CONJUGATION IN PARAMECIUM 227 



in search of one another. After a while they come together 

 in couples and conjugate. Two individuals become attached 

 together mouth to mouth in such intimate union that there is 

 actual protoplasmic continuity from one to the other. The 

 two conjugating individuals or gametes are exactly like one 

 another, though of small size as compared with normal free 



Fig. 48. 



Stages in the conjugation of Parainccium caudatunt, A, Stage A, the micro- 

 nucleus in each gamete preparing for division. Z>, Stage B, the daughter 

 nuclei in each gamete dividing. C, Four micronuclei in each gamete. J), 

 Three of the four micronuclei are disintegrating; the surviving nucleus in 

 each gamete has divided to form (J the male, and O- tne female pro- 

 nucleus. , The male pronuclei crossing over. F, Conjugation effected ; 

 separation of the gametes and division of the combination nucleus. (After 

 Maupas.) 



swimming forms. The usual length of Paramedum caudatum 

 is 300-325 /A, the gametes rarely exceed 210 //, in length. As a 

 rule the process of conjugation begins during the late hours 

 of the night, and the early hours of the morning, and lasts till 

 late in the following afternoon. The first event following on 

 the union of the gametes is that the micronucleus of each 

 leaves its normal position in a cleft of the meganucleus, lies 



