131 



The micruspores arise in the m\cclium of lesser diameter, and 

 appear to form first in the vicinity of the vascular tissue of the 

 ])ineap])le. The rather dariv mycelium, which owes its color 

 ])artlv to the refractive nature of its numerous granules, gives 

 rise to colorless elongated non-granular microspores, each 

 generally with a single excentric refractive body. 



A remarkable growth of the microconidia was produced by 

 the following procedure. A pinea])ple so far rotted that the 

 macrospores had appeared for about an inch at the base of the 

 core was halved i)y an axial longitudinal cut. An examination 

 of the tissues showed that the mycelium was present in great 

 quantities even near the surface of the rind almost to the very 

 tip of the fruit. The tissues were watery and the juice of the 

 fruit was exuding on to the surface on which the pineapple 

 lay. The fruit was so soft it had to be handled carefully in 

 making the section lo avoid breakage. 



After eighteen hours a frosty-looking growth had appeared 

 on the cut surface of the pineapple, which had meanwhile lain 

 exposed to the air. The first thought was that the growth 

 was immature penicillium, but a casual glance threw doubt on 

 this supposition. Then, for an instant, I wondered whether 

 crystalisable salts in the fruit had possibly crystalised and 

 formed a surface incrustation as a result of evaporation. 

 These random thoughts are mentioned merely to illustrate the ^j)- 

 pearnce ot the growth. An examination showed that thid 

 growth was purely microconidial and aerial. The chains oi 

 spores were either isolated or grouped in contact, and the 

 depth of the growth was fully one millimeter at its deepest 

 part. The appearance under a two-thirds objective was that 

 of a deposit of hoar frost. At the base of this growth of 

 microconidia, and in the wet tissues of the pineapple, the 

 macroconidia were in process of formation, and many were 

 alreadv fully formed, so that the tissues acquired a dark color. 



The appearance of the chains of microconidia was not that 

 ordinarily seen when these are produced in the tissues of the 

 fruit. Under such circumstances the conidia are to be seen 

 forming in the mycelium of the fungus, and after they are 

 complete they are pushed forth from tlie ruptured ends of the 

 cyl-indrical mycelium. The walls of the spores can be seen to 

 he entirelv separate from that of the mycelium. In the case 

 of these aerial microconidia, however, the appearance was en- 

 tirely diiTerent. The conidia were in moniliform chains of the 

 most beautiful regularity, the spores remaining joined at the 

 ■central part of the area between them, so that the appearance 

 was that familiar in the case of the aerial conidia of 

 SphacrofJicca pamiosa and other Erisypliaceae. Outside these 



