xvi CONTENTS 



PAGE 



theory, 250. The cell-theory becomes harmonized with the pro- 

 toplasm doctrine of Max Schultze, 25 1. Further modifications of 

 the cell-theory, 252. Origin of cells in tissues, 252. Structure of 

 the nucleus, 253. Chromosomes, 254. Centrosome, 256. The 

 principles of heredity as related to cellular studies, 257. Ver- 

 worn's definition, 258. Vast importance of the cell-theory in 

 advancing biology, 258. 



CHAPTER XII 



Protoplasm the Physical Basis of Life, 255 



Great influence of the protoplasm doctrine on biological progress, 259. 

 Protoplasm, 259. Its properties as discovered by examination of 

 the amoeba, 260. Microscopic examination of a transparent leaf, 

 261. Unceasing activity of its protoplasm, 261. The wonderful 

 energies of protoplasm, 261. Quotation from Huxley, 262. The 

 discovery of protoplasm and the essential steps in recognizing 

 the part it plays in living beings, 262-275. Dujardin, 262. His 

 personality, 263. Education, 263. His contributions to science, 

 264. His discovery of " sarcode " in the simplest animals, in 1835, 

 266. Purkinje, in 1840, uses the term protoplasma, 267. Von 

 Mohl, in 1846, brings the designation protoplasm into general 

 use, 268. Cohn, in 1850, maintains the identity of sarcode and 

 protoplasm, 270. Work of De Bary and Virchow, 272. Max 

 Schultze, in 1861, shows that there is a broad likeness between 

 the protoplasm of animals and plants, and establishes the proto- 

 plasm doctrine. The university life of Schultze. His love of 

 music and science. Founds a famous biological periodical, 272— 

 274. The period from 1840 to i860 an important one for biol- 

 ogy, 274. 



CHAPTER XIII 



The Work of Pasteur, Koch, and Others, 276 



The bacteria discovered by Leeuwenhoek in 1687, 276. The develop- 

 ment of the science of bacteriology of great importance to the 

 human race, 276. Some general topics connected with the study 

 of bacteria, 277. The spontaneous origin of life, 277-293. Bio- 

 genesis or abiogenesis, 277. Historical development of the ques- 

 tion, 277. I. From Aristotle, 325 B.C., to Redi, 1668, 278. The 

 spontaneous origin of living forms universally believed in, 278. 

 Illustrations, 278. II. From Redi to Schwann, 278-284. Redi, 



