624 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
Stamens of Solanacese.* * * § — Prof. B. D. Halsted describes a peculiarity 
in the stamens of Solanacese which is quite independent of their 
variable mode of dehiscence in the different genera. The central 
portion of the anther is very fleshy, and is termed by the author the 
“ columella ” ; the pollen-bearing portion being in the form of a very 
broad horse-shoe, while all between is cellular tissue. The wall 
inclosing this pollen-layer often separates early from the columella. 
In Solarium carolinense there are two pollen- cavities in each anther lobe. 
In S. rostratum one of the five stamens is three or four times the size 
of the other four, but the pollen-cavities themselves are no larger. 
Development of Ovary and Placenta.f — Herr B. Schafer has 
traced out the history of development of the ovary and placenta, 
especially in Ailanthus glandulosa, and in the orders Malvaceae, Scro- 
pliulariaceae, Solanaceae, Caryopliyllaceae, Compositae, Campanulaceae, 
and CEnotherese. A point on which he lays considerable stress is the 
area of the receptacle consumed in the formation of a carpel. The 
superior ovary of Angiosperms is the product of the development of 
the carpels (leaves), the axis, especially in the inferior ovary, serving 
only as a support to the carpels. The various forms of placenta can 
always be traced back to a massive development of the margin of the 
carpels ; where the ovules are scattered over the surface of the carpels 
there is no true placenta. The placentation in inferior corresponds 
in all respects with that in superior ovaries. 
Bracts of the Involucre of Composite. — M. L. Daniel draws the 
following conclusions on the structure of these organs : — (1) The 
structure of the bracts nearly always differs from that of the foliage- 
leaves. (2) The orientation of the foliage-leaves being but slightly vari- 
able the types of structure are few ; they are either homogeneous (both 
surfaces alike), or normally heterogeneous (with palisade-tissue on 
the upper surface) ; occasionally one finds the inverted heterogeneous 
type (with palisade-tissue on the lower surface). (3) The orienta- 
tion of the sheath is constant. (4) The orientation of the bracts is 
exceedingly variable. (5) The absence of chlorophyll or the presence 
of lacunas on the two surfaces should not prevent the structure being 
considered homogeneous. (6) A colourless parenchyme with one sur- 
face close and the other provided with lacunae, and a parenchyme of the 
same form, but with chlorophyll more abundant on one of the surfaces, 
belong to the heterogeneous type. (7) The heterogeneous parenchyme 
is not necessarily of a palisade form on the surface most exposed to 
light. 
Stone of Drupes.§ — M. A. G. Garcin distinguishes two types of 
structure in the stone of stone-fruit, — those which are homogeneous, and 
those which are composed of different kinds of tissue. They may also 
be classified into the indehiscent, and those which are partially or 
entirely dehiscent. The former includes true drupes — Prunus , Zizijphus , 
* Bot. Gazette, xv. (1890) pp. 103-6 (1 pi.), 
f Flora, lxxiii. (1890) pp. 62-104 (4 pis.). 
x Ann. Sci. Nat., xi. (1890) pp. 17-119 (6 pis.). 
§ ‘ Contrib. a l’etude des pe'ricarpes charnus. Du noyau dcs drupes,’ Lyon, 1890. 
See Bot. Centralbl., xlii. (1890) p. 343. 
