38 DR. MARGARET BENSON, MISS E. SANDAY, AND MISS E. BERRIDGE ON 
The absolute-aleohol material was removed after two days into methylated spirit, 
where it was left to harden for a week, and then transferred into a mixture of equal 
parts of absolute alcohol, glycerine, and distilled water for preserving. 
The material fixed in weak Flemming’s solution was placed, after about two hours, 3 
in 5 per cent. chromic acid solution for 16 to 18 hours, then washed in running water A 
for several hours. The material was finally passed up through alcohols of increasing ; 
strength into methylated spirit, left there for a week to harden, and transferred l 
eventually into the same preserving mixture as before. | 
The strong Flemming material was treated in the same way, except that it was left in 
the fixing reagent for a somewhat shorter period. | 
To prepare for microtome sectioning, as much extraneous tissue as possible was | 
removed from the ovules, which were then passed through absolute alcohol, bergamot 
oil, and paraffin of various melting-points, being cut finally in paraffin of 52 degrees 
melting-point. The sections were mostly cut of the thickness 16 u. 
Two stains were used, viz. Flemming's triple stain and Ehrlich's haematoxylin. | 
The former stained well after fixing in Flemming's solution, and the best examples of 1 
nuclear fusion were obtained with it, the male gamete being differentiated from the [ 
other nuclei by a redder tint; it did not, however, stain the pollen-tubes readily. This 
Men A more successfully with the hematoxylin, especially after fixing with absolute 
aleohol. 
We wish to record our obligation to Miss Sar 
in selecting the best methods for this 
critieism throughout. 
gant for most generous preliminary help 1 
piece of work, and for her kind advice and . 
STRUCTURE AND DEVELOPMENT OF THE EMBRYO-SACS. 
The embryo-sacs, while still isodiametrie, 
teristie of the Angiosperms. 
the base of the nucellus, and 
contain the normal polar groups chara | 
They very early develop long cæca, which may penetrate 
o eee | frequently become much swollen. The antipodals remain 
UE lodged in their original position, and thus appear to project into the neck of the caecum. 
e The upper polar nucleus attaches itself to the one from the antipodal group, and the i 
io descend ihe cecum together, generally becoming fused on the way, and formin 
ay ahi Eom nucleus which is found in the basal part e the fully develop 
eS awaschin states for Corylus that the polar nuclei do not fuse until fertilization has 
Wig Pas but tbis is certainly not the case in Carpinus, nor in Castanea (Trans. 
ar Soc. ser. 2, Bot. vol. iii. (1894) pl. 67. fig. 21), for, in both, definitive nuclei are 
found in unpollinated sacs. 
| To return to Carpinus. A considerable number of embryo-sacs, such as have ` en 
: uo os ov ia in one nucellus, and it is not unusual to meet with | 
ap ges ipe. its definitive nucleus, in one longitudinal section. Af! 
| 5 f Penn. nds i ar | E reds of slides showing unfertilized ovules, the uniform charac E 
d PE Yy uec becomes very familiar. In such sacs the egg-cell is always naked, 
