VARIATION AND FUSION OF COLONIES IN 

 COMPOUND ASCIDIANS. 



BY FRANK W. BANCROFT, 



CONTENTS. 

 Plate XVII. 



I. Introduction 138 



II. Natural History 139 



Length of Life of Botryllus Colonies 143 



III. Color Variation 143 



A. Nature of the Color Variation 144 



1 . Variations of the Same Zoom 146 



2. Variations in Different Regions of the Same 



Colony 146 



3. Variations Occurring at Different Times in 



THE Same Colony 147 



(a) Due to Age 147 



(b) Due to External Influences 148 



4. Variations Among Colonies Produced by the 



Same Mother 150 



(a) The Ground Color 151 



(b) The Color Markings of Class (b) 151 



(c) The Color Markings of Class (c) 151 



B. Specific Characters 154 



1. Thickness of the Colony 154 



2. Number of Zooids in a System 155 



3. Size of Zooids and Colonies 155 



4. Colors of Zooids and Ampulla 156 



IV. Fusion of Colonies 162 



1. Unrelated Adult Colonies 164 



2. Isolated Pieces of the Same Colony 164 



3. Grafting in Botryllus and Botrylloides 165 



4. Fusion of Related Botryllus Colonies 167 



5. Details of the Process of Fusion 169 



6. Physiological Characteristics of Fused Colonies. .172 



(a) Force Controlling the Systems. - 173 



(b) Correlation in Growth and Reproduction 174 



V. The Question of the Individual 175 



VI. Appendix 181 



VII. Summary 183 



Literature Cited 185 



Explanation of Plate 186 



[ 1.37 J January 31, 1903 



