MALE PERN. 353 



(3) Long colourless unicellular rhizoids, sometimes 

 branched at the free end. 



(4) The growing-point, occupying the notch and now 

 consisting of a series of initial cells which undergo active 

 growth and division. 



(5) The antheridia, seen in surface view as circular 

 bodies occupying the hinder (older) portion of the pro- 

 thallus and occurring 011 both the cushion and the lateral 

 wings. 



(6) The archegonia, occurring on the cushion at the 

 front of the prothallus (a little behind the growing-point) 

 and showing their necks as little finger-like projections 

 the older archegonia are conspicuous owing to their brown 

 colour. 



496. Antheridium and Archegoiiiimi. Examine the 

 sexual organs more closely with the high power. 



(a) Antheridium. In surface view, note the central 

 group of autherczoid mot her- cells, small spherical 

 bodies, surrounded by the antheridium wall which may be 

 seen as either a ring of cells or as a single ring-like cell ; 

 the whole antheridium is smaller than the prothallus cell 

 on which it is seated. In the small and more or less fila- 

 mentous (and often branched) prothalli, which may bear 

 only antheridia, the latter may be seen in side view, and 

 the wall can be made out as consisting of two superposed 

 ring-like cells with a dome-like cap-cell on the top. 



(6) Archegonium. In surface view, note the four rows 

 of cells of which the neck is composed, and the neck- 

 canal ; by focussing more deeply, the canal-cells and the 

 oosphere may be seen in an archegonium which has not 

 yet opened ; in an older archegonium that has been ferti- 

 lised, the embryo may be seen by focussing down to the 

 embedded venter. 



497. L. S. o Frothallns (Fig. 88). Cut median Ion. 

 gitudinal sections of an alcohol-hardened prothallus, held 

 in pith ; only those sections passing through the cushion 

 are required, but with care several useful sections may be 



Pr B, 23 



