57. 



expect to find this stage most abundant during kay, June 

 and July. 



L The daughter-redia stage, i.e., the rediie pro- 



is !known to exist it ? .11 

 ducing cercariae/aeasone of the year in California, yet 



it io found most abundantly in the fall. That the 

 germ balls grcr-v little cr none during the months of December, 



January, Pebrunry, and Ha rah is evidenced by the fact that 



tUs - s. ri*>i ii r 



during the sixty -three : ays from December 6th to February 

 7th. not a single eercaria was tc be found, and from 



February 7th to the first cf April they were very rarely 



9 * ; r * >} i n. * to n tax n i n& Up t aYil^ . 



seen, altho tlie rediae were abundant. The temperature of 

 the water is probably the ccn trolling factor. The tempera tur 



of water of three la^es about the size of Stow Lake has 



;$ tr -pre du''** 



been ye.it daily for several years. Th^e three Ia>e3 are 

 close to Stow Lake and are about the same size so that their 

 temperature probably differs but little. During the thr ee 

 winter months the averse temperature of the water is 52?, 



occasionally dropping as low as 48. Beginning tne first 



a 

 of March there is/quite rapid and steady rise in tne tempera- 



ture which is accompaniad by a ccr responding increase in the 

 number of active cercariae. During the three warraest 

 no nth 3, July, August, and September the temperature averages 

 67 F, occasionally reaching 70. During these three 

 months and the month following the active oeroariae con- 

 tinually increase in number. It seeraa cbviouo that the 

 degree of temperature controls the development of oercariae 

 and possibly of mother -rediae and the enclosed daughter-redia< 



