Notes. 
107 
in my opinion, a matter of some importance ; the study of the 
sporangium in Pteridophyta has long been based upon the examina- 
tion of the highly specialized and strictly constructed sporangium of 
the Leptosporangiatae. The conclusion is, however, becoming obvious 
that such strictness of construction and regularity of segmentation is 
exceptional, and that in the Eusporangiatae such strictness is not the 
rule. 
Other Marattiaceae, and especially Kaulfussia , have also been 
examined, and they are all found to conform to one fundamental 
type, though differing in detail ; it appears that, as regards the sorus, 
Danaea is the least specialized, and Angiopteris the most specialized, of 
the living genera, and that they form a very natural series. Such 
a series in plants of so antique a stock deserves the most careful 
comparative study, and the results should carry unusual weight. 
F. O. BOWER, Glasgow. 
DIRECT NUCLEAR DIVISION IN THE EMBRY O-S AC 
OF LILIUM MARTAGON. — In the course of some work on the 
nuclear divisions immediately preceding the formation of the ovum in 
Lilium Martagon , I have observed the interesting fact that the two 
lower antipodal nuclei appear to be regularly formed by a process 
of direct division. 
The primary nucleus of the embryo-sac divides by the indirect 
method, and the daughter-nuclei divide again after a very short period 
of rest. These divisions have been frequently figured as typical 
examples of karyokinesis. The four nuclei thus formed remain in 
the resting condition for some time, during which the embryo-sac 
increases greatly in length. At first the resting nuclei are all alike, in 
spite of the curious difference in the number of chromosomes which 
go to build up the micropylar and chalazal pair respectively (Guignard, 
Nouvelles fitudes sur la Fecondation, p. 187). But towards the end 
of this resting period the nuclei are differentiated in pairs. At the 
micropylar end the two nuclei have increased little in size since their 
formation. They are usually rather egg-shaped, and are separated 
from the chalazal nuclei by a vacuole which occupies the centre of the 
embryo-sac. The two chalazal nuclei have grown a good deal : the 
upper one is usually somewhat flattened, and the lower one of rather 
irregular outline, fitting neatly into the pointed chalazal end of the 
embryo-sac. 
