68 Psyche [April 
The appearance and contents of the posterior part of the alimen- 
tary canal of the nymph—from the mid-gut sphincter to a little 
within the pouch—differ from that of the adult in being of an 
opaque white (due to the contents) and swollen with a great quan- 
tity of semi-translucent, colorless or whitish granules varying from 
one to fifteen microns in diameter, the majority being about five; 
the contents of two nymphal posterior guts were analyzed at the 
Trinidad Government Analyst’s Laboratory and the granules were 
found to be amorphous insoluble calcium phosphate and to consti- 
tute about 80 per cent. of the contents of the gut; the remaining 
contents consisted of organic matter (which would be chiefly old, 
detached cell fragments from the epithelium of the gut) and sodium 
chloride and potassium phosphate. A quantity of the roots of the 
grass on which the nymphs chiefly feed was also analyzed by the 
Government Laboratory; they contained small quantities of cal- 
cium salts and phosphates, but there was no evidence of the pres- 
ence of insoluble forms of calcium phosphate. The Cercopid, very 
shortly after moulting to adult, voids a quantity of a white sub- 
stance like plaster-of-paris, which dries on the leaf or other object 
and takes its impress, afterwards drying and becoming hard and 
brittle. This is often left under the old froth and moulted skin, as 
the adult usually remains in the spittle until its integument becomes 
hard and fully colored. This white substance is chiefly calcium 
phosphate, and gives canary-yellow crystals when heated with a 
solution of ammonium molybdate in nitric acid. Thus it seems 
that the greater part of this phosphate is retained in the posterior 
part of the gut of the nymph and only evacuated after the final 
moult. Each insect voids about two milligrams of this substance.! 
The epithelial cells of the posterior portion of the gut are usually 
loaded with dark granules (food in process of absorption); those of 
the anterior part—before the sphincter—are fairly clear and the 
gut is semi-translucent pale yellowish-brown, as it is throughout 
in the adult as a rule: rarely an adult also has the posterior portion 
of the gut white as in the nymph, due to its contents being of the 
same nature. 
19.4 milligrams of this exerement was dried at 100° C. when its weight was 6 mg., and was 
analyzed by Mr. Shrewsbury of the Trinidad Government Laboratory. ‘‘Percentage compo- 
sition of excrement: organic matter, 20.0; water, 36.0; ash calcium potassium phosphate with 
minute trace of iron, 44.0. The organic matter was largely ammonium urate. The micro- 
scopic appearance of the globular particles of which this excrement was composed was exactly 
similar to that of urinary calculi.” 
