26O WALDO SHUMWAY. 



constituent parts, which shortly assumed the typical Fron- 

 tonia leucas appearance. 



While the writer has not actually observed the process of 

 transformation from the two-cell to the four-cell stage assumed 

 above, he feels convinced from the facts cited as well as from 

 sectioned material in which the macronuclei of the two anterior 

 and the two posterior cells seem to have just undergone division, 

 that these chains are formed by two successive transverse divis- 

 sions without separation of the daughter cells and not by a single 

 quadrupartite or by three successive terminal divisions as 

 might be argued from a priori grounds. 



Division preceded by encystment is not unknown among 

 the free-swimming ciliates. In Otostoma carteri and Ampliilep- 

 tus meleagris according to Saville-Kent the divisions are some- 

 times multiple, but the daughter cells separate immediately 

 after each division. 



Chain formation too is not unknown among the ciliates, 

 although heretofore it has been observed only among the asto- 

 matous forms parasitic in the digestive tracts of vertebrates. 

 In these parasites, however, the chains are often of great length 

 and are formed, so the weight of evidence appears, by a process 

 of terminal budding. For an excellent discussion of these forms 

 see Cepede (1910). 



Jennings ('08) records a strain of Paramcecia appearing 

 in his cultures which had apparently lost the power of separation 

 after division. The general appearance and weak vitality of 

 these forms, however point to the conclusion that Jennings was 

 dealing with a weakened pathological race and not a genetic 

 mutation. 



The frequency with which these chains appeared, nearly 

 ten per cent, of all the Frontonia observed, leads the writer 

 to conclude that the phenomena described in this paper form 

 part of a normal method of reproduction. 



I have made attempts to raise these forms on hay infusion, 

 rotten lettuce infusion (recommended by Popoff, '08), thyroid 

 extract and the filtered water of the medium in which they 

 were discovered. All were unsuccessful. I have been unable 

 to maintain isolated individuals in Syracuse glasses of their 



