954 APPENDIX. BOOK II. 



Page 204, paragraph (4). Sachs points out (Ueb. orthotrope und plagiotrope Pflan- 

 zentheile, Arb. d. bot. Inst, in Wiirzburg, II. 2, 1879) that most monosymmetrical or 

 bilaterally symmetrical organs present not only two symmetrical (right and left) halves, 

 but also dorsal and ventral halves which are of different internal structure; such organs he 

 describes by the term dorsi'ventral. When this is the case the two halves react differently 

 to external forces (light, gravity, etc.), and the organ is, according to his terminology, 

 plagiotropic. Some bilateral organs are therefore plagiotropic, but this peculiarity is not 

 confined to them, for some polysymmetrical organs are plagiotropic also (see Book III. 

 p. 854 ; also Goebel, Ueb. die Verzweigung dorsiventraler Sprosse, Arb. d. bot. Inst, in 

 Wiizburg, II. 3, 1880). The term * actinomorphic ' is often used as synonymous with 

 * polysymmetrical.' 



Page 209. On the morphology of Begonia, see Eichler, Ueb. Wuchsverhaltnisse der 

 Begonien, Sitzber. d. Ges. naturfor. Freunde, Berlin, 1880. 



Page 224, line 1 6 from bottom : dele ' germinal vesicle.' 



For an account of sexual reproduction more in accordance with our present know- 

 ledge, see Book III. p. 896, et seq. 



Page 226. Alternation of Generations in Thallophytes. It is extremely doubtful if 

 any real alternation of generations can be detected in the life-history of Thallophytes, 

 more particularly in the one {Penicillium) given as an example in the text. The sexual 

 and the asexual modes of reproduction both occur, but their relation in time and space is 

 not so definite as to warrant the comparison of the life-history of one of these plants with 

 that of a Moss or a Fern. In some, such as the Coleochseteae, sexual individuals occur 

 periodically with a number of intervening asexual generations ; the same might be said of 

 some of the jJEcidiomycetes (such as yEc. Berberidis) if only the existence of a sexual act 

 were proved. These remarks are also applicable to the accounts of the life-histories of 

 various plants given in the Introduction to the Thallophytes in Book II. (See Pringsheim, 

 Jahrb. f. wiss. Bot. XI, 1878 ; and Vines, Journal of Botany, 1879.) 



BOOK II. 



Page 246. Cyanophyceae (or Phycochromaceae, or Schizophyceae). Goebel (Bot. 

 Zeitg. 1880, p. 490) has observed the formation of zoogonidia in Merismopedia. 



Janczewski, Observ. sur la Reprod. de quelques Nostocacees, Ann. Sci. Nat. sir. V, 19. 



The segments into which the filamentous forms of this group break up have been 

 termed by Thuret Hormogonia. 



Page 248. Rostafinski, Quelques mots sur VHsematococcus lacustris, MIm. de la 

 Soc. Nat. des Sc. Nat. de Cherbourg, 1875 ; Dyer, Sexual Reproduction of Thallophytes, 

 CLJ. M.S. 1875. 



For ' Clorophyll ' read ' Chlorophyll.' 



Schizomycetes. The formation of gonidia in these plants was first observed by Cohn 

 in Bacillus (Beitr. z. Biol. d. Pflnzn. I). The filaments elongate very rapidly and become 

 diffluent, and then rows of highly refractive gonidia make their appearance in them. 



The following additional references will suffice as an introduction to the very ex- 

 tensive recent literature. Dallinger and Drysdale, On the Existence of Flagella (cilia) in 

 Bacterium Termo, Monthly Microscop. Journ. XIX, 1875: — Warming, On new forms of 

 Bacteria, Vidensk. Meddel., Copenhagen, 1875 :— Suringar, On Sarcina, Amsterdam, 1866: 

 — Papers by Cohn, Koch, and others, in Cohn's Beitr. z. Biol. d. Pflnzn. vol. 2, and vol. 3. I, 

 1877-79:— Geddes and Cossar Ewart, Proc. Roy. Soc. 1878 {Spirillum): — Reports in 

 Q1.J. M. S., vols. XVIII and XX, 1878-80) :—Kuehn, Ein Beitrag zur Biologic der Bac- 

 terien, Dorpat, 1879 :— Nencki, Beitrage zur Biologic der Spaltpilze, Leipzig, 1880 :— Lister, 



