528 CANNON: STUDIES IN PLANT HysBrIDs: 
EXPRESS X SERPETTE 
Like Fillbasket x Debarbieux, this isa second generation hybrid, 
and it also, as has been described in a preceding paragraph, shows 
the splitting into several types after the law of Mendel. ‘The re- 
version of Express x Serpette as regards the quality of size and 
form of the plants is fairly well indicated by f, 34-37, where the 
pure parents are also represented. It should be noted that the 
sketches are drawings from photographs and that the plants were 
photographed at the same time and under precisely the same con- 
ditions, so that the figures faithfully reproduce the relative forms 
and sizes of all of the plants. 
The sporogeny of Express x Serpette corresponds closely in 
the points examined to that of Fillbasket x Debarbieux, although 
in certain regards, which will be indicated, a difference between the 
two was noted. Also some phases of development were repre- 
sented in my preparations of Express x Serpette, not found in 
those of the other hybrid, and these will be mentioned, in addition 
to the preceding, rather than a more complete account. By this 
method I shall avoid unnecessary duplication; the two hybrids 
are so nearly alike in the matter of spore origin and development 
that a description of these processes in the one would for the most 
part answer perfectly well for the other. 
The series representing the nuclear divisions in young anthers 
was not so complete in Express x Serpette as in Fillbasket x De- 
barbieux, and possibly for this reason I have not so complete evi- 
dence of the association of the chromosomes in pairs in the last 
sporogenous division in the former as in the latter hybrid. It 
was observed, however. An apparently good example of the 
pairing was seen where perhaps one would not expect it, namely, 
in the division by which the sporangial wall is separated from the 
inner sporiferous tissue. The outer cell resulting from this division 
by further division gives rise to three series of cells, the inner of 
which forms the tapetum ; the inner cell of the division noted be- 
comes converted without further division into a spore mother-cell. 
The division referred to occurs rather late in the pea. Both of 
the nuclei resulting from this division had their chromosomes ar- 
ranged in twos. If the curious association of the chromosomes 
