186 MINNESOTA BOTANICAL STUDIES. 



Tetraspores are known only in C. sitchensis. They are ob- 

 long and zonate, lodged in nemathecia. The nemathecia are 

 found exclusively on the lower surface of the frond more abun- 

 dant near the outer half. They are in the form of delicate, 

 slightly-raised " wart-like," often confluent bodies of a whitish 

 color. They average 3.5-4 mm. in diameter and often become 

 so numerous that they completely cover a very large part of the 

 lower surface of the frond. The nemathecia are covered by the 

 gelatinous layer on the surface of the paraphyses. The para- 

 physes are elongated, narrow, peripheral cells (Figs. 11, 12). 

 The tetraspores arise as club-shaped elongations of peripheral 

 cells between the paraphyses and are divided zonately into four 

 chambers. The tetraspores are numerous in each nemathecium. 

 Their average size is 108 x22 mic. 



Endophyte. — In a large majority of sections and upon all 

 material examined, are present peculiar green approximately 

 spherical bodies imbedded in the cortical tissue of the frond. 

 They are endophytic algee and probably the Chlorochytrium in- 

 chisum of Kjellman. In general they are pear-shaped with 

 their small end toward the surface and the cell wall at that end 

 thickened. They are greenish in color and contain a number 

 of conspicuous pyrenoids, the central areas of which stain very 

 readily, having a particular affinity for aniline blue. The proto- 

 plasm is denser toward the small end where the cell wall is also 

 thick. It is with this end that the endophyte breaks through 

 the cortical tissues of the nurse plant. I have as yet been un- 

 able to detect any zoospore formation. This interesting little 

 endophyte will receive a more complete discussion in a subse- 

 quent paper. 



Conclusions. — The material upon which these observations 

 are based was distributed by Miss Tilden as Constmitinea 

 sitchensis Post, and Ruprecht. A careful comparison of it 

 with the plates and descriptions of Postels and Ruprecht shows 

 however that the plant under observation might as well perhaps 

 be placed under Constantinea rosa-marina. The material 

 agrees in almost every particular with C. rosa-marina hav- 

 ing, however, single terminal fronds and an occasional evi- 

 dent dichotomy of branching. The differences enumerated 

 above in the descriptions of the two species can hardly be con- 

 sidered of specific importance. The length of the internodes 

 may vary considerably. The greater part of the material under 



