534 
Reginald Ruggles Gates 
mother cells it was believed to be more accurate to treat tbe cell 
as a sphere, taking the average of the two dimeusious as its dia- 
meter. The result differs but little, however, if the volume is com- 
puted as in the epidermal cells, squariug the longer dimension and 
multiplying bv the shorter (Tables II and III). 
Comparing the volumes of the cells in gigas and La- 
marclciana in tbe petal epidermis tliey are seen to be al- 
most exactly 2:1, in complete harmony with Boveri’s law. 
The surface cells of the Stigma, however, are almost ex- 
actly 3:1 on the same basis of compntation. Of course it must 
be recognized that owing to deviations of the cells from the rectan- 
gular shape as well as variations in the unmeasnred dimension of 
the cells, the ratio can probably be regarded only as approximate. 
Nevertbeless, such a great difference in cell size as indicated by 
the ratio of 3 : 1 iustead of 2 : 1 shows that these size relationships 
must vary in different tissues. It is probably safe to say that the 
cells of the petal epidermis are approximately twice as large in 
gigas as in Lamarckiana, wliile the surface cells of the Stigma are 
approximately three times as large. An explanation of such diffe- 
rences can only be suggested. It is probably due either to a diffe- 
rence in the size of the chroinosomes in stigma and petal of an 
individual (wliich would result in a change in the Kernplasma relation) 
or to an independent change in the Kernplasma relation without a 
change in the size of the cliromosomes, or to botli. The chromo- 
somes of the pollen mother cells are very much larger in Oenothera, 
as is usually the case in plants, than those of the somatic cells. It 
is probable that less marked differences in chromosome size also 
occur in different somatic tissues, though I have not made measure- 
ments to determiue this. Neither have extensive counts of the 
number of cliromosomes in the somatic cells been undertaken, but 
wlien such counts have been made in flower tissues I have always 
found them to be the same as in the pollen mother cells, so 
that the number is probably in most cases quite constant in these 
tissues. The tapetum however is an exception, as these cells soon 
become multinucleate and the late nuclear divisions are frequently 
amitotic. 
Further measurements of the nuclei of these tissues have not 
been made, to determiue whether the Kernplasma relation is diffe- 
rent in different somatic tissues, or whether as is more likely, the 
sizes of nucleus and cell vary together. If the latter alternative 
