MY GARDEN ON AN ONION. 



73 



With such a microscope I saw transparent, branching, inter- 

 lacing threads, called hyphce, and thousands of loose spores. Many 

 of the threads ended in little tassels. These tassels I found to he 

 formed in a very interesting manner. First, the creeping liyphce, 

 send branches into the air. Then these branches bear each three 

 or four branchlets. From the ends of the branchlets grow a num- 

 ber of fine, parallel threads called sterigmata. The ends of these 

 sterigmata contract and form 

 little round, bead-like bodies 

 commonly known as spores. 

 As they are, however, actual 

 bits of the branching JiyphcB 

 bits exactly like the rest of 

 the hyphen in their constitu- 

 tion they have no right to 

 be called spores. The name 

 conidia has, therefore, been 

 made for them, from a Greek 

 word meaning dust. As soon 

 as each of these conidia or 

 dust-like bodies is completed, 

 another forms behind it, a 

 third behind the second, and 

 so on ; the first being thrust 



forward until at last it is pushed off altogether and falls. The sec- 

 ond shortly follows it, and then the third, and so the process goes 

 on, old conidia falling off at one end and new ones forming at the 

 other. It is these strings of conidia that give the tassel-like look 

 to the ends of the aerial hypho?,. To the botanists who first stud- 

 ied them they suggested little brushes ; the brushes that artists 

 call pencils camel's-hair pencils, for instance. The Latin name 

 for brush being penicillum, this " brush "-bearing fungus received 

 the name of Penicillium. Moreover, to distinguish a Penicillium 

 with sage-green brushes, a second name, glaucum, was found. The 

 first crop to appear on my onion was, thus, Penicillium glaucum, 

 a fungus by no means confined to onions. My housekeeper has 

 taken felted masses of it out of her cans of fruit ; has bewailed its 

 sage-green conidia on her jam, and even on her bread and pies. 

 Indeed, she has to keep a sharp lookout for them, never knowing 

 where they may next appear. I can only tell her that the air is 

 full of them, and that they settle here, there, and everywhere, and 

 will surely grow wherever they find moisture and nourishment to 

 suit them. 



The next crop that my onion bore made grayish patches on 

 the outermost of those juicy layers, the bases of last year's leaves. 

 With the eye alone I could make out the separate little plants, 



Fig. 1. Penicillium glaucum. 



