INTERACTIONS OF PROTOPLASMIC MASSES. 



tered to pieces upon making contact, after which the animal 

 \\<>uld move off, leaving the remnants of its own and the frag- 

 ment's protoplasm behind. On the 6th, 7th, and 8th days con- 

 tact was followed by a slight shattering of protoplasm, and later 

 some or all of the remnants were appropriated by tlu- reacting 

 nism. On the 9th, roth, nth, and I2th days of coexistence 

 (/DC organism would fuse with a fragment of the other practically, 

 if not quite, as readily as with one of its own fragment >. No 

 Inn her observations were made after the twelfth day. 



SUMMARY or Kxr ERIMENTS INVOLVING IDENTICAL ENVIRON- 

 MENTS. 



By continually interchanging small quantities of media from 

 old cultures of one line of a given clone to new cultures of the 

 oilier line, cross-fusion between the two lines can be prolonged 

 for sixty-five generations (perhaps indefinitely?). After two 

 lines of a clone have ceased to fuse with each other's fragment-, 

 the property of cross-fusion can be restored by: (a) frequently 

 exchanging small quantities of media between the cultures thus 

 bringing them to a common state; (6) frequently transferring 

 small quantities of medium from only one culture to the other 

 thus bringing one line to the condition of the other; (c) creating 

 a different environment in both lines by adding I percent. MU i 

 to the culture medium and then exchanging media between them 

 frequently. Quicker and more satisfactory results can be ob- 

 tained, if members of the two lines to be tested are rultivated in 

 the same container. By this method, two lines of a clone that 

 have been negative to each other's protoplasm for month-, can 

 be brought back to a state of cross-fusibility even though they 

 are removed from the clonal parent by as many a^ Jo<> genera- 

 tions. A normal specimen was put in the same concavit) with 

 an abnormal relative. Though reacting negatively in the be- 

 ginning, they readily fused with each other'- ents <>t proto- 

 plasm after living together for four day-. An unrelated (?) nor- 

 mal specimen was placed in the same container with an al>n< .rmal 

 Arcella. In this case the shattering reaction \\. ( - exhibited until 

 the ninth day of coexistence ; from then on, tu-ioii occurred readily 

 between one organism and pseudopodial fragment- of the other 



