44 On Hybridisation of some Species of Salix 



or, if we add plants of i/-type and those of New type together, we have 



G-type M-type+New type Totals 



1. G-type X G-type ... 187 32 219 



2. ill- type X G-type ... 77 82 159 



3. 3I-type X M-type ... 3 15 18 



Totals ^7~ 267 129 396 



(=67-4%) ( = 32-6°/,) 



As will be seen from the above tables the fertilisation between the 

 (r-type $ and the 6^- type (/ , which we may perhaps consider as 

 corresponding to the self-fertilisation of a certain F^ plant which bears 

 hermaphrodite flowers, gives rise to many (r-type and few ilf-type 

 F2 plants (cf. No. 1 in the above tables). The diametrically opposite 

 behaviour will be seen in the fertilisation between Tlf-type F^ % and 

 ilf-type F2 c/ plants, for then comparatively many ilf-type and com- 

 paratively few G-type plants are produced (No. 3 in the above tables). 

 In contrast to the two above cases the fertilisation between % and </ 

 plants belonging to the two different types gives rise to the offspring 

 of both types in almost, though not quite, equal numbers (No. 2 in the 

 above tables). From these experiments we see that each of the F^ 

 plants, whether 6^-type or il/-type, is heterozygous, and gives rise 

 by a fertilisation corresponding to self-fertilisation in hermaphrodites, 

 not only to offspring of the type similar to itself, but also to a 

 small proportion of those belonging to the other\ The occurrence of 

 segregation of the catkin character under consideration in F^ is thus 

 quite evident ; it must however be remarked that the ratio of the 

 numbers of plants of both types is then very different from the usual 

 Mendelian one. 



Before proceeding further, I must make some remarks about plants 

 marked as " New type " in the above tables. These plants which have 

 arisen in F.^ from either if-type x (r-type (in the ratio of almost 10 7o) 

 cf the above tables) or ilf-type x if-type (in that of almost 28 °/^), but 

 never from (r-type x (r-type, are very similar to those of if-type, and 

 differ from the latter simply by the entire absence of hairs in catkins 

 (Plate I, fig. 5, (/ — ?)^ The catkins of this form appear to be much 

 more intensely black than in plants of (r-type or ilf-type, but this is 

 only apparent, because though the bracts of the two latter are in 



1 "With some reserve in the case of IT-type plants, because I was not able to get male 

 M-typed plants in F^, and have depended upon the fertilisation M-type Fi x ilf-type F2. 



" At least to the naked eye, because examined under the microscope, the bracts of 

 catkins of this form are found to possess a few short hairs. 



