GLOSSARY 513 



TER-A-TOL'-O-GY. The science which deals with monstrous or 

 abnormal forms. 



TET'-RADS. Bivalent chromosomes which appear 4-parted in 

 the maturation divisions. 



TO-TIP'-O-TENCE. The capacity of a cleavage cell to give rise 

 to a whole animal. 



TOX'-IN. A poisonous substance particularly such as is pro- 

 duced by bacteria. 



TRI-HY'-BRID. The offspring of parents differing in three char- 

 acters. 



TROPH'-O-BLAST. The outer layer of the blastodermic vesicle 

 of a mammal. 



TRO'-PISMS. Automatic movements of organisms toward or 

 away from a source of stimulus. 



UNIT CHARACTER. A character which is inherited as a whole 

 and cannot be sub-divided. 



VEGETATIVE POLE. The pole of an egg opposite the polar 

 bodies. 



VIL'-LI. Processes which grow out from the embryonic mem- 

 branes of a mammal and connect it to the walls of the 

 uterus. 



VI-TEL'-LIKE MEMBRANE. A delicate membrane around an egg 

 secreted by the egg itself. 



VIV-I-PAR'-I-TY. Young brought forth "alive," in an advanced 

 stage of development. 



ZY'-GOTE. The product of the union of male and female sex 

 cells. 



