Dr. A. Korotneff on Poljparium ambulans. 217 



turned away. In this respect, therefore, Polyparium makes 

 no special exception. 



Notwithstanding all this, it is necessary to show why the 

 change which we find in the strength of the muscles in Poly- 

 parium has been brought about. This question may be 

 decided upon a mechanical principle. We have seen that 

 the transverse bands [q.m) project strongly into the interior 

 of the gastral cavity, pass over with their fibres to the side- 

 wall (m.b), and in this way form an arch, the points of 

 fixation of which are to be sought laterally upon the side- wall. 

 During movement, in the creeping of Polyparium, the trans- 

 verse fibres are the most active, and when they contract they 

 must, as in .the bent bow, widen the lumen of the interior 

 chamber (fig. III.) . If we could imagine that the above-men- 

 tioned transverse bands projected, not into the interior chamber 



Fig. Til. 



m.b 



a, interior chamber ; h, intermediate chamber ; in.h, side- wall ; st. I, 

 supporting lamella ; q.m, transversa muscular bands ; l.m, longi- 

 tudinal muscles. 



but into the intermediate chamber, then the interior chamber 

 (a) would be closed by their contraction. But we must con- 

 sider that the nutrition of the animal must depend uncon- 

 ditionally upon its movement ; the animal, or the colony, 

 only creeps in order to obtain nourishment, and therefore 

 during locomotion the buccal aperture must remain wide 

 open, in order that the food met with may pass directly into 

 the stomach. Thus it becomes clear that the occurrence of 

 the transverse bands in the interior chamber and of the ver- 

 tical musculature in the intermediate chamber is not only 

 Ann. ds Mag. N. Hist. Ser. 5, Vol. xx. 15 



