EFFECTS PRODUCED BY CUTTING PARAMECIUM CELLS. 39 



difference in the percentage of successful results in the different 

 races I shall not particularize but will deal with them all as of 

 OIK- race. I "p to the present in these experiments, no systematic 

 effort has been made to study the regenerative power at different 

 period- between division phases, as in the studies on I'ronychia. 

 Tin- percentagt of cases of regeneration was so small that -uch 

 .1 stud} -eemed valueless, but with a race now under experi- 

 mentation more -ati-factory rc-ults are expected. Of the -even 

 f regeneration obtained in the one hundred and forty- 

 nil)- rei.,rded. five \\ere cells that wen- cut while 

 either di\idin^ or conjugating. re-tilt- indicating tliat not only 

 di\ i-ion a^e bin ra< ial age i- al-o a potent factor in regeneration. 

 Further work on tin- pha-e of the -ubject i- now under \\ ay and 



uill undoubtedly yield interc-th Its. 



In the follouiiu table- the experiment- are grouped according; 

 to tlie region df the cell on-inally cut. The cell i- by no mean- 

 hoi! QUS and the different portion- are not equipteiit. It 

 \\e imagine the /'.; :ini \]]<^ diameter to be di\ided into 

 I oi 11 equal pan - by three cut-, t he cent ral "lie would pa-- through 

 the |ilaiie of di\i-ioii o| tin cell, the upper one would divide the 

 anterior hall into t\\o di-Hinilar quarter-, the lower one \\oiild 

 di\ide the po-terior halt of" the Paramecium into di imilar 

 qiiarlei--. In the table-, the /one- indicating the-e -exei'al 

 (jiiai lei- are numbeie. 1 from One to four, 1 bein^ the in.i-t anterior, 

 2, the next anterior. ;, the po-terior central /one and 

 4 tin- terminal p-.-let i-.r /one text li-un t The 

 mo-t ini|ioi lain - of the cell are contained in 

 /oiu-- J and 3, /one j coin ainin;; the macro- and 

 mii-roinicleii-. and /one ^ containing the mouth, 

 /one- I and 4 do not contain any of' the more im- 

 portant organs, and yet, as the -equel -how-. th< 

 pan- it injured are ratel\ replaced and their ab-eiu e ha- a re- 

 markable elleci on further acti\itie- of the cell. 



