214 



Methods in Plant Histology 



the violet. Achromatic structures are very prominent during these 

 three divisions. 



For the older sporophytes of Marchantia, it is better not to cut 

 the whole receptacle. Remove the radiating branches. The 

 sporophytes are in radiating rows, alternating with the branches. A 

 piece 2 mm. wide can be cut so as to include two of the radiating 

 rows, one on each side of the stalk, and such a piece will include early 



A 



FIG. 67. 'Anthoceros laevis: A, longitudinal section of lower portion of sporophyte 



imbedded in the gametophyte; X45 ; B, transverse section of lower portion of sporophyte; 



X200; C, vegetative cell from lower portion of the sporophyte; X560; D, spore mother 



cell showing three of the four chloroplasts with numerous starch grains; the nucleus in 



the metaphase of the first division; X560. 



stages in other rows. By taking such care, you can get median 

 longitudinal sections of nearly all the sporophytes. For class work, 

 5 to 10 fji is a good thickness, but for figures, especially the reduction 

 mitoses in the spore mother cells, the sections should not be thicker 

 than 2 or 3 /x. 



Among the Bryophytes no form affords a better opportunity 

 for studying the development of spores than Anthoceros, since a 

 single longitudinal section of the sporophyte may show all stages, 

 from earliest archesporium to mature spores (Fig. 67). The sporo- 



