EDWARD S. KLINE 155 



TABLE 2 

 Hydroxyproline contend of whole Hydra and of nematocyst protein (From ref. 9) 



Fraction Hydroxyproline Nitrogen g. Hydroxyproline 



(mg. ) (mg. ) per 16 g. N 



Hot — TCA — precipitate 



from 6,800 hydranths 3.568 5.21 1.74 



Nematocyst preparation 0.230 0.285 12.7 



contains a protein belonging to this class of componnds. The 

 isolated nematocysts exhibit JDirefringence, visually resist trypsin 

 digestion, show extreme stability to autoclaving, stain blue with 

 the Masson trichrome reagent, show metachromasia with toluidine 

 blue, and stain positively with alcian blue (9, 3). Except for the 

 heat stability exhibited by the nematocyst preparation, all of these 

 properties are indicative of a collagen type structure. One of the 

 best known characteristics of the classical collagens is its property 

 of forming gelatin upon heating, yet the nematocyst capsule retains 

 its morphology even after many hours in the autoclave at 121'. 

 I do not know whether this is due to the presence of other material 

 in the capsule that "holds it together" or to the intrinsic inertness 

 of the hydroxyproline-containing protein. Other lines of evidence 

 have led Phillips ( 16 ) to postulate that the capsule of the anemone, 

 Metridiiim senile, contains a cartilaginous material. 



TOXIN 



In connection with the work carried forth in our laboratory, 

 the word "toxin" is probably inappropriate. I use it, only for the 

 lack of a better term, to denote any nonstructural material which 

 we believe to be present inside the nematocyst. We have no definite 

 information tha^ these materials constitute a toxin or even part 

 of a toxin. 



Stwcinoxidase Inhibitor — In an attempt to correlate the activity 

 of oxidative enzymes with the phenomenon of regeneration we 

 found that succinoxidase activity is virtually absent in Hydra homo- 



