516 GEORGE CARRINGTON PURVIS. 
which marks out the axis-cylinders in a way not to be ap- 
proached by any other method of gold treatment. This method 
has, however, a slight disadvantage, inasmuch as the muscles 
are generally rendered so clear and transparent as to be scarcely 
recognisable as muscular fibres.’ This difficulty may be ob- 
viated by cautiously dehydrating the sections after reduction of 
the gold, by acting on it with several grades of alcohol up to 
absolute, then clearing with clove oil, and mounting in balsam ; 
the clearing medium, by some peculiar chemical action, at once 
causes the muscular fibres to assume a dark reddish or violet 
tint, leaving the connective tissue almost perfectly transparent. 
Having, however, determined that the nerve terminations lie 
in connective tissue, by far the most direct method is to mount 
in glycerine, without previous treatment with alcohol. This 
necessitates the cementing or ‘‘ ringing” later on with gold size 
or zine white. 
THE STRUCTURE OF THE TERMINAL ORGANS. 
The organ may be said to consist of three distinct portions. 
(1) A capsular part, which is merely the expanded terminal 
portion of the outer or grey sheath of the nerve-fibre, and is 
very often marked by obliquely disposed lines, which give it 
the appearance of being spirally striated (fig. 1). The capsule 
is usually of an oval form. 
(2) An axial portion, which is a continuation of the axis- 
cylinder of the nerve-fibre, more or less convoluted. ‘The axis- 
cylinder terminates in a small dilatation, which is generally 
pyriform (fig. 4) or globular (fig. 1) ; sometimes it is distinctly 
unciform (fig. 2). | 
(3) A protoplasmic portion, consisting of clear protoplasm, 
filling up the space between the capsule (1) and the axis- 
cylinder within it (2). 
1 Kiihne’s modification of Golgi’s method (‘ Zeitschr. f. Biologie,’ vol. xxiii, 
1887) was at the time (1888) unknown to me. The injurious effects of arsenic 
acid on the muscular fibres are greatly lessened by this mode of treatment. 
