SPIROG YRA. 



139 



ing gamete, while that of the receiving cell is the receiving 



gamete. 



291. How the protoplasm moves from one cell to another. Before any 

 movement of the protoplasm of the supplying cell takes place we can see 



Fig. 130. 



Conjugation in spirogyra ; from left to right beginning in the upper row is shown the 

 gradual passage of the protoplasm from the supplying gamete to the receiving gamete. 



that there is great activity in its protoplasm. Rounded vacuoles appear 

 which increase in size, are filled with a watery fluid, and swell up like a 

 vesicle, and then suddenly contract and disappear. As the vacuole disap- 

 pears it causes a sudden movement or contraction of the protoplasm around 

 it to take its place. Simultaneously with the disappearance of the vacuole 

 the membrane of the protoplasm is separated from a .part of the wall. This 

 is probably brought about by a sudden loss of some of the water in the cell- 

 sap. These activities go on, and the protoplasmic membrane continues to 

 slip away from the wall. Every now and then there is a movement by 

 which the protoplasm is moved a short distance. It is moved toward the 

 tube and finally a portion of it with one end of the chlorophyll band begins 

 to move into the tube. About this time the vacuoles can be seen in an 

 active condition in the receptive cell. At short intervals movement con- 



