GLOSSARY 189 



Concretions. Roundish mineral masses, formed in concentric layers, 

 like the coats of an onion. See p. 27. 



Cotyledons. The first leaves of an embryo. In many cases packed 

 with food and filling the seed. See fig. 58. 



Cross Fertilization. The fusion of male and female cells from 

 different plants. 



Cuticle. A skin of a special chemical nature which forms on the 

 outer wall of the epidermis cells. See p. 54, fig. 21. 



Earth Movements. The gradual shifting of the level of the land, 

 and the bending and contortions of rocks which result from the 

 slow shrinking of the earth's surface, and give rise to earthquakes 

 and volcanic action. 



Embryo. The very young plant, sometimes consisting of only a few 

 delicate cells, which results from the divisions of the fertilized egg 

 cell. The embryo is an essential part of modern seeds, and often 

 fills the whole seed, as in a bean, where the two fleshy masses 

 filling it are the two first leaves of the embryo. See fig. 58,. 

 P- 77- 



Endodermis. The specialized layer of cells forming a sheath 

 round the vascular tissue. See p. 55. 



Endosperm. The many-celled tissue which fills the large " spore Jr 

 in the Gymnosperm seed, into which the embryo finally grows. 



See fig. 57. 



Epidermis. Outer layer of cells, which forms a skin, in the multi- 

 cellular plants. See fig. 21, p. 54. 



Fruit. Essentially consisting of a seed or seeds, enclosed in some 

 surrounding tissues, which may be only those of the carpel, or 

 may also be other parts of the flower fused to it. Thus a peapod 

 is a fruit, containing the peas, which are seeds. 



Gannister. A very hard, gritty rock found below some coal seams. 

 See p. 25. 



Genus. A small group within a family which includes all the plants 

 very like each other, to which are all given the same "surname"; 

 e.g. Pinus montana, Pimts sylvestris, PimiS Pinaster, &c. &c., are 

 all members of the genus Pimis, and would be called " pine trees " 

 in general (see " Species "). 



Hyphse. The delicate elongated cells of Fungi. 



Molecule. The group of chemical elements, in a definite proportion, 

 which is the basis of any compound substance; e.g. two atoms of 

 hydrogen and one atom of oxygen form a molecule of water, H._,O. 

 A lime carbonate molecule (see definition of "Carbonate") is 

 represented as CaCO 3 . 



Monostelic. A type of stem that contains only one stele. 



