io8 



NEMERTINEA 



either all unite and form a collar (Fig. 55, v.s) round the 

 oesophagus, or they break up into a number of lacunar or open 

 spaces in free communication with one another. 



The blood is usually colourless, but in some cases the cor- 

 puscles are coloured red by haemoglobin. 



Excretory System. Max Schultze * found in Tetrastemma 

 obscurum, on the outer side of, but near to the lateral blood-vessels, 



it 7"f 



Fig. 56. Excretory system of Nemertines. A, Drcpanophorus spectabilis Qtrf., part 

 of one of the lateral vessels encircled by branches of the excretory organ, x 585 ; 

 e, main canal of the excretory system : B, D. crassus Qtrf., a terminal branch of 

 the excretory system, x 585 ; /, ciliated flame : C, Malacobdella grossa 0. F. Mull., 

 entire animal, slightly magnified, showing the excretory system (black) and the vas- 

 cular system ; e.a, excretory aperture ; d.v, dorsal vessel ; l.v, lateral vessel. (From 

 Burger.) 



a pair of canals. He observed ciliary movements in the canals, 

 but could not discover flame cells. Further contributions to our 

 knowledge of the excretory system were made by Semper, 2 von 

 Kennel, 3 Hubrecht, 4 and Oudemans. 5 The latter states that the 

 excretory system consists of a pair of canals situated laterally near 

 the anterior end of the body. Each canal communicates with 

 the exterior by one or more ducts having lateral regularly- 

 arranged apertures. In some cases he was unable to make out 

 any communication with the vascular system, but in others 



1 Beitriige zur NaturgeSchichte dcr Turbellarien, Griefswald, 1851. 



2 Arb. Inst. Wurzburg, Bd. iii. 1876, p. 115. 



3 Ibid. Bd. iv. 1877, p. 305. 4 Zool. Am. vol. viii. 1885, p. 51. 

 5 Quart. J. Micr. Sci. vol. xxv. 1885, suppl. p. 1. 



