j'j'J Lutz. Triploid IMutants in Ocitot/icrii. 



The remaining 9 may be roughly classified as follows: 



Number of chromosomes 21(?) 24(??) 28(?) 28, 29 or 30 

 Number of individuals 512 1. 



Of the remaining 19 hybrids in which the chromosomes were 

 not examined, the majority appeared, from the nature of their veg- 

 etative characters, to be intermediates (as previously stated). However, 

 several died as young rosettes and several more were dwarfed by 

 their proximity to a lar-e tree, so that a few remain in question, 

 but it is certain under all circumstances that none of these had 

 vegetative characters suggestive of low chromosome numbers. 



It will be seen that we have at least 11 (which I am inclined 

 to believe represents the full number) in a total of 80 which may 

 have been derived from unreduced female germ cells. This is 

 approximately one in every eight and indicates that 0. lata at least 

 may quite frequently produce unreduced female germ cells 32 ). How- 

 ever, it can not be said that the 15-, 28(?)-, 29- and 30-chromosome 

 hybrids are positive evidence of the production of unreduced female 

 germ cells in 0. lata, as it will be later shown that there is another 

 explanation possible (though less probable) for the origin of each 

 of these numbers. 



It is at once apparent, however, that none of the numbers 

 found among the offspring of this cross 15, 21, 22, 23, 28 (?), 

 29 and 30 can be explained on the basis of the union of a 

 reduced female with an unreduced male germ cell. Therefore, 

 while I believe that this phenomenon also occurs occasionally in 

 the male germ cells, and that the union of a diploid female 

 with a diploid male germ cell is the explanation of the origin 

 of the tetraploid condition in 0. giyas, it is probable that unreduced 

 male germ cells are produced much less frequently than unreduced 

 female. The true test will be the approximate determination of 

 chromosome number in 100 or more offspring of 0. yiyas (28) X 0. 

 If/ta (15), for it may be that this phenomenon appears more com- 

 monly in the germ cells of 0. fata than some other forms 33 ). 



32) This statement does not imply that apogamous offspring are frequently 

 produced by 0. lata or any other form. The few tests which I have made for 

 apogamy in 0. Lamarckiana and 0. lata have given only negative results. 



33) In this connection the somatic chromosome numbers of offspring of (). 

 l.innarckiana (14) X () - , ( /ig<*s (28) and the reciprocal, 0. fiiaas (28) X U- Lamar- 

 ckiana (14) become of intense interest. In each case the union of normally reduced 

 male and female germ cells should produce 21 -chromosome offspring exclusively. 

 De Vries grew the former culture in 1905, 1907 and 1908, and the latter in 1907 

 and 1908. He found (6) that, with the exception of certain linear-leafed forms 

 appearing among the progeny of the two crosses, and a dwarf mutant in the 

 culture of 0. Lamarckiana X 0. gigas, the hybrids of these two crosses were all 

 of one type, and intermediate between the two parents with respect to vegetative 



