EEPORT ON THE AMPHIPODA. 507 



In each foot of the pera3on the arterial blood courses as well by the anterior as the posterior rim 

 of the side-plate. In the four first pairs the anterior stream supplies the side-plates and the 

 accessory branchite (whore such exist). The cavity of the side-plate is formed into three 

 longitudinal canals, which on the lower rim unite, and besides communicate with one another 

 by numerous cross canals. The arterial current flows down in ther front and middle canals, 

 while the venous current ascends in the hinder. The hinder arterial current of the foot 

 passes partially into the branchia>, partially into the foot itself, and partially into the 

 lamella of the brood-pouch in the female or its homologue in the male. In the three last 

 pairs of perteopods the front arterial current provides for the foot and its accessory branchia, 

 the hinder sends its secondary currents into the branchia, the side-plate and the marsupial 

 lamella. In the side-jilate the current runs round beside the rim. [With this account 

 should be compared Dr. Delage's account of the circulation in corresponding parts of 

 Talitrus locusfa.] 



From each appendage of the perreon and pleon a single venous current proceeds. All these take 

 their way to the dorsal side of the body-cavity and debouch in a spacious venous sinus, 

 bounded below by the intestine and its adipose -tissue, on the sides by the muscles of the 

 back, and above by the back of the animal. [This Delage calls the pericardiac sinus, and 

 assigns it a bounding membrane of its own, open only to the thirteen pairs of peritotr^Tiac 

 vessels.] In this sinus, which lies over the hinder aorta and over the heart, a hinder and 

 an anterior current are to be distinguished. The former flows from the hinder end of the 

 body forwards to the third perfeon-segment, the other has a backward direction and reaches 

 the same segment. In the hinder current debouch the venous currents of the five last 

 perajon-segments and of the whole pleon, to the anterior belong the venous currents of the 

 antennae, the head and the two first perseon-segments. 



At the diastole the blood collected in the (pericardiac) sinus passes through the gaping ostia into 

 the heart. This movement is helped by the upper wing-like muscles, as by their contrac- 

 tion the sinus in its horizontal and perpendicular diameter is contracted, and its two 

 streams in ,this way are pressed towards the third perseon-segment, and rush with greater 

 energy through the slits, the heart acting like a suction pump. The front slit takes only 

 the blood of the front current, the hindmost of the hinder, the middle the leavings of 

 both. 



It thus appears that tlie arterial currents from the two aortas and their branches wash various 

 organs of the body, as the intestinal canal and the nerve-centres, and then in full tide press 

 into the articulated appendages, finally to c^uit them as venous currents and pass into the 

 dorsal sinus. Wrzesniowski found no direct bending round of the hinder arterial current 

 into the dorsal sinus, such as Clans has described in Phronima sedentaria. The whole blood- 

 content of the venous dorsal sinus passes, he says, direct into the heart, without previously 

 traversing the branchias as Spence Bate states, Sessile-eyed Crustacea, i. p. xxxii. On the 

 contrary the branchiae receive their blood from the same arterial streams which supply the 

 feet, and the contents of the venous dorsal sinus present a mixture of the blood returning 

 from all parts of the body, which has been subjected not only in the branchia?, but, at least 

 partially, also in the antennae, side-plates and legs, to oxygenation. A separation o£ the 

 arterial and venous blood is therefore not arranged for. \ 



The blood-plasma in young specimens of Goplana polonica appears of a yellowish-red colour, in 

 adults of more or less greenish, sometimes even emerald-green hue. The body becomes 

 paler, when the blood is drained away. The blood-corpuscles in this species are of 

 considerable size, consisting of a soft, granular protoplasm, in which clear, pseudopodial-like 

 processes sometimes make their appearance. More or less numerous fat-drops in the plasma 

 of the blood circulate with it throughout the body. 



