278 THE EVOLUTION OF CONTINUITY 



s 



Soyphistoma, 103 



Sea-anemone, 84; primitive, 155 



Sea-urchin, chemical fertilisation of 

 eggs, 48, 246 



Segmental Individuals, 112; Con- 

 tinuously Segmental, 113 



Segregation, 166, 214 



Serial Continuity, of cells, 59 ; of 

 zooids, 70 



Sexual cycle of malarial amoeba, 42, 

 44 



Sexual element " plans," 37, 40 ; in 

 Variation, 137 



Side-roads of Evolution, 38, 59, 76, 

 134 



Sieve-tubes, 124 



Silurian Period, 159, 168 



Solar Attraction, 218, 221 



Sphserella, 48 



Spirilla, 67 



Spirogyra, 53, 163 ; theory of fila- 

 ment's development, 54 



Sporangia, 60 



Spores, of malarial amoeba, 43 ; 

 bacterial, 69 



Sporocytes, 43 



Sporophyte, 57, 58 



Sporosac, 92, 173 



Sporosac-gonoblastidium, 93, 96, 100, 

 104, 173 



Sporozooites, 44 



Starfish, 107 



Strobila, 116 



Swimming-bladder, 218 



Tentacles, of Hydra, 71 ; medusoid, 

 96 ; of cephalopod, 198 



Terminal compression, in Fungi, 

 66, 81 ; in Continuously Zooidal 

 Individuals, 81 ; in evolving 

 Fish, 185, 226, 229 



Testis of Hydra, 73 



Thallophytes, 169 



Thread cells, 71 



Tissue-continuity, 70 

 Tortoiseshell butterfly, 142 

 Torula condition, 62, 69 

 Trachymedusse, 99 

 Transmission of characters, 134 

 Tumours, 260 ; due to escape from 



unnatural arrest, 263 ; to escape 



from natural arrest, 268 

 Types of Continuity, 41 ; evolution 



within, 76 



U 



Unicellular Individual, 39, 67 ; Uni- 

 cellular organisms, 39 



Unit cycle, 25 ; Unit Growth-cycle, 

 32, 33 



Unit " somatic tissue," 34 



Variation, 134 ; Natural variations, 

 135 ; Life the Great Variation, 

 149 



Velum, 96 



Vertebrate, evolution of, 180 



W 



Waldeyer and Thiersch, theory of, 



270 

 Water-friction, 226 

 Water-pressure, 161, 185, 225 

 Water- vascular system, 107 

 Worker-bee, 38 



Zooid, definition of, 71, 82. Zooids, 



sexual, 79 ; vegetative, 80 

 Zooidal arrest, 55, 75, 78 

 Zooidal colony, 77, 79 

 Zooidal filament, 78, 83 

 Zooidal evolution, 164 

 Zoogonidium, 48 

 Zygospores, 60 

 Zygote, 44, 133 



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