242 GLOSSARY 



GASTRULATION. The process of gastrula formation. 



GEMMATION. Asexual reproduction by budding. 



GENETICS. The science of heredity. 



GERM PLASM. The reproductive protoplasm distinguished from the so- 

 matic or organ-forming protoplasm of the individual. 



GONAD. A reproductive organ in which the germ cells are formed. 



HAEMATOCHROME. A red coloring matter formed from chlorophyll. 



HAEMOCOEL. A body cavity containing blood, and different from a coelom. 



HAPLOID. Refers, in connection with chromosomes, to the half number 

 subsequent to reduction. 



HEPATO-PANCREAS. The digestive gland of the Crustacea. 



HEREDITY. The appearance in offspring of characters, the factors for which 

 are in the germ cells. 



HERMAPHRODITE. An organism with both male and female organs of re- 

 production, or capable of producing both eggs and spermatozoa. 



HETEROZYGOUS. Containing two factors or allelomorphs for the same 

 character in heredity. 



HOLOBLASTIC. Cleavage in which the division planes cut through the entire 

 cell mass. 



HOLOPHYTIC. Like green plants in the manufacture of food. 



HOLOZOIC. Animal-like in mode of nutrition. 



HOMOLOGY. Genetic relation of parts; implies morphological likeness or 

 structural affinity. 



HOMOZYGOUS. In heredity, containing one kind only, of two alternative 

 factors for the same character. 



HORMONE. An internal secretion necessary for the full activity of some 

 organ at a distance. 



HYDRANTH. A single asexual individual of a hydroid colony. 



HYDROID. Hydra-like, or pertaining to Hydroidea, a group of coelenterates. 



HYDROLYSIS. A form of chemical decomposition by which a compound is 

 resolved into other compounds by taking up the elements of water. 



HYDROLYTIC. Capable of producing dissolution through the addition of 

 water. 



IMMUNITY. Protection against disease. 



INDUSIUM. Membrane covering a sorus or fruit-dot in ferns. 



INTUSSUSCEPTION. Reception of foreign matter by all parts at once of 

 living matter, leading to interstitial growth as opposed to growth by 

 accretion or addition on the outside. 



IRRITABILITY. The property possessed by all protoplasm of responding 

 to stimuli. 



KARYOKINESIS. The phenomena of nuclear division involving the forma- 

 tion and the division of chromosomes; same as mitosis. 



KATABOLISM. Destructive metabolic processes in the living organism, 

 whereby protoplasm and its derivatives are broken down, forming 

 compounds of lower energy potential and transforming stored energy 

 into energy of heat and movement. 



LININ. The substance of the nuclear reticulum other than the chromatin. 



