Self- digestion of the Endosperm of some Graminaceae . 461 
two days wholly lost the amyliferous tissue, nothing remaining of the 
sections but the aleurone layer and seed envelopes. 
Hence it may be concluded that in the Rye endosperm there is a 
cytase which is not confined to the scutellum. Certainly, it is true that the 
endosperms had stood for twenty-four hours in water before they were cut 
from the scutella and embryos, a time which might seem sufficient for exos- 
mosis of enzyme from the scutellum ; but it is easy to prove that if Rye 
endosperms are put to evacuate in the usual manner, from which the scutella 
and embryos have been cut before the seeds were moistened, the same 
phenomenon of rapid isolation of the cells may be observed. 
Moreover, as direct experiments have proved, the Barley cytase also 
dissolves the cell-walls of Rye and Wheat very rapidly, while it has 
no action upon those of Maize. So Rye is not alone in producing an 
energetic cytase soon after the beginning of germination. 
The disintegration of the amyliferous tissue at the beginning of evacua- 
tion shows in a convincing way that there is no trace of vitality. Never- 
theless, the researches on cytological behaviour were repeated on the Rye. 
The results did but confirm the above conclusion. In the endosperm cells 
of Rye no trace of plasmolysis could be seen, and it was impossible by any 
means to discover a nucleus in the cells filled with starch. 
By vital staining the whole amyliferous part of the endosperm stained 
immediately and completely. 
In this case also self-evacuation is caused by a pro-enzyme which 
becomes active in presence of air or of dilute acid. For instance, an endo- 
sperm juice, under conditions of aseptic autolysis, gave in the first amylase 
test only a trace of CuO, while after twenty-one days 129-93 mg. were 
obtained for 5 c.c. juice ; in the corresponding scutellum and embryo juice 
only vestiges were found in the first amylase test, while in the last 25-6 mg. 
CuO were obtained. 
Conclusions. 
The starchy endosperm of the investigated grains, Maize, Barley, 
Wheat, and Rye, can digest itself in the absence of the scutellum and other 
parts of the embryo, though to a very different degree ; hence the diverse 
results reached by previous authors. 
The self-emptying can go on in the absence of any vitality in the 
amyliferous cells, because the starch hydrolysis is accelerated by a strong 
amylase which, little by little, arises from a pro-enzyme which exists in the 
endosperm of the resting seed, and becomes active even though every trace 
of vitality has been removed from the entire endosperm or seed by 
mechanical means. Nevertheless, one cannot deny any vitality whatever to 
the endosperm cells. On the contrary, our researches lead one to admit 
that vitality, which is certainly possessed by the aleurone cells situated at 
I i 2 
