VII 



EXPERIMENT ON A URELIA 



355 



in consequence of the shock, to contract rhythmically like an 

 entire specimen, while the central portion sank to the bottom 

 as if dead. Then I made cuts through the outer edge of the 

 ring inwards for 1 cm. between every two nerve-centres, so 

 that the portions which each contained one of the latter were 

 only connected by eight bridges, \ cm. wide, at the inner edge 

 of the rincr. The co-ordination of the movement of the several 

 parts continued still as before. It continued also when I pro- 

 longed half of the cuts till only a thin coimecting strand was 

 left. I also prolonged the other four cuts, and then made 

 alongside each of these another cut in the opposite direction 

 from the internal edseof the 



ring nearly to the natural 

 margin. Thus three of the 

 portions were connected 

 together and with their 

 neighbours only by a flat 

 piece of tissue a few mm. 

 broad, and only directly 

 connected in the direction 

 of one of the diagonals of 

 these flat pieces. Now, 

 the CO - ordination of the 

 contractions of the several 



Fig. 3. 



portions became uncertain 



the more uncertain the smaller the connecting bridges 

 of tissue. Thus it is proved that the several nerve-centres 

 are connected, not by a ring -nerve, but by the delicate 

 nerve -fibrils which pass in various directions through the 

 gelatinous tissue, that is, by nerves which in this case again 

 have by no means the morphological character of ordinary 

 nerves, but which have the appearance of connective-tissue- 

 fibres, and which are not yet united into bundles, into proper 

 nerve- cords. 



I repeatedly observed that the co-ordination of the move- 



