CONTENTS. 



I. The Evolution of the Sporophyte in the Higher 



Plants. DOUGLAS HOUGHTON CAMPBELL . i 

 II. The Nature of the Evidence exhibited by Fossil 

 Plants, and its Bearing upon our Knowledge of 

 the History of Plant Life. D. P. PENH ALLOW 19 



III. Influence of Inversions of Temperature, Ascending 



and Descending Currents of Air, upon Distri- 

 bution. PROF. D. T. MACDOUGAL ... 37 



IV. Significance of Mycorrhizas. PROF. D. T. MAC- 



DOUGAL 49 



V. Instinct. EDWARD THORNDIKE 57 



VI. The Associative Processes in Animals. EDWARD 



THORNDIKE 69 



VII. The Behavior of Unicellular Organisms. HER- 

 BERT S. JENNINGS 93 



VIII. The Blind-Fishes. CARL H. EIGENMANN . . . 113 

 IX. Some Governing Factors usually neglected in Bio- 

 logical Investigations. ALPHEUS HYATT . 127 

 X. On the Development of Color in Moths and But- 

 terflies. ALFRED GOLDSBOROUGH MAYER . 157 

 XL The Physiology of Secretion. A. MATHEWS . . 165 

 XII. Regeneration: Old and New Interpretations. 



T. H. MORGAN 185 



XIII. Nuclear Division in Protozoa. GARY N. CALKINS 209 



XIV. The Significance of the Spiral Type of Cleavage 



and its Relation to the Process of Differentia- 

 tion. C. M. CHILD 231 



XV. The Aims of the Quantitative Sttidy of Variation. 



C. B. DAVENPORT 267 



XVI. On the Nature of the Process of Fertilization. 



JACQUES LOEB 273 



