POLYMORPHISM. 185 



rvithout, among the seed which is sown, but that has been 

 until now quite disregarded. It is of great importance in 

 practice, but in truth, for our present purpose, synonymous with 

 what we have already written. Those learned in the science of 

 this kind of culture lay great stress on its importance, and 

 many apparatuses have been constructed, called *' purely cultivat- 

 ing machines," for the purpose of destroying the spores which 

 are contained in the substratum, and preventing the intrusion of 

 those from without. The mixture in the seed which is sown 

 has of course not been obviated. These machines may } perhaps, 

 in every other respect, fulfil their purpose, but they cannot 

 change the form of the question, and the most ingeniously con- 

 structed apparatus cannot replace the attention and intellect of 

 the observer. * 



Two distinct kinds of phenomena have been grouped under 

 the term " polymorphy." In one series two or more forms of 

 fruit occur consecutively or simultaneously on the same indi- 

 vidual, and in the other two or more forms appear on a dif- 

 ferent mycelium, on a different part of the same plant, or on a 

 matrix wholly distinct and different ; in the latter case the con- 

 nection being attested or suspected circumstantially, in the former 

 proved by the method suggested by De Bary. It will at once be 

 conceded that in cases where actual growth and development 

 substantiate the facts the polymorphy is undoubted, whilst in the 

 other series it can at best be little more than suspected. We 

 will endeavour to illustrate both these series by examples. 



One of the first and earliest suspected cases of dualism, which 

 long puzzled the older mycologists, was observed amongst the 

 Uredines, and many years ago it was held that there must be some 

 mysterious association between the "red rust" (Trichobasis ruligo 

 vera) of wheat and grasses and the " corn mildew " (Puccinia 



* The method pursued by Messrs. Berkeley and Hoffmann of surrounding the 

 drop of fluid, in which a definite number of spores or yeast globules had been 

 placed, with a pellicle of air, into which the germinating threads might pass 

 and fructify, is perhaps the most satisfactory that has been adopted, though it 

 requires nice manipulation. If carefully managed, the result is irrefragable, 

 though doubts have been cast, without any reason, on their observations. . 



