EFFECTS OF REORGANIZATION 341 



p. 268). On emerging from its cyst the organism is treated as 

 though it were an ex-eonjugant and the first five individuals are 

 maintained as five pure lines of the series. Such series are indicated 

 in the table, p. 336, by an asterisk. The vitality of the first sixty 

 days of a cyst series is compared with that of the parent series for 

 the sixty days following encystment and the results are practically 

 the same as with ex-conjugants. In some cases the cysts are kept 

 dried for a period of weeks or months but this has no effect upon 

 the vitality of the organism when it emerges. In all cases the 

 evidence of rejuvenescence is the same as for ex-conjugants from 

 young series. 



The general results of these experiments with Uroleptus mobilis 

 leave little ground for reasonable doubt of the rejuvenating effect 

 of conjugation. The view of Woodruff and Spencer (1924) that 

 loss of vitality and death here are due to conditions of the milieu 

 seems rather far-fetched when we consider that series after series 

 with the similar sequence of renewed, waning, and exhausted 

 vitality pass by in apparently endless succession, and all in the 

 same milieu so far as it is possible to make it the same, from the 

 beginning of the experiments to the end. It is quite a different 

 question whether or not conditions of the medium can be so altered 

 as to bring about the same results as conjugation. The explanation 

 must be looked for in the protoplasmic happenings at the period of 

 conjugation or of endomixis (see Chapter VIII) . In both cases these 

 result in a rearrangement of the chromatin and cytoplasm which 

 according to Erdmann (1921) gives rise to new sets of autocatalyzers 

 and new cytoplasmic matrices for their activation. 



The general and philosophical aspects of the phenomena described 

 above, particularly those pertaining to the so-called physical 

 immortality of the ciliates, are important or not according to the 

 individual point of view. To my mind the phenomena in these 

 forms lead to the conclusion that Protozoa and Metazoa are funda- 

 mentally alike in respect to protoplasmic continuity and proto- 

 plasmic death, the difference between them is bound up with our 

 definitions of the "individual." So far as immortality of Protozoa 

 is concerned, Hertwig's (1914) conclusions appear to sum up the 

 situation: "However these investigations may turn out, one may 

 say this now, that the doctrine of the immortality of the Protozoa 

 in the form established by Weismann at a time when we did not 

 know anything of the fertilization processes of the Protozoa, cannot 

 be retained. The beautiful investigations of Erdmann and Woodruff 

 do not detract from my conception based on former work and 

 repeated here, but furnish a new affirmation that death in many- 

 celled animals is the result of peculiarities which are present in 

 everything that is alive, and that the life process contains within 

 itself the germ of death and that the harm connected with it (death) 



