GLOSSARY 509 



Mott-PHOL'-o-GV. The science which deals with structure and 



form. 

 Mxrs'-CA. A genus of flies including the house-fly. 

 Mtj'-takt. a sudden variation or sport which breeds tnie. 

 Mu-ta'-tions. Inherited variations which are more or liess 



striking. 

 Nec-tu'-rus. a large salamander; the mud-puppy. 

 Nem'-a-tode. a round-worm or thread-worm. 

 Ne'-he-is. a marine annelid, or ringed worm. 

 Neuhai. Geoove. The groove on the dorsal surface of the 



embryo of a vertebrate which develops into the brain and 



spinal cord. 

 Neurai. Tube. A tube formed from the neural groove and 



giving rise to brain and spinal cord. 

 No'-TO-CHORD. The cellular rod which forms the basis of the 



backbone. 

 Nu'-ci-E-us. The central organ of a cell, composed Of chro- 

 matin and achromatin. 

 NuLLipLEX Factors or Character. A condition in which a 



character is absent because its determiner is found in 



neither parent. 

 On-tog'-e-kt. Development of an individual. - 

 O'-o-CYTE. The ovarian egg before maturation (formation of 



polar bodies). 

 O-o-gen'-e-sis. The development of an ovum from a primitive 



sex-cell. 

 O-o-Go'-Ki-A. The earliest generations of cells which produce 



ova; primordial egg cells. 

 O'-O-SPERM. The fertilized egg after union of egg and sperm. 

 Order. The chief sub-division of a class. 

 OEGAifizATioir. Differentiation and integration, i.e. different 



parts united into one whole. 

 Or-gan-og'-e-ny. The formation of varioiis organs of the 



body. 

 Or-tho-gen'-e-sis. The doctrine that the course of evolution 



is definitely directed by intrinsic causes. 



