and Fertilization in the Hemlock Spruce . 587 
frequently finds three or four cells in the neck of a mature 
archegonium (Figs. 8-10). Differences of opinion concerning 
the number of neck-cells in the archegonia of Tsuga are 
probably due to the fact that the division often occurs late. 
After examining a large number, I must agree with Hofmeister 
that two cells are more frequently present than any other 
number. Had Mottier (1892) examined more of the mature 
archegonia, he would have probably found two cells even 
more frequent than he supposed. 
Returning to the condition of the central cell after the 
neck-cell was cut off, it will be remembered that it tapers 
towards its lower extremity and is almost entirely free from 
protoplasmic contents. Though its nucleus remains at the 
apex just beneath the neck, rapid changes take place in the 
form and contents of the cell. It increases greatly in size, 
and a delicate reticulum appears with numerous vacuoles in 
its meshes containing cell-sap (Fig. 11). Enveloping the 
central cell is a sheath of cells rich in protoplasm which 
furnish the central cell with food, the endosperm still growing 
vigorously and crowding back the disorganized nucellar 
tissue. In place of the delicate network shown in Fig. 11, the 
central cell soon shows spherical vacuoles filled with granules 
and other food-masses (Fig. 12). These appear first at the 
periphery near the food-cells and later come to occupy the 
whole cavity, with the exception of one or two large vacuoles 
at the centre. A transverse section of a prothallium with 
five archegonia at this stage is shown in Fig. 16. 
I cannot confirm for Tsuga the results of Arnoldi’s recent 
studies (1900) on the proteid vacuoles of the Abietineae. It 
may be that further search on my part will reveal the passage 
of the nuclei of the sheath-cells into the central cells, but 
very careful examination of numerous archegonia in all stages 
of development has thus far failed to show a single un¬ 
doubted example of such passage. I find the nuclei of the 
sheath-cells staining diffusely at times, as described by Ikeno 
(1898) for Cj/cas } and I observe collections of granules in the 
outer vacuoles of the central cells which very much resemble 
