xxxiv Journal of Comparative Neurology. 



next ganglion or pass beyond it. They also form the peripherad fibres of 

 the nerves, into which also enter fibres from the longitudinal commissures, 

 these latter apparently derived from the axial processes of cells in other 

 ganglia. The ganglion cells differ greatly not only in form but also in the 

 structure of the protoplasm. The dotted substance consists essentially of 

 the accessory processes of ganglion cells and branches from the axial 

 fibres. The accessory as well as the axial processes must be regarded as 

 nervous. Neither a direct origin of nerve fibres from ganglion cells 

 without accessory processes to the dotted substance nor an indirect origin 

 of axis-cylinders from the dotted substance occurs. Numerous details 

 respecting peripheral nervous organs are also given. Like the other 

 volumes of this series, this paper is richly illustrated. 



Motor Functions of the Crustacean Nervous Svstem. 



J. Demoorl has attempted localization of the nervous system by ex- 

 tirpation with interesting results. Various portions of the supracesoph- 

 agal ganglion were injured by a thrust with a sharp needle without open- 

 ing the thoracic walls. Four varieties of "forced movements" were pro- 

 duced. Rotation about the longitudinal axis, circus coursing, and 

 somersaults were developed by injuries to various parts of the brain. The 

 motion is always away from the injured side, proving that there is no 

 decussation of motor fibres. 



Injury to the right side of the mid-brain region produces circus 

 motions from right to left ; if farther lateral, there is rolling from right to 

 left and then rotation in a circle in the same direction with somersaults. 

 The authors also find anatomically that there is little decussation of the 

 nerve termini in the central system. There is no specific function in the 

 anterior ventral ganglion, and a destruction of the commissure connecting 

 brain and ventral ganglia does not disturb the function of the eyes and 

 antennae. 



Technique and Memoranda. 



An extremely valuable method of composing diagrams from actual 

 camera drawings of sections is suggested by Schaffer (Zeitsch. f. rvissensch. 

 Mikros. Vn, 3, 1890.) The method consists in drawing the successive 

 sections upon oiled paper which when accurately superposed and held 



1. Etudes lies mauifestatious motriees des Crustacees. Arch. ZooL Exper. et, 

 Gener. IX, p. 191. 



