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MINNESOTA BOTANICAL STUDIES. 



7. Cross section of epidermis and cortex of holdfast, x 250. 



8. Cross section through epidermis and cortex of stipe, x 250. 



9. Detail of cortex eel Is of stipe, x 250. 



10. Cross section through pith strand of stipe, x 250. 



11. Longitudinal section through pith strand of stipe, x 250. 



12. Cross section through epidermis of lamina, x 250. 



13. Cross section through cortex and pith strand of lamina, x 250. 



14. Diagram of cross section of leaf showing thickening of margin 

 due to increase of cortex and pith strand, x 30. 



15. Section of cystocarp showing spores inclosed by row of clear 

 cells, x 250. 



1 6. Oogonium and accessory cells among cortical cells of lamina 

 X 250. 



17. Another oogonium and accessory cell, x 250. 



PLATE XLV. 



1. Outline of young thalius of Microcladia coulteri from the base 

 of which project long rhizoid-like cells into the cortex of the host 

 plant, x 170. 



2. Young filament of Callithamnion among cells of host, x 170. 



3. Filament of Callithamnion bearing tetragonidia, x 170. 



4. Young frond of Porphyra epiphytic on parasitic Callithamnion, 

 X 170. 



5. Chlorochytrium inclusum lying in epidermis of host, x J 7o. 



6. Endophytic parasite of unknown genus consisting of four cells, 

 X 170. 



7. Same parasite surrounded by epidermal cells, x 170. 



8. A diagram of cross section of lamina showing relative positions 

 of cystocarp, parasitic Callithamnion and endophyte, x 20. 



