200 THE MICROSCOPIST. 



another, the nucleolus. Dr. Beale discovered certain gan- 

 glion-cells in the sympathetic of the tree-frog (in the au- 

 ricular septum of the heart), one of whose poles is encir- 

 cled spirally by the others (Plate XXI, Fig. 156). 

 ' The ultimate structure of ganglia or nervous knots, 

 and the relation of the fibres to the cells, opens a wide 

 field of research. In the muscle of the heart, etc., many 

 of these ganglia seem to form special nervous systems. 

 Dr. Beale has described the nerves ramifying on the capil- 

 laries and involuntary muscular fibrils of the terminal ar- 

 teries as a self-regulating mechanism for the distribution 

 of blood (Plate XXI, Fig. 157). Thus, if a tissue receives 

 excess of pabulum, the capillary nerve-fibre is disturbed 

 and transmits a change to the ganglion, and thence 

 through the efferent nerve to the muscular fibres of the 

 artery, and vice versa. 



Meissner has shown many ganglionic plexuses in the 

 submucous coat of the alimentary canal. Another system 

 of the same kind, called the plexus myeniericus, was dis- 

 covered by Auerbach between the muscular layers of the 

 intestinal tube. Similar plexuses exist in other organs. 



As to the peripheral termination of nerve-fibres, there 

 is still considerable discussion. Most of the German his- 

 tologists consider the nerves of voluntary muscles to ter- 

 minate in end plates, in which the neurilemma becomes 

 continuous with the sarcolemma of the muscular fibre. 

 Dr. Beale maintains that there is a plexus of minute nerves 

 over the fibrils. In some of my own preparations, espe- 

 cially some stained with soluble Prussian blue, a disk 

 formed of a plexus of excessively minute nerve-fibres is 

 observed, from which tortuous branches go to other mus- 

 cle-fibres. 



In the cornea, Cohnheim and Klein have traced fine 

 nerve-fibres to the epithelial cells of the conjunctiva, by 

 means of chloride of gold staining. 



3. Glandular tissue consists of a fine transparent mem- 



