GLOSSARY. 41 



Duct of Gaert'ner. A tube derived from the middle part of 



the Wolffian duct, which exists in connexion with the 



uterus of the sow and several ruminants. 

 Ducts of Belli'ni The excretory tubes of the kidney. 

 Ducts of Cu'vier. Two short veins which in early foetal life 



open, one on each side, into the heart. 

 Ducts of Rivi'nus. The ducts of the sublingual salivary gland 



which open separately into the mouth. 

 Duc'tus ad na'sum (L. duct to the nose). The nasal duct, by 



which the tears are conveyed to the nose. 

 Duc'tus arterio'sus (L. arterial duct). A short duct which 



during foetal life connects the pulmonary artery and aorta. 

 Duc'tus Botal'li (L. duct of Botallus). A duct which in some 



of the Amphibia is produced by the obliteration of the 



upper part of the first pair of aortic trunks. 

 Duc'tus cochlea'ris (L. duct of the cochlea). The membranous 



canal of the cochlea of the internal ear. 

 Duc'tus commu'nis chole'dochus (Gr. c/wle, bile; dechomai, I 



receive). The common bile-duct. 

 Duc'tus veno'sus (L. venous duct). A duct which in fcetal 



life connects the inferior vena cava and the portal vein. 

 Duc'tus vitello-intestina'lis (L. vitello-intestinal duct). The 



duct by which the primitive intestine and the yolk sac 



communicate in the vertebrate embryo. 

 Duode'num (L. duodeni, twelve). The first portion of the small 



intestine ; so called from being in some animals about 



twelve fingers' breadth in length. 

 Du'ra ma'ter (L. hard mother). The tough fibrous outer 



investment of the brain and spinal cord. 



Du'ramen (L. hardness). The heart-wood of exogenous trees. 

 Dyspnce'a (Gr. dyspnoia, difficulty of breathing). The first stage 



of asphyxia or suffocation. Laboured breathing. 

 Dysporomor'phae. A subdivision of the Carinate birds which 



comprises the Cormorants. 



Ec'deron (Gr. ecdcro, I skin, flay). The outer layer of the 

 integument in the lower animals corresponding to the 

 epidermis in the higher. 



Ec'dysis (Gr. ekdusis, a going out). The periodical casting of the 

 shell which takes place in some of the Crustacea and Insccta. 



