The Fine Structure of 

 the Stenoteles of Hydra' 



George B. Chapman 



Department of Anatomy, Cornell University Medical College, New York, N. Y 



111 the more than two hundred years which have passed since 

 Leeuwenhoek ( 9 ) and Trembley ( 13 ) first referred to the nemato- 

 cysts of hydra, these structures have been the subject of a great 

 number of anatomical, biochemical and physiological investiga- 

 tions. As is usually the case, as many questions were raised as 

 were answered. Recently, in an attempt to answer some of these 

 questions, Hess et oJ. (6), Slautterback and Fawcett (12) and Chap- 

 man and Tilney (3, 4) studied ultrathin sections of nematocysts 

 in the electron microscope. It goes without saying that these studies 

 have contributed appreciably to our knowledge of nematocyst 

 structure, development and function. Incidentally, the studies have 

 reviewed rather thoroughly the extensive literature in this field. 

 This report, therefore, omits such a review and refers to the previ- 

 ous work only where it is pertinent to the discussion of the most 

 recent observations. 



It is especially gratifying that the nematocyst, a structure worthy 

 of study solely on the basis of its morphology, should also provide 

 valuable information on cellular differentiation and synthesis, as 

 Slautterback and Fawcett (12) have so clearly shown. Thus, once 

 again, resort to the study of a classic animal has provided new data 

 —in this case, concerning the role of the Golgi apparatus and endo- 

 plasmic reticulum in the production, by the cnidoblast, of an 

 elaborate and highly specialized cell inclusion. Furthermore, evi- 



^This work was supported l)v United States Public Health Services research tyrant 

 E-3517. 



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