Marvels of the Universe 615 
hold when at rest. A pair of antenne, or feelers, or, 
as they are sometimes termed, “ foot-jaws,” le just 
above the paired eyes. They are the organs of some ‘ eS + 
special sense and probably of taste (page 614). NS < ace 
The mouth and feeding organs are of a complex 1 SOs coe 
nature and lie in the centre of the body. An 
incision is made in the skin of the fish with a pair of 
minute serrated jaws, which lie within a pouch- 
like organ called the siphon, and a long telescopic 
proboscis, or poison-sting, is inserted into the 
Leys 
wound. The reason for this is not very clear, but 
it is probable that an irritating fluid is injected, 
which induces inflammation and a flow of blood ; 
at any rate, the blood of the fish forms the diet of 
the Argulus. The latter sometimes takes two or . 
three days at a stretch to finish its meal, without 
once relinquishing its hold on the unfortunate host. Photo by] CF. Noad Clark. 
A most noticeable feature is the incessant motion THE EYE OF THE ARGULUS. 
of the swimming feet, in which the four pairs One of the compound eyes, showing the kernel- 
shaped crystalline bodies and the dark pigment 
participate simultaneously. Each of these is 
divided into two branches of equal length, bearing 
comb-like hairs (page 614), which latter are again subdivided into delicate secondary hairs. This 
patches. (Magnified one hundred times.) 
movement is never arrested during life, even when the creature is at rest on its host or when 
depositing eggs. The Argulus swims with a darting motion, frequently making a series of somer- 
saults, and occasionally it is seen to maintain for an hour or more a whirling motion in the water. 
When about to attach itself, the current of water caused by the movement of the fish’s fins gently 
carries it on to the fish. When once attached by means of the powerful suckers, all efforts of the 
fish (and they do struggle strenuously) to shake it off are in vain. On page 011 are shown two Arguli 
attached to a stickleback, giving some idea of their 
relative size. When searching for these Arguli, one 
finds about one in every four or five fish affected. 
The favourite place of attachment is on the gills, 
although they are frequently found on the fins and 
tail, and in some cases upon the eye itself. Let 
us hope that the sensitiveness of the fish’s eye 
does not approach that of the human eye. They 
are evidently distasteful to the fish, and have often 
been observed to be taken into the mouth and 
shortly afterwards ejected uninjured, even when 
the fish are hungry. Between the suckers and 
the swimming feet is a pair of jointed legs, or foot- 
jaws, whose use is to assist the Argulus in attaching 
itself to the fish and for locomotion. The stomach 
of the Argulus is on a comprehensive scale, and 
branches of it ramify throughout the greater part of 
k Photo by) [f. Noad Clark. 
the body. In this way food is stored up and the THE SUCKER OF THE ARGULUS. 
creature is enabled to live for a considerable time Found only in the adult stage. By means of the 
many-jointed rays and the muscles the Argulus 
away from its food supply. I have a record of an 
adult living a fortnight without food. Under the tenaciously to its host. (Magnified about fifty times.) 
can produce a vacuum which enables it to adhere so 
