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th the formation of zoospores the end of the cell next tlie epulonnis of 

 host becomes a little elongated and bluntly conical ; the pointed end 

 penetrates the cortical reticnhim of the host, and an ostiole is formed at its 

 apex through which the zoospores are set free into the surrounding water. 

 Kjellman observed that the individuals growing near the centre of the host 

 are usually very much developed, measuring up to 275 /* in diameter, while 

 their walls are striated and uniformly much thickened. He considered that 

 they were probably cells which had entered into a resting state. 



Ill 1898 Freeman*. described an alga which he believed to be a summer 

 state of the same species. Freeman's material was not always completely 

 imbedded in the nurse-plant, and in these cases he frequently observed a 

 considerable thickening and striation of the cell- wall of the endophyte on 

 the outer side. Tlie cells were usually more or less pear-shaped, with the 

 suialler end pointed towards the epidermis of the host, beyond which they 

 never projected more than half the thickness of their cell-wall : they were 

 ovoid, ellipsoid, sphseroid, or in the shape of a figure of eight. They were 

 only occasionally enclosed in the centre of a frond, but in these cases the 

 figures show them to be ellipsoid, with an uniformly thick cell-wall. The 

 cell-wall varied in thickness up to 28 /i on its outer surface and up to 8 /a 

 round the rest of the cell^ but it was usually not more than hrdf these dimen- 

 sions. The chloroplast formed a single yellow-green parietal plate, containing 

 a varying number of conspicuous pyrenoids which were observed to project 

 from the inner surface of the chloroplast into the cavitv of the cell. Free- 

 man's figures show in addition that the inner surface of the chloroplast was 

 somewhat uneven, being raised into small projections bearing, in some cases 

 a pyrenoid at the free end. The production of zoogonidia was never observed 

 in this material, but Freeman considered it to be the same species as that 

 described by Kjellman, since all the differences between the two could be 

 quite satisfactorily attributed to a difference of host-plant and to the 

 difference in the time of year at which the collections were made. 



The alga described f under the name ChlorocJt//trhim Schmitzn, Rosenvinoe 

 (189-4), should certainly be considered only as a form of C, iiidusinn, KjellnT., 

 since Rosenvinge's separation of the two species is based entirely on the 

 shape of the cell and the absence of a conical papilla on the outer side of 

 the cell. The basal attenuation supposed to be characteristic of C. Schmkm 

 may be entirely due to the nature of its host — Cruoria a?Y'f/ra— especially 



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Kjellman and Freeman point out that the inner ends of cells of 

 C. i7iclHsum become variously irregular according to the pressure of the 

 surrounding tissues of the host. Again, Freeman definitely states that in his 



* Freeman. Minnesota Bot. Studies, vol. ii. Part III. (1898?). 



t Rosenvinge, M. L. K. "Les Algues marines du Groenland." Ann. Sci. N"at Bot 

 7nie S6r. xix. (1894) p. 161, fig. 56. ' ' 



