Lecture IX —123- Structure 



expressed whether any such absolute distinction could be made between 

 the two. Kamienski (according to Grosglik, 1885) had early said 

 that in cupulifers hyphae penetrate into inner tissues of the root and 

 extract nutrient; and Melin (1922) said that intracellular infection 

 does occur in ectotrophic mycorrhizae of Larix, suggesting that 

 earlier the intracellular hyphae may have been overlooked (Melin, 

 1923a). Melin called these mycorrhizae which combined characters 

 of both the preceding sorts, ectendotrophic. Intracellular hyphae in 

 ectotrophic mycorrhizae were described by Masui (1926a, h) for 

 Alnus and Abies; by Johansen (1931) for the cactus, Neomammil- 

 laria, which has a white mantle about the root with hyphae penetrat- 

 ing between epidermal cells and into cortical cells where apparently 

 vesicles were formed; and by Klecka & Vukolov (1935), who 

 found individual hyphae enter cells as short branches or barrel-shaped 

 structures. 



But Endrigkeit (1937), in a study of both sorts, came to the 

 conclusion that in ectotrophic mycorrhizae of Tilia, Quercus and 

 Pinus in East Prussia there is no such infection : "The opinion re- 

 cently expressed as to the endophytic character of the ectotrophic 

 forest tree mycorrhiza finds no support in the writer's investigations". 

 He thought that no nutritional or physiological significance can be 

 attributed to the occasional observation of rudimentary intracellular 

 infection or the common intensification of the "Hartig net" on a 

 decayed primary cortex. In pine, Young (1938) observed that "My- 

 corrhizal development varies from strictly ectotrophic in the case of 

 untreated controls, through the typical ectendotrophic in the 1^ lb. 

 of S treatment to the almost purely endotrophic in the 3 lb. S treat- 

 ment." Both ecto- and endotrophic mycorrhizae were found on 

 Corsican pine by Aldrich-Blake (1930). 



Ectotrophic Mycorrhizae: — In cupulifers, according to Frank 

 (1885), the root is surrounded by a fungal mantle that is mostly 

 many-layered; now colourless, now a light to dark brown pseudo- 

 parenchyma which lies close upon the true epidermis. It sends hyphae 

 in between the cells but never quite into the innermost layers of root 

 cortex, growing always in the membrane of the cell only which they 

 thickly weave about ; but they never enter the cell lumen. The oute*- 

 surface of the mycorrhiza is not infrequently smooth but root hairs 

 are never formed, their place being taken by a felt of loose hyphae 

 that extend out into the surrounding soil. 



Mangin (1910) described the ectotrophic mycorrhiza of Castanea 

 as follows: The diameter of the root augments and the piliferous 

 cells, covered over by mycelial mantle, are never permitted to form 



