504 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
Structure of Hypecoum.* — Prof. E. Martel discusses the structure 
and affinities of this genus, intermediate between the Fumariaceee and 
the Papaveracese. He finds it to exhibit very much the original types 
from which the Cruciferae must have sprung. The sepals appear to be 
organs in the course of atrophy ; the stamens belong to two distinct 
whorls. 
#. Physiology. 
(1) Reproduction and Embryology. 
Embryo-sac of Monocotyledons.-] - — Dr. K. M. Wiegand has shown 
that the two extreme types of embryo-sac formation, as illustrated by 
Lilium and Canna , are connected in a manner not before observed. In 
Convallaria , which represents the transitional type, a septum is formed 
after the first division of the hypodermal nucleus, but not after the 
second. This represents an axial row of 4 cells with 2 septa omitted. 
The remaining septum at length breaks down, so that a single cavity 
results containing 8 nuclei. The single cell of Lilium is therefore 
derived from the 4 axial cells of Canna, not primarily through the 
absence of any divisions of the mother-cell, but by the absence of the 
septa. 
Embryology of Taxus.J — The development of the female prothal- 
lium of Taxus has been traced by Mr. E. J. Durand from one cell of an 
initial axial row of about three cells. The nuclei which result from the 
division of that of the megaspore arrange themselves in a peripheral 
layer, and walls are formed between them, so that the young prothallium 
has the form of a hollow sphere. The hollow centre gradually becomes 
solid from the ingrowth of the cells. The archegones are developed at 
the distal end of the prothallium. The neck consists of four cells, not 
of one, as usually stated. 
Development of the Pollen-grain in Symplocarpus and Peltandra.§ 
— Mr. B. M. Duggar has investigated the development of the pollen- 
grains in these genera, belonging to the Araceae. Division in the 
primitive archespore is of the vegetative type, and the number of 
chromosomes is that of the whole number of the sporophyte. Synapsis, 
or the contracted state of the chromatin thread in the late reticulum 
or early spirem, was found abundantly at a definite period in the life- 
history of these cells prior to actual division. The formation of the 
spindle is multipolar. The first division in general indicates that there 
is a longitudinal division of the chromosomes. In the second division 
the daughter segments separate longitudinally. There is no return of 
the nucleole prior to the second division, but a true dispirem is formed. 
In the division of the microspore nucleus, the nucleus first migrates 
to one side of the cell, and the entering kinoplasm forms a multipolar 
somewhat barrel-shaped spindle. This finally becomes completely 
attached at one pole, forming a truncated cone, while the other pole of 
the spindle may be completely conical. 
* Mem. R. Accad. Sci. Torino, xlviii. (1899) pp. 209-20 (2 pis.). 
t Proc. Amer. Ass. Adv. Sci., xlvii. (1898) p. 430. 
X Tom. cit., p. 430. § Tom. cit., pp. 429-30. 
