MODES OF REPRODUCTION 



WITH reference' TO THE ORIGIN AND GRADUAL APPEARANGE OF SEXUAL DIFFERENTIATION.* 



r Fission. 



Agamogenebis 



■[ Bacferiat Protococct, Sic. 



SegmentatiOIl. { Ij^ reproductive chambers of Fungi, AlgcE. and Lichens, and in 'embryonal areas' of Pellicle 



Gemmation. 



a. External — Torulcz and other Fungus-spores, &c. 



b. Internal — (Edogonium^ Meloseir'ece^ KolpocUst &c. 



c. External and internal — Vorticellin^^ &c. 



ixcipient 

 Gamogenesis. 



Gem.m.ation and I ^' 

 Conjiigation. t- ^. 



L Conjugation^t 



Gamogenesis 



combined with 



Agamogenesis. 



\ Ovulation. 



In two similar parts (contiguous cells) of same individual— i>iV(?o'''^' 



Of two similar parts of different individuals. { - -Union in jonnectin^ tf,"'-^™|.-- 



a. Of two similar individuals 



iro^yra, 

 r. Producing two embryos much larger than parents — Diatomacecs. 



■c A • «^ ^„^v^«,^ /«• Which develops without segmentation— /)tfjw zV^zi?. 



l^roclucmg one emoryo | which segments into many others— Palmoglcaa, Gregarina, &c. 



b. 



Bacteria- 

 Of many similar individuals. - 



■•■{:; 



Algoid Corpuscles- 



1 



I, Producing single embryo mass which does not segment — Paramecium, Kol- 



Jioda, &c. 



Producing embryo mass which subsequently segments and yields— A/i'?;rt^J, 

 A??i(ri>ce, or Fungus-spores. 



) 

 Producing single embryo mass which does not segment — Hydatina seuta. 



\ a. 



Occurring as 

 distinct pro- 

 cesses. 



^i. Multiplication pnncipally agamogenetic— Lichens and Fungi. 



a. Reproduction by 'gemma;' of individuals which possess both male and female organs- 

 Hydra, Ckaraceie, Fucus canaliculatus, and many Flowering Plants (bulbils). 



I 



2. Multiplication 

 more rarely 

 agamogenetic. 



"I, Gemmation not takii^ place in definite organs — 

 Fiicus vesiciilostis, Floridzee, Ciliograde Acalephcs, 



iS. Reproduction by 'gemmae' where Actinia lacerata, 



male and female organs occur ^ 



in separate individuals. I 2. Gemmation taking place within female sexual organs 



j — Rotifem {?), Acari^ Daphn-uSy Aphides, LepidO"' 



L ptera, &c., Colehogyne and other plants. 



y. Reproduction by bullnls, in addition to a process of ' alternate generation '—Marchantiacece 

 and Mosses. I 



h: Occurring as distinct though related processes 



I 



-Selaginella. and Marsileace<^^ 



I. Multiplication by * gemmation' of representatives of lower meta 

 ' ' phoric stages — Lycopodiacea^ Equisetacece^ FiliceSy Tenia echino 



fa- Metamorphic 



development. 



c. Occurring in 

 different stages 

 of the process 

 of develop- 



.ment. 



I- 



Union of male and 

 female elements 

 developed in same ■ 

 individual 

 (Hermaphrodite). 



2. 



Multiplication by * gemmation' repeated through several deriva- 

 tive generations — Treniatoda^ Hepatzcce^ and Mosses* 



«. Units remaining aggregated — Bryo- 

 zoa and Compound Ascidians, 



Vegetation of lower me- 

 tamorphic stage into 

 an associated colony. 



b. 



Units separating when sexual organs 

 are mature — Many Te?iice and some 

 Annelids. 



4- 



No multiplication of lower metamorphic stages 

 Synapta^ Cirrhipedia^ solitary Ascidia^ &c# 



Holothnriday 



I 



L^. Uninterrupted development— ^/^(^wi**^ and Tre^natoda (with large ova), Lamellibranchiatay 

 Brachiopoda^ &c. 



I, Metamorphic /Multiplication by 'gemmation' in lower stages- 

 development. \ Salpa. 



\ 



fa. 



2, 



Union of male and 

 female elements 

 developed in dif- 

 ferent individuals* 



Individuals 



similar 



(Hermaphrodites). 





X. Uninterrupted 

 development. 



'I, Metamorphic 

 development. 



/3. 



Individuals 

 dissimilar (Male 

 and Female). 



2. Uninterrupted 

 development. 



r 



a. Embryo undergoes process of fission — Eolis. 



4 



b. Embryo undergoes no process of fission- 

 it^ w^r^aVi?*^, Gasteropoda (pulmoniferous), 

 Pteropoda^ &:c. 



a^ Multiplication by 'gemmation' in lower stages 

 ^^Tubularian Hydroida^ some Gasteropoda 

 and some Mosses. 



b. No multiplication by 'gemmation' — EchtnO' 

 dermata^ Crustacea^ Dorsibra^tchiate Mot- 

 lusca and TubtcolcE^ Gasteropoda (aquatic), 

 l7tsecta and Amphibia^ 



~a^ 'Fission* m one of parents (whereby male re- 

 productive organs are separated)— K-2^/i'i** 

 neria and Argonauts 



K 



Fission' may or may not occur in earliest 

 stages of embryo — Many Flowering Plants, 

 Helianthoid and Asteroid Polypes^ Gecar- 

 ciniis and Astactis flti'viatilis^ Arach7nda^ 

 Piscesy Reptilia^ Aues^ AlaniTnalia. 



* Whilst this table is far from being so full as it might have been made, it is we hope sufficiently minute td show the gradual rise of sexual differentiation, and the way in which 

 a single germ mass may give rise to multiple products even throughout the whole Animal and Vegetable king(^oms. 



f It is well not to forget the remnants otsuch a process which are to be met with even in animals comparatively high in the scale of organization, as in the embryology of 

 Buccinitim and Purpura; in the conjugation of two flukes to form Diplozoon paradoxum; and in the organic union of male and female in Synganius trachealis, as well as other 

 somewhat similar peculiarities described bj^ Mr. Darwin amongst many of the sessile Cirrhipedia^ 



{Tofacf^. 552, vol. ii. 







