438 TVD E. [VoL. IX. 
the posterior nerve, the appendages beat about in all directions. 
Therefore, the posterior nerve contains also sensory fibres. 
(c) The anterior nerve was exposed, ligatured, and cut ; no 
movement occurred when the electrode was applied to the 
distal end. But each time that it was applied to the proximal 
end, the appendages beat about and the carapace moved. The 
anterior nerves contain consequently only sensory fibres. 
(2) The abdominal cord was cut, and when the posterior cut 
end was stimulated with the electrode, the gill-plates posterior 
to the cut made inspiratory movements. 
G. Experiments on the Lateral Nerve Chains. 
The lateral nerve chains, as was said, extend on each side of 
the abdominal cord. They receive fibres from the anterior 
nerves, and are considered, by some authors, to be the Sympa- 
thetic System. 
Both the right and left chains were exposed, ligatured, and 
cut, and the proximal and distal ends stimulated electrically, 
mechanically, and chemically. In every case the stimulus pro- 
duced no apparent effect. Several hours after the operation 
the respiratory movements were quite normal. The lateral 
chains exercise, therefore, no influence over the respiratory 
movements. 
II. REGULATION OF THE RESPIRATORY MECHANISM. 
We know that the respiration of higher animals is influenced, 
among other causes, by muscular activity, sensory stimuli, and 
the condition of the medium surrounding them. 
It became of interest to know whether the respiratory move- 
ments of Limulus were also affected by these. For this 
purpose several experiments were made, of which the following 
are the chief ones: 
A. Variations of Respiratory Activity. 
(a) The following experiment was made to ascertain if 
muscular activity had an influence on the respiratory acts of 
Limulus. If the second ganglion of the cord is extirpated, it 
