34 SUMMARY OF CURRENT RESEARCHES RELATING TO 



out, the axis-cylinder of the nerve dividing dichotomously, and the 

 nerve forming a reticulum in the plate. In the Frog no such 

 reticulation is formed, but the divisions of the axis-cylinder come 

 into contact with the nuclei which overlie the muscle-fibre. In the 

 beetle the nerve-substance of the plate is separated from the muscular 

 substance by a membranous structure which is connected with 

 Krause's transverse lines. Strong contraction, produced by electricity, 

 causes resolution of the transverse lines of the muscle into molecules ; 

 but fine stripe, due to the approximation of Krause's lines, are still to 

 be seen, except after very violent contraction. All the described 

 forms of cross lines can be seen in the Coleopteran muscle. The 

 outer sarcolemmar sheath is in connection with the outer sheath of 

 the tendon ; a reticular lymphatic canal-system ramifies from the latter 

 and terminates in the uniting substance of the fibrils, showing cell- 

 like granular structures at the points of division. 



These canals show connective-tissue cells bearing processes shaped 

 like windmill-sails at the point of insertion of the tendon. The main 

 nerves of the muscles lie in special " perineural " cavities, lined with 

 a multilaminar sheath. Isolated muscular fibres of Eydrojjhilus piceus, 

 connected with end-plates, show the Ki-ause's lines next to the mem- 

 braneous neural septum to be in close apposition, whereas towards 

 the sides they become gradually more distant ; they appear to converge 

 towards the plate when near it, but to diverge when remote from it. 



Terminatioiis of the Motor Nerves in the Striated Muscles of 

 Insects.* — H. Viallanes has studied the mode of termination of the 

 nerves in the muscles of the larvae of Stratiomys chamceleon Macq. and 

 Tipula gigantea Macq., and finds that in both the muscular fibre is on 

 the same plan as that of Vertebrata ; and consequently diff'ers greatly 

 from that of adult insects, which is histologically distinct. The 

 results which he obtained cannot therefore be compared with those 

 obtained by most of his precursors, who studied chiefly adult insects. 



In Tipula each muscular fibre receives only a single nerve, and 

 has only one Doyere cone : but in Stratiomys each receives several 

 nerves, and has several Doyere cones. 



The sheath of the nerve continuous with the sareolemma constitutes 

 the wall of the Doyere cone. 



The axis-cylinder having penetrated to the summit of the cone 

 divides into two principal branches, which give off secondary branches ; 

 these again divide dichotomously a gi-eat number of times. There 

 results a terminal nervous plexus beneath the sareolemma, and com- 

 parable to that in the Vertebrata. The author claims to have been 

 the first to point out such a plexus in other animals than Vertebrata. 



This plexus occupies a considerable area in Tipula ; but is much 

 reduced in Stratiomys. 



As in the Vertebrata, all the branches of the plexus are situated 

 between the sareolemma and the contractile mass; they seem to 

 terminate in a slender point as in the frog. 



Special nuclei are adherent to the branches of the plexus, and 



* « These pour le Doctorat en Medicine,' 8vo, Paris, 1881 (45 pp. and 3 pis.). 



