J863.] . 671 



a is a nerve-fibre which was followed over more than twenty elementary mus- 

 cular fibres from a dark-bordered fibre. One of the subdivisions of this fibre is 

 seen at/, where it again runs with a very fine dark-bordered fibre (o). The dark- 

 bordered fibre (o) was some distance higher up in the specimen, but its place has 

 been altered in order to avoid the necessity for a still larger drawing. Above b a nu- 

 cleus of a very fine nerve-fibre is seen. Such nuclei lie upon the surface of the mus- 

 cular fibres, external to the sarcolemma. The nucleus often appears as if it were 

 within the sarcolemma (c), but the fibres proceeding from each extremity render 

 such a position impossible. The relation of these nerve-nuclei to the sarcolemma 

 is seen at I in profile. The nuclei, as well as the fibres for a certain distance, 

 often adhere to the sarcolemma very firmly ; but in the thin mylo-hyoid muscle 

 the course of the fibres over or under, but always external to the muscular fibres, 

 may be readily traced if the muscular fibres be separated slightly from each 

 other, as represented in the drawing. 



At d fine nerve-fibres accompanying the fine fibre continued from the dark- 

 bordered fibre, as described in the ' Philosophical Transactions ' for 1862, are re- 

 presented. Such fibres are also seen at e and/. 



m, n, and o dark-bordered fibres, with nuclei near their distribution, m 

 would probably pass over sixty or seventy muscular fibres, and n over perhaps 

 twenty, before it divided into fibres as fine as those seen at d, e,f, I. 



p a very fine capillary vessel with a nerve-fibre running close to it. 



q a bundle composed of six very fine nerve-fibres near their distribution. 

 These fibres exhibit a very distinctly beaded appearance, which is also observed 

 in many other fine fibres in different parts of the specimen. 



Traces of connective tissue are seen in all parts near the fine nerve-fibres and 

 around the muscular fibres. Here and there some very fine connective tissue- 

 fibres, which were not altered by acetic acid, are represented. These represent 

 the remains of fine nerve-fibres, which existed in a state of functional activity at 

 an earlier period. 



The drawing, with the exception of the position of the nerve-fibre (o) above 

 mentioned, is an actual copy from nature. The relative position of the muscular 

 fibres, the form and general characters of the so-called nuclei, and the position 

 and size of the nerve-fibres and their nuclei have been carefully preserved. 



I have traced the very fine nerve-fibres in so many instances from one trunk, to 

 another ramifying at a very considerable distance, that I cannot believe any true 

 terminations or ends exist. 



XVI. " Note on the Minute Structure of the Grey Matter of 

 the Convolutions of the Brain of Man, the Sheep, Cat, and 

 Dog." By LIONELS. BEALE, M.B., F.R.S.,&c. Received 

 June 18, 1863. 



By a new process of investigation, I have succeeded in demon- 

 strating the connexion between the nerve-cells and fibres in the grey 

 matter of the convolutions and in other parts of the mammalian 

 brain, and have followed individual fibres for a much greater distance 



