GLOSSARY-INDEX 397 



dextrose. A form of sugar found in fruits; glucose, 9. 



dialysis. See osmosis. 



diaphragm. A muscular membrane separating the chest from the abdomen. 



diastatic. Capable of turning starch into sugar. 



diastole (Gr. diastole = an expansion). The period in each beat when the 



heart is relaxed, 188. 

 Diatoms, 136, 219. 

 dichotomous (Gr. dicha = in two + temnein = to cut). Branching by 



regular division into pairs, 

 differentiate. To become unlike; usually applied to parts originally similar 



but which acquire different structure and function, 95, 283. 

 digestion. A series of changes in the chemical and physical nature of the 



food which renders it capable of absorption, 204, 305. 

 digestive cells, 145. 

 digestive juices. The secretions which render the food capable of absorp^ 



tion, 55, 62, 204. 

 digits. Fingers and toes. 



digitigrade. Walking on the tips of the fingers and toes, 

 dimorphism (Gr. di- = twice + morphe = form). Showing two distinct 



forms, 

 dioecious (Gr. di- = twice + oikos = house). Having the sexes in different 



plants. 



diphtheria, 231, 232. 



direct development. Development without a metamorphosis, 290. 

 disease germs, 82. 



disintegrate. To break to pieces, 4. 

 dispersal. The power of organisms to distribute themselves from centers, 



379. 



dissepiment. See septum. 

 distal. Farthest from the main body, 

 distribution, in space, 379; in time, 383. 



divergence. The appearance of two or more lines of descent from a com- 

 mon center, 337, 339. 

 diversities. The slight differences found among individuals of the same 



species. 



diverticulum. Any sac-like outgrowth, 

 dogs, origin of, 339. 

 dominant characters (Lat. dominari = to rule). Those which appear mosL 



prominently in the first generation after the crossing of races, 360. 

 dorsal. Pertaining to the back, 155. 

 drones. Male bees. 

 Drosera, 223. 



