164 MINNESOTA BOTANICAL STUDIES. 



12. Sections of upper portion of stipe (rachis) to show origin of 

 gonidiophylls. 0, transverse section; 3, longitudinal section in which 

 the midrib has also been sectioned. Areas indicated as for Fig. n. 

 g, gonidiophyll ; /, lamina. 



13. Cross-section of stipe showing outer cortex and epidermis. 

 The chloroplasts in the cortex are shown. 



14. Inner cortex of stipe, cross-section. 



15. Pith area of a stipe in cross-section showing the anastomosing 

 cells, embedded in a gelatinous matrix. 



1 6. Epidermis and outer cortex of stipe in longitudinal section. 



17. Inner cortex of stipe in longitudinal section. 



18. Tip of a haptere of holdfast, longitudinal section. 



19. Longitudinal section of haptere from the side. 



20. Longitudinal section of stipe at origin of a haptere. #, cortex 

 of stipe ; , cortex of haptere. 



21. Cross-section of a haptere at a branch. 



22. Diagram, cross-section of midrib indicating the lamina proper 

 and the tissues of the midrib, x IO by measurement. 



23. Cortex of midrib in cross-section. 



24. Longitudinal section showing epidermis and cortex of midrib. 



25. Pith area of midrib in longitudinal section. There is prac- 

 tically no difference whatever between the long and cross-sections, as 

 the anastomosing cells run in all directions. 



26. Section of lamina cut perpendicular to and very close to the 

 midrib. 



27. Section of lamina cut parallel to the midrib and at a distance 

 from it. 



28. Diagram of gonidiophylls, natural size, <z, large and ma- 

 ture; , before the formation of gonidangia. 



29. Cross-section of a young gonidiophyll before the formation of 

 gonidangia. 



30. Cross-section of a mature gonidiophyll showing gonidangia and 

 paraphyses. 



LITERATURE CONSULTED. 



1. De Toni. Sylloge Algarum, III : 325. 1895. 



2. Grabendorfer, J. Beitrag zur Kenntniss der Tange. Bot. Zeit. 43 : 

 609. 1885. 



3. Kjellman in Engler & Prantl. Nat. Pflanz. Fam. I. 2: 255. 

 1893. 



4. MacMillan, C. Observations on Nereocystis. Bull. Torr. Bot. 

 Club, 26: 273. 1899. 



5. MacMillan, C. Observations on Lessonia. Bot. Gaz. 30: 318. 

 1900. 



