870 GLOSSARY OF TECHNICAL TERMS. 



KERATOSE. Gr. keras, a horn. The fibrous horn-like material out of which the skeletal 



elements of many sponge-forms are constructed. 



LjEOTROPOUS. Gr. laia, left ; trope, a turning. Turning to the left. 

 LIGULATE. Lat. ligula, a little tongue or strap. Having a strap-shaped contour. 



LORICA. Lat. lorica, a coat of mail. The organically distinct protective sheath or 

 domicile, excreted and inhabited by many Infusoria such as Vaginicola, Tintinnus, 

 and Salpingoeca. 



MACROSPORES. Gr. macros, long ; spora, seed, The spore-like elements, few in number 

 but of relatively large size, into which the bodies of many monads become sub- 

 divided. 



MASTIGOPODA. Gr. mastix, a whip ; pous, a foot. A term conferred by Huxley on all 

 those Protozoa which possess cilia or flagella, and thus embracing the two Infusorial 

 Classes of the Ciliata and Flagellata as delimited in this treatise. 



MEMBRANELL^E. Lat. dim. of membrana, membrane. A term proposed by Sterki for 

 the distinction of the relatively large flattened cilia that constitute the peristomal 

 fringe in many Ciliate Infusoria, synonymous with Cirri. 



MESOBLAST. Gr. mesas, middle ; blastos, germ. The middle germinal layer of the 



Metazoic embryo, equivalent with the Mesoderm. 

 MESODERM. Gr. mesos, middle ; derma, skin. The middle germinal layer developed in 



all forms more highly organized than the Ccelenterata, and out of which are chiefly 



developed the general connective tissue, internal skeleton, the muscular system, the 



lining of the body-cavity, the vascular and excretory systems. 



METABOLIC. Gr. meta, change; hallo, I throw. Changeable in form; applied by Cohn 

 to the Infusoria in the same sense as polymorphic. 



METAMORPHIG. Gr. meta, change ; morphe, shape. Changeable in form. 



METAZOA. Gr. meta, change, beyond ; zoon, animal. Term applied to all those animals 

 above the Protozoa, which in the course of their development undergo certain 

 metamorphoses, consisting of the primary segmentation of a true egg or ovum, and 

 subsequent passage through an embryonic condition in which they possess two 

 distinct germinal cellular layers. 



METAZOIC. Gr. meta, change ; zoon, animal. Relating to the Metazoa. 



MICROSPORES. Gr. mikros, small ; spora, seed. The spore-like elements, of exceedingly 

 minute size but very numerous, produced through the encystment and subsequent 

 subdivision of many monads. 



MICROZOOIDS. Gr. mikros, small ; zoon, animal. Title here conferred upon the free- 

 swimming zooids of abnormally minute size, which conjugate with or become buried 

 within the substance of the bodies of the normally sized sedentary animalcules of 

 many Vorticellidae. 



MENISCOIDAL. Gr. meniskos, a little moon ; eidos, resemblance. Having a lens-shaped 

 or watch-glass-like contour, convex on the one side and concave on the other. 



MOLECULAR. Fr. molecule, a small particle of matter ; from Lat. moles, mass. Relating 



to the ultimate quantitative elements of an organic body. 



MONADIFORM. Monad ; forma, shape. Having the aspect of a simple monad. 

 MONADIGEROUS-LAYER. Monad; gero, I bear. Applied by H, James-Clark to that 



stratum in the sponge-structure which is chiefly composed of monadiform elements. 



MONILIFORM. Lat. monile, a necklace ; forma, shape. Jointed so as to resemble a string 

 of beads. 



MONOBLASTIC. Gr. monos, single ; blastos, germ. Relating to that condition of the 

 Metazoic embryo, immediately succeeding segmentation, in which a single germinal 

 layer is alone represented. 



