STUDIES ON CELL CONSTANCY IN THE GENUS 

 EORHYNCHUSi 



H. J. VAN CLEAVE 

 From the Zoological Laboratory of the University of Illinois 



FORTY-SIX FIGURES 



CONTENTS 



Introduction 254 



1. Materials 254 



2. Cell constancy and its relation to cell lineage 254 



3. The fields of cell constancy 256 



4. Methods 258 



5. Cell constancy vs. nuclear constancy 259 



Proofs of cell constancy in the genus Eorhynchus 260 



1. Cuticula 260 



2. Subcuticula .260 



3. Lemnisci 266 



4. Proboscis and proboscis receptacle 269 



5. Proboscis wall and receptacle wall 271 



6. Invertors of the proboscis 273 



7. Retractors of the proboscis receptacle 273 



8. Cement gland 274 



9. Male genital apparatus 275 



10. Female genital apparatus 277 



11. Brain 278 



12. Genital ganglion 279 



13. Body musculature 279 



Summary of cell constancy in the genus Eorhynchus, with table of results .... 280 

 General problems relating to cell constancy 281 



1. Cell size vs. body size 281 



2. Beginnings of cell constancy 285 



3. Factors involved in the production of cell constancy 286 



4. Cytomorphosis 287 



5. Known extent of cell constancy in the animal kingdom 289 



6. Significance of cell constancy 289 



Bibliography 292 



' Contributions from the Zoological Laboratory of the University of Illinois, 

 under the direction of Henry B. Ward, No. 28. 



253 



JOURNAL OF MORPHOLOGY, VOL. 25, NO. 2 



