KFFKCT OK (O.X.HCA'noX />.>.) 



(liftoi-('Ut l);ict(M'ial coiitcnl from ihal of another, tlio animal- of 

 (liflVrciil \\\\v> were fi'(>(ni<'utly inlcrcliaii.n'cd : line 1 l)('iii<^' traiis- 

 fcn'cd into a droj) in which line '2 has been h\'inii, and \ic(' xcrsa. 

 I'lic (h'ops were for the same i)ni'|)os(> frccincnlly int('rmix('(L 



]f two snch lines as ?\o. 1 and \o. 1() (of the eoiijuoants) sliowed 

 in i]io loll,*;' rnn about the same i-ate of hssion, hut with accidental 

 fluctuations from jx'i'iod to pei'iod, then of coui'se in some periods 

 No. 4 would show a <;reater number than Xo. Ki, whilc^ sonu^times 

 the re\'erse would occur, ^\'hen we find }iowe\"er tliat such a 

 line as Xo. 4 has uniformly a tireatei- iunnl)er of fissions than 

 another, and this contimies foj- so lonji a tiuu^ as ten weeks. with 

 no external differences to cause these results, wv must conclude 

 that the lines themseh'es are diffei-entiated. 



^^'e may make then as tlie test of inherited differentiation the 

 condition that one line shall show in e\-(M'y one of the fi\'e periods 

 of table 33 a distincfly higher fission rate than another. This is 

 an extremely severe test, and one that is be^'ond question more 

 than sufficient to show actual inherited differentiation. In the 

 slow process of ex]ierimentation th(\se repeat(Hl differences are 

 most striking and surpi-isino-. Qui' first ])eriod C()\(>rs eighteen 

 days; during this time one finds that conjugant Xo. 1 divides 

 more rapidly than Xo. S oi- X'o. Ki. To test the matter, the three 

 are kept under identical conditions for twehe days longei- (second 

 period). Again Xo. 1 shows the highest rat(s Xo. S a lower on(N 

 X^). 1() a still lower one. To mak(^ assurance doubly sure, W(^ 

 keej) them fourteen days moi'(> (third pcM-iod); agaii'i they show 

 the sairi(^ relative rates, ^^'e k(>e)i them a fourth piM'iod of tw(4ve 

 days; a fifth one of fourteen days; these confirm the differenccvs 

 shown in the first three periods. There can be no iiuestion but 

 that the cause of the dixcrsities is in the lines tluMnselv(\s; in 

 other words there is differ(Mitiation inherited from generation to 

 genei'at ion. 



On this basis it is cl(>ar that among the conjugants, X^os. T, 

 S and Ki I'epresent three lines with inherited diff(M'(Mitiat ion in 

 rat(M)f fission. It is hardly doubtful i)ut that other different iated 

 lines exist, accidental fluctuations bi-inging these ecjual to one 



