io8 



DISCOMYCETES 



[CH. 



centimetres or more across as in P. vesiculosa. The genus Humaria includes 

 similar but smaller species, often less than one centimetre in diameter. In 

 Otidea the sides of the ascophore are laterally split, or vertically incurved 

 and wavy. In Acetabula and Geopyxis the ascophore is stalked. In Lachnea, 

 as well as in some other genera, the fruit is beset with hairs and in Sepultaria 

 it is hairy and more or less sunk in the soil. 



Lachnea stercorea is a small orange species occurring during the winter 

 and spring on the dung of various animals, especially of cows. With 

 Humaria granulata and Ascobolus ftirfuraceus, it is among the very common 

 coprophilous forms, appearing in many parts of Britain with great regularity 

 when the Piloboli have died down, and the cow pad is beginning to dry. 

 It is about 4 mm. in diameter and is furnished with numerous stout, septate 

 hairs. 



The archicarp arises as a side branch from the vegetative mycelium, and 

 divides to form four or more cells. The terminal cell or oogonium is oval 

 in shape and larger than the others. It contains between two and three 

 hundred nuclei and is filled with finely granular cytoplasm. In the cell next 

 below the oogonium, the cytoplasm is also more dense and the nuclei more 

 numerous than in the other cells of the fertile branch. 



Hyphae grow up from the lower cells of the archicarp, and from the 

 branch which bears it, and form a dense weft above which the oogonium rises. 



Fig. 65. Lachnea stercorea (Pers.) Gill.; a. young archicarp, x 800; b. archicarp 

 and antheridium, X500; P. Highley del. 



The oogonium sends out either laterally, or from its apex, a stout branch 

 or trichogyne. It is cut off by a wall and divides into four to six cells, the 

 terminal of which is much larger than the others (fig. 6s«). The tip of the 

 trichogyne protrudes for a time beyond the developing sheath, but later, 

 with the whole fertile branch, it is enclosed by vegetative hyphae. 



