Lecture XII — 169 — Mycotrophic Phagocytosis 



mis is direct and the fungus passes through "Kurzzellen" or passage 

 cells intO' the cortex where, in consequence of presence of fungus, the 

 starch dwindles. Inter- or intra-cellular hyphae become swollen or 

 wurst-shaped, either terminal or intercalary. In age, in addition to a 

 number of nuclei, they have great fat vacuoles with protoplasm be- 

 tween, like cross-walls. When intracellular, vesicles are always 

 terminal, and the small glomerules described by Busich were never 

 found by Demeter. The content of the vesicle may be resorbed into 

 the hypha as there is seldom a cross-wall evident; and the function 

 of the vesicle is apparently to serve as a temporary storage organ. 

 "Germination" of the vesicles has been reported, said Demeter, by 

 Bernard and Busich only; and the very infrequence bespeaks a 

 slight significance for the germination. But more important in the 

 lives of both symbionts are the arbuscles, and both the simple and the 

 compound sorts described by Gallaud are found in the Apocynaceae 

 and Asclepiadaceae. Simple arbuscles are always terminal, formed 

 at the end of hyphae which have penetrated cells. In the end branches 

 in young stages of arbuscles there are little granules arranged in 

 nebulae, and staining deeply with haematoxylin. From their origin 

 these nebulae appear to be protein precipitates. As a result of action 

 of free H-ion in the cell-sap, the tips of the arbuscles burst and empty 

 their content into the host-cell. It is possible, said Demeter, to form 

 these "plasmoptyse" of the endophyte in pure culture, the action oc- 

 curring in vitro at an optimum acidity of 0.025 N HCl, and on the 

 basis of this observation, the name of "Plasmoptysen mycorrhizae" 

 was chosen. "Sporangioles" are merely the last structureless residue 

 of the arbuscles which have been made harmless, a residue which is 

 finally resorbed. 



Just as the hyphae can be broken down in HCl and the content 

 extruded as in the "plasmoptyse", so in pure culture Demeter found 

 that by use of different concentrations of sugars he could produce 

 peculiar stuntings of growth which recalled arbuscle formation. 



Phagocytosis in Ericaceous Mycorrhizae: — Kamienski 

 (1884), in his pioneer work on Monotropa, saw that the roots of this 

 plant are much branched and interlaced, and fragile; the epidermis, 

 being covered by a fungal mycelium of septate hyphae that form a 

 pseudoparenchymatous mantle two or three times as thick as the 

 epidermis. The fungus lives on the surface and never penetrates liv- 

 ing cells except sometimes in older portions where those cells are 

 filled with a brown "tannin" content. In older parts of Monotropa 

 roots the epidermis disorganizes at the same time as the mycelium 

 develops. It is evident that the epidermal cells play an important 



