Palaeontologie. 607 



Their structure is fully described and illustrated. They are 

 compared vvith the leailess rhizomes found in the Psilotaceae, 

 in Corysanthes^ Corallorhiza, and some other saprophytes. The 

 cortical tissues are well developed, consisting of thin-walled 

 cells with dark contents, and are differentiated into three 

 resions. The cells oi the medio-cortex show indications of 

 fungal hyphae, and closely resemble in their appearance the 

 Gurions, contracted masses („clumps") described by various 

 atithors in the aerial roots of Orchlds, and in the absorptive 

 Organs of saprophytic Monocotyledons, and of Psilotiim. The 

 exo-cortex, though also containing hyphae, possesses none of 

 these „clumps". Hyphae are hovvever very rarely met with in 

 the endo-cortex. It is pointed out that the specialization of the 

 hyphae in two different regions of the cortex is a very com- 

 mon phenomenon in mycorhizae. There is also evidence here 

 that the fungus was not of a destructive nature, or it would 

 probabiy have penetrated into all the living tissues of the plant. 



In the outer cortical layers, the course of the fungus is 

 somewhat irregulär, both horizontally- and vertically-running 

 hyphae being met with. On the whole, however, the mycelium 

 seems to grcw along the mycorrhiza. The hyphae seem to be 

 intra-cellular, but there are indications that a few of them run 

 between the cells. In this region, especially in the sub-epider- 

 mal cells, curious pear-shaped bodies are found at the ends, 

 or apparently at the ends, of certain hyphae, resembling those 

 described by Williamson on the hyphae of the fossil Pero- 

 nosporites antiqiiarius, and also those occurring in recent 

 mycorhizae. The nature of these bodies is fully discussed. 



In the medio-cortex, „clumps" occur, consisting no doubt 

 partly of cell-contents, partly of fungal Clements; but they are 

 as a rule so dark in colour that no details of their structure 

 can be made out. They are connected to the cell-walls by 

 threads. There is an obvious resemblance between these 

 „clumps" in the fossil plant and those of recent mycorhizae. 

 The preservation of the specimen suggests that the host-plant 

 was deriving some benefit from the presence of the fungus. 



As to the systematic position of the fungus and host-plant, 

 such slender evidence as is available inclines to the view that 

 the former was possibly referrible to the Phycowycetes, and the 

 latter to the Lycopodiales. It is suggested the fossil should be 

 provisionally referred to the genus Mycorhizoniiim. 



Arber (Cambridge). 



Weiss, F. E., The Vascular Supply ofStigmarian root- 

 lets. (Annais of Bot. Vol. XVIII. p. 180-181, and text- 

 figure 34. 1904.] 



In a former paper by the same author it was pointed out 

 that certain vascular branches of Stigmarian rootlets terminate 

 in the outer cortex in wide, spirally-thickened cells, resembling 

 in appearance the transfusion-cells of leaves. A further section 



