50 



RESEARCHES ON FUNGI 



development of the mycelium, and the early stages in the forma- 

 tion and growth of the fruit-body. 



Germination of Spores, Growth of Mycelium, and Formation of 

 Primordia of Fruit-bodies. — Sporangia of Pilobolus longipes {cf. 



Fig. 18) were caught on a clean glass 

 plate and then crushed in warm water, 

 and some of the spores were then trans- 

 ferred with the help of a platinum loop 

 to a drop of dung-agar hanging in a van- 

 Tieghem cell. In other cultures the 

 powder from crushed sporangia was sown 

 and, in still other cultures, sporangia were 

 sown as wholes. In each culture, at room 

 temperatures, a small percentage of the 

 spores germinated. 



On germinating, a spore swells up 

 considerably and then puts out one or 

 sometimes two germ-tubes (Figs. 19 and 

 20, A-G). The germ- tube then grows 

 rapidly in length and branches mono- 

 podially. A well-grown mycelium has 

 rather thick main hyphae from which 

 come off lateral hyphae which are much 

 thinner and which in their turn give 

 rise to still thinner branches (Fig. 20, G). 

 The main hyphae (Fig. 21, A) come to 

 contain numerous red particles, doubtless 

 oil-drops containing carotin, and it is these 

 branches alone which are destined to form 

 the primordia of fruit-bodies. Two days 

 after the spores have been sown, here and there in a well-grown my- 

 celium a thick main branch for some distance along its length begins 

 to swell laterally ; and, in the course of a few hours, the swelling 

 develops into a fruit-body primordium or tuber (Figs. 20, H, and 21, 

 B-D). As the primordium develops, protoplasm flows into it from 

 the apical and basal portions of the main hypha and from all the 

 adjacent smaller lateral hyphae. As a result of this flow, the tuber 



Fig. 18. — Pilobolus longipes. 

 A group of fruit-bodies 

 in air, just before the 

 disi'liarge of tlie spor- 

 angia. In each fruit- 

 body are shown the 

 iqjper part of the 

 slender stipe, the large 

 .subsporaTigial swelling 

 fille(l with cell-sap, and 

 the terminal black 

 sporangium. The red 

 protoplasm at the 

 junction of the stipe 

 and su bspo rangial 

 swelling appears black 

 and may be readily ob- 

 served in the fruit-body 

 on the right. Magnifi- 

 cation, 20. 



