﻿BOTANICAL GAZETTE 



[JANUARY 



not continued too long the vesicles may entirely disappear and the 

 organism apparently recover. A longer exposure causes the inner 

 wall which separates the organism from the vesicle to rupture and 

 the protoplasm to flow out into the vesicle; while a still longer 

 exposure may cause the outer wall of the vesicle to rupture, per- 

 mitting the protoplasm to flow out into the surrounding water, with 

 which it is miscible. Sometimes the protoplasm disorganizes and 

 rounds up into drops before it flows into the vesicle. This type of 

 photolysis requires a total exposure of about 30 seconds. 



2. Cytolysis in which parts of the protoplasm coagulate. — In this 

 type of cytolysis an exposure of 10 seconds causes small areas of 

 the protoplasm to coagulate. The coagulated masses move to the 

 side of the organism and are extruded at once. A longer exposure 

 causes more masses of coagulum to form. As the exposure con- 

 tinues, the masses of coagulum form faster than they are extruded. 

 A swelling appears on one side of the body, which increases in size 

 and then bursts, allowing the protoplasm to flow out into the sur- 

 rounding water. 



3. Cytolysis in which the protoplasm disintegrates directly. — When 

 Stylonychia is exposed to the light from a hydrogen discharge tube 

 excited by a current of 18 milliamperes, the organism is stimulated 

 and its rate of motion is increased. It then loses its power of 

 coordination, moves about in circles for a time, and finally comes 

 to rest with its cilia still vibrating. Suddenly the outer membrane 

 breaks at some point and a little protoplasm squirts out. Then, 

 starting from this point, a wave of disintegration passes over 

 the organism, leaving the protoplasm in isolated rounded drops. 

 The drops show surface tension against each other, and also against 

 the fluid in which they lie; but a further exposure may cause some 

 of them to unite. If the discharge tube is excited by a stronger 

 current, 50-70 milliamperes, the cytolysis begins at once before 

 the loss of coordination occurs. Cytolysis begins at the posterior 

 end of the organism. The infusorian darts across the field, 

 leaving behind it a trail of its cytolyzed protoplasm. It continues 

 its motion until only a very small amount of the original proto- 

 plasm remains intact, and this cytolyzes at the instant motion 

 ceases. 



