1889-90.] MORPHOLOGY AND PHYSIOLOGY OF THE CELL. 259 



of time necessary to give the tissue its proper depth of stain, and I 

 determined that a stay of eight or ten hours longer than usual in the 

 diluted hematoxylin solution, did not seem to increase the depth of the 

 stain, or to make it more diffuse. Probably the explanation of this is 

 that the equilibrium between the coloring matter in the diluted solution 

 and that deposited in the tissue is reached when the chromatin is 

 saturated. This, of course, is merely an application of the principle, 

 that length of time and degree of concentration are elements in the 

 right employment of staining methods and that these are, roughly 

 speaking, in inverse proportion to one another. 



In order to determine if the nebenkerne contribute in any way to the 

 elaboration of the secreted elements of the pancreas I resorted to the use 

 of pilocarpin. I had a large nnmber of Diemyctyli at my disposal, and 

 on these I studied the action of the drug, so far as the nebenkerne are con- 

 cerned. Batches of ten, twenty and thirty were taken, and into the ab- 

 dominal cavities of each of these less than 2 mgrm. of pilocarpin was 

 injected. Three of these were, at certain periods after the injection, decapi- 

 tated, the pancreas ot each removed, hardened with corrosive sublimate, 

 and treated as described above. These periods were usually : i, 2, 3, 4, 

 5, 7, 9, [2, 17, 22, 36, 44, 52 and 60 hours, and these were chosen in some 

 cases for convenience. I took three at each period, because, if I depended 

 on one, misleading results might be obtained. It was found that the 

 averages of the results obtained from each three agreed with each other 

 in presenting an unbroken outline of the history of the nebenkerne. 



I treated very young forms of Amblystoma punctatum also with pilo- 

 carpin, the method of employment of the latter in this case being to dis- 

 solve twenty to fifty milligrams in about half a litre of water and placing 

 the animals therein for a period of five to twelve hours. As they mea- 

 sured between thirty and thirty-five millimetres in length, it is obvious 

 that an intra-abdominal injection of a solution of the drug was out of the 

 question. 



The specimens of Nectums kept in the laboratory aquarium were not 

 used for this investigation, since, owing to their not having been fed for a 

 long time, the pancreas presented a more or less atrophied condition. It 

 was found impossible to stimulate the gland in these to activity, or even to 

 make it secrete at all. 



There is a great advantage to be obtained from the concurrent use of 

 the two hardening reagents, corrosive sublimate and Flemming's Fluid. 

 The former fixes thoroughly and quickly the zymogen granules as well 

 as the cellular and nuclear structures in the pancreas, while with Flem- 



