MATROCLINIC INHERITANCE 
129 
condition for crossing, the uniform first generation culture of mut. 
dehilis did not contain a single plant on which enough flowers remained 
to suffice for all of the crosses. The detailed analysis of the mutation 
crosses is given in Table II. 
In brief, the results of the mutation crosses are as follows: 
typica X semialta — > typica 
typica X debilis — > typica 
typica X bilonga -> typica + yellow twin 
semialta X typica semialta 
semialta X bilonga — > semialta 
debilis X t^^pica — > debilis 
debilis X semialta -> debilis 
debilis X bilonga -> debilis + bilonga 
bilonga X typica — > bilonga + yellow twin 
bilonga X semialta — > bilonga + yellow twin 
With one exception the scheme of inheritance is strictly matroclinic. 
The type of pollen used is immaterial, providing it does not come from 
mut. bilonga. All progenies which did not have mut. bilonga as the 
pollen parent were exactly the same as they would have been if the 
mother plant had been self-pollinated. The fact has already been 
mentioned that progenies of self-pollinated mat. bilonga consist of a 
mixture of green and yellow plants. Every cross into which mut. 
bilonga entered as the pistillate parent showed exactly the same 
mixture of green and yellow plants, of which the former developed as 
normal mut. bilonga and the latter died. It is obvious, however, that 
the crosses with mut. bilonga as pollen parent constitute a real ex- 
ception to the prevalence of matroclinic inheritance in the mutation 
crosses. 
In the case of mut. debilis X mut. bilonga the progeny contained 
both the maternal and the paternal types, the latter in such large 
numbers that it was not possible to view them as having arisen de novo 
by mutation from debilis eggs. Thus the progeny from the cross 
contained 18 plants of mut. bilonga out of a total of 47 plants^. By 
way of contrast, the progeny of the pistillate parent, mut. debilis, 
self-pollinated, included only two individuals of mut. bilonga in a 
total of 62. Mut. bilonga was therefore roughly twelve times as 
frequent in the cross as in the progeny resulting from self-pollination, 
— a difference that one must ascribe to the pollen parent. Incident- 
ally, it seems worth while to call attention to the fact, without attempt- 
