Ii6 



BOTANY. 



reproduction. 



Fig. 92. 

 Thread of spiro- 

 gyra, showing long 

 cells, chlorophyll 

 band, nucleus, 

 strands of proto- 

 plasm, and the 

 granular wall layer 

 of protoplasm. 



If we select mats of spirogyra which have lost 

 their deep green color, we are likely to find differ- 

 ent stages of this sexual process, which in the 

 case of spirogyra and related plants is called 



conjugation. 



Demonstration 

 30. 



200. To demonstrate 

 the conjugation of spiro- 

 gyra. — From a tangle of 

 the threads on a glass 

 slip, which are conjuga- 

 ting, mount a few in 

 water, tease the threads 

 apart, place on a cover 

 glass, and prepare for 

 observation under the 

 microscope. Let the 

 pupils sketch conju- 

 gating cells, and make 

 notes upon the different 

 stages of the passage of 

 the protoplasm, and on 

 the other characters of 

 the fruiting threads, as 

 outlined below. 



201. Conjugation. 



— If the material is 

 in the right condition 

 we will see in certain 

 of the cells an oval 

 or elliptical body. 

 If we note carefully 

 the cells in which 



Fig. 93. 

 Zygospores of spirogyra. 



these oval bodies are situated, there will be seen a 

 tube at one side which connects with an emptycell 

 of a thread which lies near as shown in fig. 93. If 



