206 MODE OF TERMINATION OF MOTOR NERVES, BY W. KUHNE. 



the interior of muscles, sometimes appearing in the form of a few 

 short striae, scattered through all parts of the fibre ; sometimes as 

 long bands lying between the contractile substance and the sar- 

 colemma ; and often, also, filling the interior of a canal running 

 through the whole length of the fibre. In many instances the 

 muscles of Crustacea present these masses in the form of a com- 

 plete cylindrical tunic lying between the sarcolemma and the 

 muscular substance. The masses may again be entirely isolated, 

 or may communicate through the entire muscular fibre ; those 

 which lie in the central canals sending off radial processes which 

 run towards the surface to join with the superficial portions, 

 whilst in those which lie immediately beneath the sarcolemma, 

 the processes extend towards the extremities of the fibres, and 

 thus come into contact with others. 



The most appropriate objects for the examination of the mode 

 in which nerves terminate, appear to be the muscles of insects, 

 and amongst these the best are the muscles of the great black 

 water beetle (Hydrophilus piceus), which is to be preferred to 

 the nearly allied Dytiscus marginalis. Instead of the muscles 

 of the legs, it is better to employ the large colourless fasciculi 

 lying in the thorax, which are attached by broad processes to 

 the internal wing-like apodemata of the coxae. If the muscle 

 be suddenly separated from both its attachments by scissors, 

 we obtain a preparation which, either without any addition, or 

 merely with the addition of a little of the blood of the beetle, 

 or a drop of 0'5 per cent, solution of chloride of sodium, will pre- 

 sent, after gentle manipulation with needles, many beautifully 

 isolated muscular fibres. These fibres are quite free from con- 

 nective tissue, and are only bound together by nerves and 

 tracheae, both of which can be torn across with the greatest 

 facility. Amongst the nerves many extraordinarily thick pri- 

 mitive fibres are to be found, invested by a distinct mem- 

 brane, beneath which are very pale vesicular, and in parts 

 also very finely granular medullary sheaths, whilst the axial 

 portions present a fibrillar structure. The thick nerve fibres 

 undergo repeated division, rivalling in this respect the ramifi- 

 cations of the bloodvessels of higher animals, and send off finer 

 and still finer branches to the muscular fibres, each of which 

 contains an extraordinary number of ultimate terminations. It 



