INDEX 



635 



Segmentation, equal and un- 

 equal, 575 ; dis- 

 coid, 575 

 superficial, 383. 



575 

 metameric, see 



Metamere 



,, -nucleus, 572 



Selection, natural and artificial, 



226, 227 



Self-fertilisation, 348 

 Seminal funnel, 347 



,, vesicle, 194, 347, 467 

 Sense-organs and cells, 179, 315, 



344. 351. 380, 409, 424, 432, 



4 6 4. 533, 592 

 Septa, of earthworm, 333 

 Septum : lucidum, 531 ; nasal, 



42, 493 ; interorbital, 487 

 Serous membrane of embryo, 



609, 610 



Sesamoid bones, 502, 505 

 Seta, 328, 350, 351, 362 

 Sex-cells, primitive, 566, 568 

 Sexual characters, external, 7, 



382, 433, 486 

 Sexual generation, see Gamo- 



bium 

 Sexual organs, see Reproductive 



organs 

 Sexual reproduction, see under 



various types 

 Shank, 5 



Shell, 396 ; larval, 410 

 Shell of egg, 470, 566 

 Shell-gland of mussel-embryo, 



410 ; of dogfish, 469 

 Shoulder-girdle, see Pectoral 



arch 

 Sinus : blood-, 376, 377, 408, 



457; lymph-, 18, 27; urinary 



and urinogenital, 466, 



467 ; venosus, 80, 89, 449, 



520 

 Siphon, inhalant and exhalant, 



397 

 Skeleton, see Endo- and Exo- 



sk^leton 



Skin, see Integument 

 Skull : Frog, 16, 35, 39 ; Dogfish, 



436 ; Rabbit, 487 ; develop- 

 ment of, 604 

 Smell, organ of, see Olfactory 



organ 

 Snout, 4 



Somatic layer of mesoderm, 580 

 Somatopleure, 580 

 Spawn, 9 

 Species, 215 et seq. ; origin of, 



222, 225 

 Sperm, or Spermatozooid, 194, 



382, 568 ; and see under 



various types 

 Spermary, 25, 193, 194 ; and see 



Reproductive organs 

 Spermatic substance, 9 

 Spermatogenesis, 194, 566 

 Spermatophore, 382 

 Spermiduct, 193, 347, 382, 466, 



53 8 - 603 



Spermotheca, 347 



Sperm-reservoir, 347 



Sperm-sac, 347, 467 



SPH^RELLA : general characters, 

 240 ; rate of progression, 240 ; 

 ciliary movements, 242, 250 ; 

 colouring matter. 242 ; motile 

 and stationary phases, 244 ; 

 nutrition, 245 ; source of 

 energy, 248 ; dimorphism, 

 250 ; reproduction, 250 ; con- 

 jugation, 251 ; animal or 

 plant ? 255 ; practical direc- 

 tions, 259 



Sphincter, 71 



Spinal cord, 27, 155, 424, 459, 



53 2 . 592 



Spindle, nuclear, 560 

 Spiracle, 432, 449 

 Spiral valve, 445, 515 

 Spireme, 560 

 Splanchnic layer of mesoderm, 



580 



Splanchnopleure, 580 

 Spleen, 23, 98, 447, 516 

 Spontaneous generation, see 



Abiogenesis 

 Spores, 254, 275, 286 

 Sporozoa, 284, 292 

 Sporozoite, 287 



