608 GLOSSARY 



secondary sexual characters. Characters of an animal associated with the sex but 



not connected with the reproductive system. 

 secretion (se kre' shQn). The passage out from a cell of a substance produced in it 

 which can be utilized by the body; also the substance itself secretory (se' kre to rl), 

 pertaining to secretion. 

 Sedgwick, Adam. English zoologist; 1854-1913. 



segregation (seg re ga' shun). The separation of paired genes during the maturation 

 of the sex cells, which thereby pass on only one gene and are "pure" for the 

 corresponding character. 

 self-fertilization. The fertilization of an egg cell by a sperm cell produced in the 



same individual. 

 semi- (sgm' I). L.; half. 

 seminal receptacle (sem' I nal re s6p' ta k'l). A sac in the body of a female animal 



in which the sperm cells are stored until used. 

 seminal vesicle (ves' i k'l). A sac in the body of a male animal in which sperm cells 



are stored until transferred to the female. 

 semipermeable membrane. A membrane permitting the passage of solvents but not 



of substances in solution unless they can be dissolved in the membrane. 

 senescence (se ngs' 6ns). The period during which the organism is growing old. 

 sensation. The effect of a stimulus when registered in a center of consciousness in 



the brain. 

 sense organ. An organ for the reception of stimuli. 

 serosa (se ro' sa). A membrane which secretes a watery fluid; the secretion is termed 



serous (se' riis). 

 serum (se' rum). The plasma of the blood from which the clot has been separated. 

 Servetus (ser ve' tiis), Michael. Spanish author; 1511-1553. 

 sessile (ses' II). Attached and not capable of locomotion. 



seta (se' ta). A fine bristle or spine; used in the annelids as a locomotor structure. 

 sex. The sum of the characters that distinguish male and female individuals; adj., 



sexual (sek' shu al). 

 sex chromosome. A chromosome the presence or absence of which in a sex cell is an 

 important factor in determining whether the animal produced will be a male or 

 female, 

 sex -linked. A term applied to a character which is associated with sex, the gene 



corresponding to it being in the sex chromosome. 

 Shelf ord, Victor E. American zoologist, at the University of Illinois; 1877- . 

 skeleton (skel' e tiin). The firm supporting parts of an animal body; adj., skeletal, 

 skull. The bones of the head in a vertebrate. 

 society. An association of animals of the same species. 

 som (s5m). G.; body. 



somatic (so mat' Ik). Referring to the body cells as distinguished from the germ 



cells; or to the wall of the body as distinguished from the viscera contained in it. 



somatoplasm (so' ma to plaz'm). The protoplasm of the body as distinguished from 



the germ plasm. 

 somite (so' mit). A metamere. 



special creation. The conception that each species of animal is the result of a particu- 

 lar creative act. 

 specialization. The distribution of functions to certain organs or parts, which become 



adapted to the performance of the respective functions. 

 species (spe' shez). A distinct kind of animal; adj., specific (spe sif' ik). 

 sperm, sperm cell, or spermatozoon (spur ma to zo' 6n). The sex cell of the male. 

 spermary. A gonad producing sperm cells. 



