I30 



CYCLIC CHANGES 



IV 



angle between the body axis of the fish and the water-level. 

 By plotting the angular increase and decrease against time, 

 the Figures 89 and 90 have been produced. 



Jaski distinguishes autonomous and heteronomous eleva- 

 tions. The former result from endocrine activity in the 

 female, the latter through the action of the male. 



In virgin fishes and in the absence of any males, individual 

 estrous cycles occur. From the moment males are brought 

 together with such females the cycles are co-ordinated. When 



6 7 

 Days 



Fig. 89. Elevation curves. The time is plotted horizontally; vertically: 

 the angle of inclination of the part of the spinal column between the 

 swimming-bladder and the anal fin, the angle being determined at least 

 four times a day. The figure shows the average for 20 females after 

 administration of copulin, the autonomous cycle not being suppressed. 

 The copulin was that of males kept in another aquarium. (JASKI). 



^0* 

 30° 

 20° 

 40° 

 30° 



20°^- 

 0°. 



Days 



Fig. 90. Elevation curves of two different animals from the experiment 



of Fig. 89. These two curves show the greatest deviation from the 



average (JASKi). 



