98 ANATOMY OF AMPHIOXUS. 



NOTES. 



1. (p. 49.) LANKESTER has made the suggestion that there 

 are not distinct capillaries and ccelomic space around the hepatic 

 coecum, but that the space itself is capillariform. This view is in 

 accordance with what one observes in transverse sections. 



2. (p. 50.) The fullest account of the contractile blood- 

 vessels of Amphioxus, as observed in the living animal, is that 

 given by JOHANNES MULLER. He observed the peristaltic con- 

 tractions of the branchial artery (which is filled with a perfectly 

 colourless blood), beginning from its hinder end, where it is joined 

 by the hepatic vein (which also undergoes peristaltic contraction 

 from before backwards along dorsal side of coecum) and extend- 

 ing to the front end of the pharynx. The intervals between the 

 successive contractions last about a minute. Immediately suc- 

 ceeding upon the contraction of the branchial artery, the bulbils, 

 which occur at the base of the primary or^forked gill-bars, contract 

 too. He says that the heart-like "aortic arch" which occurs to 

 the right of the velum (he thought there was one on the left side 

 as well) contracts from below upwards, and that its contraction 

 enabled him to discover it. As mentioned in the text, van Wijhe 

 states that it has no communication with the branchial artery. 

 Johannes Mliller also observed the peristaltic contraction of the 

 sub-intestinal (portal vein), and states that it extends to the 

 anterior end of the coecum. It should be remembered that his 

 observations were made on young transparent individuals, and the 

 statement as to the extent of the contraction of the sub-intestinal 

 vein is open to doubt. 



3. (p. 51.) A genital artery running longitudinally above the 

 gonadic pouches has been figured by Langerhans, Rolph, Schneider, 

 Lankester, and Boveri, but its relations to the rest of the vascular 

 system have not been made out. It is doubtful whether its 

 presence is constant. 



4- (P- 58.) The "brown funnels" were discovered by LAN- 

 KESTER in 1875, an d were subsequently compared by BATESON with 

 the collar-pores of Balanoglossus. (See Chap. V.) This com- 

 parison was made on the supposition that the posterior free oper- 



