COLLECTION AND PRESERVATION OF MATERIAL. 427 



minute black specks on the surface of the leaf. The leaves 

 should be preserved dry after drying under pressure. 



Liverworts. 



Marchantia. — The green thallus (gametophyte) of marchan- 

 tia may be found at almost any season of the year along shady 

 banks washed by streams, or on the wet low shaded soil. Plants 

 with the cups of gemmse are found throughout a large part of 

 the year. They are sometimes found in greenhouses, especially 

 where peat soil from marshy places is used in potting. In May 

 and June male and female plants bear the gametophores and 

 sexual organs. These can be preserved in 2%% formalin or in 

 70$ alcohol. If one wishes to preserve the material chiefly for 

 the antheridia and archegonia a small part of the thallus may be 

 preserved with the gametophores, or the gametophores alone. 



In July the sporogonia mature. When these have pushed out 

 between the curtains underneath the ribs of the gametophore, 

 they can be preserved for future study by placing a portion of 

 the thallus bearing the gametophore in a tall vial with 2$ for- 

 malin. Plants with the sporogonia mature, but not yet pushed 

 from between the curtains on the under side, can be collected in 

 a tin box which contains damp paper to keep the plants moist. 

 Here the sporogonia will emerge, and by examining them day 

 by day, when some of the sporogonia have emerged, these plants 

 can be quickly transferred to the vials of formalin before the spo- 

 rogonia have opened and lost their spores. In this condition the 

 plant can be preserved for several years for study of the gross 

 character of the sporogonia and the attachment to the gameto- 

 phyte. From some of the other plants permanent mounts in 

 glycerine jelly may be made of the spores and elaters. 



Riccia. — Riccia occurs on muddy, usually shaded ground. 

 Some species float on the surface of the water. It may be pre- 

 served in 2^ formalin or 70$ alcohol. 



Cephalozia, ptilidium, bazzania, jungermannia, frullania, and 

 other foliose liverworts may be found on decaying logs, on the 



