48 Hardy, Note on the Contractile Vacuole. 



Vict. Nat. 

 Vol. XXXII. 



until, near the acute extremity, it was too large to pass further 

 into the angle formed by the converging limits of the cell. 

 This extremity, however, accommodated itself to the size of 

 the vacuole, and distended to allow of its passage, such granular 

 matter as would have been otherwise imprisoned having, as 

 it were, in anticipation, moved round to the other side. 

 During the fraction of a second there seemed to be a limiting 

 hyaline film common to cell and vacuole. Then the funnel- 

 like distension collapsed, and either the water from the vacuole 

 escaped and the latter began invisibly its diastole, or else the 

 globule of water was ejected and a new vacuole formed, 

 the movement being too sudden to allow of certainty of observ- 

 ation. 



It would have been difficult — perhaps impossible — to fix the 

 point of origin of the succeeding vacuole. I used an Abbe" 

 condenser, and with magnification of 500 diameters its appear- 

 ance was first noticed, at about io/t from the apex, its diameter 

 being then about 2^, and the length of the cell about 100^. 



Meanwhile, there was a steady Eorward streaming oi the 

 protoplasm, but I failed to notice any return current, and there 

 was no contraction of any part of the cell visible to cause the 

 stream. [Wallich suggested that the Eorward How of the 

 plasm in Amoeba was due to the contraction of the after pari 

 oi the cell.] 



The subsequent behaviour ol the organism may have been 

 due to the fact that the drop of water on the slide was evapor- 

 ating and desiccation approaching. Soon after the collapse 

 of the sixth vacuole, and just when anothei was expected to 

 come into view, a pseudopodium was near that spot laterally 

 produced; the forward movement of the cell ceased, the 

 protoplasmic stream slowed down and seemed troubled, and 

 the pseudopodium, with its own stream accelerating, developed 

 rapidly into a broad, blunl lobe. Next, from a form roughly 

 bilobed, the cell became approximately stellate, with blunt 

 rays; and after a tew minutes, during which there was no 

 nucleus 01 vacuole visible, the organism encysted, the cell 

 being then spherical, with the granulai mattei concentrated 

 and with hyaline endoplasm peripheral, rhe vacuole was nol 

 seen aftei the cell abandoned its symmetrical form and straight- 

 forward limacoid progression for the evolutions which preceded 

 its i.ipid encystment. This non-production by an active 

 amoeboid eel] of a vacuole for excretory purposes was probablj 

 due to cessation ol metabolism and the approaching disin- 

 ation "i the cell, the encystmenl 01 partial encystmenl oi 

 •. hi'li is in many cases .1 premonitory symptom. 



