Heredity in Protozoa ■ 615 



I Mutilations in adults. Whenever the ectosarc is punctured, 

 the internal contents flow out and the animal dies. But in a few 

 cases mutilations were produced without puncturing the ectosarc. 



Thus, a fine glass rod was drawn across an individual near its 

 middle; leaving a deep constriction, while the two halves of the 

 body were swollen (Fig. 17, a). This constriction persisted for 

 some hours, becoming gradually less marked. The next day the 

 animal was perfectly normal. 



In another similar experiment, blister-like swellings were pro- 

 duced, and the anterior portion of the body became totally irregu- 

 lar (Fig. 17, b). But within 24 hours the normal form was com- 

 pletely restored. 



Thus it is clear that the adult Paramecium has the same power 

 of regulating form that is so well known in Stentor and other infu- 



Fig. 17 Mutilations produced by drawing the tip of a glass rod across the adult animal. See text. 



soria. But this can come into play only when the injury has not 

 been of a nature to puncture the ectosarc and so to cause disinte- 

 gration. 



Many attempts were made to remove only a part of the internal 

 fluid (endosarc), without causing death. The ectosarc was 

 pierced with the tip of an excessively fine capillary glass rod.* 

 But in all cases where any of the endosarc flowed out, the remain- 

 der followed, and the animal died. 



2 Mutilations in dividing specimens. It was thought pos- 

 sible that specimens undergoing fission might show a different 

 physical state of the protoplasm, such as to permit mutilations 

 without immediate disintegration. To a limited extent this was 



*These can easily be made so fine that the tip is apparently not larger than a cilium of Paramecium. 



