EFFECTS OF REORGANIZATION 345 



the so-called mutations in Radiolaria described by Haecker (1909) 

 the observations in this case being somewhat casual and not followed 

 up experimentally so that the matter of permanency is in doubt. 



The extensive experiments on Paramecium made by Jollos 

 (1913, 1923) offer many illustrations of change in organization and 

 subsequent return to normal, sometimes after many vegetative 

 divisions, sometimes after endomixis, and again only after conjuga- 

 tion. The effects of arsenic acid calcium compounds, and extreme 

 temperatures, were lasting through one or more periods of endomixis 

 and conjugation, but such effects were ultimately lost. A significant 

 fact, however, is the difference in effect produced by treatment with 

 arsenic or heat at critical periods. If treated during vegetative 

 life the results were as described above, i. r., 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 Stentor when about to divide, produced individuals in which 

 the original beaded nucleus was unequally distributed, one indi- 

 vidual receiving 16 beads, the other only 3. Both individuals 

 reorganized perfectly after fission, but the one with 3 beads was 

 about one-quarter the size of the individual with 10 beads. The 

 two types were persistent and divided 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 Stentor was suddenly 

 cooled so that the division 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 Stentors was obtained by reproduction, the indi- 

 viduals breeding true for a period of about six w T eeks. An analogous 

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

 scintillans, by treating individuals in the early phase of division 

 with a dilute solution of sodium bromide (16 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 halves were again resolved into one. In this maimer 

 Chatton obtained individuals with two mouths, several micronuclei 

 and only one macronucleus each. On reproduction some of the 



