14 



Miss D. J. Lloyd. Influence of Osmotic 



A B 

 Fig. 12. 



A. — Gut cells from worm regenerating in 100 c.c. distilled water + 50 c.c. sea-water. 



43 days. 



B. — Gut cells from worm regenerating in 100 c.c. sea-water + 20 c.c. 2|M NaCl. 



32 days. 



g.c, gut cell, v., vacuole. 



section, the parenchyma cells congregate in the region of the wound (see 

 above), but in the solution of high osmotic pressure they only travel to the 

 wound very slowly. The first result of this slow migration appears in the 

 greater length of time required to heal the wound (6-10 days as compared 

 with 3-5 days in sea-water). The next point to be noticed is that the 

 parenchyma cells do not collect together at the hind end to form the mass 

 which is subsequently to become the new tail (figs. 13 and 14). These tailless 

 forms never develop the perforation for the new mouth. They develop a thin 

 muscle layer under the new epithelium, but the circuit of the nervous system 

 is not restored. From the third week after section they develop large 

 vesicular spaces (see fig. 8, 7 and 8, v.) in the gut, or in the pharynx 

 chamber, after 7-8 weeks these become filled with masses of disintegrating 

 tissue, and the animals subsequently die. A similar retardation of the 

 movements of the parenchyma cells is found in the strongly hypotonic 

 media. 



This checking in the processes of restoration is also to be found to a 

 parallel degree in the processes of reduction. For instance, in sea-water an 

 anterior half is completely restored in 8 weeks, and during restoration every 



