SoS 



GLOSSARY 



proach of dang^er is thus communicated to 

 other members of the communit}-. 

 Simple epithelium, epithelium only one cell 



thick. 

 Sinupalliate (L. siutis, a bay), in Bivalve 

 Molkiscs, with a posterior indentation in the 

 palHal line, caused by the attachment of a 

 muscle for drawing" back the siphons. 

 Siphon (L. sip/io, a siphon), in aquatic Mol- 

 luscs, a tubular prolong'ation of the mantle 

 by which water enters (inhalent siphon) or 

 leaves (exhalent siphon) the gill-chamber. 



Siphuncle (L. siphunculus, a small pipe), in 

 the Pearly Nautilus and many extinct Ce- 

 phalopods, a sort of tube that runs through 

 the chambers of the shell. 



Society, an association of gregarious animals. 



Soma (Gk. for bod\'), the body of an animal 

 exclusive ot the germ-cells. 



Somatic variation, variation of the soma 

 (which see). 



Spat, the free-swimming larva? or fry of Oy- 

 sters, Mussels, (Sec. 



Special creation, applied to the almost obso- 

 lete view that all species or kinds of organism 

 have been independently created. See Evolu- 

 tion. 



Sperm (Gk. spi^rma, seed), a small and usually 

 motile propagative cell, which fertilizes an 

 egg-ccU (ovum) by fusing with it. 



Spermaceti, in the Sperm-\Mialc, liquid fat 

 contained in a deep depression on the upper 

 side of the skull. 



Spermary, an organ producing sperms. 



Spicule, (L. spiciiluni, a sharp point), in some 

 Zoopln'tes (Co:;lenterata), Sponges, and Ani- 

 malcules (Protozoa), an element of the 

 skeleton, of varied shape and chemical com- 

 position. 



Spinal cord, or Spinal marrow, a cylindrical 

 nerve-mass, constituting the hinder part of 

 the central nervous system in a vertebrate 

 animal. 



Spinal nerve, a nerve taking origin in the 

 spinal cord. 



Spinnerets, in Spiders, small rounded projec- 

 tions on the under side of the abdomen, on 

 which the silk glands open. 



Spiracle, (L. spTro, I breathe): (i) the external 

 opening of the Spiracular cleft (which see); 

 (2) the blow-hole (nostril) of a whale. 



Spiracular cleft, the front gill-cleft of some 

 Fishes {e.g. Sharks), which is losing or 

 beginning to lose its original function. 



Spleen (the Greek name), a large abdominal 

 ductless gland in Vertebrates, of doubtful 

 function. It is richly provided with blood- 

 ■\'essels. 



Splenic fever. See Anilirax. 



Splint-bones, in the Horse, .ScC:, the dwindled 

 remains of 2nd and 4th metacarpals or meta- 

 tarsals. 



Spore (L. sporn, seed), in some Animalcules, 

 one of the minute parts into which the body 



breaks up during- veg-etative propag^ation of 

 a particular kind. 



Spore-formation, in some Animalcules, vege- 

 tative propagation by means of spores. 



Sporocyst (Gk. spora, seed ; cystis, a bladder), 

 in Flukes, a shapeless bag-like stage in the 

 life-history. 



Sporoduct, in some Gregarines, one of the 

 tubes by which the spores pass out of the 

 firm case (cyst) in which the}' are produced. 



Sporosac (Gk. sp<Sra^ seed), in Zoophytes, a 

 degenerate Gonophore (which see). 



Staggers, in Sheep, a disease due to the 

 presence of tape-worm cysts on the brain. 



Stamen (Gk. stemnn, a thread), a slender 

 modified flower-leaf, which produces pollen. 



Statoblast (Gk. statos, resting; blastos, a bud), 

 in fresh-water Moss-Polypes, an internally 

 formed winter-bud. 



Sternal: (i) in \'ertebrates, relating- to the 

 breast-bone or sternum; (2) in Arthropods, 

 near the sternal or under side of the body. 



Sternum, pi. -a (Gk. sterjibn, the breast or 

 breast-bone): (i) in Vertebrates, the breast- 

 bone; (2) in Arthropods, that part of the 

 cxoskeleton covering the ventral surface of 

 a segment. 



Stigma, pi. -ata (Gk. for a mark): (i) the 

 opening of an air-tube In Insects, &c. ; (2) in 

 Plants, the receptive surface to which pollen- 

 grains adhere. 



Stimulus, pi. -i (L. for an ox-goad), any 

 physical or chemical agent by which a sense- 

 organ is thrown iato activity. 



Sting, a piercing weapon that inflicts a poi- 

 soned wound. The name is not applied to 

 parts connected with the mouth, such as the 

 ]ioison-fangs of a Viper. 



Stipes (L. for a branch, or stump), in Insects, 

 the second joint of the second jaw. 



Stratified; (i) of epithelium, more than one 

 cell thick; (2) of rocks, arrang"ed in layers. 



Stratum, pi. -a (L. for pavement), a layer of 

 rock. 



Struggle for existence, a metaphorical way 

 of expressing the strenuous nature of Ac- 

 commodation (which see). 



Sturdy. See Staggers. 



Subclavius, in Birds, the muscle which raises 



the wing". 

 Sublingual glands, a pair of salivary glands 



situated under the tongue. 

 Submaxillary glands, a pair of salivary glands 

 situated between the halves of the lower jaw. 

 Submentum (L. .y^^^, under; vienium, the chin), 



In Insects, the basal part of the lower lip. 

 Supination (L. snpiims, lying on the back), 

 position of forearm when palm of hand Is 

 directed upwards. 

 Supra - scapula, a skeletal element present 



above the scapula in some animals. 

 Sur-royal, the fourth branch of a Red Deer s 



antler (counting from its base). 

 Survival of the fittest. See Natural seleciioyx. 



