38 ATLAS OF BIOLOGY. 



FIG. VIII. Transverse section of one of the digestive co3ca. 



The preparation drawn was frozen in gum, by means of the " Golding Bird" ether 

 microtome; the sections were transferred as ciit to 1 p.c. osmic acid solution, the fatty 

 globules of the liver-cells (I.e.) being thus stained black, as drawn. D. 3. 



Weber (37), who first fully elucidated the real nature of this so-called liver, significantly 

 termed it the " hepato-pancreas." 



FIG. IX. Dissection from the left side, to show the relations of the gills. 



The branchiostegite was removed, the larger appendages were cut short, and only 

 sufficient of the bases of the branchiae borne by them were left to indicate their positions. 

 (Typical podobranchiae are figured, in detail, on Plate VIII.) 



The shaded areas represent the interarticular membranes, a.m. x 11. 



FIG. X. The same, after injection of the branchio-cardiac trunks, and their factors 

 the efferent branchial vessels. 



All the branchiae were removed, excepting the solitary functional and the three vistigial 

 pleurobranchiee, _p.Z>. These were, in this specimen, at their maximum of development, x li. 



In injecting, the branchiostegite was first dissected off, and a small hole drilled in the 

 carapace from above ; through this the syringe was inserted into the pericardial sinus, 

 injection being completed before the removal of any of the gills. 



FIG. XI. The pericardial sinus, the heart and related structures, as seen from above. 



The pericardium was opened up, after 24 hours in alcohol ; the left side of the heart 

 was removed to the level of its lateral valve, and sufficient of the extensor abdominis muscle 

 dissected out to render clear the osculae of the branchio-cardiac trunks. 



FIG. XII. The heart, after removal from the pericardium, seen from the ventral aspect. 

 The hepatic artery of the left side was torn away at its base ; only its aperture therefore 

 is indicated. 



(Figs. XI. and XII. x i|.) 



FIG. XIII. The arterial system and pericardial sinus, seen from the left side. 



The specimen was pinned down in the position drawn, sufficient of the carapace being 

 removed to expose the lateral cardio-pericardiac valve ; from the aperture bounded by this 

 injection was performed. 



With the exception of the last ambulatory limb, the genital duct related thereto and 

 the posterior gastric muscle, the entire postoral portion of the body was, on the left side, 

 removed to the level of the middle line and with it the digestive gland. All the organs in 

 front of and including the inaudible, were left untouched. 



The pericardial sinus the limits of which are indicated in deep black was carefully 

 dissected after two days' immersion in alcohol, s . x 1|. 



All the arteries give off in addition to those branches here figured small ones to 

 immediately adjacent parts. 



