1915] MICHELL—STRIGA LUTEA 129 
Changes in endosperm and testa 
At a very early stage in the formation of the endosperm, the 
outer wall of the outermost layer of endosperm cells becomes 
cutinized, and it is clearly impossible that food can pass through to 
the embryo, which must therefore derive its nourishment through 
the haustoria. 
As the embryo grows, absorbing the food stored in the endo- 
sperm and integument, the walls of the outer layer of the endosperm 
become thickened, but are still composed of cellulose. It is these 
thickened cells which compose the endosperm in the mature seed. 
Proteid reserves alone are found, neither starch nor oil being 
present. 
There is no well defined tapetal layer around the endosperm as 
is the case in most Scrophulariaceae already investigated. 
All the food stored in the integument is absorbed by the haus- 
toria and only the outermost layer of the integument persists in the 
mature seed. This layer undergoes a good deal of change. Its 
radial walls increase in size, assume a wavy outline, and become 
lignified. It is to this last fact that the brittleness of the testa 
is due. 
It is a well known fact among farmers that the seed of Striga 
lutea may retain its capacity for germination for several years (11), 
owing no doubt to the protection afforded by the lignified testa and 
cutinized outer wall of the endosperm, as well as to the reserves of 
proteid material in the endosperm. When to this is added the fact 
that each ovary produces hundreds of seeds, practically every one 
of which is fertile, it is not difficult to realize why it is that this 
plant is so difficult to eradicate once it has obtained a hold on a crop. 
Discussion 
Since the middle of the last century the ovules of the Scrophu- 
lariaceae have from time to time been the object of investigation. 
Among the earlier workers on this subject-are to be found DEECKE 
(6), TuLasNne (15), HormeIsTerR (9), CHATIN (4), and others. 
It is rather interesting to note that Pedicularis sylvatica was in 
1855 the subject of a violent controversy between DEECKE and 
CHACHT on one hand, and HorMEIsTER, VON Mout, and TULASNE, 
