THE SEA-SQUIRT. 51 
This operation is difficult and requires great care, as 
the mantle is closely attached to the internal viscera. 
Notice the bright orange liver near the end furthest 
removed from the peduncle; the intestine, generally 
filled with mud, lying in a loop, the bight of which 
is close to the peduncle ; and the reproductive organs 
in rows of rectangular blocks lying in the loop of 
the intestine. These are either transparent, or greyish, 
or yellowish white. 
4. Take the loop of the intestine with the reproductive 
organs, and turn it back towards you, detaching it 
and the liver carefully from the respiratory sac 
which lies below. This is easily recognised from its 
rectangularly netted appearance. Wash with a 
ecamel-hair brush, and cover with clean water. Notice 
that the opening furthest away from the peduncle 
does not lead into the respiratory sac, but into the 
atrvwm. 
5. The alimentary system.—The stomach leads from the 
respiratory sac at that end furthest away from the 
peduncle—the fundus. On it lies the liver, formed 
by five or six ramified follicles om each side; these 
follicles are not symmetrical. The intestine is nearly 
as broad as the stomach ; at the apex of the loop it 
is coated with yellow esloueed cells—the renal organ. 
The rectum lies loose in the atroum, but is attached 
to the wall of the chamber, where it passes through 
it ; the anus is simple. 
6. The reproductive system consists of four rows of more 
or less rectangular blocks, each set of blocks being 
connected together by a narrow efferent duct, which 
leads along the intestine into the atrium. Two of 
these rows of blocks are larger, and are attached 
more firmly to the mantle than to the intestine. _ Ex- 
