must be a specific substance, 

 the nervous substance, different from protoplasm, a nerve- 

 fibril analogous to the muscle-fibril. But the difference 

 between substance and protoplasm is in practice difficult to 

 determine, so that we will start from the scientifically justi- 

 fiable distinction of nerve-substance and nerve-corpuscles. 

 The elements of nervous tissue are ganglion-cells and ncrvc- 

 fibres. 



The ganglion-cells range from very small corpuscles up 

 to very considerable spheres, which in animals are sur- 

 passed in size only by the eggs, and correspondingly 

 also they have a large nucleus reminding one of the ger- 

 minal vesicle. Multipolar and bipolar ganglion-cells are 

 chiefly distinguished in the vertebrates (Fig. 49). The 

 bipolar cells are so called from the two projections which 

 become nerve-fibres, and consequently are cell-bodies 

 interpolated in the course of a nerve-fibre. In the 

 case of the multipolar ganglion-cells two kinds of pro- 

 cesses are found : the dendritic or protoplasmic processes, 



