80 GLOSSARY. 



Mec'kel's car'tilage. The cartilage of the chondrocranium 



which forms the axis of the mandible. 

 Meco'nium (Gr. mckon, a poppy). Poppy-juice; the faeces 



passed by a new-born infant 

 Me'dian (L. medius, middle). Middle. 

 M6dias'tinum (L. mcdtus ; sto, I stand). A middle partition ; 



as the mediastinum formed in the thorax by the union of 



the two pleurae. 

 Me"difur'ca (L. mcdius, middle; furca, a fork). The middle 



apodemes which project into the thorax of some Insecta. 

 Me'dius (L. middle). The third digit. 

 Medulla (L. marrow). The marrow of bones; the pith of a 



plant 

 Medulla oblonga'ta (L. elongated marrow). That portion of 



the cerebro-spinal axis which lies between the spinal cord 



and the iter of the brain. 

 Medu'sae. The sea-nettles or jelly-fishes, so called because 



their tentacles resemble the snakes which formed the hair 



of the Medusa, the chief of the Gorgons. 

 Medu'soid (Gr. Medusa-like). A term applied to the zooids in 



the Hydrozoa which produce reproductive organs. 

 Meibo'mian (named from Meibomius, who first discovered 



them). The name given to certain glands on the inner 



surface of the eyelids. 



Mela'nochroi (Gr. melds, melanos, black ; chroia, skin, com- 

 plexion). A group of the human race which includes the 



" dark-whites." 

 Membra'na adamanti'nea (L. adamantine membrane). A 



name applied to the epithelium on the surface of the pulp 



of a tooth. 

 Membra'na cap'sulo-pupilla'ris (L. capsular membrane of the 



pupil). A highly vascular membrane which in the foetus 



surrounds the crystalline lens of the eye. 

 Membra'na e"boris (L. ivory membrane). The external cellular 



layer of the pulp of a tooth. 

 Membra'na granulo'sa (L. granular membrane). The lining 



membrane of the Graafian vesicles of the ovary. 

 Membra'na lim'itans (L. limiting membrane). The membrane 



which bounds the anterior and posterior surfaces of the 



retina. 



Membra'na nic'titans (L. winking membrane). The third eye- 

 lid in birds, amphibia, and some mammals, formed by a 



fold of the conjunctiva. 



