EXPLANATION OP PLATES 



All drawings were made with the aid of a camera lucida; Leitz Oc. No. 4, Obj. 

 No. 6 unless otherwise indicated. 



PLATE 1 



EXPLANATION OF FIGURES 



1 Gill filament of Quadrula ebenus which had been in soap solution for five 

 davs. A, fat droplets; B, blood corpuscles containing fat droplets; C, chitinous 

 rod. 



2 Section from the same mussel as in figure 1, showing fat droplets in epithelial 

 cells of A, ostium. 



3 Epithelial cells of water tube of gill of same mussel as in figure 1. 



4 (Mil filament of Anodonta imbecillis which had been for five days in soap 

 solution which had been stained with Sudan III. A, pink colored fat droplets; 

 B, blood corpuscles containing pink fat droplets; C, chitinous rod. 



5 Epithelial cells of mantle of Lampsilis ventricosa which had been sus- 

 pended for forty-eight hours in such a manner that only the extremity of the 

 foot and mantles were immersed in soap solution. 



6 Epithelial cells of mantle of the control for figure 5, the mussel being sus- 

 pended so that the foot and mantles were in water. 



7 Epithelial cells of foot of the same mussel as figure 5. 



8 Epithehal cells of foot of same mussel as in figure 6, control for figure 7. 



9 Epithelial cells of left mantle of Lampsilis ventricosa. These cells are 

 from the edge of the mantle which was immersed in soap solution, the remainder 

 of the mussel being in the air. 



10 Epithelial cells of right mantle of the mussel shown in figure 9. These 

 cells were not exposed to the solution. 



11 A, B, and C, gill filaments of Quadrula ebenus which had been in filtered 

 water for thirty days. 



12 Gill filaments of Q. ebenus which had been in albumin solution for thirty 

 days. The relatively heavier stippHng in this drawing in comparison with that 

 in figure 11 indicates the difference in depth of eosin stain taken by the cells 

 of the two mussels. 



28 and 29 Gill filaments of Q. ebenus which had been for 4 days in starch 

 solution stained blue with iodine. Mouth plugged. G, blue granules of starch. 



30 Gill filament of Q. ebenus which had been in water only. Control for 

 figures 28 and 29. 



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