874 GLOSSARY OF TECHNICAL TERMS. 



Systole. Gr. sustello, to draw together. A term applied to the contracting action of 



the structure known as the contractile vesicle of Infusoria and other Protozoa. 

 Taxonomy. Gr. taxis, arrangement ; ii07nos, law. The systematic statement and gene- 

 ralization of the facts of morphology, in such a manner as to arrange living beings in 

 groups, according to their degrees of likeness. 

 Tentaculiferous. Lat. tentaculum, a tentacle ; /<?^(?, I bear. Bearing or possessing 



tentacles. 

 Tentaculiform. Lat. tentaculum, a tentacle or feeler ; forma, form. Having the 



form of a tentacle. 

 TRABECULiE. Lat. trabeaila, a little beam. Connecting rod- or bar-like structures. 

 Tractellum. Lat. traho, tractum, to draw. Term introduced by Ray Lankester for 

 the distinction of the anteriorly projected flagellum of ordinary flagellate Infusoria, 

 whose movements serve to draw the body through the water, 

 Trichocysts. Gr. thrix, trichos, hair; kustos, a bladder. Minute rod-like bodies 



developed in the cortical layer of many Infusoria. 

 Uncini. Lat. 7incinus, a hook. The claw-like modification of ordinary cilia possessed 



by many hypotrichous ciliate Infusoria. 

 Vacuolate. Lat. dim. of vacuus, empty. Having a number of clear spaces or inter- 

 stices. 

 Velum. Lat. velum, a veil. Here appHed to the delicate veil-like membrane bordering 



the oral orifice in such forms as Cyclidium and Pleuronema. 

 Vermicular. Lat. venniculus, a little worm. Resembling a worm in shape. 

 Vestibulum. Lat. vestibulum, a forecourt. The excavated chamber or fossa into 



which both the oral and anal apertures debouch, as developed in the Vorticellidae. 

 Vestibular-SETA. The bristle-like cilium or seta that projects from the vestibulum or 



oral fossa of many Vorticellidae. 

 ZOOCAULON. Gr. Z0071, animal ; caulos, a stem. Title conferred by the author on the 



erect tentaculiferous branching colony-stocks of the genus Dendrosoma. 

 Zoocytium. Gr. zoon, animal ; kutos, a cell. A term applied by the author to the 

 gelatinous matrix excreted and inhabited by various colonial Infusoria, such as 

 Proterospongia, Phalatisterium, and Ophrydiutn. 

 ZOODENDRIUM. Gr. zoon, animal; dendron, a tree. A term applied by the author for 

 the distinction of the dendritic or tree-like colony-stocks of such Infusoria as Dendro- 

 monas and Epistylis. 

 ZOOID. Gr. zoon, animal; eidos, shape. An animal organism not independently 

 developed from a fertilized egg or ovum, but derived from a preceding individual by 

 the process of fission or gemmation. Specially applicable to the Infusoria and other 

 Protozoa, and to the component members of all stock-building communities, such as 

 Polypes, Corals, and Polyzoa. 

 Zoospores. Gr. zoon, an animal ; spora, seed. The ciliated locomotive germs of Algse 



and Protophytes. 

 ZOOTHECIUM. Gr. zoon, animal ; theca, sheath. A term applied by the author to the 

 compound tubular structures excreted and inhabited by such colonial Infusoria as 

 Rhipidodendron and Schizosiphoti. 

 Zygosis. Gr. zugon, a yoke. The genetic union or conjugation of two Infusoria. 

 Zymotic. Gr. zumotos, fermented. Pertaining to or caused by fermentation. Zymotic 

 diseases, that large class of contagious diseases supposed, and in many cases proved, 

 to be caused by the reception into the system of a protophytic virus which acts as 

 a ferment. 



