INDEX AND GLOSSARY 



143 



Double monsters, as examples 

 of heteromorphosis, 63. 



Doubling division. When an 

 amoeba reproduces by simple 

 division, the daughter-amoe- 

 bae are identical, and each 

 is identical with the parent 

 except in size ; from one 

 amoeba two have been 

 formed. A doubling division 

 of the nucleus is such as 

 would result in the forma- 

 tion of two nuclei alike in 

 every respect, ix ; visible 

 evidence for, xv, 24; in 

 unicellular organisms, 40 ; 

 occurrence of, with differen- 

 tiating division, 78. 



DRIESCH, experiments on eggs, 

 54 ; separation of segmenta- 

 tion spheres, 60. 



E. 



Echinoderms, a group of marine 

 animals, of which the star- 

 fish is the most familiar type, 

 eggs of, 54. 



Echinoidea, a group of echino- 

 derms, 61. 



Ectoderm, the tissue in an 

 adult derived from the epi- 

 blast (which see), 19. 



Egg, relation between structure 

 and division of, 94 ; specific 

 character of, 135. 



EMERY, on polymorphism in 

 ants, 128. 



Endoderm, the tissue in an 

 adult, derived from the 

 hypoblast (which see), 19. 



Enfoldment. See Evolution. 



Epiblast. In the development 

 of all multicellular animals, 

 the young embryo soon be- 

 comes divided into two sets 



of cells, the epiblast and 

 hypoblast ; where a gastrula 

 is formed, the outer layer of 

 cells is the epiblast, the inner 

 layer the hypoblast, xviii. 



Epigenesis, the doctrine that 

 the formation of a new indi- 

 vidual is not the mere out- 

 growing of particles hidden 

 in the egg-cell, but the result 

 of moulding external forces, 

 xiii ; Roux's definition of, 7 ; 

 Weismann's denial of, 9 ; 

 epigenetic explanation of 

 stages in development, 98 ; 

 summary of Hertwig's ac- 

 ceptance of, 136. 



Evolution. Originally the 

 term was applied, not to the 

 origin of existing forms of 

 life from common ances- 

 tors, but to the doctrine that 

 every living creature con- 

 tained within it the whole 

 series of its future descend- 

 ants, and that the growth of 

 a living creature was evolv- 

 ing of one of these enfolded 

 miniatures, xiii, 1, 2, 3 ; 

 Eoux's contrast of, with epi- 

 genesis, 6 ; the new evolu- 

 tion, 10 ; Hertwig's partial 

 agreement with, 135, 136. 



Experiment, Weismann's cau- 

 tion against, 10. 



F. 



Fertilisation, the union of the 

 nuclear matter of a male cell 

 with the nuclear matter of a 

 female cell, xii, xiv. 



Foraminifera, a group of pro- 

 tozoa provided with shells, 

 44. 



FOREL, on eyes of ants, 126. 



