Glossary 361 



SPI-RIL'-LA. A spiral type of bacteria. 



STEN'-TOR. A ciliated protozoan. 



STER-E-O-I'-SO-MERES. Molecules having the same composition but differ- 

 ent properties dependent upon varying spatial relations of their con- 

 stituent atoms. 



STIM'-U-LUS. Anything acting on an organism which calls forth a response. 



STY-E'-LA. A genus of Ascidians. 



SYM'-ME-TRY. The condition where opposite sides or poles are alike ; 



bilateral, having equivalent right and left sides. 

 SYN-AP'-SIS. The conjugation of maternal and paternal chromosomes 



preceding the maturation divisions. 



SYN-DAC'-TYL-ISM. The condition of having webbed fingers or toes. 

 TE-NEB'-RI-O. A genus of beetles, the larva of which is the common 



meal worm. 

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



forms. 



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

 tion 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 produced by 



bacteria. 



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

 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 membranes of a 



mammal and connect it to the walls of the uterus. 

 VI-TEL'-LINE MEMBRANE. A delicate membrane around an egg secreted by 



the egg itself. 

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



of development. 

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



