PETERS. — METABOLISM AND DIVISION IN PROTOZOA. -159 



that might have been counted, but only the larger ones. In all the 

 applications of chemicals to Protozoa during the course of the present 

 investigation, I have never observed this potassic chloride reaction to 

 occur in any Protozoan except Stentor, nor with any other substance 

 than potassic chloride ; neither does it occur in Stentor under normal 

 conditions. When the test medium for drop-preparations of Stentor was 

 made to contain, besides its normal salts, from .01 m. to 0.0167 m. 

 potassic chloride, and the results were compared with the control prepa- 

 rations lacking the potassic chloride, the effect of the reagent was un- 

 mistakable. With the greater of the two proportions above mentioned, 

 the effect began to appear sooner than with the less. The formation of 

 new Stentors was in a portion of the cases apparently normal, as judged 

 by the normal appearance of the process aud by the size of the new 

 Stentors ; but in other cases one or the other of the following abnormal 

 methods prevailed. In normal division the attachment of the anterior of 

 the two new organisms to the posterior one is at some point of the pe- 

 riphery of the frontal area of the latter. In one of the abnormal methods 

 there resulted a dumb-bell shaped figure in which the attachment was at 

 the middle of this area. In these cases there was a gradual constriction 

 extending with equal rapidity from all sides. A wrinkled appearance of 

 the pellicula was usually evident at the narrowest part of the constric- 

 tion. In the other abnormal method the process had exactly the appear- 

 ance of budding, a globular protrusion being gradually constricted off at 

 a point not far behind the adoral band. Many of the new Stentors 

 originating by either method, including both large and small sizes, were 

 of globular form. In view of the possibility that these might be simply 

 portions of extruded cytoplasm, I observed them further. Upon closer 

 examination I rarely failed to find in them one or more of the beads of 

 the nucleus. An adoral band of cilia was not present at first, but grew 

 while the individual was taking on the typical conical form of a normal 

 Stentor; this was true of the dwarfs as well as of those of normal size. 

 To test the vitality of these small Stentors, individuals were removed 

 from the drops in which they occurred, examined for the presence of a 

 nucleus, and then placed in a separate preparation in a medium of hay 

 infusion. This test showed a considerable degree of mortality in such 

 dwarf Stentors, but also yielded numerous apparently perfect, though 

 dwarf, animals. Owing to lack of a proper food-containing medium their 

 further history was not pursued to determine whether they would grow 

 to full size. I regard their growth to full size as highly probable. The 

 above account has been confined as much as possible to a description of 



