EFFECT OF CONJUGATION 359 



experiment, not even mentioning the number of cases examined; 

 but some cultures obtained from the split pairs were kept as long 

 as three months: 



Als erstes Resultat ergab sich mir eine auffallencle Fruchtbarkeit der 

 an der Conjugation verhiiiderten Thiere; obwohl ich meine Versuche 

 noch nicht abgeschlossen habe, so mochte ich jetzt schon hervorheben, 

 dass die klinstlich getrennten Thiere lange Zeit iiber sich energischer 

 theilten als Paramaecien, welche die Conjugation durchgemacht hatten 

 ('89, p. 223). 



These observations led Hertwig to endeavor to save the theory 

 of rejuvenescence through conjugation, by holding that lack of 

 conjugation results in a rate of fission so great as to be harmful; 

 conjugation would then rejuvenate by slowing and regulating 

 this immoderate rate of reproduction ('89, p. 226). 



But the facts appear to be clear, so far as the infusoria go. 

 In view of the large number of experiments made by Maupas on 

 this point, the absolute agreement of his results with those of 

 Richard Hertwig; the fact that these men are perhaps the most 

 thorough investigators that have ever worked along these lines; 

 the further fact that there exist no careful experimental results 

 opposed to these; and finally, the very large body of evidence 

 presented in the present paper, all giving the same results — is it 

 not time that the statements or implications that in the infusoria 

 conjugation results in increased reproduction should disappear 

 from the literature of science? 



EFFECT OF CONJUGATION ON MORTALITY 



The experiments show that as a rule mortality is much higher, 

 under the same conditions, among those that have conjugated 

 than among those that have been prevented from conjugation. 

 This is true both for conjugation among unrelated individuals, and 

 for that among individuals belonging to the same pure strain. 



Accidental influences increasing the death rate quite without 

 relation to conjugation are so numerous, especially in experiments 

 carried on under uiifa\'orable conditions, that here the principle 

 is particulary important that one extensive experiment carried 

 through under ideal conditions, without extrinsic disturbing 



THE JOURNAL OF EXPERIMENTAL ZOOLOGY', VOL. 14, NO. .3 



