T. M. SONNEBORN 315 



the second is typical aurelia; the third is characteristic of variety 

 12. (See pp. 161, 162, 169, 178, 179, 198, 232.) 



3. My variety 15 and Giese's variety 16 are almost certainly 

 identical; both will hereafter be called variety 15. It has two con- 

 stant mating types (XXIX and XXX) with diurnal periodicity 

 stated in the text. It also has two other types (XXXI and XXXII). 



XXXI behaves as if it was XXIX at night, XXX during the day; 



XXXII behaves in the reverse way. There are thus four mating 

 types based upon two mating specificities. Not all strains require 

 tube culture in order to conjugate. Another variety (from Mexico) 

 is now called variety 16; it has the aurelia body size, but multi- 

 micronucleatum micronuclear size, number, and structure (see 

 addendum 2). (See pp. 163, 166, 169, 171, 178, 179, 185, 189, 

 190, 194,198,207,301.) 



4. Beale ( in press ) has found a mate killer in variety 1 of group 

 A. (See pp. 179, 226, 234, 304.) 



5. The short immature periods after these variety 15 crosses ap- 

 pear to be due to macronuclear regeneration. (See pp. 191, 207.) 



6. Newly found strains of variety 13 contain caryonides some 

 of which stay pure for mating type XXV during the period be- 

 tween fertilizations. Autogamy has now been found in variety 13. 

 (See pp. 188, 193, 198, 214, 258, and Table III.) 



REFERENCES 



Austin, M. L. 1951. Sensitivity to paramecin in Paramecium aurelia in 

 relation to stock, serotype, and mating type. Physiol. Zool, 24, 196. 



Austin, M. L., D. Widmayer, and L. M. Walker. 1956. Antigenic 

 transformation as adaptive response of Paramecium aurelia to 

 patulin; relation to cell division. Physiol. Zool., 29, 261. 



Beale, G. H. 1952. Antigen variation in Paramecium aurelia, variety 1. 

 Genetics, 37, 62. 



Beale, G. H. 1954. The Genetics of Paramecium aurelia. Cambridge 

 University Press, Cambridge, England. 



Beale, G. H., and M. Schneller. 1954. A ninth variety of Paramecium 

 aurelia. J. Gen. Microbiol., 11, 57. 



