lyo DESIGN IN NATURE 



PLATE LXIX {contimied) 



Ym. 13. — Spheroidal cell combinations or rosette genimnles of typical collared monads, x 800. Tlie symmetry displayed in tliis 

 Figure and in Figs. 1 and 11 is very remarkable. The rosette arrangement of Fig. 11 is especially striking (the Author). 



Fifis. 14 and 15. — Simple planuloid swarm gemmules or ciliated larvse of Grantia compressa (Bowerbank) in various stages of 

 development seen superficially and in longitudinal optical section. At Fig. 15 the larvas consist of similar closely opposed conical 

 uniflagellate elements, x 350. Fig. 15 reveals a well-marked radiating arrangement. In both figures the cilia form a striking feature. 

 These are useful for causing currents either for securing food or for propulsion. 



Fig. 16. — Planuloid swarm gemmule with internally contained cell spherules as seen in optical section in Ascetta primordialis 

 (Oscar Schmidt). 



Fig. 17. — Portion of lateral wall of swarm gemmule of same sponge showing cell spherules (a), derived from the uniflagellate 

 elements which assume an amoeboid form and creep into the common central cavity seen in Fig. 16 (Oscar Schmidt). 



Figs. 18, 19, 20, 21, 22, 23, 24, 25, and 26. — Polymorphic phases of adult monads (Herpetomonas muscse-doniedicse), x 650. At 

 Figs. 25 and 26 the monads are dividing by longitudinal fission. The shapes assumed are remarkable and various. 



Fig. 27. — Social colony of collared monads {Proterospongia haeckeli) inhabiting a common gelatinous matrix resembling the 

 cytoblastema of an ordinary spimge, x 800. a, Hyaline gelatinous matrix ; h, normal zooids with collars expanded ; c, normal zooids 

 with collars contracted ; d, zooids with collars and iiagella withdrawn and presenting an amoebiform appearance as in the cytobksts 

 of a sponge body ; these divide by transverse fission ; e, spore mass (W. S. Kent). Shows centrifugal and centripetal action of collar 

 of zooid, the amoeboid and sporular phases of zooid, and its power of changing shaj^e in any direction (the Author). 



Fig. 28. — Portion of inner wall or lining of sponge {Ascetta primordialis), x 350. a, Pore aperture surrounded by flagelliferous 

 monads ; h, b, b, spore groups produced from ordinary collared monads believed by Haeckel to be sperm cells ; c, a, large amoeboid 

 bodies, the result of metamorphosis and coalescence of collared cells, which later develop into ciliated swarm gemmules (Haeckel). 



Fig. 29. — Fragment of peridium or indurated outer wall of sporangium of Didymium farinaceum (Fries), with substallate calcareous 

 spicule, X 390. 



Fig. 30. — A spicule of .same further enlarged. These spicules present well-marked crystallic shapes. 



PLATE LXX 



This plate illustrates how the lower animal forms divide by longitudinal and transverse fission ; how they 

 come together and coalesce ; how they retrogress and assume the amoeboid condition prior to reproducing them- 

 selves ; how they form sporocysts with spores — the spores being scattered when the sporocysts burst ; how, in 

 many instances, they assume plant shapes ; how certain of them present a spiral appearance, and how their con- 

 tractile vesicles open and close as in the diastole and systole of the heart, thus identifying rhythmic movements 

 with the very beginnings of hfe. 



Figs. 1 and 2. — Progressive phases of transverse fission of adult monad (Cercomonas typica), x 1750. 



Figs. 3 and 4. — Examples of tran.sverse fission in adult monad (Spumella guttula, Ehr.), x 600. The fusion of smaller with larger 

 monads is seen at Figs. 6 and 7. The division, segmentation, and blending of rudimentary animal forms have an obvious bearing on 

 development, differentiation, and division of labour in the higher animals (the Author). 



Figs. 5, 6, and 7. Free-swimming monads (Simmella guttula, Ehr.). «,, Aperture ; n, nucleus ; cv, contractile vesicle. The monads 

 are coalescing or conjugating in Figs. 6 and 7. 



Fig. 8. — Shows a phase of longitudinal fission. 



Fig. 9.— An encysted group showing stalked (o) and stalkless (b) cyst, and large cyst with two stalks (c) ; the latter the result of 

 the conjugation of two zooids, x 1500. 



Fig. 10. — Normal attached monad {Spumella guttula, Ehr.), x 600. 



Fig. 11. — Shows longitudinal fission of a monad. 



Figs. 12 and 13.— Illustrate the alternating diastole and systole or opening and closing of the two contractile vesicles of a free- 

 swimming monad {Fhysomonas socialis), x 1000 (W. S. Kent). Similar opening and closing rhythmic movements are witnessed in 

 plants. They liave great significance as indicating the inherent fundamental nature of rhythms (the Author). 



Figs. 14 and 15.~-Normal adult monads {Heteromita lens, Mull), x 800. Show nucleus and contractile vesicle. 



Figs. 16 and 17. — Irregular-shaped amcebiform conditions of same monads. 



Figs. 18 and 19. — Two of same monads about to coalesce. 



FKi. 20.-Conjugation or union proceeding and resulting in a spheroidal sporocyst as seen in Figs. 21, 22, and 23 (same monads) 

 Tlie blending and fu,smg of monads mto each other and the production of new individuals bv spore° is analogous to reproduction in 

 its several phases m certain plants (the Author). ' ° ^ ">j.ui,i,iuii 



Fig. 24.— Two sjjorocysts containing eight or sixteen macrospores (same monads). 



Fig. 25.— One sporocyst containing four macrospores (same monads). 



Fig. 26.— The sporocyst burst and liberating biilagellate germs same as in Figs. 14 and 15, but smaller, x 1000. 



Figs. 27, 28, 29, and 30.— Minute uniflagellate monaditorm germs developed from macrospores, x 2500. 



Fk!. 31.— Colony stock or zoodendrium {Gephalotliamnium cuneatum), x 1250. Presents a very decided plant-like appearance 



