118 CURREY, ON FUNGI. 



of the generic distinction between Phragmidium and the 

 allied genera Puccinia, Uromyces, Triphragmiunij and Xcno- 

 dochus. The number of divisions or apparent divisions of 

 the spore affords no safe criterion, for it is not uncommon to 

 find Phragmidium and Puccinia reduced to a single dis- 

 sepiment, and the reniform shape of the so-called sporidia, 

 which are produced by the germinating filaments of the 

 latter, and Avhicli Tulasne mentions as a distinguishing cha- 

 racteristic, is not constant, as I have myself witnessed. The 

 fruit of Phragmidium, moreover, sometimes assumes a form 

 quite similar to Triphragmium. There is a species of Tri- 

 phragnium [T. deglubens, Berk, and Curt.) in which the 

 dissepiments are arranged precisely as in Phragmidium. 

 The number of the pores through which the germinating 

 filaments make their exit has been advanced as another 

 ground of distinction between these genera ; but here, again, 

 there is no sufiicient certainty, for Phragmidium has a vari- 

 able number, and the rest have only one. These pores, 

 moreover, are frequently, I may say usually, not discernible 

 in the natural condition of the fruit, and only become visible 

 upon the application of some chemical agent, which renders 

 the epispore more transparent. 



It is quite impossible to arrive at any correct notion of 

 the anatomy of Phragmidium by examination with the 

 microscope alone, for the fruit in its natural condition is 

 far too opaque to admit of its structure being ascertained by 

 inspection. The idea of the fruit consisting of sporidia 

 united together and forming a chain is certainly not in 

 accordance with the true structure, which will be foimd to 

 approach more nearly to that of the ascigerous fungi than 

 any other tribe. The sporidia are not united to one another 

 in any way, but, although closely packed for want of space, 

 they are in fact free in the interior of what may be called a 

 sporangium or ascus. Perhaps the term sporidia is hardly 

 applicable to the bodies in question, but, before discussing 

 this point, it will be better to show what the structure of the 

 fruit is, and the mode of ascertaining it — and the best method 

 I find to be as follows.^ 



A considerable number of the spores of the Phragmidium 

 must be scraped oft" with a lancet or fine-pointed knife, care 

 being taken to scrape gently, so as to avoid tearing oft' the 

 tissue of the leaf, which would interfere with the observation. 



* The term "sporiilia" was originally applied to tlic apparent yoz'w/* of the 

 fruit ; and some confusion has been introduced by the application of the 

 same term by Tulasne to the globular orange-coloured bodies produced in 

 the early stage of germination, and which are noticed hereafter. 



