352 THE POPULAR SCIENCE MONTHLY. 



the Phytophtliora infestans of the books, seems to reach, every 

 cell and every tissue, so that a whole potato-field once infested 

 will go down as if smitten by the frost of night. Kindred fungi are 

 upon many of the plants about us. Peronospora viticola attacks 

 the leaves of the grape. In wet seasons it is not uncommon to see 

 the wild grape-vines along our western streams completely white 

 with this overwhelming assailant, nor are our Concord vineyards 

 ever quite exempt. The mycelial filaments thread the soft inte- 

 rior tissues while fruiting hyphse come forth in delicate tufts or 

 pencils through the open stomata on the under surface of the leaf. 

 It is pleasant to think that weeds of various kinds suffer from 

 similar fungal invasions. Thus goosefoot {Chenopodium, sp.) 

 bears every spring upon its earlier leaves a tiny parasite, which 

 seen under our lenses seems a miniature forest, while the fruit 

 masses itself in violet tinted patches plainly to be seen by the 

 naked eye. 



Even the evergreens, the cone -bearers, that ancient race of 

 hardy conservatives, are compelled to pay tithes and tribute to 

 these all-assailing Vandals. I suppose the cedars of Lebanon are 

 not exempt ! At all events, who has not seen our native cedars 

 bending after some warm shower in June with orange-colored 

 fruit, beautiful, but to the cedar costly as it is fair ? (Fig. 4 a.) 

 Cedar-apples, men say, and they are not a few who would insist 

 that the cedar is actually blooming and fruiting. Such fruit has 

 actually been planted — vain expectation. Cedar-apples are but 

 the excrescences caused by the persistent development of a fun- 

 gus parasitic upon branch or leaf ; they are receptacles from 

 which the fungus throws out at a favorable moment gelatinous 

 masses of orange-colored spores (Fig. 4 b). No fruit of the cedar 

 are apples such as these, fruit rather of the cedar's malignant 

 foe. Trees are sometimes seen whose crop of " apples " becomes so 

 heavy that disaster almost to extinction marks successive years. 

 Strange to say, the cedar does not bear its affliction alone. The 

 hawthorn has a part in the matter, and on its leaves are borne 

 fringed cups of fungal fruit supplemental to the cedar's parasite, 

 just as the cluster-cups on the barberry-leaves are congeners of 

 the rusts on fields of standing grain. In fact, with these micro- 

 scopic forms parasitism is the rule, whether as affecting the vege- 

 table world as we have seen, or in more insidious guise assailing 

 the animal as well, when bacteria and bacilli in phantom myriads 

 appear to baffle surgery and sanitary science. Here, as has been 

 well said, is " the arrow that flieth by day ; the pestilence that 

 walketh at noonday." The discussions of a decade have rendered 

 these organisms familiar, at least by name, to every reader. Every 

 wise physician is an experimenter in the field. A new literature 

 has grown up, to which the scientific world makes daily contri- 



