476 THE SOOTY MOULD OF CITKUS TREES, 



distinguish a parietal and a central part; but the parietal is not of 

 solid structure, parenchymatous, as it consists of a number of dark 

 coloured glomerules, just like those described as belonging to the 

 second conidial form. In the centre of this pseudo-perithecium 

 we find innumerable spherical cellules, large, discoloured, with 

 delicate walls, and one or two small guttules in the interior, 

 isolated or united by a very narrow, ligature. The peripheric 

 glomerules, as well as the central cellules, may reproduce, on 

 germination, the ' morfea ' on another leaf of a Citrus-plant." 

 This is rather an economical form of reproductive-body, since the 

 cajisule itself, as well as its contents, is utilised in this way. 



The Heterobotrys-stage is found both in Italy and Australia, 

 with differences in detail, and it is conclusively proved, chiefly 

 from the New South Wales specimens, that it is derived from the 

 colourless or pale green filaments of the fungus. The coloured 

 hyphpe give rise to several other reproductive bodies, which are 

 generally recognised as of three kinds — SjDermogonia, Pycnidia 

 and Perithecia — but when a number of specimens are examined 

 it is not always easy to assign the forms met with to these three 

 categories. In the present instance, if we compare the forms 

 with those of allied and known species such as Capnodium salici- 

 num, Mort., there is no difficulty with the perithecia from their 

 containing Asci, nor with the regular pycnidia and their septate 

 stylospores or pycnospores; but there is a residue of forms which 

 cannot, with any show of consistency, be all considered as 

 spermogonia. And the settlement of the question is not rendered 

 easier by the fact that one branch of the pycnidium in C. salici- 

 num may produce spermatia and another branch pycnospores.* 

 There are at least three sufficiently distinct kinds with unicellular 

 spores, and although we have not applied the test which De Bary 

 lays down, that spermatia differ from spores in being incapable 

 of germination, still the one which approaches nearest to the 

 general type of a spermatia-bearing organ will be reckoned as 

 such. 



* Sorauer's Pflanzenkrankheiten, p. 336, 1886. 



