^. "'l^"' 



Fig. 1 8. Comparative sizes of sporangia in OjOTM«</a. x 5. a, diploid; 



b, triploid; c, tetraploid. 



Fig. 19. A cell at the beginning of meiosis at the stage known as leptotene (literally the thin thread 

 stage) before chromosome pairing has occurred. One complete, unpaired, chromosome has been 

 separated from the tangled mass of the others at the top of the field. Permanent acetocarmine 

 preparation of triploid Osmunda. x 2000. After Manton (1939). 



32 



