THE ANATOMY. BLOOD-GLANDS 



77 



blood away from the ventral vessel to the parietes. 

 There are thus two sets of vessels which convey blood 

 to the integument the dorso-integumentary and the 

 ventro-integumentary. From the integument a series of 

 intestino-integumentary vessels again returns the blood 

 to the intestinal network, whence, as before stated, it 

 reaches the dorsal vessel. 



Fig 21. 



Uv.I. 





el- 



VII. BLOOD-GLANDS. 



Connected with the vascular system there are in 

 several Oligochaeta structures which seem to bo of 

 a glandular nature. Such structures occur in the En- 

 chytraeidae, the Lumbriculidae, the genus Plureodrilus, 

 the Perichaetidae, and perhaps the Eudrilidae. 



It will be convenient to commence with a descrip- 

 tion of these various organs in the groups mentioned, 

 before discussing the morphology and the functions 

 which they may perform. 



In the Enchytraeidae the dorsal vessel sometimes 

 contains a cellular rod which has been named the 

 'Herzkb'rper' by MICHAELSEN (woodcut, fig. 22). It 

 was described first in the genus Mesenchytraeus 

 (MICHAELSEN), where it consists of a solid rod of 

 cells attached to the ventral side of the dorsal blood- 

 vessel, and extending along its whole length; 'in M. 

 mirabilis and M. primaevus it is thick with irregular, 

 often strong swellings multicellular in section. In 

 M. falciformis, M. beumeri, and M. flavidus, it is 

 thinner, quite smooth, with only feeble swellings, and 

 in section shows only a few cells.' The organ is figured 

 by MICHAELSEN. In a later paper the same organ was 

 described in Stercutus. It has been justly compared by 

 him to the cardiac body of certain Polychaetes, such 



~ '*7_7' 1 _P J_l A J_ *i. '"' **'*' V ' "*' i-"-'*o** vcooc*. \,, v, v-njii- 



as l j ectinaria beigica, and a lew Others. AS tO Its tractile heart, c. i. Intestinal heart, v. 



. , Supra-intestinal vessel. v. I. Lateral 



function it was suggested by MICHAELSEN that it served vessel. e..VentraI vessel, v.t. Peri-intes- 



. tinal vessel. t.r.,i.t. Smaller branches 



to ease the contractions of the dorsal vessel ; he pointed O f ventral vessel. 



ir.i.- 



PONTOSCOLEX. CHIEF TRUNKS 

 OF VASCULAR SYSTEM. 



(After Perrier.) 

 v. d., v. m. Dorsal vessel. c. I. Con- 



