EXPLANATIONS OF THE PLATES. XVII 



6, 7, 8. Successive stages of its development into a filament. 



9. Immature filament, showing at a the annulation of the Endochrome 

 produced by the regular arrangement of vacuoles, and at b the frothy 

 appearance produced by the multiplication of vacuoles. 



10. More advanced stage, showing at a the aggregation of the Endo- 

 chrome into definite masses, which become star-shaped as seen at b. 



11. The star-shaped masses of Endochrome, a, draw themselves toge- 

 ther again and become ovoidal, as at b; definite openings, c, show them- 

 selves in the cell-wall. 



12. Entrance of the Antherozoids, d, through the openings c, c. 



13. Formation of mature Oo-spores within the filament. 



14. Contents of another filament, a, becoming converted into Anthero- 

 zoids, which move about at b within their containing cell, and escape (as 

 seen at d) through the opening c. 



15. Antherozoids swimming freely by means of two motile filaments. 



PLATE XII. (p. 409). 



TRANSVERSE SECTIONS OF EXOGENOUS STEMS (Original). 



Fig. 1. Young Stem of Clematis: — a, pith; b, b, b, woody bundles; 

 c, c, c, medullary rays. 



2. Portion of stem of Cedar:— a, pith ; b, b, b, wood ; c, bark. 



3. Stem of Buckthorn (Rhamnus). 



4. Portion of ditto more highly magnified. 



PLATE XIII. (p. 412). 



TRANSVERSE AND VERTICAL SECTIONS OF EXOGENOUS STEMS (Original). 



Fig. 1. Portion of transverse section of a Fossil Wood, showing the 

 Medullary Rays, a a, a a, a a, running nearly parallel to each other, and 

 the openings of large Ducts in the midst of the Woody fibres. 



2. Vertical (tangential) section of the same Wood ; showing the Woody 

 fibres separated by the Medullary Rays, and by the large Ducts, bb, bb. 



3 and 4. Transverse and vertical (tangential) sections of a Fossil Wood, 

 showing the separation of the Woody plates, a, a, by the very large 

 Medullary Rays, b, b. 



PLATE XIV. (p. 464). 



sexual reproduction of infusoria (after Balbiani). 



Fig. 1. Conjugation of Paramecium aurelia; a, Ovarium (nucleus); 

 6, Seminal capsule (nucleolus) ; c, oviducal canal ; d, seminal canal ; 

 e, buccal fissure. 



2. The same, more advanced ; a, Ovary, showing lobulated surface ; 

 b, b, secondary Seminal capsules. 



3. One of the individuals in a still more advanced stage of conjugation, 

 showing the Ovary a, a, broken up into fragments connected by the 

 tube m ; b, b, Seminal capsules ; v, Contractile vesicle. 



4. Paramecium ten hours after the conclusion of the conjugation ; 

 a, a, unchanged granular masses of the Ovary ; of which other portions 

 have been developed into the Ova, o, o, still contained within the con- 

 necting tube m ; b, b, Seminal capsules. 



5. The same, three days after the completion of the conjugation. 



6 — 12. Successive stages in the development of the Seminal capsules. 

 13 — 18. Successive stages in the development of the Ovules. 



19. Acinetos in different stages, a, b, c. 



20. Paramecium containing three .iemeta-parasites, q, q, q', lying in 

 introverted pouches, of which the external openings are seen at x, x. 



21. Slentor in conjugation. 



