876 SUMMARY OF CUERENT RESEARCHES RELATING TO 



Balfour's Comparative Embryology.* — It is impossible to speak 

 too bigbly of tbis book, now completed by tbe issue of tbe second 

 volume. Students of embryology will no longer bave to depend upon 

 uneartbing tbe various papers relating to tbe subject from tbe scat- 

 tered pages of a mass of periodical literature, but bave now for tbe first 

 time ready to band an invaluable guide to all tbe researcbes of embry- 

 ologists tbrougbout tbe world. Tbese bave been summarized, syste- 

 matically arranged, and worked up into a connected wbole, witb tbe 

 addition tbrougbout of tbe autbor's own original observations, at an 

 expenditure of labour unsurpassed in any zoological work of recent 

 times. Tbe Invertebrata are dealt witb in tbe first volume and tbe 

 Vertebrata in tbe second ; and besides numerous figures tbere is a 

 copious classified bibliograpby wbicb is of very great practical value. 



B. INVERTEBRATA. 



MoUusca. 



Vessels of the Ink-bag of Cephalopoda.f — Continuing his re- 

 searcbes on tbe ink-bag of tbe Cepbalopoda,J P. Girod proceeds to 

 consider its vascular suj^ply. Tbe arteries are derived from tbe 

 anterior aorta, tbe veins from tbe " large vein." In Sepia officinalis, 

 wbicb fairly represents tbe condition of tbis system in the whole 

 group, the anterior aorta sends out, from a point only 1 mm. from its 

 origin, an artery, the artery of the gland, which dips downwards, runs 

 along tbe upper side of tbe bag, and at 10 mm. from its lower end 

 divides into five or six vessels, wbicb enter its wall and break up in 

 tbe trabeculae of the ink-gland. An intestinal branch and a number 

 of twigs supplying tbe posterior surface of the sac are given off by 

 the artery of tbe gland before it sinks into the wall. After sending out 

 tbis vessel tbe anterior aorta, in passing the front wall of the sac, 

 sends out another branch, the artery of the wall, which covers the wall 

 of tbe sac witb its ramifications, then ascends, sending four branches 

 to the vesicle or excretory sac, and numerous other ones to the duct, 

 the rectum, and tbe anus. The supply of tbe vesicle is thus quite 

 distinct from that of tbe ink-gland. 



There are two sets of veins ; the deeper ones take tbe blood from 

 the internal coat of the bag and of tbe gland, and unite to form 

 the vein of the gland wbicb becomes attached to the artery of the 

 gland ; the second set, or veins of the icall, arise from tbe surface of 

 tbe vesicle and duct, in tbe former case proceeding to join a larger 

 vein on tbe right, in the latter to behave similarly on the left. 



The ultimate ends of the two sets of vessels show different modes 

 of distribution in different genera, but in all tbe chief stem or its 

 branches penetrate the trabeculfe, and break up in tbe limiting mem- 

 brane of the gland. The main part of tbe capillary system lies within 



* Balfour, F. M., 'A Treatise on Comparative Embrj'ology.' Vol. I., xi, 492 

 and xxii pp. and 275 figs. ; Vol. II., xi, 655 and xxii pp. and 429 figs. (8vo, 

 Macmillan, 1880-1.) 



t Comptes Eendus, xcii. (1881) pp. 1241-3. 



X See this Journal, ante, pp. 227 and 586. 



