10 TJJr)w/.<< State Lahondonj ()f Natifral Histori/. 



tubular (gainoplnjUous)^ ox composed of separate leaves of pe- 

 culiar shape, then called involucral leaves (polyphyllous). In 

 Fossombronia the archegonia are naked on the dorsal surface of 

 the thallus, there being no involucres, and in several genera 

 either the outer or inner involucre may be absent. 



Sporogony Phase. The so-called "fructification," or 

 " asexual generation," is properly neither, but merely a phase 

 or stage of growth in the life-history of the plant, as the cat- 

 erpillar is a mere phase in the life-history of a butterfly. It 

 may be called the sporogony j^hase (Gr. sporos^ seed, and gone/a, 

 generation). This varies slightly in the various orders, but' 

 essentially consists of a capsule containing the spores and, with 

 the exception of the Order Ricciace.e, eJaters, whose function 

 is to aid in distributing or scattering the spores. The capsule, 

 with its appendages, constitutes the sp)orogonium, and consists 

 of an elongate, two-valved, projecting pod in Anfhoceros; a 

 thin-walled ball sessile on the thallus or sunken in its tissue in 

 Riccia; a short-stalked ball in Marchantia, and a more or less 

 long-stalked ball in Jungermania^ the four named genera each 

 forming the type of an order. In Targionia the capsule is sit- 

 uated in a bivalved receptacle beneath the apex of the thallus. 

 Altho the sporogonium appears like an outgrowth of the ma- 

 ture sexual plant, it nowhere unites with the surrounding vege- 

 tative structure, even when its pedicel penetrates into its tissue. 



Calyptra. In the course of the development of the spo- 

 rogonium the lower portion, which has become considerably 

 expanded, separates into two portions, the outer called the 

 calyptra (Lat. a covering for the head), which is ultimately of 

 a thin and delicate texture, and closely invests the capsule 

 formed of the inner portion. The upper portion of the arche- 

 gonium not expanding, forms a blunt point, which crowns the 

 calyptra. and is called the style. 



Spores. The product of this phase is the spores, which 

 are developed in fours in a sort of globular utriculus, which 

 disappears when the spores mature and allows the spores to 

 separate. In some of the Ricciace.^ the spores remain united 

 and form a coccus or berry. 



The surface of the spores may be smooth, reticulate, papil- 

 lose or granulose. The spores on germinating produce the 

 sexual phase. 



