1917} MCNAIR—FATS FROM RHUS 335 
When the drupe is planted, the growing embryo does not utilize the 
fat, as it remains unchanged. The fat, however, may be of service 
to the seed as a protection against cold on account of its low power 
for heat conduction, increasing its chance of dispersal by streams, 
as it is far lighter than starch (specific gravity of starch 1.56, 
fat 0.9872); as a protection from rain and humidity; as a pro- 
tection from fungi (PFEFFER 9); and as an attraction to birds 
and therefore a factor in seed dissemination. The ripe fruits 
persist on the plant during the winter, long after the leaves have 
fallen, some until May. Birds, therefore, can see them for.a long 
distance. When eaten,,the fatty covering of the drupe only is 
digested; the ejected seeds can still germinate. Mésrus (8) has 
observed the fruits of R. vernicifera eaten by half-wild pigeons at 
Frankfurt. REINECKE (10) has recorded the doves of Samoa as 
eating the fruit of R. tahitensis. BARRows (1) speaks of the con- 
sumption of the fruit of R. venenata and R. Toxicodendron by the 
crow. After eating the fruits the crow rapidly digests the nutritious 
pulp and ejects from the mouth (in less than 40 minutes after 
eating) the seeds clean and devoid of pulp, together with the sand 
swallowed to aid in digestion. Of these ejected seeds go per cent 
germinated. 
Bryant (3) has observed that the favorite food of the roadrunner 
(Geococcyx californianus) during the winter season consists of the 
fruit and seeds of R. integrifolia. Unlike many birds which turn 
their attention to vegetable food during the winter season, the 
roadrunner appears to discriminate as to the kind of seeds taken. 
Of the stomachs examined, those of 26 (31.3 per cent) contained 
the seeds or fruit of R. integrifolia, and 8.4 per cent of the food 
taken by all the birds was made up of this element. The attention 
of the roadrunner is apparently attracted to this vegetable food only 
during the winter season, when insects, lizards, and other kinds 
of food are least abundant. 
Summary 
1. Substances more similar to Japan wax than to any other fat 
have been isolated from the ripe fruit of R. Jawrina and R. diversi- 
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