344 



ELECTRO-PHYSIOLOGY 



CHAP. 



of the axis- cylinder, running in opposite directions, within the 

 substance of the expansion. These are for a short distance 

 parallel with the long axis of the muscle-fibre, and then appear 

 to end freely. In other cases they send out a few short side- 

 ' branches, the presence of which is sometimes indicated only by 



isolated dark - blue droplets. 

 Finally, the nerve -endings (in 

 consequence of the great in- 

 stability of the intrinsically 

 delicate, naked axis - cylinder) 

 often appear merely as an ac- 

 cumulation of greater and smaller, 

 and no longer coherent, drops 

 (stained blue) within the expan- 

 sion their real nature being 

 apparent only on comparison 

 with other parts of the same 

 preparation. Similar observa- 

 tions have recently been com- 

 municated by Eina Monti (53) 

 upon different insects. 



Foettinger (53) gives a differ- 

 ent account of the motor nerve- 



FIG. 226.-Nerve-endin g inamuscie- endings in insects, pointing to a 



fundamental difference between 

 vertebrates and insects. In the 

 beetles investigated by him 

 ( Chrysomela ccerulea, Lina tremula, 

 Hydrophilus piceus, Passalus 

 gkiberrimus) there were, as a 

 rule, several, often many, nerve- 

 endings to one primitive fibre, 

 and these as may be verified on 



hardened preparations are frequently (? always) the starting- 

 point of waves of contraction. After treatment with osmic acid 

 and alcohol, delicate fibrils or filaments may sometimes be dis- 

 tinguished in the side-view of a Doyere's expansion ; these start 

 from the junction of the ingoing nerve-fibres, and pass to the 

 intermediate discs (Fig. 226). If this be a real irradiation of 

 the axis -cylinder, there must be direct continuity between 



fibre of Hydrophilus picei 

 (Foettinger.) 



