98 NOTES AND MEMORANDA. 



threads ; sometimes the most external cells are the longest. 

 Fructification not known. 



These curious Rhodophyceans parasite, living half in and 

 half out of the host-plant, occur on Delleserieee, Polysi- 

 phonia, Sphserococcus, Gigartina, E-hodomela, Laurencia, 

 Ceramium, the various examples coming from far-distant 

 localities. The first observed representative of this genus 

 was that named by the author Choreocolax Polysyphonue, 

 found by him on P. fasiigiata, taken on the northern coast 

 of North America. Examples may possibly be found on our 

 own coasts of these remarkable growths, if sought for by our 

 marine algologists. Sometimes the mass of the parasite ex- 

 pands out considerably larger than the stem of the infected 

 plant on which it grows, and causes a good deal of distortion 

 of the constituent cells of the latter. These, for instance, 

 in the form named Choreocolax mirahilis, growing in the 

 stems and branches of Rhodomela subfusca, may become dis- 

 located in some numbers, and in section can be seen more or 

 less displaced and commingled with and surrounded by the 

 cells of the parasite. The cells of the host embraced by the 

 parasite are described as becoming much altered, their con- 

 tents deprived of colour, and completely filled by a granu- 

 lose matter, assiiming, on application of sulphuric acid and 

 tincture of iodine, a bluish-violet, the cuticular stratum 

 becoming dissolved, but the primary cellulose membrane 

 remaining unchanged ; at the same time the contents of the 

 cells of the parasite becoming deeply coloured a dusky purple, 

 the primary membrane unchanged. The contents of the 

 cells of the parasites ajipear, for the most part, as composed 

 of a nitrogenous substance (albumen), those of the host of an 

 amylaceous matter. 



The author describes also a further allied genus — Syrin- 

 gocolax (n. g., Reinsch) — also strictly parasitic, and, as to 

 habit, like the preceding, living partly within and partly 

 without the host-plant. Here, as in Choreocolax, the plant 

 is made up of two portions, one immersed in the parenchyma 

 of the infected plant, and composed of very slender threads, 

 passing in amongst the cells of the host-plant, the external 

 portion (as in Choreocolax) rising above the surface of the 

 infected plant, here by a short pedicel, is irregularly figured. 

 The substance of this external portion is formed of hetero- 

 morphous threads, the lower densely intricate, subcontorted, 

 very slender, the outer oval, disi^osed in thicker tubular 

 threads, forming a regular cortical stratum, externally 

 bounded by a rather thick continuous covering. Fructifica- 

 tion seems to be Polysporangia produced by the cortical 



