172 E. M. Cutting. 
Professor V. H. Blackman in his paper of 1898 (1) makes no 
reference to the relative size of the nuclei, but he has informed me 
that in one of his sections he remembers seeing two quite similar 
male nuclei and thg,t they were situated very low down in the 
nucellar tissue just above the archegonia. 
Coulter in 1897 (5) reported the existence in Pinus Lnricio of 
two similar male cells containing two equal sized nuclei 1 , and 
Chamberlain (2) in 1899 confirmed this. In 1901 Miss Ferguson 
(8) made a comprehensive study of the male apparatus in Pinus 
Strobus, P. austriaca (which is merely a variety of P. Laricio), P. 
montana var. uncinata and P. rigida. Working with these she was 
unable to agree completely with any of the previous workers. In 
every case two unequal male nuclei were formed, but these re¬ 
mained embedded in one naked mass of protoplasm, no wall being 
formed between them. 
In some serial sections of Pinus sylvestris ovules, prepared for 
demonstration purposes, I have observed several pollen-tubes con¬ 
taining male nuclei, and in all these cases there was only one cell, 
and enclosed in this two unequal nuclei. The smaller nucleus was 
directed towards the micropylar end of the nucellus, and in some 
cases lay quite close to the boundary of the protoplasm of the cell. 
The difference in size of the nuclei was more marked in those pairs 
which were near the archegonia than in those which were near the 
top of the nucellus. I am inclined to interpret this observation, as 
Miss Ferguson did in the case of Pinus Strobus (8), that is to say 
that in their journey down the nucellus the difference between the 
nuclei gets more and more pronounced. The instance noticed 
above, when Professor Blackman found equal male nuclei quite 
near an archegonium, seems to be against this view, and suggests 
that Pinus sylvestris presents a state of affairs intermediate between 
Pinus Strobus (8) and Pinus Laricio, as described by Coulter (5), 
forming at one time equal and at another time different grades of 
dissimilar nuclei. That is to say, if one regards the form with 
the equal nuclei as more primitive than the one with the unequal, 
Pinus sylvestris is a transition form from one state to the other. 
There seems to be no a priori reason against one species of a 
genus having equal male nuclei while another species has unequal. 
Indeed, such a case has been recorded in the genus Cephalotaxus, 
1 Coulter’s figure showing the pollen tube in this condition is re¬ 
produced in Strasburger’s Text Book of Botany, 3rd English 
Edition, 1908. 
