‘ bi ‘ . r iA oF vos ee 4 ht eee 
330.) ©=©—— Structural and Physiological Botany. ue fe, 
Fic. 451.—Jsoéles lacustris ; 1. the whole plant (natural size); II. transverse section 
through the peculiarly thickened stem (natural size); III. macrospore (x 60); 
IV. longitudinal section through the pro-embryo with an archegonium a (x 40) ; 
3 sey with three mother-cells of antherozoids (x 500); VI. antherozoid 
X 500). 
