468 NOTES. 



viewed. Cf. on this subject, in addition to the four important 

 works, here quoted, by Auerbach, Biitschli, Hertwig, and Stras- 

 burger, the most recent annals of the progress of the history of 

 evolution (Waldeyer in Yirchow-Hirsch's " Jab.resberichten," 

 Berlin; Hertwig in Hofmann-Schwalbe's " Jahresberichten," 

 Leipzig). 



55 (i. 185). Protozoa and Metazoa. Cf. vol. i. p. 248 ; ii. 92. 

 The Protozoa and Metazoa are genetically and anatomically so 

 very distinct, that the former, as Protista, may even be excluded 

 entirely from the animal kingdom, and may be regarded as a 

 neutral intermediate kingdom between the plant and animal 

 kingdoms. — " Generelle Morphologie," vol. i. pp. 191-230. Ac- 

 cording to this view the Metazoa alone are really animals. 



56 (i. 186). The Unity of the Zoogenetic Conception, result- 

 ing from the Gastrjea- theory, has as yet not been destroyed by 

 the numerous attacks directed against that theory : for none of 

 these attacks have succeeded in substituting anything positive ; 

 by pure negation no advance can be made in this dark and 

 difficult subject. 



57 (i. 187). The Egg-cleavage and Gastrulation of Man, as 

 represented diagrammatically in Figs. 12-17 of Plate II., is most 

 probably in no essential way different from that of the Rabbit, 

 which has as yet been most closely examined in this point. 



58 (i. 188). Ernst Haeckel, " Arabian Corals " (" Arabische 

 Korallen"). "A Journey to the Coral Banks of the Red Sea, and 

 a Glimpse into the Life of Coral Animals. A popular lecture, 

 with scientific explanations." With 5 coloured plates, and 20 

 woodcuts. Berlin, 1876. 



59 (i. 189). The Number of the Segmentella, or cleavage- 

 cells, increases, in the original, pure forms of palingenetic egg- 

 cleavage, in regular geometric progression. But the point to 

 which this proceeds varies in the various archiblastic animals, 

 so that the Morula, as the final result of the cleavage-pi*ocess, 

 consists sometimes of 32, sometimes of 64, sometimes of 128 

 cells, and so on. 



60 (i. 189). The Mulberry- germ, or Morula. The seg- 



