and Fertilization in Oenothera. 
309 
become impregnated with the substance (Text-fig. XII, 8), which is coloured 
black with Flemming’s fluid or beautifully stained with safranin, malachite 
green, and iron-alum-haematoxylin in the fixed material. According to 
Werner ( 73 ) those cells which contain the chromatic substance are destitute 
of nucleus due to gradual disintegration. In the material examined by the 
writer, however, they possess sound nuclei (Text-fig. XIII) even at the time 
of endosperm formation ; they are very easily seen if treated with yellow 
prussiate and chloride of iron. Before the first appearance of such impregna¬ 
tion, liquid substance of another kind, which is stained with light green 
in the fixed material and gives a tannin reaction with chloride of iron in 
the fresh condition, appears in the lowermost cells of the inner integument 
and in those of the neighbouring region at the terminal end of the conduct¬ 
ing tissue (Text-fig. XII, 4). 
Text-fig. XIII. Portion of chalazal tissue containing chromatic substance, x 900. 
Then it spreads to the inner cell layer of the inner integument, but 
sooner or later it becomes replaced by the one first mentioned, perhaps 
owing to a chemical change, except that in the upper half of the integu¬ 
ment, which remains unchanged. Moreover, in a mature ovule a cylindrical 
layer of cells surrounding the conducting passage and a sheet of cells in the 
basal part of the outer integument are also filled with granular substance, 
which, in the fixed material, stains also with light green. Though this 
chromatic substance cf the third kind at least may contain tannic substance, 
the chemical nature is left undecided, for the test tried was found unsuccessful 
to determine it. As the cells which contain any of those three kinds 
of the chromatic substance stain light black colour with Sudan III in 
the fixed material, it was found advisable to study the ovules in fresh 
condition. But having no material of Oe. nutans or Oe. pycnocarpa at 
hand, Oe. biennis var. canescens and Oe. odorata were used, which are nearly 
the same as far as the internal structure are concerned. The result is 
as follows : 
