SPERMOGONIA 197 



advanced stage the sporophores (or spermatiophores) could be traced as 

 outgrowths from the peripheral hyphae, directed in palisade formation 

 towards the centre of the hyphal coil about 20-30 (jl long and very slender 

 and colourless. They begin to bud off spermatia almost immediately, as it 

 has been found that these are present in abundance while the developing 

 spermogonium is still wholly immersed in the thallus. Meanwhile there is 

 gradually formed on the outside a layer of plectenchyma which forms 

 the wall. Additional spermatiophores arise from the wall tissue and push 

 their way inwards between the ranks of the first formed series. The sper- 

 mogonium slowly enlarges and stretches and as the spermatiophores do not 

 grow any longer a central hollow arises which becomes packed with sper- 

 matia (or spores) before the ostiole is open. 



A somewhat similar process of development is described by Sturgis^ in 

 the spermogonia of Ricasolia amplissima, in which species the primordium 

 arises by a profuse branching of the medullary hyphae in certain areas close 

 to the gonidial zone. The cells of these branching hyphae are filled with oily 

 matter and gradually they build up a dense, somewhat cylindrical body 

 which narrows above to a neck-like form. The growth is upwards through 

 the gonidial layer, and the structure widens to a more spherical outline. It 

 finally reaches the outer cortex when some of the apical cell membranes 

 are absorbed and a minute pore is formed. The central part becomes hollow, 

 also by absorption, and the space thus left is lined and almost filled with 

 multicellular branches of the hyphae forming the wall; from the cells of 

 this new tissue the spermatia are abstricted. 



b. Forms and types of Spermatiophores. The variations in form of 

 the fertile hyphae in the spermogonium were first pointed out by Nylander''^ 

 who described them as sterigmata^ He considered the differences in 

 branching, etc. as of high diagnostic value, dividing them into two groups : 

 simple "sterigmata" (or spermatiophores), with non-septate hyphae, and 

 arthrosterigmata, with jointed or septate hyphae. 



Simple " sterigmata " comprise those in which the spore or spermatium is 

 borne at the end of a secondary branch or sterigma, the latter having arisen 

 from a cell of the upright spermatiophore or from a simple basal cell. The 

 arthrosterigmata consist of " short cells almost as broad as they are long, 

 much pressed together, and appearing almost agglutinate especially toward 

 the base; they fill almost the whole cavity of .the spermogonium." The 

 arthrosterigmata may grow out into the centre of the cavity as a single 

 cell-row, as a loose branching network, or, as in Endocarpon, they may form 



^ Sturgis 1890. ^ Nylander 1858, pp. 34, 3;. 



^ Nylander, Crombie and others apply the term "sterigma" to the whole spermatiophore. In 

 the more usual restricted sense, it refers only to the short process from which the spermatium is 

 abstricted. 



