DEVELOPMENT OF DIGITIFOEM GLAND 333 



the junction of the two posterior cardinal veins in Raja, and 

 the genital sinus in Torpedo. Howes ('91) stated that the 

 artery to the digitiform gland is the inferior (posterior) branch 

 of the superior mesenteric group. Neuville ('01, fig. 6, Acan- 

 thias, and fig. 9 Raja) pictured the dorsal intestinal artery and 

 vein as terminating on the digitiform gland. 



The functions attributed to the digitiform gland are nearly 

 as numerous as the descriptions of it. Home (1814) likened 

 it to the ink bag of cuttle-fish and to the intestinal caeca of birds. 

 Leydig ('52) stated that it resembles the acinous glands of Briin- 

 ner. Hyrtl ('58) thought it accessory to the reproductive sys- 

 tem. Milne-Edwards ('62) — (Howes '91 to the contrary) — 

 referred to it as a urinary bladder. Dumeril ('65) stated that 

 the digitiform appendix is a true organ of secretion. Blanchard 

 ('82 a and '82 b) obtained from the digitiform gland extracts 

 able to digest starch and emulsify fats but which had no action 

 on proteins. He considered the gland analogous to the circu- 

 manal glands of some higher forms. He stated that it probably 

 does not function in digestion although potentially able to do 

 so. Howe's ('91) argued from its blood supply that the gland 

 may be considered as similar to the vermiform appendix and 

 caecum of higher animals. Crawford ('99) obtained the urea 

 reaction with the substance found within the gland. Wieder- 

 sheim ('07) thought that it might correspond to the caecum of 

 higher forms. Sullivan ('07) stated that the digitiform gland 

 has no digestive activity. Pixell ('08) obtained a starch and 

 fat-splitting enzyme from the digitiform gland by a sodium 

 carbonate extraction. Morgera ('16) stated that the gland 

 may have an internal secretion which contracts the intestine. 



Development of the digitiform gland 



External form. Half way between the spiral valve and cloaca 

 on the right dorso-lateral surface of the intestine in an Acan- 

 thias embryo of 15 mm. there appears a very slight bulging of 

 the wall which may be called the area of evagination, or anlage, 

 of the digitiform gland (fig. 1). The alteration of the part 

 of the intestine concerned in this formation is rather diffuse, 



