GLANDULAR CELLS OF THE FROG'S PANCREAS 403 



logical or pathological changes. I am of the opinion that they 

 must be derived from two sources totally differing in character. 



a. We have seen in the section on 'structure of the cytoplasm' 

 that the protofibrillae which may be regarded as preexistent in 

 the cytoplasm, adhere to one another in consequence either of 

 the action of fixatives or of the subsequent manipulation, so 

 that there are formed various structures according to the degi ees 

 of adhesion, such as thin or thick bundles, crescent- or shell- 

 formed, spirally coiled, or even irregular spherical corpuscles. 

 They are characterized, first, by fibrillar structure. It often hap- 

 pens, however, that they appear homogeneous, when relatively 

 well preserved or examined with a lower magnifying power. 

 Secondly, they vary greatly in shape. Finally, the contour of 

 these corpuscles is very irregular, as if it had been gnawed, or 

 fibers arise from them and continuously pass into the cytoplasmic 

 filaments. 



It will be seen when my figures are compared with those of 

 various investigators above mentioned, that these artificial prod- 

 ucts agree in character with those 'nebenkerne' which are de- 

 scribed as being of irregular shape or as exhibiting fibrillar struc- 

 ture. Of the views advanced concerning the origin and signifi- 

 cance, that of Eberth and Muller and of Mathews is nearly in 

 agreement with that of my own. The former workers say : "sie 

 sind umgewandelte Protoplasmafaden, welche, indem sie mit 

 ihren Nachbarn verschmelzen, zu spindelformigen, sichelfor- 

 migen, kommaahnlichen Korpern werden, die vielleicht vortiber- 

 gehend, vielleicht dauernd ihre fibrillare Zusammensetzung noch 

 mehr oder weniger bewahren oder dieselbe ganz verlieren und 

 dann glanzende homogene Korper darstellen. ' ' Mathews also is of 

 opinion that the structures in question are derived from the cell- 

 threads ; he says : ' ' The threads are not, however, perfectly straight, 

 but in all cases are more or less twisted and bent .... 

 and often contorted or even spirally coiled on themselves. These 

 spiral twists, or coils, form the so-called 'Nebenkern' of the pan- 

 creas." How these corpuscles are formed, that is to say, the 

 question whether they are produced under physiological condi- 

 tions or by the action of fixatives, remains unanswered. 



