44 R - T. YOUNG. 



claim as to rhythmical constancy in Paramecium. Certainly 

 variations of from fifteen to twenty-five days in periods never 

 exceeding forty-five days are scarcely in accord with his state- 

 ment "... that once established the rhythmic period charac- 

 teristic of the species is maintained within rather narrow limits " 

 ('176, p. 452). 



In both his joint paper with Erdmann ('14) and his most re- 

 cent one ('176) Woodruff cites Tables I, 2 and 3 ('14, pp. 462-463) 

 as evidence of synchronism of endomixis. Again a careful 

 reading of these tables fails to support his contention. Of 

 twenty-one endomixes shown in Table i for example, fifteen 

 show close or fairly close synchronism, but of these four occurred 

 in lines which had but lecently been branched off from the 

 parent lines, and hence had not yet had opportunity to vary to 

 any considerable degree from the condition of the latter. I 

 refer to the endomixis at generation 4101 in line VIC and to those 

 at about generation 4180 in VId, e, and g. If we reject these as 

 proving nothing one way or the other, we find that out of seven- 

 teen endomixes eleven support Woodruff's claim, while six fail 

 to do so. The exceptions in other words are too numerous to 

 "prove the rule." Of especial interest are those lines which, 

 while only recently started, show a marked divergence from the 

 parent stock, showing that the supposed synchronism may be 

 disturbed within a very few generations (VIb-4O92, VIf~4i89). 

 This fact has been noted by Woodruff and Erdmann ('14, p. 

 461), but passed by with the remark that it "... has no 

 significance from the standpoint of the synchronal appearance 

 of the process in sister lines . . ." Further evidences of lack of 

 synchronism are afforded by line Ilia, generation 4271, Table 

 2 and line V, generation 4115, Table 3. 



Synchronism is better shown in P. caudatum (cf. Table I, p. 

 69, Woodruff and Erdmann, '16) but even here there are a few 

 exceptions (cf. lines I and III, generations 1-9, column i). 

 Other exceptions are shown in line lea, generations 180-270, 

 column 3, and in line le generations 270 to 450, columns 4 and 5, 

 in Table 3 (7. c., p. 71). 



Regarding the synchronism of the same races of Paramecium 

 when bred in different environments, Woodruff's table ('176, 



