A NK\V SPEI [ES OF PA RAM EC I I'M. 525 



true <>f the individuals in which luit two or tlmv micronuclei 

 u.-re found, other- e\i-iin- lut in a les- vi-ible location. 



Finding ihu- that tin- cultures in hand contained nothing but 

 thi- -aim- type of Paramecinni, I next pron-edi-d to u-t the per- 

 manence of the type. On October o. I i-ol.ued live indi\ idual-, 

 pl.t, i h in a rle.m watch glass c< mtainini; a definite pro- 



portion -.f -terile and bacterially infected water. Thc-e indi- 

 vidual-, however, lived but .1 day. I then a^ain -elected live 

 more, \ar\inu tin- proportion- of the- fluid media. Of the-e. the 

 l u . i which were pl.u ed in u ater c miaininv; the hi'Jie-t perceir 

 of ba<teria lived, uhile the other- did not. Three more were 

 Marled in the -ame manner ,1- the t u successful ones and all 

 the' e lixinu cultures. ( >\ the li\e li\iirc culture- thu- 



obi, lined tuo pp.\ed much -iron-er than the other-, de-pile the 

 lh. it the condition- \\ere kept as con-t.mt .1- po--ible in all 

 two iii' I rapidly in number-, uhile the other- 



but litlle and lill.tlK died olll allel li\e \\eek-. 

 the-e tuo strong culture-, |ott\ in. li\ idual- were kill..!, 

 -t. lined .ind mounted on \o\einber JJ and about lill\ more OH 

 I ). . ember 17. All of ihe-e pi . '\ ed identical in l\p- uith tin- 

 ori-inal uild stock. The minute micronuclei \\.re pre-eiit .1- 

 before, and ,uain -eeiiie.l (o \ar\ from ihr.e to -e\eii in number, 

 uhich ditleieiice .|e|u-ii<led. in |iart at least, upon the -lain and 

 the iraii-pareiic\ of ihe indi\ idual. 



Unfortunately during <'hri-tma- \\eek extreme ...Id uealhcr 

 and |),ulial failure of heating (ilaiit c.m-ed the death of .ill i-..l,i- 

 tion culture-, the ..luinal cullure. houe\ mainin. 1 rom 



thi- lailer. -in^le individual- Wl iiu i-olated and neu cul- 



ture- -I art ed on January 1\ , the culture media I tried OS in 



|)n-\ ion- in-i.ince-. Thi- re-ulted auain in culture- of \ar\ini; 

 degrees of -irengih. One of the best, which I will de-i-n.ite as 

 culture X. u.i- chosen and le-ted \>\ mounting a number of 

 individual- all of uhich a^ain i>ro\ed [ be of the mull imicro- 

 nucleaie t\pc. Thi- culture X was now accordingly taken as a 



basis for all furllu'r uoik. l ; roin it -ix culture- were -larted, 

 the medium bi'invi modified in (hi- case b\ ihe u-e of different 

 pro|)ortion- of agar agar infected uith the customary bacteri.i. 

 Of the-e six culture- one, culture V, \\a- \\orihy of e>pecial 



