46 ON DICHJi:NA RUGOSA. 



spores are large, it is not improbable that the normal number is 

 eight. The spores are oval, and the largest about -001 inch in 

 length ; they are filled with granular matter, of a pale brownish 

 tinge, variegated by a mixture of bluish-green. These spores when 

 mature escape through the aperture at the summit of the granules. 

 Scattered over the edges, and at times imbedded between the plants, 

 we find the masses of green bodies (gonidia) which are very minute, 

 varying in shape from distinct circles to ovals or oblongs, encircled 

 by a hyaline or transparent border with a double-cell wall. The 

 green matter in the smaller of these bodies (which is probably 

 chlorophyl) is homogeneous. In the larger we find segmentation 

 commenced, and they are divided into two, four, or eight masses, 

 separated by a distinct partition, but still enclosed in the hyaline 

 cell wall. It must be remembered that each of these granular 

 brownish -black bodies is a separate plant, and it is only by their 

 rapid increase and aggregation into masses that the patch we see- 

 on the tree is produced. It is a matter of considerable difficulty to 

 convey in writing a clear description of these minute forms of life. 

 I may mention that no reaction is found on the contents of the 

 perithecium either by potash or iodine. 



The question first arises, after having ascertained its structure, 

 Where are we to look for it? The general appearance is certainly 

 that of a lichen, and the black oblong, or ovoid .peri thecia have 

 much the appearance of some of the Graphidese. The spores and 

 asci give us no help, as they may belong either to a lichen or a 

 fungus. The great difficulty arises from the presence of the 

 green particles, termed gonidia, which are , identical* with some 

 of the Algse, and have been figured and described under vari- 

 ous names by Kutzing, Hassal, and others, as separate and 

 distinct plants ; but similar bodies are also found in lichens ; and 

 we find the Rev. M. J. Berkeley, one of our greatest authorities, 

 in his " Introduction to Cryptogamic Botany " defines Fungi as 

 " plants Hysterophytal (that is, living upon dead or living 

 organic matter), or Epiphytal (that is, growing ui)on another 

 plant) nourished by the matrix, never producing gonidia," whilst 

 his definition of Lichens is, " Aerial, nourished by air, and not 

 by the matrix, producing gonidia." Of course, with these de- 

 finitions, anyone would naturally expect to find our plants amongst 

 the Lichens, but a most careful examination of Leighton's "Lichen 

 Flora," the latest and best work on this tribe, together with Mudd's 

 " Manual " and other works, failed to show me any description that 

 would agree in all respects with the appearance shown by the plant I 

 have described. I then asked Mr. MuUer to examine it, and as- 

 certain if it could be a Fungus. The mixture of distinguishing 



* If these bodies are free Algae, similar to the bodies found in lichens, it cer- 

 tainly may lead to a wrong conclusion to apply the term " g:onidia." Are they 

 ever found enclosed in the substance or developed from the Dichcena ?—Ed. 

 Grevillea. 



