160 SUMMARY OF CURRENT RESEARCHES RELATING TO 



female consists of two portions united by a thin stalk. The rounded 

 posterior or external portion contains the reproductive organs and bears 

 two large egg-sacs. In it are certain spaces with thick epithelium-hke 

 walls, which probably represent the gut. The anterior portion or root 

 system is an elongated body lying within the host (a Polynoid worm), 

 and composed of vacuolated tissue penetrated by a lacunar system, which 

 unites into a main branch, runs up the stalk, and becomes continuous 

 with the gut spaces in the external portion. The root is probably an 

 absorbing organ, nourishment being carried from it to the external por- 

 tion of the body by the lacunar system. 



In one specimen the body contained numerous eggs, lying in the 

 diverticula of the two oviducts, and each oviduct terminated in a thick- 

 walled glandular portion. In the posterior region of the animal was a 

 median vesicle communicating on each side with a lateral one ; into the 

 duct between the two there opened the glandular oviduct, and from there 

 a short duct led to the exterior. In this s^ecrmen there was no trace of 

 a gut. 



The parasite is usually attached to the head of the worm, and in the 

 two specimens cut, the root pierced the cerebral ganghon and lay by the 

 side of the oesophagus. 



The male is minute and sac-like, consisting only of reproductive 

 organs, anteriorly drawn out into a conical prolongation which is inserted 

 into the female. It forms two large spermatophores with long necks. 

 Most of the body of the adult remains enclosed in the last larval skin, 

 which shows antennse, maxillipedes, and three pairs of thoracic swimming 

 legs. 



Annulata. 



Minute Structure of Haemocoel in some Annelids. * — Anna 

 Dyrssen has studied this in Glrratulus cirratus, Aitdouinia flligera^ 

 Amphitrite rubra, and other forms. She concludes thai: the heart is a 

 mesodermic structure ; that the hgemocytes are immigrant coelomocytes ; 

 that the vessels, like the visceral blood sinus, have an internal connective- 

 tissue membrane ; that there is no vaso-epithelium ; and that the walls 

 of the vessels are mesodermic. But she points out that these conclusions 

 require to be tested embryologically. 



Vascular System of Serpulidae.f — Eugen Lee gives an account of 

 the minute structure of the blood-vessels and sinuses in species of 

 Frotula, Fermilia, and other Serpulids. The main channels are deter- 

 mined by the metamerization and differentiation of the mesoderm-bands 

 W'hich arise from the pole-cells. Graps between the splanchnopleure and 

 the intestinal epithelium, or between the neural and haemal mesenteries 

 and the septa, give rise to the channels for the nutritive fluid diffusing 

 through the epithelium of the gut. The channels are at first without 

 proper walls. The walls of the visceral sinus and of the dorsal and 

 ventral vessel are due to a muscular differentiation of the splanch- 

 nopleure. The lumen of other blood-channels is interseptal, and closed 



* Jen. Zeitschr. Naturw., xlviii. (1912) pp. 365-97 (4 pis. and 5 figs.), 

 t Jen. Zeitschr. Naturw., xlviii. (1912) pp. 432-78 (6 pis. and 1 fig.). 



