OF ARTS AND SCIENCES. 67 



countrj'. Cut to abandon the oldest specific name of Puccinia, and 

 substitute for it an older name given to the ^cidium which is sup- 

 posed to be connected with it, is to encounter difficulties and produce 

 a confusion which is unnecessary. Suppose, to refer to another order 

 of Fungi, that the conidial form of a Pleos-pora had been described as 

 a Cladosporium before the ascosporic form had been described, would 

 mycologists suppress the original name given to the ascosporic form, 

 and retain that given to the conidia ? Certainly not. The generic 

 distinctions in the Uredinece are mainly derived from the characteris- 

 tics of the teleutosporic stage, and the generic names are, as far as 

 possible, those originally given to the teleutospores. The discovery 

 that the so-called species of ^cidium are states of Puccinia, Uro- 

 myces, and other genera, has not affected the generic terminology at 

 all, and I see no reason why it should affect the specific names. As 

 it is, the greater number of species of Uredinece, excepting of course 

 the purely secidial forms, are recognized by the names given to the 

 teleutosporic or Uredo condition, and if hereafter any particular secid- 

 ial form is found to belong to them, I see no reason why the specific 

 name should be changed because the ^cidium was described before 

 the other stages. As soon as an ^cidium is found to be connected 

 with another form, its name should disappear, and it should simply be 

 called the aicidial or hymeniferous condition of the species of Puccinia, 

 or other genus to which it belongs, unless, of course, for purposes of 

 what may be called mechanical convenience, one retains the aecidial 

 name unchanged in exchanges or lists. 



For practical reasons, if for no other, the custom of substituting an 

 aecidial specific name for a name given to a Uredo or teleutosporic form 

 should by all means be avoided. Of all the Uredinece described by 

 older writers, probably none are more difficult to determine satisfac- 

 torily at the present day than the species of ^cidium so called. 

 Original specimens of that genus are as a rule not so well preserved as 

 those of other genera of the order, and if one usually gets little satis- 

 faction from examination of what is left of the original types, he is 

 scarcely any better off on reading the older descriptions. It was not 

 unfrequently the habit of older mycologists to describe as varieties of 

 one ^cidium forms found on the most diverse plants, and most 

 certainly it is going too far to substitute for the name of a Puccinia, 

 let us say, which has passed current for many years, the name given 

 by an old authority like Persoon or Link to what he considered a 

 variety of an ill-defined ^cidium. It cannot be said that any want of 

 respect to the older writers is shown by abandoning their gecidial names 



