212 Glossary. 



Compositae. — Plants in which the inflorescence consists of numerous 

 small flowers brought together into a dense head, the base of which 

 is enclosed by a common envelope (e.g. the Daisy, Dandelion, &c). 



Congenital characters. — See Plasmogenetic characters. 



Conjugation. — This term is applied to a process observed in the 

 Protozoa (q. v.), which seems to correspond to the sexual reproduction 

 of the Metazoa (q. v.). The majority of the Protozoa cannot long 

 continue to reproduce themselves asexually without becoming 

 degenerate, or rather without becoming altogether extinct. Two 

 individuals (as a rule) consequently unite either temporarily or 

 permanently. In the former case, an exchange of material is effected ; 

 and in the latter, complete fusion takes place. 



Correlation. — The normal coincidence of one phenomenon, character, 

 &c, with another. 



Cytoplasm. — See pp. 30 and 32. 



Determinant. — See p. 123. 



Ectoblast. — Syn. of epiblast and ectoderm. The general result of the 

 division of a fertilized ovum is a two-layered ball of cells (a gastrula). 

 The outer layer is called the ectobhst and the inner layer the ento- 

 blast. (See Darwin and after Darwin, p. 137 et seq.). 



Embryology. — Hence embryogenesis, &c. The study of the develop- 

 ment or the early growth of the individual. 



Entoblast. — Syn. of hypoblast and endoderm. See Ectoblast. 



Epigenesis (Harvey). — The theory that organisms are formed by the 

 development of the egg itself, and not by the expansion of a miniature 

 within the egg (preformation). 



Fallopian Tubes. — The tubes through which the spermatozoa pass to 

 effect fertilization, and through which the ova pass from the ovary to 

 the uterus. 



Fission. — Syn. of fissiparous separation. The breaking into two 

 (without karyokinesis — q. v. N of a cell, which has, by overgrowth, 

 disturbed its physiological equilibrium. This process is almost 

 mechanical. 



Formative material. — See p. 56. 



Gemmation. — That form of asexual reproduction known as budding. 



Gemmules (Darwin). — Minute granules, formed by the division of the 

 general body-cells, which are supposed to be dispersed throughout the 

 entire system. These themselves multiply by division, and are 

 collected from all parts of the body to constitute the sexual 

 elements. 



Germ-plasm. — See p. 32. 



Hydroids. — Belong to a division (Hydrozoa) of the stinging-animals 

 or Coelenterata. They occur both in the sea and in fresh water, and 

 are solely polypoid (i.e. tubular and tentacled). 



