8 



COMPARATIVE MORPHOLOGY OF FUNGI 



they are called conidiophores and the spores themselves conidia (Fig. 6). 

 A special type of thick-walled conidium is called a chlamydospore or, 

 in the resting state of the mycelium, a gemma. Chlamydospores have 

 an entirely different morphological significance in different orders, as 

 we shall see in the course of this book. 



In the higher fungi, the hyphae forming the conidiophores show a 

 tendency to come together into groups or fructifications. When these 

 groups have the form of fascicles, they are called coremia ; if they form 

 widespread cushions, they are called sporodochia in saprophytes and 

 acervuli in parasites; the tissue from which they arise is known as their 

 stroma. If the conidial hyphae join in groups of plectenchymatous 

 structures in whose interior they cut off their spores, these structures are 



Fig. 5. — Mucor Mucedo. 1. Sporangium with spor- 

 angial wall, m; sporangiospores, sp; and columella, c. 

 2. Sporangium rupturing intermediate substance, z. 

 (After Brefeld.) 



Fig. 6. — Penicillium crusta- 

 ceum. Conidiophores. St, ster- 

 igma; Ph, phialide; M, metula; 

 A, primary branch. (After 

 Strasburger.) 



called pycnia (pycnidia) and the conidia themselves (for better differ- 

 entiation from other conidia) are called pycnospores, pycnidiospores or 

 stylospores. In case the pycnia arise by growth and division of a single 

 portion of a hypha with the aid of neighboring branches of the same 

 hypha, the method is called meristogenous. If they arise by the inter- 

 twining and coiling of hyphae of different origin, however, their method 

 is called symphyogenous. These distinctions have a limited value as 

 these types pass into each other and are at times found in the same spe- 

 cies, e.g., the pycnia of Phoma conidiogena are formed entirely meristo- 

 genously with poor media and more symphyogenously with good media 

 (Schnegg, 1915; Kempton, 1919; B. O. Dodge, 1923a). 



These different spore forms — oidia, gemmae, conidia, etc. — may be 

 formed on a suitable part of the haplont (rarely also on the diplont in 



