PART I.] Paramecia Developed Amidst the Granular " Heaps r 2)7 



stage of molecular aggregation and the development of the smaller-sized cysts. A few 

 of the after changes, however, were more easily followed. A slow rolling kind of 

 motion commences in the mass of granules, in the midst of which a clear space or 

 vacuole becomes more and more distinct (2), at first non-contractile, then it suddenly 

 goes out and does not return for two or three minutes : gradually these intervals 

 become shortened : contraction and dilatation occurred pretty regularly at intervals of 

 fifteen seconds. In a few hours it commences to spin like a top without in the least 

 altering its position. Then it stops, its nucleus becomes extinguished, and the body 

 appears pretty much as it did at first. After a shorter or longer period the action 

 recommences, and eventually it becomes elongated, gets out of the heap into the 

 fluid, and rushes about as if locomotion were nothing new to it. No cilia can be seen, 

 nor any trace of nucleus, merely a contractile vesicle at the broader posterior end, 

 with granules and molecules universally distributed (3). In those parts of the field 

 where the fluid is rather thick, it creeps along something after the manner of an 

 amosba (4). On the next day, the eighth, several were seen to move very slowly, and 

 to become circular and still. They became surrounded by a clear hyaline capsule, and 

 the vacuole again disappeared. A few hours after this the field presented the appear- 

 ance shown at Plate XIX, Fig. Ixxxi. Some were perfectly still, and had no contractile 

 vacuole ; in others the molecular contents showed active movements, with or without a 

 vacuole ; in some two vacuoles were visible, not contracting simultaneously, and in such 

 cases there seemed to be two centres of movement —two irregular masses seemed to 

 move within the cyst. The evidence of division was frequently more marked, a regular 

 line of separation existing, and in others two oval bodies are seen to revolve within 

 the capsule. In the drawing the remains of two cysts are also evident. In order 

 to know exactly the phenomena associated with the escape of the animalculse, the 

 pair delineated at Plate XX, Fig. Ixxxii, 1, were selected and continuously watched. 



The escape out of the cyst commenced by a rolling movement among the molecules 

 of the smaller one, which increased, until at last each molecule seemed to dance past 

 the other. The vacuole went and came rapidly, lasting about six seconds, and in the 

 course of another six seconds returned, then became perfectly still ; movement 

 recommenced and stopped in the same way. Thus it acted for some time ; each time, 

 however, the outline of the contents became more evident, and the cyst became more 

 and more distended, finally ruptured (2), and the body rolled out. It was evidently 

 not yet free, and its outline was indistinct. Very active movements were now set up, 

 pseudopoda pushed out in every direction, and it was seen to be still surrounded by a 

 very delicate sac. By continually turning itself about, this film became much distended, 

 and so transparent that its form was distinctly visible (3). At last the pellicle became 

 so attenuated that it escaped without trouble (4). The same process takes place when 

 the animalcule has divided into two or four. 



In the encysting process which follows, the cysts seem to become thicker, and a 

 little fluid is frequently seen between the inner lining of the cyst and the delicate 



