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[VOL. II. 



appear. I did not attempt to determine the position of the 

 new band in its relation to the region of closure of the piece. 

 In several cases in the last two experiments, and in some 

 other experiments like those shown in Fig. 6, A, B l , C l , small 

 pieces were sometimes cut off that contained a part of the old 

 peristome, but which did not fix themselves, or assume the 

 characteristic form. As these pieces were generally small, 

 although not below the minimal size, there can be little doubt 

 that most of them did not contain any part of the nucleus, and in 

 several cases I proved this to be the case by staining the pieces 

 in picro-carmine. The result shows that in the absence of the 

 nucleus a piece containing a part of the old peristome cannot 

 complete the peristome from the remaining part. This is the 



B 1 



D l 



FIG. 6. A, anterior end of stentor cut off and then divided into three pieces. Two of these, 

 B l , C 1 , were apparently without nuclei, and did not produce a new peristome or assume 

 the typical form. 



less to be expected since it has been shown that even in nucle- 

 ated pieces the new peristome is produced not by the old one, 

 but by the development of a new peristomial band. The result 

 is interesting in connection with a result obtained by Gruber, 

 viz., that if a non-nucleated piece containing a part of the newly 

 forming ciliated band is obtained it produces from the band 

 a new peristome. My results show that a piece of the old 

 band cannot act in this way. That the presence of the 

 nucleus is connected with the formation of a new peristomial 

 band seems highly probable, but I can easily imagine that 

 could a non-nucleated piece be supplied with certain unformed 

 elements it might be capable of producing a new peristome. 

 The results do not seem to me to show more than that the 

 nucleus supplies certain products of metabolism that must be 

 present before the protoplasm can successfully carry out its 



