434 RECORD OP CURRENT RESEARCHES RELATING TO 



vessels, and in the smaller ones — those formed within the connective- 

 tissue fibres, as above mentioned — minute pale corpuscles sometimes 

 occur. The blood supply to the nephridia is very perfect, each cell 

 being enclosed by at least one capillary loop. 



The nephridia, or excretory glands, as now determined by Mr. 

 Bourne, present different characters in different parts ; in one part 

 the duct has an arborescent origin in each cell ; or the cells may be 

 entirely perforated by a duct ; or they may — as at the base of the 

 gland — simply be hollow cylinders encapsuling a duct. The lobes of 

 the glands also each present a large intercellular duct. The vesicle 

 or bladder has ciliated walls, and contains needle-like particles of a 

 substance apjiarently allied to uric acid. Maceration in Miiller's 

 fluid breaks up the gland cells into fibrillfe. Cellular structure was 

 not detected in the walls of the blood-vessels, and no communication 

 was found between the nephridial duct and the body cavity. 



The intestinal epithelium lining the cfeca differs from that usually 

 found in such a position in consisting of hemispherical granulated 

 cells with pale nuclei, each emitting during digestion a drop of viscid 

 hyaline liquid. 



Structure of the Echiurida.* — Dr. Greef has been examining the 

 curious small tubes of the Echiurida, to which so many different 

 functions have been ascribed ; he now looks upon them as gills and 

 as homologous with the " water-lungs " of the Holothuroida. A care- 

 ful investigation of Thalassema Moebii revealed no sign of the 

 presence of infundibular orifices in these structures, but, much to the 

 astonishment of the writer, they were found to be completely cut off 

 from the coelom. Injections through the orifice into the rectmn were 

 then made with Echiurus Pallasii, in which infundibula are so 

 abundant ; here it was found that neither the funnels nor their canals 

 received any of the colouring matter ; this only filled the numerous 

 cleft-like lacunae which project into the lumen of the tube, and the 

 canal system of which does not communicate with the infundibula ; 

 these latter have, however, a special system of canals connected with 

 them which traverse the other set ; this system appears to belong to 

 the blood-vascular series, and the function of the anal tubes as gills, 

 and apparently as gills only, is hereby confirmed. The coelom of the 

 Echiurida, just as of the Holothuroida, is filled with blood, and both 

 the tubes connected with the anal region have a respiratory function. 



The new species Thalassema Moehii has three pairs of genital 

 tubes, corresponding in form and position to the two pairs of Echiurus 

 Pallasii, and in all the specimens examined the tubes were either 

 filled with ripe eggs or" with masses of semen. Further observations 

 on Echiurus lead the author to support the doctrine that in all 

 Echiuri the generative organs have the same structui'e and position, 

 and that the anterior pair are to be regarded as true segmental organs. 

 Nothing as yet known about other Gephyrea leads us to believe that 

 there obtains in them the remarkable dimorjihism of the sexes which 

 has been signalized by Vejdovsky and by Marion in Bonellia ; at any 

 * ' Arch. Naturg.,' xlvi. (1880) p. 88. 



