MORPHOLOGY AND PHYSIOLOGY OF GENUS URONYCHIA 365 



cut into two pieces, if such a neuromotor system exists in Urony- 

 chia. As the immediate effects of tlie injury wore off, the cirri 

 would become quiet and coordinated movements would again 

 be possible with the reestablishment of a neuromotor center. 



•%>-.. . .|p;^,/s.:8^i'^■;•V^.■.V.■Y■, • 



^}^0^^0^--{mr. 





Text fig. C Drawings of two sections (a and b), showing the granular pro- 

 toplasm, the basal bodies (b.b.), and the fibers which join with them (/). The 

 protoplasm is so granular that it is impossible to trace the fibers to any central 

 body or motorium. 



Cells cut in first fifteen nmiutes after division 



Summary of table 1. Thirteen individuals of the species 

 U. setigera were cut into practically equal pieces during the first 

 fifteen nainutes after division. In only one case (no. 26) did 

 both pieces die without dividing. In six cases parts w^hich were 

 supposed to be without micronucleus died without any trace of 

 regeneration. The pieces which were probably provided with a 

 micronucleus regenerated and later divided. In five cases the 

 fragment without a micronucleus showed slight regeneration. 

 That is, the cut surface closed over and new cirri apparently 

 began to form, but it is doubtful whether they would have com- 

 pleted regeneration, for some lived three to five days without 

 doing so. In only one case (no. 50) did the piece without a mi- 

 cronucleus grow to be at all normal. This individual was cut a 

 little to the left of the center in a longitudinal plane (long. B). 

 The amicronucleate fragment was somewhat larger and must 

 have had in it most of the posterior part of the macronucleus. 



