692 



THE NATURE BOOK 



have been destroying his 



" moulds 

 produce. 



Sometimes, in agricultural districts, 

 whole crops of grain and fruit are com- 

 pletely ruined by these pests ; indeed, 

 where a particularly virulent species gets 

 the upper hand, it often means that vast 

 areas of land are completely devastated ; 



A MOULD THAT GROWS ON OVER-RIPE 

 FRUIT, BREAD. ETC. 

 (Magnified 60 diameters.) 



desolated vineyards and famine fre- 

 quently being the outcome of its destruc- 

 tive work. Vine mildew, potato disease, 

 onion mildew, American gooseberry mil- 

 dew, etc., are foes of this order, all greatly 

 dreaded by the agriculturist. 



I have previously stated that every 

 plant probably has its fungus parasite ; 

 it is remarkable, however, that the familiar 

 mushroom, and various toadstools, should 

 suffer from parasitism of the same class. 

 Cultivated mushrooms are often attacked 

 by a minute mould or fungus (Hypomyces 

 Perniciosus) that distorts the spore-bearing 



parts [i.e. the mushroom) until they become 

 swollen and diseased masses. Such para- 

 sitism is analogous to that which inspired 

 the poet who penned the famous lines : 



" Little fleas have smaller fleas 

 Upon their backs to bite 'em," 



and, seeing that eventually these secondary 

 parasites themselves become the prey of 

 still more simple fungi (bacteria), we may 

 add the remainder of the poet's verse : 



" And these again have lesser fleas, 

 And so ad infinitum." 



for where such parasitism ends it is 

 difficult to say. 



In the same manner animal life is equally 

 open to attack by these imps ot mischief. 

 Man and domestic animals suffer from 

 innumerable diseases entirely due to these 

 lowly organisms ; hence it is the aim of 

 modern surgery, in the dressing of wounds, 

 in operations, etc., to prevent access to bac- 

 terial germs (which are moulds reduced to 

 their lowest terms), and by the use of anti- 

 septics to destroy their virulent properties. 



While these minute fungi are bad 

 masters, they, nevertheless, ma}^ become 

 very good servants. By their orderly 

 working we are enabled to prepare many 

 valuable food materials, such as bread, 

 beer, wine, vinegar, cheese, etc. ; while 

 others of their kind, by their united action, 

 are continually renewing the fertility of 

 the soil. Even in their most destructive 

 moments they are carrying out a useful 

 function in Nature's economy ; although, 

 T fear, it would be difficult to persuade 

 the farmer thus far who has lost a valuable 

 crop b}^ their baleful agency. Neverthe- 

 less, Nature is clearing off her score. The 

 spore of the vine mould cannot penetrate 

 the tough skin of the perfect and healthy 

 grape ; not until it ripens and turns soft» 

 as decay is approaching, can it make an 

 attack ; likewise, the weak and badly 

 cultivated crop is always open to receive 

 the enemy, for Nature abhors the weak- 

 ling, and is ever ready to lay it low. The 

 lowly fungi constitute the scythe by 

 means of which she cuts it down ; only, 

 though, to reconvert its dead and putre- 

 fying substance into new and more per- 

 fect life forms. The fungi are Nature's 

 scavengers that sweep her garden path 

 and keep her house in order. 



John J. Ward. 



