THE GAMETES IN PLANTS AND AMMALS 345 



genie, male-producing, and the zygogenic, female-producing, eggs 

 have, so far as I am aware, been described. But the morph(;logical 

 differences in the daphnids and plant lice are evidently extreme, 



Figs. 183-185.— Fig. 183, ovary 

 of PlumatcUa (bryozoan), showinj,' 

 eggs in various stages of growth 

 and dififerentiation. From Braem, 

 '97; Figs. 184, 185, growing egg 

 of Stcrnaspis (annelid), attached 

 to a stalk which contains a vas- 

 cular loop; full-grown egg. 



and it is possible either that much less conspicuous morphological 

 differences e.xist in the bees, or that the physiological differences 

 are so slight as to be morphologically inappreciable; probably 



