SETCHELL— PARASITISM AMONG RED ALG^. 159 



growths of the plants on which they are found, but some are un- 

 doubtedly parasites. Such are some of the plants belonging to his 

 genera Choreocolax and Syringocolax, but Reinsch did not find any 

 cystocarps or other organs of frutification on any of his specimens. 



The work of Reinsch produced little immediate efTect and the 

 basis of truth in it was not recognized until some years had passed. 

 In 1877, however, there appeared the first convincing description 

 and illustration of a parasitic red alga. In this year, Solms Lau- 

 bach published his paper on Jancsczuskia verruca: formis which pos- 

 sessed all the characteristics convincing of parasitism, viz., deep 

 penetration of the host plant (Laurcncia obtusa), reduction of the 

 thallus to a tubercle and color varying from dark red, through 

 orange to pale yellow. In addition to these, it showed cystocarps, 

 antheridia and tetrasporangia. In the case of Jancsezvskia, as de- 

 scribed by Solms, there can be no doubt either as to the parasitism 

 or as to the nature of the parasite. It is to be noted here also, that 

 the parasite is very closely related to its host and is the first of this 

 sort of parasite to be described among the red algae. 



Between the years 1876 and 1889, little was done to further our 

 knowledge of parasitism among the red algse. McNab (1876) re- 

 corded the finding of Choreocolax polysiphonicu Reinsch near Dublin 

 and speaks of its tubercular thallus and penetrating rhizoidal por- 

 tion, but mentions no reproductive organs of any kind. Bornet, in 

 1878 (pp. 97-99, pi. 50, f. 1-8) described on Jania ruhens Lamour a 

 very distinct parasite which he named Melobesia Thureti, noting 

 that it had been described by Harvey as early as 1849 (pl- 201) as a 

 second kind of tetrasporangial conceptacle of CoralUna squamata 

 Park. In 1881, Solms Laubach (p. 57, pi. i, f. 5, pi. 3, f. 12) de- 

 scribed a second parasitic CoralUna which he named Melobesia de- 

 formans growing on and in Jania natalensis Harv. and whose apices 

 it distorts through the action of its penetrating rhizoidal filaments. 

 Moebius, also, described a Ceramiaceous parasite on Centroceras 

 clavidatum (Roth.) J. Ag. in 1885 (pp. 77-80, pi. 7), which he named 

 Episporium centroceratis. 



The year 1889 may be considered to be the real starting point in 

 the genuine study of the parasitic red algas. Farlow (1889, p. 6) 

 made known the tetrasporangia of Choreocolax Polysiphonice' 



