J 



i) i 



COMPENSATORY REGULATION. 



BY 



CHARLES ZELENY. 



General Introduction 2 



Data 5 



I. The Leaflets of the Compound Leaf ^ 



II. The Rate of Regeneration of the Arms in the Brittle-star, Ophioglypha lacertosa .... 7 



1. Introduction 7 



2. Method 8 



3. Data 14 



4. Discussion 16 



III. The Opercula of Serpulids 18 



1 . Comparative Anatomy 19 



1. The genus Hydroides 19 



2. Other genera of Serpulids 24 



3. Distribution of the Opercula between Right and Left Sides 32 



4. Exceptional Degrees of Development and One Case of a Supernumerary 



Operculum 37 



2. Development of Opercula — 



1 . Ontogenetic Development 38 



a. Introduction 38 



h. Historical Review 39 



c. Observations 41 



d. Summary of Data and Discussion 51 



2. Regeneratory Development 54 



a. Introduction 54 



6. Unoperated Condition of the Opercula in H. dianthus 55 



c. Operations on Functional Operculum 55 



d. Operations on Rudimentary Operculum 58 



e. Operations on Both Opercula 59 



/. Body Cut in Two 62 



g. Progressive Changes in Opercula 6c 



h. Experiments on Group V 65 



/. Experiments on Group LV 67 



j. Experiments on Group VI 69 



k. Discussion of the Data 71 



3. Probable Phylogenetic Development 72 



3. Comparison of Regeneratory, Ontogenetic and Probable Phylogenetic Develop- 



ment 74 



4. General Discussion of the Facts of Compensatory Regulation in the Opercula of 



Serpulids 76 



