i 74 E. M, Cutting. 
chance of fertilizing an archegonium; and since his paper many 
other investigators have remarked that in those cases in which 
both the nuclei in the pollen tube have an opportunity of fusing 
with an egg-nucleus, two equal male cells were differentiated, 
while in the cases in which only one nucleus could fertilize an 
archegonium either unequal cells or unequal nuclei were formed 
(11), (4), &c. 
This reduction of the male cells seems to me to be connected 
with the differentiation of a smaller number of archegonia. When 
the latter are numerous, as in jfuniperus or Sequoia , they are more 
likely to be situated near each other, and this would necessarily 
offer greater chances of both male nuclei fertilizing an arche¬ 
gonium, while, when the archegonia are few they are scattered 
and offer less or no opportunity. One pollen tube comes thus to 
be restricted to one archegonium, and, as a response to this, the 
male cells and nuclei are differentiated as to size, the larger being 
the effective one in fertilization. As a further reduction we get the 
stage in which the division of the male cell is omitted, although 
two male nuclei are still formed 1 . From this point of view it 
follows that the reduction in the male apparatus follows the 
reduction in the female, and is not coincident with it. A conifer 
with a few archegonia might therefore still possess equal male 
cells if the habit of forming few and scattered archegonia had only 
recently been acquired in that form. 
Several conifers exhibit a great variety in the number of 
archegonia formed. Taxus baccata is a very good instance of this. 
It usually forms about five to eight archegonia, but Jager has 
reported as many as eleven, and Miss Robertson has even recorded 
seventeen. The latter writer also says that two archegonia some¬ 
times occur without any intervening prothallial cells. Taxus 
therefore connects the Pintis - with the Sequoia-aruX jfuniperus- type, 
both in the numerical variations of the archegonia and the 
occasional non-development of prothallial tissue between adjacent 
archegonia. 
An unpublished observation of Professor Blackman’s on 
Pinus sylvestris seems to me to have some bearing on the question 
of a wider distribution of archegonia on the prothallus. A few 
' This latter state might sometimes be reached by passing 
through a stage in which equal male nuclei were formed, but 
only one cell (compare Cephalotaxits drupacea). One would 
however expect any reduction first to find expression in the 
nuclei, for the nuclear division precedes the cell division. 
