326 



GLASS ASCOMYCETEAE 



Fig. 105. Aspergillales, Family Aspergillaceae. Aspergillus (Evrotium) sp. Peri- 

 thecia, ascus and ascospores. (After Ellis and Everhart : The North American Pyreno- 

 mycetes.) 



narrow tubular extension near the tip of which a nucleus, formed by the 

 division of a nucleus in the sterigma, takes its position. A delicate cross 

 wall is then formed and the basal portion of the tube elongates and forms 

 a second cell in the same manner. This process continues until a chain of 

 cells is formed, the oldest at the tip. Within the segments of this tubular 

 extension the spores round up and each secretes a thicker wall within and 

 separate from the wall of the tube to which it may adhere or from which 

 it may be free. Thus the conidia are in reality formed internally and are 

 on that account called "endogenous" by Sartory and Sydow (1913). 

 The thin-walled portions of the original tube, lying between the conidia, 

 are often spoken of as "connectives." (Figs. 105, 194.) 



In recent years the genus Penicillium, especially P. notaium Westling 

 and other species of this and related genera have acquired great impor- 

 tance because of the discovery that some of the products of the growth of 

 the mycelium are of great value as antibiotics. These are substances 

 which are able to bring about the destruction of various other organisms, 

 harmful or otherwise, even when introduced into the living bodies of man 

 and other animals infested by these organisms. 



CitromyceH is much like Penicillium but the conidiophores or their 

 branches are somewhat thickened. The chief distinction is a biological 

 one, viz., the production of large quantities of citric acid when grown on 

 a medium containing sugar. Monascus is usually distinguished by its red 

 or pink mycelium. The conidia are on short chains. The mature peri- 



