GLOSSAEY. 731 



Metabolism. The intimate chemical changes occurring in the 

 various organs and tissues upon which their nutrition and func- 

 tions depend. 



Metanephros. The hinder portion of the Wolffian duct which de- 

 velops into the kidney and ureter. 



Metazoa. A term used to denote all those animals whose ova undergo 

 division, in contradistinction to Protozoa. 



Micrococcus. An extremely minute fungus of a round shape. Mi- 

 crococci occur in many solutions of decomposing organic matter. 



Micturition. The act of voiding urine. 



Molecules. The smallest physical particles of matter that can exist 

 in a separate state. They are probably always constituted of 

 two or more atoms. 



Morphology. The science which treats of the forms and structure 

 of living beings. 



Morula. The stage of development of the ovum after segmentation 

 in which all the young cells are alike, before the blastoderm is 

 formed. 



Mullerian duct. An embryonic structure from which are formed 

 the genital passages in the female, viz., Fallopian tube, uterus, 

 and vagina. 



Myograph. An instrument for graphically recording muscle con- 

 traction. 



Myosin. The substance formed by the coagulation of muscle plasma . 

 It is one of the globulins. 



Natural nerve currents. The electrical currents passing through 

 an exposed muscle or nerve while in the state of rest. 



Neuroglia. The reticular connective tissue which binds together 

 the elements of the nerve-centres. 



Non-polarizable electrodes. Specially constructed electric termi- 

 nals which do not set up secondary currents on application to 

 the moist living tissues. 



Notochord. The primitive vertebral axis of the embryo. 



Nucleolus. A small spot observable in some nuclei. 



Nucleus. A central part of a cell differentiated from the main 

 protoplasm, commonly round, but sometimes elongated as in 

 muscle. 



Odontoblasts. Living cells lining the pulp-cavity of the interior 

 of a tooth, and presiding over the growth and nutrition of the 

 dentine. 



