Organs and Fertilization in Picea excelsa. 353 
overtaking and passing the latter, and is found near the tip 
of the tube with the vegetative nucleus. 
The material for the present studies was collected from 
three grown-up trees on the campus of Cornell University, 
during May and June of 1901 and 1902. The cones of one 
tree had smooth oval scales, while those of the other two trees 
had scales somewhat rhomboidal in shape with wavy margins. 
The three trees looked almost alike in the shape and size of 
the leaves, and in general appearance. Histologically, at 
least so far as the .structure of the ovule is concerned, I failed 
to find out any difference between these two forms. As 
Picea excelsa is exceedingly variable, presenting a number 
of varieties and forms, perhaps little importance should be 
attached to these individual peculiarities 1 . 
Flemming’s chrom-osmo-acetic acid solution of the stronger 
concentration was almost entirely used as the fixing fluid. 
The material was washed, dehydrated, decolorized, and im- 
bedded in paraffin in the usual way. The sections were cut 
usually from 8 to 12 fx in thickness. For staining, Flemming’s 
safranin, gentian-violet, and orange combination was exten- 
sively used. Sometimes this stain was used without safranin 
and gave some good results. 
The present studies were conducted in the Botanical 
Laboratory of Cornell University, and I wish to express here 
my best thanks to Professor G. F. Atkinson for his kind advice 
and helpful criticisms. 
Development of the Male Gametophyte. 
In the mature pollen-grain, just before pollination, the 
central cell is usually divided into the stalk- and generative 
cells, and the disintegrating remains of the first two prothallial 
cells can be seen merely as two thin and darkly staining 
bodies between the stalk-cell and the pollen-wall (PI. XVI, 
Fig. 6). This fact has already been noticed by Strasburger 
(’ 92 ). According to him Larix behaves in the same way as 
1 On the variations of Picea excelsa see Schroter, ’98. 
