168 BOTANICAL GAZETTE [SEP 
trated nearly half-way down the prothallus. Three nuclei are now 
met with in the pollen tube, all imbedded in a rather dense mass 
cytoplasm. One nucleus is considerably larger than the other 2 
is clearly differentiated from the cytoplasm. The two sma 
(stalk and the tube nuclei), on the other hand, are only with di 
seen in the position described above. The end of this pollen tu 
is shown in detail in fig. 13; and no nucleus except that of the bo 
cell can now be found. A careful and repeated search in this 
adjoining sections of the series (which is quite complete) failed 
reveal any trace of the tube and stalk nuclei, even with an oil-imm 
sion objective. Unfortunately the tube figured was the only one 
showing this stage (all others were before cell division in the pro- — 
thallus was complete), and the figure will probably therefore 
regarded as abnormal; but the whole structure of the ovule and pollen x: 
tube seemed perfectly normal in other respects, the fixation Was 
entirely satisfactory, as was the staining, and there was not the least 
indication that any part of the tube or its contents had washed off 
the slide during staining, etc. The staining reactions of the tu 
and stalk nuclei of fig. ro, together with their absence in fig. I 
indicate that they break down completely and that their substance 
-becomes blended with the cytoplasm. 
The cytological characters of the body cell nucleus are indica 
in fig. 14, and a comparison with the nucleus in fig. 11 suggests tha 
division will shortly take place, giving rise to two sperm nuclei. 
to this point no trace of archegonia or archegonium initials can be see? 
Fig. 15 represents the upper half of the prothallus (and part of 
the nucellus) at a considerably later stage, after the archegonia 
mature and fertilization has been effected.? The distribution of the 
archegonia is very remarkable and recalls that described for Sequoia 
Ps 
time. 
