MARCHANTIA POL YMORPHA. 59 



no other plant is likely to be mistaken for it. In their 

 absence it may be told from any of the lichens by the 

 small, diamond-shaped markings on its upper surface. 

 A common liverwort growing in damp places (Conoceph- 

 alns conicus) may be known in its sterile condition by 

 its larger size, larger areolae and more prominent sto- 

 mata which in Marchantia are barely visible to the 

 naked eye, but in Conocephalus are as large as pinholes. 

 A common greenhouse liverwort of similar appearance 

 (Lunularia crnciatd] may be distinguished by its cres- 

 cent-shaped cupules, lacking a border on one side. 



Marchantia grows luxuriantly in the greenhouse, 

 producing an abundance of cupules, and often fruit- 

 ing. It maybe placed on the pots in which other plants 

 are grown or given a bed to itself. 



When gathering material, care should be taken to 

 save fertile plants with young heads ; in female plants, 

 especially, some heads should be no larger than a quar- 

 ter the size of a pinhead, and which at this stage of 

 growth are to be detected in the sinus at the growing 

 end of the stem. 



To complete the laboratory work requires fresh or 

 alcoholic specimens bearing cupules and both kinds of 

 reproductive branches ; fresh specimens of the male and 

 female heads ; and iodine. 



LABORATORY WORK. 

 GROSS ANATOMY. 



A. GENERAL CHARACTERS. Note 

 i. The flattened horizontal stem or thallus, composing 

 the larger part of the plant. 



