XIII. FUNGI. 961 



sporangia of which present two superimposed cells; they are developed on an infinity of Phamogams, 

 principally on the lower surface of their leaves. Phragmidia much resemble Pucdnia; but their 

 sporangia are many-celled ; they are parasites on the Uredines which inhabit the leaves of several Rosacece. 

 Here again the frequent occurrence of this parasitism has led to the belief that Uredo is only a form of 

 Phragmidium, 



Actinothyrium, Asteroma, Pestalozzia, and the neighbouring genera have led to various statements of 

 the same nature ; some botanists have described them as Spharice, and have left to their successors the 

 task of characterizing and classing them methodically, which is extremely difficult. MM. Tulasne have 

 singularly simplified the question by considering them as conidia or stylospores of various species. If 

 this theory be admitted, it will in future be necessary to ascertain for every species of SpJueria whether it 

 is hermaphrodite, monoecious or dioecious, and to describe its spermatia, conidia, stylospores, &c. To add 

 to the difficulty, great enough of itself, considering that these plants are microscopic, we must'add others, con- 

 sequent on the various forms being only met with either at great distances apart or mingled with other 

 organs of the same nature which belong to distinct species. How, it may be asked, are these organs or 

 forms to be referred to the species they really belong to? and are we not in constant fear of referring them 

 incorrectly? And it is all the easier to fall into error, when it is remembered that a spermatium, a 

 conidium, or a stylospore has no character indicating that it belongs to one species rather than to another. 

 The new theory may be attractive, but when different isolated forms are met with, they ought to be 

 described, and their descriptions placed among those of autonomous species with a certainty which is based 

 on incontestable characters, and not, as has been done, on the authority of others. Lastly, we must admit 

 that the mode of fertilization described by MM. de Bary and Woronin as occurring in Peziza confluent, 

 Melaloma, and Ascobolus fufuraceus, does not modify our ideas with regard to conidia and stylospores ; it 

 still leaves much to be desired with regard to spermatia. For ourselves, all the ectoclinal or endoclinal 

 Fungi, although very simple in their composition, will always be regarded as complete Fungi, and as 

 worthy of attention as those whose organization is more complicated. 



The JEddia, which grow on the lower surface of the leaves of some Euphorbia, alter the appearance 

 of the latter so much, that individuals of E. Cyparissias attacked by these Fungi have been described by 

 old botanists as a different species. The ^Ecidium of the Herberts vulgaris is accused by fanners of pro- 

 ducing Rust and even Pucdnia on Graminece, which nevertheless does not prevent their frequently using 

 this shrub to enclose their fields. 1 R&stelia cancellata grows on the Pear and allied genera, always 

 avoiding the Apple ; it is first perceived towards June, in the shape of orange-red patches sprinkled in the 

 centre with black spots, on the upper surface of the leaves ; on the corresponding part of the lower surface 

 the Rcestelia appears as a small cone which opens laterally by several longitudinal slits. This Fungus pos- 

 sesses spores and spermatia, and is therefore capable of reproduction ; nevertheless it has been regarded as a 

 form of Gymnosporangium, a Tremella-like plant which grows upon Junipers (Juniperus Sabina, Oxycedrm, 

 &c.). It has been further stated that if a spray of Savine laden with Gymnosporangium be placed near a 

 Pear-tree, Rcestelia will appear upon the leaves of the latter ; but as the experiment does not always 

 succeed, one of the promulgators of this opinion was told that ' a lucky hand was necessary.' 



TEIBE IV. CYSTOSPOREJD. 



Eeceptacles flocculent, continuous or chambered, simple or branched, terminated 

 by a vesicular sporangium containing the spores. 



PRINCIPAL GENERA. 



Didymocrater. Mucor. Pilobolus. Diamphora. Hydrophora, 



Syzygites. Ascophora. Melidium. Rhizopus. Azygites. 



1 The history of this matter is curious and instruc- the other a Pucdnia (P. gramlnis). Recent observa- 



tire. The so-called Rusts of the Barberry and Wheat tions, however, on the development of Pucdnia and 



were popularly supposed to be identical, and to be Mculium have been regarded as proving them to be 



communicated from the Barberry to the Wheat. The states of one dimorphic genus, and as thus establishing 



microscope, however, showed them to be essentially the popular view as the true one. ED. 

 distinct, and that one was an JEddium (J. berberidis), 



3Q 



