TABLE OF CONTENTS. 



PA OB 



physiology -of the tissue-systems and of reproduction. The question 

 of old age, A comparison of the fern with the earthworm, and of 

 plants in general with animals in general. The physiological im- 

 portance of the chloropbylless plants 144 



CHAPTER XI. 



THE UNICELLULAR ORGANISMS. 



The multicellular body. Its origin in continued, but incomplete, cell- 

 division. The unicellular body. Its origin traced to complete cell- 

 division. The multicellular body and the unicellular body as 

 individuals. Unicellular forms physiologically " organisms." Special 

 importance of their structural simplicity. "Organisms reduced to 

 their lowest terms." , 15(> 



CHAPTER XII. 



UNICELLULAR ANIMALS. 

 A. AMCEBA. 



General Account. Habitat. Form. The " Proteus animalcule." Ap- 

 pearance. Pseudopodia. Locomotion. Foods. The encysted state. 

 Structure of the unicellular body. Cytoplasm. Nucleus. Vacuoles. 

 Reproduction by fission. Physiology. The fundamental physiological 

 properties of protoplasm as displayed in Amceba. The question of 

 old age. Related forms. The Rhizopoda or pseudopodial Protozoa. 

 Arcella. Difflugia. The "sun-animalcule." The Foramenifera. 

 The Radiolada 158 



CHAPTER XIII. 



UNICELLULAR ANIMALS (Continued). 



B. INFUSORIA. 



General account. Habitat. The "slipper-animalcule/' The " bell- 

 animalcule." Paramcecium. Its form, structure, and habits. Cyto- 

 plasm; trichocysts; vacuoles; nuclei; mouth; oesophagus; anal spot. 

 The encysted state. Reproduction by agamogeuesis; by conjugation; 

 amphimixis. Vorticelht. Its form, structure, etc. Its reproduction 

 by fission, endogenous division, and conjugation. Microgamete and 

 macrogamete. Related forms, Euglena; ZootJiamnion ; CarcJiesium/ 

 Epislylis; etc. Physiology of the Infusoria. Herbivorous, carniv- 

 orous, and omnivorous infusoria. Analogy with higher forms. The 

 problem of chlorophyll in animals. Symbiosis. Vegetating animals. 

 The claim of unicellular animals to be regarded as unicellular "or- 

 ganisms"; organs in the cell; etc. , 168 



