182 



EDWIN G. CONKLIN 



of gill filaments, and the number of lobules of the liver and ovary. The 

 number of gill filaments in three individuals, which differed greatly in 

 size, was as follows: 



Mature female Volume of body, 0.75 cc, Gill filaments, 204 



Immature female Volume of body, 0.05 cc, Gill filaments, 53 



Dwarf female (mature) Volume of body, 0.05 cc. Gill filaments, 58 



Table 7 gives the dimensions of certain tissue cells from sexually 

 mature individuals of C. plana of widely different body size. All 

 cells measured are from corresponding parts of similar organs. 

 In each instance the dimensions given represent an average of 

 about one hundred cells from at least four different individuals of 

 approximately the same size. I am indebted to Mrs. Anna N. 

 Bigelow, one of my former students, for the care with which she 

 performed the laborious task of making these many measurements. 



With the exception of the ganglion cells and the muscle fibers, 

 the differences in cell size in these different individuals is slight 



TABLE 7 

 Size of tissue cells of mature individuals of Crepidula plana of different body size 



Ectodermal epithelium 



Mantle, near anus 



Gill chamber, epithelial lining 



Foot, epithelium 



Gill filament, external ciliated cells. . 



Gill filament, cells internal to chitinous 

 rod 



Osphradium 



Ganglion cells, largest in pedal ganglion 

 Endodermal epithelium 



Liver duct 



Liver cells, with secretion 



Stomach opposite liver duct 



Rectum 



Mesoderm cells 



Kidney cells 



Muscle fibers from foot, diameter 



VOLUME OP Bopr 



Giant 9 

 0.75-.8CC. 



6 X 13 

 6 X 11 

 6x14 

 4x 15 



3 X 15 

 3 x75 



17 X 23 



6 X 21 

 15 X 59 

 13 X 54 

 10 X 28 



13 x38 

 6 



Dwaif 9 

 0.05 cc. 



M 



6x 14 

 5 X 11 

 6x 15 

 4 X 15 



4x 12 

 4 X 75 

 9 x20 



6x20 

 16 X 58 

 12 x54 

 12 X 27 



10 X 38 

 5 



Typical 6 

 0.05 cc. 



6 X 13 

 6 X 12 

 6x 15 



3 X 15 



4 X 12 

 4x78 



10 x20 



6 X 18 

 17 X 66 



11 x43 

 10 X 25 



13 X 34 



