04 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
of which is a swelling, the other a resisting tissue. The force for 
bursting the capsule resides in the turgor of the cells of the former 
layer, assisted by the remarkable extensibility of its cell-walls. This 
tissue has no intercellular spaces. L. squamaria has also a “ sling- 
fruit,” but the mechanism for its bursting is different. When the fruit 
is ripe the epidermal cells of the placenta entirely lose their epidermal 
character, and become changed, some of them into thin-walled, others 
into spirally thickened cells, which assist in the detaching of the ripe 
seeds from the placenta. 
In all the species of Lathrsea , all the underground organs, both 
rhizomes and scale-leaves, are provided with stomates ; in L. clandestina 
there are no stomates on the aerial organs ; in L. squamaria they occur 
in the bracts, sepals, and carpels, but are for the most part functionless. 
Crystalloids occur both within and outside the cell-nucleus in L. squa- 
maria , but the two kinds are never found in the same cell ; the latter in 
the epidermal cells of the corolla. In the interior of the corolla of 
L. clandestina is found a ring of stiff unbranched septated hairs which 
still contain protoplasm although their walls are thickened in an annular 
or spiral manner. 
£. Physiology. 
(.1} Reproduction and Embryology. 
Embryo-sac of Myosuras.* — Mr. G. Mann has studied in great 
detail the development and structure of the embryo-sac of Myosurus 
minimus. Among a great variety of observations recorded, the following 
are the more important. 
Division of the archespore into four cells appears to be the rule ; 
though in ovules which are formed at a later period the number is 
only three. The gelatinous swelling of the walls of these cells is in 
every respect analogous to that which takes place in the sporocyte- 
walls of other sporanges, e. g. in the pollen-sacs of Angiosperms, in 
Selaginella, &c. Of several original archespores only one performs 
its function of giving rise to a number of sporocytes, and of these 
sporocytes only one completes its function of giving rise to spores. 
The physiological sporocyte or embryo-sac-cell is at first of the same 
size as the non-physiological sporocytes, but is soon greatly enlarged. 
At a later period food-material appears to pass, through the breaking 
down of cells, to the cells lying at the micropylar end of the embryo- 
sac, i. e. to the oosphere and synergids. The author regards the 
contents of the mature embryo-sac as consisting of eight sexual (female) 
cells. Of these only one, the oosphere, is physiologically sexual ; two, 
arising from different spores, the micropylar and antipodal primordial 
cells, conjugate, and give rise to the primary endosperm-cell; the 
remaining five undergo no further development. The embryo-sac, 
therefore, is not a megaspore ; but its contents divide into four mega- 
spores, two situated at the micropylar, and two at the antipodal end, and 
these again divide into the above-named eight female cells. Although 
the two synergids as a rule undergo no further development, yet they 
may, under special circumstances, perform the physiological function of 
oospheres. The eight female cells derived from the embryo-sac corre- 
Trana. Bot. Soc. Edinburgh, 1892, pp. 351-428 (2 pis.). 
