570 BIOLOGY OF THE PROTOZOA 



arsenic or heat at different periods. If treated during vegetative 

 life the results were as described above, i. e., temporary changes 

 or enduring modifications. If treated during the later phases of 

 conjugation, that is, during the period of reorganization of the 

 ex-conjugant (Jollos calls it the "sensitive" period) then the effects 

 were found to be permanent in a very small percentage of cases. 

 Such changes are evidence of a change in the organization itself, 

 or in the genotype, and were found to be lasting for generations 

 by conjugation. Jollos is apparently right in speaking of such cases 

 as mutations. 



In this connection also we should include the numerous attempts 

 to perpetuate abnormalities in Protozoa. Popoff (1909) by centri- 

 fuging Stenfor when about to divide produced individuals in which 

 the original beaded nucleus was unequally distributed, one 

 individual receiving Ki beads the other only 3. Both individuals 

 reorganized perfectly' after fusion but the one with 3 beads was 

 about one-quarter the size of the individual with 16 beads. The 

 two types were persistent and flivided normally for a short time, 

 the progeny of the smaller form regenerating the normal number of 

 beads. The cultures were then lost so that the further history 

 is unknown. In another case a dividing Strntor was suddenly 

 cooled so that the di^■ision processes ceased. The individual was 

 then placed under conditions of normal temperature, conditions 

 where it reorganized into a single but very large individual. From 

 it a race of giant Stenturs was obtained by reproduction, the indi- 

 viduals breeding true for a period of about six weeks. An analogous 

 experiment by Chatton (1921) was made on the ciliate Glaucovia 

 scintUlans, by treating indi\iduals in the early phase of division 

 with a dilute solution of sodium bromide (Ki to 1000) for ten minutes. 

 The division processes were hastened by the change in osmosis 

 and when nearly divided the individuals were restored to their 

 normal medium where the division planes were lost and the two 

 nearly divided hahes were again resolved into one. In this manner 

 Chatton obtained individuals with two mouths, several micronuclei 

 and only one macron ucleus each. On reproduction some of the 

 offspring were similarly distomous, while some, as with the Uroleptus 

 nioJ)ilis double individual, reverted to the single type. The double 

 individuals were maintained in culture for a period of five months 

 (sic) when they were abandoned, Chatton believing that they might 

 be continued indefinitely by division. Analogous double individuals 

 were obtained by Dawson (1920) by the fusion back to back of 

 amlcronucleate individuals of Oxytncha hi/nicnostonia. The double 

 individuals reproduced double individuals for 102 generations by 

 division. Dawson's monsters ultimately died. The permanence 

 of Chatton's Glavcoma scintiJlans may well be questioned and it is 

 unfortunate that he discarded the race after onlv five months of 



