Date Endosperm for Self-Digestion. 77 
proceeds more slowly in the copper sulphate solution. This granted, 
the result is just what would be expected as a consequence of simple 
exomose in the absence of enzyme. 
Experiment No. 4. Do degermed but otherwise whole endosperms 
show any internal corrosion or evidence of auto-digestion after a long 
period under optimum conditions of germination? While preceding 
tests render a negative answer highly probable, the following experiment 
was made as a conclusive test. Twenty degermed and carefully cleaned 
endosperms were placed in a vertical position behind a rubber band 
which encircled a small crystallizing dish. The preparation was then 
placed in a dish containing sufficient 1 per cent. toluol to leave the 
endosperms standing about one-fourth submerged. Diffusion and escape 
of hydrolytic products were thus well provided for and respiration was 
not interfered with. The: preparation was then kept in the incubator 
at 35° C. for fifty-six days. A control preparation in 1 per cent. copper 
sulphate was carried. The solutions of these preparations were, with 
few exceptions renewed daily. The toluol of this strength is such a 
weak antiseptic that a daily renewal is necessary as also the bathing 
of the unsubmerged portions of the endosperms. Seeds will commence 
germination under these conditions. 
At the conclusion of the test period the endosperms were sectioned, 
stained in Bismarck brown and mounted in glycerine. After clearing over 
night microscopic examination failed to reveal the slightest evidence of auto- 
digestion, The walls were intact. No such corrosion markings as 
figured by Griiss (94a, taf. 14 and 15) could be found. Comparison 
was made with dry resting endosperms but no positive difference could 
be detected. The middle lamella showed very plainly in all three sets 
of sections, but no difference either in cell wall or cell contents could 
be noted. 
Conclusion :—The endosperm of Phoenix dactylifera is incapable ot 
self-digestion. 
While this investigation has been continued intermittently for some 
years, the major part of the results here recorded have been obtai 
during my incumbency of a research scholarship, June, July, and August, 
1905, in the New York Botanical Garden. I am especially indebted 
to Professor Wm. J. Gies, consulting chemist of the Garden, and to 
Us. 2. -T. MacDougal, assistant director, for advice and facilities in 
carrying out the work, 
