304 THE AMERICAN MONTHLY [Nov _ 
scale in Pinus, or Larix, corresponds, as is well known, 
with a carpel in the Angiosperms, but differs in that it is 
not folded on itself, but is dorsi-ventrally flattened, and 
bears the ovules upon its upper surface. The bract is a 
scale-leaf, in the axil, and perhaps partly from the upper 
surface, of which the fruit-scale arises. The relative ar- 
rangement of the xylem and phloem in these two struc- 
tures is peculiar, and has a distinct physiological bear- 
ing upon the question. In the fruit-scale we find that 
the phloem is uppermost, and adjacent to the under sur- 
face of the ovule, whilst the xylem is underneath. Inthe 
bract, on the other hand, the xylem is uppermost, lying 
adjacent to the under surface of the fruit-scale, the phloem 
being underneath. In this structure, then, the constitu- 
ents of the bundle have the same relative position as in 
an ordinary bifacial leaf, whereas in the fruit-scale they 
have received a “twist,” whereby phloem is brought up- 
permost. That the phloem should lie next the ovules is 
of importance, for the elements of this tissue merge 
gradually into those of the nucellus and seed-coat, and 
there is thus every facility for rapid diffusion of food 
material during the process of reproduction. Various 
views are held concerning the manner in which the al- 
tered relative position of xylem and phloem is brought 
about, but these need not be here discussed. 
THE STRUCTURE OF THE NUCLEoLUS.—The “definitive” 
nucleus of Caltha palustris offers many interesting points 
for observation. In the first place, its large size, rela- 
tively to the dimensions of the embryo-sac, renders great 
aid to investigation, as also does the comparative ease 
with which sections may be made of the sac in the ovules. 
A longitudinal section of an ovule of Caltha at a certain 
stage prior to fertilization will, if the section be success- 
ful and carefully stained with hematoxylin, safranin, 
and toluidin blue, show us all the structures contained in 
