COMMISSURAL ACTION. 



279 



Fig. 125. 



Pairs of arcs commissure*. 



quently becomes more intimate, and all traces of the 

 original double construction disappear. 



The letters remaining the same as in the preced- 

 ing diagrams, Fig. 125 represents the manner of 

 commissuring across the mesial plane. 



As illustrations of the manner in which these 

 mechanical principles are carried out, the following 



Fig. 12T. 



Fig. i2s. 



Fig. 126, nervous system of the larva of the sphinx li- 

 gustri, showing the successive arrangement of mul- IU trations 

 tiple nerve-arcs from 1 to 11, commissured with from various 

 one another, and all with the cephalic ganglion animals - 

 17, which is their common register. 



Fig. 127, the pupa condition of 

 the same insect, and Fig. 128 the 

 imago. (Newport.) 



Fig. 129, nervous system of the 

 asterias, in its elementary parts. 

 It consists of a series of five gan- 

 glia, gr, g, circularly arranged round 



Fig. 129. 



I 



Nervous system Nervous system of Nervous system of 

 of larva of pupa of sphinx li- imago of sphinx li- 



sphinx ligustri. gustri. gustri. 



the mouth of the animal, and giving forth 

 to each ray a pair of nerves. (Tiedemann.) 

 Fig. 130, nervous system 

 of patella : Z, Z, lateral ganglia, 

 commissured with the cephal- 

 ic, which is between them ; t, 

 the transverse or'subossopha- 

 system of g eal ganglion, commissured in 

 patella - like manner. (Cuvier.) 



Fig. 131, nervous system of sepia octo- 

 pus : C 9 cephalic ganglion ; 0, 0, optic gan- 

 glia ; <?, suboesophageal ganglion ; 1 9 Z, lat- 

 eral stellate ganglia ; a, abdominal or vis- 

 ceral ganglion. (Cuvier.) 



Nervous system of asterias. 

 Fig. 131. 



Nervous system of octopus. 



