164 
These two factors operate together on the parietes of the abdomen 
by means of the ligaments, and compel the abdomen to go downward; 
Pe, 
in my opinion the directions of the ligaments even indicate the lines 
along which the different partitions of the central blood 
upon the teguments. 
-organ operate 
Fig. 1. Zpeira diadema. On a sagittal section are represented inter alia: the heart and the pericardial space, 
the ramifications of the aorta into the cephalothorax, the three pair of abdominal arteries (a) and the posterior 
artery (ap), the “ligaments épicardiques” (1—11), some “ligaments commissuraux” (c) and “ligaments hypocardiques” (/2). 
