NOTES AND MEMORANDA. 



Leboucq on the Development and Termination of Nerves in 

 Larval Batrachians (' Bulletin de I'Academie Roy ale de 

 Belgique,' 1876j. — In this paper the author describes (1) 

 the development of the nerves, and (2) the structure of the 

 terminations of the non-muscular nerves. 



As these researches were commenced rather late in the 

 season it was not possible to obtain animals sufficiently young 

 to study the first appearance of the peripheral nerves. Accord- 

 ingly, the first part of the paper refers to the progressive 

 evolution of the nerves. 



The larval forms of various Bactrachians were examined, 

 both in the fresh state and after treatment with osmic acid. 



1. Developme?it of Nerves. — The author considers, first, the 

 nerve-fibres and their ramifications ; secondly, the enlarge- 

 ments in the course of the fibres. 



Nerte-fihres. — In the tails of young tadpoles, examined 

 without any previous treatment with reagents, the nerves 

 are recognised as filaments, whose peculiar appearance at 

 once distinguishes them. These filaments have a tolerably 

 definite contour, but the finer details of their structure are 

 made out with difficulty in the fresh state. Treatment with 

 osmic acid, however, facilitates the study of these points. 



Under high powers the nerve-trunks are seen to be marked 

 with fine strife, which seem to show that the trunks are 

 composed of bundles of fine fibrils. The primary bundles 

 divide dichotomously. 



Parietal Enlargements. — These are of two kinds, masses of 

 granular protoplasm, with or without nuclei, and true nuclei. 

 The latter are found along the course of a nerve-fibre, whereas 

 the protoplasmic masses are generally situated at the point 

 of bifurcation of a nerve, or where a collateral branch joins 

 it. These masses sometimes contain nuclei, with a less granu- 

 lar protoplasm than that surrounding them, and may possess 

 one or more nucleoli. In other cases nuclei cannot be seen, 

 but their presence here is considered probable, notwithstand- 

 ing. The size of these masses or corpuscles varies. They 



