TION 

 JCE OF SEXUAL DIFFERENTIATION.* 



d in ' embryonal areas ' of Pellicle. 



Spirogyra. 



connecting tubule Mesocarpus. 



cell of one of filaments Spirogyra, 

 nuch larger than parents Diatomacece. 

 a. Which develops without segmentation Desmidiee. 



. Which segments into many others Patntogltea, Gregarina, &c. 



icing single embryo mass which does not segment Paramecium, Kol- 

 poda, &c. 



.icing embryo mass which subsequently segments and yields Monads, 

 Amatbtz, or Fungus-spores. 



icing single embryo mass which does not segment Hydatma scuta. 

 : Lichens and Fungi. 



gemmae ' of individuals which possess both male and female organs 

 :?, Fucus canaliculatus, and many Flowering Plants (bulbils). 



r. Gemination not taking place in definite organs 

 Fucus -vesiculosus, Floridice, Ciliograde Acalephce, 



jemmre' where 

 organs occur 



,uals. 



Actinia lacerata. 



2. Gemmation taking place within female sexual organs 

 Rotifem (?), Acari, Daphniee, Aphides, Lepido- 

 ptera, &c., Colebogyne and other plants. 



ulbils, in addition to a process of ' alternate generation ' Marchantiacece 



: and Marsiteacece. 



i. Multiplication by 'gemmation' of representatives of lower meta- 

 phoric stages Lycopodiacece, Equisetacea, Filices, Tenia echino- 

 coccus. 



Multiplication by 'gemmation' repeated through several deriva- 

 tive generations Trematoda, Hepaticce, and Mosses. 



3. Vegetation of lower me 



. Units remaining a 

 zoa 



remaining aggregated Bryo- 

 and Compound Ascidians. 



Annelids. 



4. No multiplication of lower metamorphic stages Holothuridte, 

 Synapta, Cirrhipedia, solitary Ascidia, &c. 



velopment Medusa and Trematoda (with large ova), Lamellibranchiata, 

 &c. 



i. Metamorphic ( Multiplication by ' gemmation ' in lower stages- 

 development. (. Salpce. 



a. Embryo undergoes process of fission Eotis. 



b. Embryo undergoes no process of fission 



Lumbricida-, Gasteropoda (pulmoniferous), 

 Pteropoda, &c. 



.a. Multiplication by ' gemmation' in lower stages 

 Tubu.arian Hydroida, some Gasteropoda 

 and some Mosses. 



b. No multiplication by 'gemmation' Echino- 

 dermata, Crustacea, Dorsibranchiate Mol- 

 lusca and Tubicolce, Gasteropoda (aquatic), 

 Insecta and Amphibia. 



a. 'Fission' in one of parents (whereby male re- 

 productive organs are separated)- " 

 neria and Argonaut. 



i. Metamorphic 

 development. 



2. Uninterrupted 

 development 



'Fission' may or may not occur in earliest 

 stages of embryo Many Flowering Plants 

 Helianthoid and Asteroid Polypes, Getar- 

 cinus and Astacus flirviatilis, Arachnida, 

 Pisces, Reptilia, Aves, Mammalia. 



o show the gradual rise of sexual differentiation, and the way in which 



doms. 



>aratively high in the scale of organization, as in the embryology of 



c union of male and female in Syngamus trachealis, as well as other 



[ To face p. 552, vol. ii. 



