ORDER MUCORALES 



155 



in the terminal sporangium, which is often lacking. In Chaetodadium 

 the large terminal sporangium is entirely lacking. The sporangioles are 

 one-spored and may be indehiscent in some species or in other species 

 permit the spore to escape on germination. These monosporous spo- 

 rangioles are often called conidia. (Fig. 53C, K.) 



In Blakeslea the sporangium has a large columella when the fungus 

 is well nourished and is smaller and few-spored without the columella 



Fig. 51. Mucorales, 

 Family Pilobolaceae. (A, 

 B) Piloholus kleinii van 

 Tiegh. (A) Diagram of 

 optical longitudinal sec- 

 tion of sporangiophore 

 and sporangium. (B) 

 Zygospore. (C) Piloholus 

 crystalUnus Tode ex van 

 Tiegh. Heterothallic for- 

 mation of zygospore. (A, 

 after Buller : Researches 

 on Fungi, vol. 6, pt. 1, 

 pp. 1-224, London, Long- 

 mans, Green and Co. B, 

 afterjZopf •iNova^Acla Leo- 

 poldina, 52(7) :352-358. C, 

 after Krafczyk: Ber. deul. 

 botan. Ges., • 49(3) :141- 

 146.) 



when poorly nourished. In addition numerous small two- to four-spored 

 sporangioles are formed on short sterigmata from the surface of large 

 rounded heads clustered at the apex of a sporangiophore. These spores 

 differ markedly in size and shape from those produced in the sporangia. 

 In Choanephora the sporangium possesses a columella and the sporangioles 

 are borne as in Blakeslea on round heads at the apex of the sporangiophore 

 of the other type. They are monosporous and indehiscent and function, as 

 in Chaetodadium, as conidia. In Cunninghamella the sporangia are never 

 found and only the heads of indehiscent sporangioles ("conidia") are 

 developed. In Mycotypha the stalk of the sporangiophore is septate and 

 the head is a little enlarged and much elongated. It is covered with in- 



