Fungi of Ill-hioix. 143 



traced. But little by little qualified observers have acquainted 

 themselves with their existence as true species, veritable and 

 distinct plants, and little by little have learned something of 

 the mysteries of their life histories. Sometimes the advance in 

 knowledge is gained by casual and lucky observations; but 

 mostly by painstaking, systematic research, aided by all the 

 appliances of the equipped laboratory and the fruitful skill of 

 trained powers of manipulation and acute perception. A step 

 gained is not only so much secured, but renders more possible 

 other or further advance. The more becomes known, the easier 

 progress is made, since that already acquired points the way 

 towards new achievements. The beginning has been made, 

 though this can scarcely be said to have been true until within 

 very recent times. The men are now living and working who 

 have made known nearly all the ascertained facts of physio- 

 logical processes and results in these parasitic fungi. The 

 germination of fungous spores was not observed until within 

 the present century. 



During the last part of the first half of this century 

 learned discussions arose upon the specific distinction between 

 the parasite and the host, and esteemed botanists held the 

 view, that what was taken for the former was but a diseased 

 condition of the latter the rust of wheat, for example, was 

 only the degraded cell-tissu&s of the wheat itself. Such 

 difference of opinion, however, no longer exists among those 

 who have possession of the information now acquired. The 

 tissues of higher plants do not change by any processes of deg- 

 radation or transformation into the things called fungi, neither 

 do the laitter originate in any other manner than as descend- 

 ants of preexisting parent forms through as rigid specific lines 

 as can be traced among any animals or plants. It is known, 

 too, that however much the fungus is found within the tissues 

 of the host plant, it began its growth outside of the latter, and 

 gained introduction only by forcible entrance. Spores are 

 never taken up by absorption and carried by the aqueous cur- 

 rents from part to part of the plant. The fungus passes 

 through the tissues very much as roots pass through soil, some- 

 times apparently without in any degree successful opposition. 



