RELATION OF RHYTHMS AND ENDOMIXIS. 39 



In the graphs of Woodruff's recent papers ('17, a and 6) are 

 shown several instances of low division points without endomixis, 

 viz., in ('170), Fig. 2, periods I and 12; Fig. 3, periods I, and 5 

 and 6; Fig. 4, periods 2 and n; Fig. 5, period 19; and in ('176) 

 Fig. i, A, period 22; AE, periods 2 and 13; O, period n; B, 

 periods 22 and 23, and 27; Fig. 2, A T , periods 3, 19 and 25; AE T , 

 periods 12, 17, 19, 25 and 27; O T period 12 and B T period 23, etc. 



In Fig. 4 ('170) are shown two low points without endomixis 

 which appear to me essentially similar to those at which this 

 process occurred (cf. per. 2 and n). If the latter mark the 

 division point between rhythms, why not the former? In this 

 connection I wish to call attention to the author's words on p. 55 : 

 "During this time nine rhythms occurred at each of which en- 

 domixis was observed. It is hoped that readers who may possess 

 doubts concerning rhythms and endomixis will carefully consider 

 this graph. ^ 



Regarding periods 19 and 25, A T , Fig. 2 ('176) and similar 

 periods elsewhere Woodruff says (p. 446): "A second point of 

 importance is that the 'rhythms' in the division rate are to a 

 certain extent independent of endomixis that is of the definite 

 series of nuclear phenomena because the rhythms persist for a 

 while in the absence of the morphological changes. . . . So, it 

 seems to be a more or less academic question whether rhythms 

 and endomixis are independent. Certainly the rhythms occur 

 for a while without endomixis in sensu stricto but in all such 

 cases- the culture has died before very long." While this state- 

 ment applies to some of Woodruff's experiments it by no means 

 applies to all. Many of the cases cited above, and many other 

 cases shown in his graphs which I have not cited, besides several 

 cases in my own experiments noted by me (/. c., p. 47) disprove it. 

 See for example his own statement (1. c., p. 446) leferring to sub- 

 culture B T , Fig. 2, "From the character of the curve it would be 

 expected at period 23, but it was not observed." 



This leads us to the question of the meaning of "rhythm" and 

 of the influence of the graph in determining the same. Accepting 

 Woodruff's definition of the former as " a minor periodic rise and 



1 Italics mine. 



2 Italics mine. 



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