200 MINNESOTA BOTANICAL STUDIES. 



C. schmitzii was described (1893) by Rosenvinge from 

 Greenland material on Cruoria arctica. The cell is without 

 a cellulose button or papilla, is more or less attenuate at the 

 base and has a single chromatophore with sometimes two pyre- 

 noids. Zoospores were not observed. 



Collections, Methods, etc. Upon the Constantinea material 

 which was collected by Miss J. E. Tilden at different points 

 along Puget sound and was distributed as Constantinea sitch- 

 ensis Post, and Rupr., were found a large number of endo- 

 phytic unicellular, chlorophyllaceous algas, referred to the 

 genus Chlorochytrium of Cohn. The endophyte was found in 

 abundance on all of the Constantinea collected. One collection 

 was made in August, 1897, near Seattle, and in the summer of 

 1898 (May 25-July 2), five were made at as many points farther 

 up the Sound. Most of the material used in the following in- 

 vestigations was fixed and preserved in a 2 per cent, sea-water 

 solution of formalin. The green color of the endophyte was 

 well preserved. The lower ends of the cells have in very many 

 cases an irregular outline which may possibly be in part due to 

 shrinkage but is caused for the most part by pressure of the 

 surrounding Constantinea cells. In all of this endophyte 

 formalin material and in the dried material as well, though not 

 so markedly, brown bodies were found jutting out between the 

 chromatophore and the cell wall and assuming various forms 

 (see below). These bodies were undoubtedly due to a chloro- 

 phyllan reaction, the hypochlorin reaction of Pringsheim. The 

 formalin solution when tested was found to give a slightly acid 

 reaction. 



Sections of Constantinea cut freehand between elder pith 

 furnished most of the material for study. They were mounted 

 either in the two per cent, formalin sea-water solution, in glyc- 

 erine, or in glycerine jelly. Material carried through the usual 

 paraffin method stained and mounted in Canada balsam has also 

 furnished useful sections. The abundance of the endophyte 

 makes it easy to get favorable surface and sectional views of it. 



General Habit and Structure. The endophytes on Constan- 

 tinea sitchensis occur on both the upper and lower surfaces of 

 the fronds. I have been unable to find any on the stipe. They 

 are most abundant on the older fronds and especially towards 

 the peripheral portion. From some young fronds they are 

 almost altogether wanting. They occur in greatest numbers 



