BOT.— Vol. I.] PEIRCE— NATURE OF LICHENS. 225 



der Seite einer Hyphe wachst ein kruzer Ast heraus, der 

 die diinne Membran vollstandig durchbohrt und innerhalb 

 derselben mehr oder weniger kugelformig anschwillt. Bei 

 dem Eindringen der Hyphe zieht sich die Hautschicht des 

 Protoplasmas zuriick und bildet eine seichte Einbuchtung, 

 in welcher das angeschwollene Haustorium seinen Platz 

 hat — " and Schneider^ — "The tip of the haustorium may 

 pass through the algal cell-wall, forming a somewhat 

 expanded filament between the wall and cell-plasm. In its 

 highest development the haustorium, often entering the 

 algal cell, develops a much branched network which 

 encloses but does not penetrate the cell-plasm." 



Neither in my sections, nor in the living gonidia,in which 

 I found haustoria, could I detect the alleged "Einbuch- 

 tung" of the protoplasm, and certainly the haustoria do 

 penetrate the protoplasm of the gonidial cells of R. reticu- 

 lata, as the figures convincingly show. It may be that, at 

 the time of penetration, the protoplasm may contract away 

 from the intruding haustorium, but this condition is not 

 permanent, the haustorium penetrates the cell, the essential 

 and living part of the cell, as certainly as it penetrates the 

 lifeless cell-wall. 



Can one imagine that the presence of another body, 

 whether living or lifeless, within the living protoplasm of a 

 cell is not accompanied by profound disturbance of the 

 living protoplasm, is not distinctly irritating to it, is not 

 positively injurious to it ? The contrast between the 

 evidently healthy hyphse and haustoria on the one hand, 

 and on the other the haustoria-containing gonidial cells, 

 many of which in sections and in free preparations had 

 contents dead and shrunken or completely gone, at least 

 suggests very strongly, though it does not prove, that the 

 haustoria completely devour the contents of the gonidia. 



It does not necessarily follow that the penetration of 

 chlorophyll-containing host-cells by haustorial cells is fatal to 

 the host-cells. This is the case, for example, in the host- 



1 1. c, PI. I and p. 445. 



