GLOSSARY 375 



Darwinism (dar' win iz'm). The theory of natural selection, propounded by Charles 

 Darwin. (By the German biologists the term is often used to mean evolution.) 



Deaminize {de am' i nize). To remove the amino radical (NH2) from (an amino-acid). 



Deciduous {desid'uus). Falling off at maturity or at the end of a season; said 

 of the leaves of trees which fall periodically. Applied also to trees whose leaves 

 fall periodically. 



Delamination {de lam' i na' shun). SpUtting off; said of a layer of cells. 



Demospongiae (de' mo spun' ji ee). A class of Porifera (sponges). For definition see 

 Chapter XII. 



Dendrite (den' drite). A projection from a nerve cell which ordinarily conducts im- 

 pulses toward the body of the cell. 

 Dendritic [den drif ik). Tree-like. 



Dentine {den' tin). The dense bony substance composing the bulk of mammalian 



teeth. 

 Dermatemydidae {der' ma te mid' i dee). A family of turtles. 



Dermatozoa {der' ma to zo' a). A group of animals (literally, the skin or touch 

 animals) in Oken's early classification. It comprised the invertebrates. 



Dero {de'ro). A genus of worms, phjdum Annelida, subclass Oligochacta. 



Desmognathus {dez mog' na thus). A genus of salamanders. 



Devonian {de vo' ni an). Of middle Paleozoic age, next following the Silurian. 



Dextrin {deks' trin). Any one of several related carbohydrates derived bj' hydrolysis 

 from starch; among them being erythrodextrin, achroodextrin and maltodextrin. 



Dextrose {deks' trose). Glucose or grape sugar. 



Diaphragm {di' afram). A partition; specifically, the partition between the thorax 



and abdomen of a mammal. 

 Diastase {di' as tase). An enzyme that decomposes starch. 

 Dichogamy {di kog' a mi). The maturing of the male and female germ cells of a 



hermaphrodite at different times, thus preventing self-fertilization. 

 Dichotomous {di kot' o mus). Regularly dividing into two parts; said of branching in 



certain plants, also of a system of classification in which each group is divided 



into two parts. 



Diemictylus {di e mik' ti lus). A genus of salamanders. 



Differentiation (dif fer en' shi a' shun). The process of becoming structurally unlike, 



or of becoming heterogeneous. Also the condition of heterogeneity resulting from 



differentiation. 



Diffusion {dif fu' zhun). The spreading of the molecules of one substance among 

 those of another. 



Digestion {di jes' chun). The conversion of food into soluble substances which may 



diffuse through protoplasm. 

 Dinobryon {di no' bri on). A genus of colonial flagellate Protozoa in which the 



individual is enclosed in a sheath. 

 Dinosaur {di' no sawr). One of an order of extinct reptiles of Mesozoic time, mostly 



of large size. 

 Dioecious {di ee' shus). Having the male and female organs in separate individuals; 



said of species. 



Diploblastic {dip' lo bias' tik). Composed of two layers of cells. 



Diploid {dip' laid). Double; specifically, the double iiuinb(>r of chromosomes fovmd 



