166 GRIFFITHS: A NOVEL SEED PLANTER 
was formed by the rapid evaporation and the lower one by mixing 
with the drier earth below which abstracted water and furnished 
particles of sand to adhere to and mix with the mucilage making 
the mass more firm. In this way cakes were formed with a 
mucilaginous center and firm crusts on either side. All of the 
water soon evaporated, however, leaving a cake of seed and débris 
in every depression. These often measured two feet in length 
by three inches in thickness in the center. There were places 
on the mesa to the southeast of the University at Tucson where 
one could pick out an acre of ground which was one fourth cov- 
ered with cakes of this seed. As the water evaporated and the 
cakes became thoroughly dried they presented a peculiar appear- 
ance indeed, for they naturally curled up at the edges. The sur- 
face of the mesa presented an appearance not unlike the surface of 
a table with photographic prints laid upon it to dry. It is quite 
probable that all of the seeds in these cakes were destroyed. At 
least one would naturally expect this result although an oppor- 
tunity has not been given for actually observing their fate. 
There were of course plenty of seeds which were not washed 
together and it is to the behavior of these that the greatest interest 
attaches, for upon them the next year’s crop is dependent. After 
the surface of the ground had dried nearly every seed which had 
remained isolated was sunken in a little pit in the ground, the 
walls and bottom of which were made rigid .by the hardened 
mucilage. The seed was inclosed in a little cup, as it were, 
sunken into the earth—not deeply—but evidently sunken to 4 
depth about equal to the distance between its parallel side. The 
pit had a diameter of about three times that of the seed. 
The agent which caused the sinking of the seed was evidently 
the mucilage, but how such a particle of lifeless matter could 
accomplish this result so nicely did not appear clear. The seed 
was as effectually sunken as though it had been done by human 
hands. It was not covered, but this would inevitably be a 
plished in the succeeding dry months by the natural abrasion #: 
the surface of the soil. The cup would be filled by silt and san 
effectually completing the process of planting the seed. 
Several experiments have been performed for the purp° 
determining the mechanism by which this burial of the see 
se of 
d is 
