KNOWLEDGE OP THE MUTATITsG OEIS'OTHEEAS 



51 



Taele VI. 



0, (fir/crs X 0, Lamarclciana^ F^ 

 0, LdmarcJciana x 0, g^gas^ F^ 

 0, gigas x 0, hrevistgh'sy F^ 



62 plants 



969 



19 



17 



0, gigcfS X 0. rvhrinervis^ F^ 



0, rtihrinervis X 0. gigctSy F^ 23 G 



17 



5> 



Fjj 224. A constant, intermediate race. 

 Fg 180. Same as reciprocal. 



Same as above. 



J? 



»5 



J5 



?1 



0. Za^a X 0. gigas, F^ 



0. hiennis X 0. ^?'^(T5, F^ . 

 0. gigcts X 0. hiennis^ F^ . , 

 0, muricata X 0. gigct^^ F^ 

 0. <7?</a5 X 0. muricata, F^ 



133 



84 

 66 



66 

 34 



?j 



>< 



55 



?> 



68 intermediate between 0. lata & 0. gigas. 



65 



?i 



» 



0. Lamarck. & (?. gigas. 



Intermediate type. 



?? 



y5 



?» 



»> 



51 



9J 



»> 



To these may be added the results of Miss Lutz (1909), who from O 



X O 



obtained an P^ of 40 plants, containing three types : (1 

 15 chromosomes); (2) O. gigcts (six plants, each bavin 



0. lata (two plants, each bavin 



about 30 chromoso 



(3) a 



more or less intermediate and variable group of 32 plants, having also an intermed 



number of chromosomes 



3 



In similar crosses, Geerts (1911) reports the following results from counting the 



chromosomes of O. gigas hybrids : O 



O. aiaas cave an F 



1 



o 



lata 



type and a gigas-\\\<iQ lype? both having 21 chromosomes. This is contrary to the results 

 of Miss Lutz, though he omits to quote the latter. O. gigas X O. LamarchioMa and its 

 reciprocal gave a constant intermediate . type, though the Ej contained 21 chromosomes 

 and the Fo are said to contain only 14. That is, though the number of chromosomes 



2 



changes from 21 to 14, there is said to be no change whatever in the external 

 characters. In the lisrht of the results of Miss Lutz above quoted, this may well be 

 doubted. Further, I have shown (Gates, 1909 (/) that O. gigas has conspicuously larger 

 cells in its various tissues, a fact which is imdoubtedly closely connected with its 

 larc^er dimensions. It is, therefore, highly improbable that the nuclei and cells, and 



hence various dimensional characters, of the Fg are identical with those of the F^. 

 Indeed, Geerts's own figures, in the paper referred to, prove that the nuclei, and doubtless 



the cells, are smaller where the chromosome 



m 



smaller, as I had shown 



previously. 



I made the cross 

 plants the following year 



O. Tiamat 



O. gigas in 1909, and obtained an F^ of 40 



ey 



were all identical with O. Lamarck 



pect 



d several which were examined 



tained only 14 chromosomes 



T 



these plants yielded an Fg of 44 pla 



hich 



were indistinguishable 



3 very 



1^0 of 



from 



O. Lamarck 



Of 



course, there is the possibility that an error may have occurred, 

 in collecting the wrong capsule from the original mother plant, but all such errors are 

 guarded against as carefully as possible. 



These facts 



paralleled by a recent result 



Miss D 



(1912) 



ith I*Hmu 



It was found that F.florihmida var. isahellina X T. kewensis gave an Fj resembling 



the seed parent. The former pa 



has 9 chromosomes as x number, while the 



has 18 as x number, yet the Fj contained only 18 chromosomes as 2 :?? numb 



It seems probable that the extra 9 are extruded in the divisions of the embry 



2 



