MARCHANTIA POLYMORPHA 375 



specimen, and they should be carefully compared with the 

 description and figures given in the standard text-books (e.g. 

 Goebel, Outlines of Classification, Eng. Ed. pp. 150, 162). The 

 attempt should further be made to observe the actual rupture of 

 the neck of the archegonium, by preparing sections of the female 

 receptacle, mounting dry ; then, having found a suitable arche- 

 gonium, add a drop of water, when the canal cells and ventral 

 canal cell may be seen to be suddenly extruded on rupture of the 

 apex of the neck. 



Longitudinal sections should also be cut from the thallus of 

 Pellia taken in spring, so as to traverse one of the young pockets, 

 or involucres : inserted on the wide base of the pocket may be 

 found one or more archegonia in a horizontal position : their 

 structure is essentially similar to that in Marchantia. Various 

 stages of development of archegonia may be found in the same 

 section, or they can be obtained by comparing sections from 

 different specimens. 



XV. Keep some specimens of Marchantia, having 

 mature male receptacles, protected for some days from 

 access of water from above : then place a drop of water 

 on the upper surface of a receptacle, and after a short 

 time transfer it to a glass slide, and examine under a 

 high power : there will then be seen numerous motile 

 spermatozoids of elongated, slightly curved form, and 

 they are kept in active motion by two cilia attached to 

 the anterior end. In order to make them clearly visible 

 they should be killed and stained by adding a small 

 quantity of iodine solution, or of osmic acid. 



XVI. Add a drop of water containing living spermato- 

 zoids to a fresh preparation of a female receptacle con- 

 taining mature archegonia : note the directive influence 

 of the archegonia in attracting the spermatozoids to the 

 neck, which they enter, and are lost to sight in the 

 mucilage which fills it. 



