PI ARC ITT. 



[VOL. I. 



Not pausing to notice the simpler experiments already referred 

 to, such as the slight incisions, or notching of the margins, 

 excision of tentacles, etc., the first experiments consisted in 

 excising portions of the margin of the umbrella, as indicated 

 in Fig. 2. These were repeated upon about twenty specimens, 

 removing portions of the body between the radial canals and 

 portions including them. The regeneration of such portions 

 was usually quite prompt, varying from two to four clays, 

 depending chiefly and naturally upon the size of the portion to 

 be restored. In every case the regeneration seemed to be 

 perfect, including radial canals, velum, and tentacles. 



In a few specimens all the tentacles were removed by pluck- 

 ing them singly from their very roots with fine forceps. In 



FIG. i. 



FIG. 2. 



these cases regeneration followed in about the same time as in 

 the others, but the tentacles were more slender and delicate 

 than the ordinary ones. 



In the next series the manubrium was excised close up to 

 the stomach cavity, and indeed in some cases including the 

 entire thickness of the aboral body wall. The results were 

 as before, the manubrium being regenerated with promptness 

 and completeness and in about the same time, depending as 

 before upon the amount of matter to be restored. It may be 

 noted in this connection that the excised manubria themselves 

 continued to live, even for days, and to move about by a slow, 

 creeping sort of motion, but did not show any appreciable 

 tendency toward regeneration. The same was true of small 

 particles from almost any part of the body, such as tentacles, 

 bits of margins, etc. No special attention was given to deter- 

 mining from how small a portion of the animals regeneration 



