Lecture VI — 85 — Environment 



in the mycorrhiza at the same time; or, the cortical hyphae may be 

 neither parasitic nor endotrophic but peritrophic ; and the peritrophic 

 fungi may become dependent on the root plant. Jahn supposed that 

 the function of rhizospheric fungi is to change the h.i.c. of the rhizo- 

 sphere that it will correspond to the most favourable concentration for 

 optimum permeability of the roots. In an experiment to determine 

 whether it is the H- or the Ca-ion that is active, he found that several 

 fungi cultured from the rhizosphere caused heightening of the h.i.c. 

 of the culture solution without addition of calcium carbonate, but 

 with such addition the pH changes were less but nevertheless were in 

 an acid direction. With calcarous fungi there was better development 

 on addition of CaCOg than without it. It had been early suggested 

 (KuNZE, 1906) that there is not a simple relation between root- 

 secretion and mycotrophy but that the higher plant makes use of the 

 decided soil "ausschliessenden" action of fungi. So Kurbis decided 

 that the fungal flora of Fraxinus are not necessarily mycorrhizal, but 

 surround the root with acidity. He found that microorganisms were 

 greater in numbers in the rhizosphere than in root-free soil ; also, that 

 seedlings of Fraxinus dwindled and died in sterile sand but waxed 

 in unsterilized or inoculated soil. 



Salt Marsh: — Two special habitats are to be considered, the salt 

 marsh and the prairie. A salt marsh, with its high osmotic coefficient 

 because of relatively large salt content, one would not suppose to be 

 favourable to mycorrhizae, yet two papers record characteristic pres- 

 ence of these structures in it. According to Mason (1928), mycor- 

 rhizae were found in such common coastal plants as Plantago mari- 

 tima, Aster tripolium, Glaux maritima, Armeria maritima and Glyceria 

 marithna, but no mycorrhizae were found in Salicornia europaea, 

 Triglochin maritimmn and several others, including Juncus. But 

 Klecka & VuKOLOV (1937) found mycorrhizal symbiosis in the small 

 roots of Juncus Gerardi, Salicornia herhacea, Suaeda maritima and 

 Triglochin maritimmn which duplicated that of endotrophic mycor- 

 rhizae of woody plants. The material was collected from saline soil 

 about Neusiedler See and from Auschitz and Louny in Bohemia ; and 

 the authors thought it very interesting that the fungi endured an high 

 osmotic pressure in root cells of these species. We would like to be 

 assured that these salt-marsh soils were truly saline, for our experience 

 with the New Jersey marshes indicates that such soil is not necessarily 

 salty. 



Of 14 halophytes collected on the west coast of Sweden by Fries, 

 six bore thamniscophagous mycorrhiza which contained arbuscles, 

 vesicles and hypertrophic nuclei. (Bot. Not. 1944:255-264). 



