210 



AN INTRODUCTION TO ZOOLOGY 



female reproductive organs 

 were found in a single speci- 

 men. 



MALE REPRODUCTIVE OR- 

 GANS. The male organs (Fig. 

 106) consist of a testis and two 

 vasa deferentia (j) which open 

 through the coxopodites of the 

 fifth pair of walking legs (4, 

 5). The testis lies just be- 

 neath the pericardial sinus. It 

 is a soft white body possessing 

 two anterior lobes (Fig. 106, /) 

 and a median posterior exten- 

 sion (2). The vasa deferentia 

 are long coiled tubes. 



FIG. 106. Male reproductive organs of 

 the crayfish. i, right anterior 

 lobe of testis ; 2, posterior lobe of 

 testis ; j, vas deferens ; 4, external 

 opening of vas deferens ; 6, base 

 of fifth walking leg. (From Ship- 

 ley and MacBride.) 



SPERMATOGENESIS. - 

 The primitive germ cells 

 within the testis pass 

 through two maturation 

 divisions, and then met- 

 amorphose into sperma- 

 tozoa. These are flat- 

 tened spheroidal bodies 



when inclosed within the 

 .107. A spermatozoon of the crayfish. A , - , 



testis or vas deferens, but 

 (From Andrews, in Anat. Anz.) 



if examined in water or 



some other liquid they are seen to uncoil, finally becoming star- 

 shaped (Fig. 107). 



FIG 



