EFFECTS PRODUCED BY CUTTING PARAMECIUM CELLS. 37 



MATERIAL AND METHOD. 



Of the thousands of Paramccinm that I have succeeded in 

 cutting with a scalpel as in the Uronychia work, only about two 

 hundred, of which one hundred and fifty approximately are 

 here described, have given complete records. The cell to be 

 operated i- placed on a glass slide with a drop of water of 

 minimum size and the cell is cut with a fine scalpel under a 

 binocular micro- It i- a comparatively simple matter to 



actually cut the cell in two parts but if the knife pa--es through 

 the macronucleu- r its membrane, the fragment- are u-cless 

 for the nucleti- i- never retained and both parts quickly collap-e. 

 The re-ult- -h..\v a marvellously delicate coordination of the 

 part-; of the cell, a very -li'Jit injury, as the following record- \\ ill 

 -ho\v, throwing the ph> -iol, ,-ical mechanism out of ;<ear. 



Immediately after cuttit '1 the peristoine depiv ion tills 



out, leaving tin- ell periphery perfectly -niooth; the mouth 

 ca\ity, ho\\e\er. does not di-appear but per-i-t- as a miniature 

 cave in the protopla-m. In from fifteen minute- to half an hour 

 atti-r the operation the part remaining of the old peri-tome ie- 

 appear-, movements of translation and rotation are continued 

 as before, but in mosl ell is truncated and the cut 



Mirlace ap|>ear- a- I. .111 < lit and -month a- though a wax model 

 of /',:>,::<< iuni lial been cut \\ith a -harp knil'i-. If the cut cell 

 li\ed tor four hour- after the operation it ua- recorded as .1 



-licce fill e\|)erimellt and tile re-lilt- llefe dr-eribcd \\ere m.nle 

 on i ell- that in\ariabl\ recovered from the -hock of the operation 

 and li\ed at lea-t four hour- afteru ard-. I'la-nient- li\in.L; 

 alter thi- four hour test \\ere ke]>t i-olated in -mall watch ^la-- 

 culture ili-he- in a nmi-t chamber. Tin- culture fluid was 24- 

 hour-old hay tea made by boiling a -mall iiuantii> of ha>- in 

 tap \\ater. The di\ i-ion rate of normal Purnmccinm kept under 

 -imilar c.mditii'ii- varied from one to three divi-ion- ]ier da\ ac- 

 cordinc to the race under nb-er\alioii. 



In th' of I'rnnychin both fra-meiits of the cell re-ulting 



from a -in^le cut. continue to live for at lea-t 24 hours, and 

 frequently -uch fragment- continue to live for three or four days 

 \\ithout rei;eiu-ration. With Pdramccinm, on the other hand, 

 the smaller fragment almo-t always collap-e-. One or t\\o 



