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1883.] Physiology. 681 
one illuminated dark blue, green or white, with ultra-violet re- 
spectively, the conditions being the same as regards light, inten- 
sity, radiant heat, etc. In one set of experiments the animals 
were in the normal state; in another, the anterior end of the 
worm, and the eyes of the Triton were removed.——Nature. 
PHOSPHORESCENCE AND RESPIRATION IN ANNELID WorMS.—Mr. 
W. A. Haswell has investigated the structure and functions of the 
elytra or scales, the possession of which is one of the most char- 
acteristic peculiarities of the Aphroditacea. 
‘With regard to the functions of the elytra, the author distin- 
guishes (1) protection, (2) production of phosphorescent light, (3) 
sensation, (4) respiration and (5) incubation 
The protective function is in some cases the predominating one. 
Thus in Iphione the scales are of extreme density, and cover the 
entire dorsal surface with a complete armor. In others the scales, 
though tough, are more readily detached, and in many instances 
do not completely cover the dorsal surface, or are so delicate and 
So readily parted with when the animal is irritated, that their 
direct protective action must be very slight. 
When certain species of Polynoé are irritated in the dark, a 
flash of phosphorescent light runs along the scales, each being 
illuminated with a vividness which makes it shine out like a 
shield of light, a dark spot near the center representing the sur- 
ce of attachment where the light-producing tissue would appear 
to be absent. The irritation communicates itself from segment 
attention of the assailant in the dark recesses which the Poly- 
Noidz usually frequent. : 
t the elytra act, like dorsal cirri, as organs of some special 
sense, seems probable from their abundant innervation, as well as 
from the presence, in many instances, of fimbriz and other appen- 
S, some of which act as end organs for the nerve branches. 
In Aphrodita and Hermione the scales have been observed by 
Williams and Quatrefages to perform an important mechanical 
on in connection with respiration. In these genera the dor- 
sal surface is covered with a coating of felted hairs, which stretch 
_ 8cross from one side to the other, and enclose a canal open in 
front and behind, and having for its floor the dorsal wall of the 
with the elytra and the “branchial” tubercles. These 
