RESEARCHES ON EUNGI 



CHAPTER I 



INTRODUCTORY AND HISTORICAL 



Pilobolus and its Subsporangial Swelling — The Discovery, Structure, Taxonomy, 

 and Life-history of Pilobolus — Sex in the Pilobolidae — The Cytology of Pilobolus 

 — Crystalloids — The Orange-red Pigment — Parasites of Pilobolus — The Excre- 

 tion of Drops by the Sporangiophore and its Cause — Premature Discharge of 

 the Sporangia — Influence of External Conditions on the Breadth of the Sub- 

 sporangial Swelling — The Ballistics of the Projectile — Pilobolus in its Relations 

 with Light — The Effect of Light on Fruit-body Development — The Holio- 

 tropic Response of the Fruit-body to Light of Various Colours — Allen and 

 Jolivette's Investigations — The Subsporangial Swelling as an Ocellus — The 

 Solution of the Problem of the Non-resultant Heliotropic Reaction of Pilobolus 

 to Two Beams of Light — The Discharge of the Sporangium. 



Pilobolus and its Subsporangial Swelling. — The genus Pilobolus 

 belongs to the Phycomycetes, is a close relative of Mucor, and 

 includes about sixteen species. Most of these species come up along 

 with those of Mucor and other moulds upon the solid excrement of 

 herbivorous animals, such as the horse and the cow, while one 

 species occurs upon river mud. The general appearance of a 

 Pilobolus, when growing on horse dung, is shown in Figs. 1, 5 

 (pp. 2, 8), and 13 (p. 37). 



Pilobolus differs from Mucor in that, as a prehminary to the 

 dissemination of the spores, the sporangium is shot away from the 

 sporangiophore, whereas in Mucor this does not take place. The 

 sporangiophore of Mucor is an organ which serves merely to raise 

 the sporangium above the substratum, and thus to put it in a 

 favourable position for the passive dispersion of the spores by 

 insects and other agencies. On the other hand, the sporangiophore 



VOL. VI. B 



