GLOSSARY. 179 



Medullary sheath. That portion of a white nerve which 

 surrounds the axis cylinder. Also called " White sub 

 stance of Schwann." 



Mel'anin. A pigment occurring in iris, choroid, skin, &c. 



Membrane of Brtich. A delicate layer of connective tissue 

 separating choroid from retina. 



Merkel's cells. Tactile corpuscles or Grandry's cells. 



Mesone'phros (Gr. mesos, the middle; nephros, a kidney). 

 The central portion of Wolffian mass which becomes the 

 Wolffian body and subsequently ovary or testis. 



Metab'olism (Gr. metaballo, I change). The processes where- 

 by living organisms take up nutritive matter and convert 

 it into potential energy, which in turn is transformed into 

 kinetic energy. 



Metane'phros (Gr. meta, beyond ; nephros, a kidney). That 

 portion of Wolffian mass which becomes the kidney. 



Met'hsemoglo'bin (Gr. me fa, beyond ; haima, blood ; globus, 

 a round body). A variety of haemoglobin which contains 

 more oxygen than oxyhaemoglobin, and is more stable. 



Metop'ic suture (Gr. meta, beyond; ops, the eye). The 

 frontal suture. 



Micrococ'cus ureae (Gr. mikros, small; kokkus, a kernel). 

 A ferment which is concerned in the decomposition of 

 urea, in ammoniacal urine. 



Molecule (dim. L. moles, a mass = a little mass). The 

 smallest particle of matter which can exist separately. 



Mulle'rian duct. The duct of the pronephros, which becomes 

 Fallopian tube and uterus in female. In male is represented 

 by hydatid of Morgagin, verumontanum, and prostatic 

 portion of urethra. 



Mure'xide test (murex, a genus of gasteropodous mulluscs 

 which yields a fine purple colour). For uric acid, which 

 gives with nitric acid and ammonia a purple colour. 



Mus'carin. An alkaloid of agaricus muscarinus. Has a power- 

 ful inhibitory action upon heart : stops it in diastole. 



Mydri'asis (Gr. mudriasis). Dilated condition of pupil. 



Myoglo'bulin (Gr. mus, muscle ; globulus, a small round 

 body). A proteid substance occurring in muscle 

 serum. 



Myo'gram (Gr. mus, a muscle ; gramma, a letter). A muscle 

 tracing. 



My'ohsematin (Gr. mus, muscle; haima, blood). Muscle 

 pigment. 



