ILLUSTRATIONS 



Plate 1. Finished steel ring for use in ring pendulum 24 



2. Milling machine arranged for grinding the steel ring shown in plate 1 24 



3. Comparator used in ring-pendulum experiments 24 



1. Fig. 1. CI a allium parvifolia __ 38 



2—4. ( 'laytonia megarrhiza 38 



5-6. Clayton in sarmentosa 38 



7. Clayton in chamissonis 38 



8. Clayton ia. diffusa 38 



2. Fig. 9. Claytonia megarrhiza 38 



10-18. Claytonia virginica 38 



19. Mont in rivularis 38 



1. Result of experiment upon a dog, using Ludwig's stromuhr 70 



2. Result (if experiment upon a dug, using Ludwig's stromuhr 70 



3. Result of experiment upon a frog's heart, using Williams's apparatus 70 



1-5. Phoronis arch itecta 116-124 



6-10. Actinotrocha 126-134 



11. Actmotroclin and Phoronis architecta 136 



12-17. Phoronis architecta 138-148 



1. Dipleurosoma elliptica Brooks 156 



1. Commelina nudiflora L 192 



2. Commelina virginica L. and Tradescantia rosea Vent 192 



3-4. Commelina nudiflora L 192 



5. Commelina nudiflora L. and Commelina hiriella Yah] 192 



6. Commelina nudiflora L., Commelina hirtella Vahl., and Commelina virginica L 192 



7. Commelina hirtella Vahl., Commelina virginica L., Tradescantia rosea Vent., and Tradescantia 



virgin ica L 192 



8. Tinantia anomala (Torr.) Clarke, Tradescantia war, eidcziana Kunth and Brouche, and Weldenia 



Candida Sehult. fll 192 



Figure 1. Diagram illustrating calculation of the vibration of a perfect ring 4 



2. Diagram illustrating calculation of radius of equivalent "simple ring" pendulum 5 



3. Diagram illustrating calculation of effect of flaws in ring pendulum 6 



4. Diagram illustrating calculation of effect of flaws in ring pendulum 7 



5. Diagram illustrating calculation for errors of figure in ring pendulum '■< 



6. Diagram illustrating calculation for errors of figure in ring pendulum 10 



7. Diagram illustrating calculation for errors of figure in ring pendulum 11 



8. Diagram illustrating calculation for azimuth error in ring pendulum 12 



9. Diagram illustrating determination of temperature coefficient of ring in ring pendulum 16 



10. Diagram illustrating variation in diameter of ring in ring pendulum 16 



11. Plan of piers, pendulum case, and scheme of illumination in ring-pendulum experiments 18 



12. Diagram illustrating method of making azimuth adjustment in ring pendulum 19 



1. Kroneker's apparatus for measuring action of alcohol upon the isolated reptile heart 56 



2. Williams's apparatus for measuring action of alcohol upon the isolated reptile heart 57 



3. Wood and Hoyt's apparatus for measuring action of alcohol upon the isolated reptile heart 60 



v 



