I 5O A. J. CARLSON. 



and at the aortic ends. The presence of the communicating branch 

 between the gastric ganglion and the visceral nerves is of interest 

 in view of the statement by Bottazzi and Enriques (1901) that the 

 cerebro-gastric commissure in the oesophagus contains accelerator 

 fibers to the systemic heart (Octopus}. 



9. Tlie Decapod Crustaceans. - - Considerable work has been 

 done on the innervation of the heart in the decapod crustaceans. 

 Lemoine (1868) describes, in the crab, a branch to the anterior 

 and dorsal surface of the heart from the gastric nerve. The gas- 

 tric nerve makes direct connection with the cerebral ganglia and 

 the cesophageal commissures, but not with the thoracic ganglion. 

 The existence of this cardiac nerve or nerve of Lemoine was 

 confirmed on anatomical as well as physiological grounds by 

 Young (1878, 1879), Plateau (1878, 1880), and Moquart (1883). 

 Plateau states that "1'existence du ncrf cardiaqne de Lemoine 

 est incontestable." Both Young and Plateau conclude that this 

 cerebro-cardiac nerve is accelerator in function, and that in addi- 

 tion to this accelerator nerve the heart is also supplied with 

 inhibitory nerves from the thoracic ganglion. Important modi- 

 fications and additions to these results have been made by Jolyet 

 and Viallanes (1892) and by Connant and Clarke (1896). 

 Jolyet and Viallanes found that in the crab (Carcinus) both the 

 accelerator and inhibitory centers for the heart are situated in the 

 thoracic ganglion, and that when the cerebro-thoracic commis- 

 sures are severed, stimulation of the cerebral ganglia or the gas- 

 tric nerve has no effect on the heart. Nor could they find the 

 "nerve of Lemoine" anatomically. In the pericardium they 

 found a plexus of nerve cells and nerve fibers, from which pro- 

 ceed three nerves on either side in a ventral direction towards 

 the thoracic ganglion, but the connection of these nerves with 

 the ganglion was not made out. This pericardial nerve plexus 

 had previously been described by Dogiel (1878). The results of 

 Jolyet and Viallanes were confirmed by Connant and Clarke on 

 the crab (Callinectes). They were equally unable to obtain any 

 anatomical or physiological evidence of the existence of the 

 " nerve of Lemoine," but they traced the connection between the 

 thoracic ganglion and the six nerves which Jolyet and Viallanes 

 had described as entering the pericardial nerve plexus. These 



