240 



SPECIFIC MICRO-ORGANISMS 



are susceptible to inoculation and natural infection has been ob- 

 served in horses, cattle, sheep and dogs. 



Many other species of pathogenic aspergilli have been de- 

 scribed, of less frequent occurrence than A . fumigatus. 



Penlcillium crustaceum l[glaucum) 

 is the commonesl contaminating mi- 

 cro-organism met with in the labora- 

 tory, and is probably the most widely 

 distributed mold. Ascospores, similar 

 to those of Aspergillus glaucus have 

 been observed, but they are rarely 

 produced. The aerial fruiting hypha 

 (conidiophore) is erect, septate and 

 branched at the upper end Uke a brush. 

 At the end of these branches are bot- 

 tle-shaped stergmae from which the 

 conidia are constricted off. The 

 growth is at first white and then it 

 becomes blue-green, the development 

 of color being at the center. It is 

 not pathogenic, but the extracts from 

 cultures of some varieties are poison- 

 ous when injected into arimals. It 

 is possible that several distinct species 

 have been included under this one 

 name of Penicillium crustaceum. One 

 nearly related organism, Penicillium 

 important agent in the ripening of 



Fig. 94. — Penicillium crusta- 

 ceum. Conidiophore with verti- 

 cillate branches, s', s"; b, st, ster- 

 igmata abstricting chains of 

 conidia. XS40. (From Jordan 

 after Slrasburger.) 



rocqueforti, Thorn., is an 

 Rocquefort cheese. 



Claviceps Purpurea. — This is a fimgus parasitic upon rye and 

 a few other plants. The spores gain access to the flower of rye 

 and develop a mycelial mass which grows in the utricle, dis- 

 placing the grain, the rudiment of which lies above the mass of 

 the mold. Closely packed conidiophores produce oval coaidia 

 and, at the same tine secrete a sweet milky fluid which attracts 



