SCIENTIFIC SUMMARY. 
539 
MEDICAL SCIENCE. 
Structure of the Nerve-cells in the Frog . — Perhaps one of the most in- 
teresting and exquisitely illustrated memoirs that has ever been presented 
to the Royal Society is that of Dr. Lionel Beale on the above subject. 
In order to thoroughly grasp the difficulties of this branch of microscopic 
anatomy, the reader must refer to the monograph itself, which has been 
published separately; but by reference to the accompanying plate (PI. 
XXI.), the following conclusions which the author has reached will be 
rendered explicit : — 
(1) In all cases nerve-cells are connected with nerve-fibres, and the cell 
probably influences only the fibres with which it is structurally con- 
tinuous. (2) Apolar and unipolar cells have no existence, all nerve-cells 
having two fibres in connection with them. (3) In certain ganglia of the 
frog there are large pear-shaped cells, from which two fibres proceed — a, a 
straight fibre continuous with the central part of the body of the cell ; 
and 5, a fibre or fibres connected with the circumferential part, and coiled 
spirally round the straight fibres. (4) These two fibres, after lying very 
near to, and in some cases, when the spiral is very lax, nearly parallel with 
each other, at length pass toward the periphery in opposite directions. (5) 
Ganglion cells exhibit different characters, according to their age. In the 
youngest cells, neither of the fibres exhibits the spiral arrangement ; in 
fully-formed cells there is a considerable extent of spiral fibre ; but in old 
cells the number of coils is much greater. (6) These ganglion cells may 
be formed in one of three ways : a , from a granular mass like that which 
forms the early condition of all structures ; h , by the division or splitting 
up of a mass, like a single ganglion-cell, but before the mass has assumed 
the perfect form ; c, by changes occurring in what appears to be the nu- 
cleus of a nerve-fibre. (7) During the development of a ganglion cell, 
there is reason to believe that the entire cell moves away from the point 
where its formation commenced, so that the fibres connected with it will 
become elongated. (8) There are nuclei in the body of the cell ; and 
there are nuclei connected with the spiral and also with the straight fibre, 
the nuclei of the cell being found both on its surface and in its substance. 
(9) The matter of which the nucleus is composed has been termed (by Dr. 
Beale) germinal matter. From it alone growth takes place, and in all 
cases the matter of which the nerve fibre consists was once in the state of 
germinal matter. (10) The nucleolus also consists of germinal or de- 
veloping material. (11) The ganglion cells are connected with both dark- 
bordered fibres and fine ones. (12) Contrary to Kolliker’s statement, 
there are neither apolar nor unipolar cells in the ganglia of the heart. 
(13) The muscular coat of the arteries is supplied with nerve-fibres. 
(14) The connective-tissue-corpuscles are quite distinct from the nerve- 
fibres. (15) The so-called nucleated capsule of the ganglion-cells in the 
ganglia of mammalia usually consists of nerve-fibres. (16) As nerve- 
fibres grow old, the soluble matters are absorbed, leaving a fibrous 
material which is known as connective-tissue. 
No one can help admiring the beauty of Dr. Beale’s drawings, and 
admitting the accuracy of most of his conclusions. In some cases, how- 
