394 



DIVISION III. MODE OF LIFE OF THE FUNGI. 



Later there follows also a penetration of the Fungus into and between the dead and 

 dying cells of the deeper-lying tissue-layers l . 



In connection with this subject it will be well to recall the fact, that the hyphae 

 of certain Fungi which are parasitic on other Fungi unite with those of the host, and 



the two protoplasmic bodies enter into continuity and 

 coalesce by disappearance of the cell-membrane in such 

 a manner that there is no longer a clear distinction 

 between host and parasite. The fact has been ob- 

 served in Chaetocladium and has been described 

 above ; it probably occurs in other cases also, for ex- 

 ample in Artotrogus 2 . The obscure and disputed 

 phenomena observed in Nyctalis and some other like 

 cases may perhaps find their explanation in a similar 

 relation between the two plants. 



SECTION CXIII. The effect which endophytic 

 and epiphytic plant-parasites exercise on their 

 host, when they do not at once put an end to its life, is 

 seen in a richly graduated series of phenomena, from 

 the slow exhaustion and wasting away of the host to 

 the characteristic transformations which in extreme 

 cases even promote the health and growth of the host, 

 and which take place when certain parasites attack plants 

 that are sufficiently young and capable of growth. 

 Examples of the first kind are to be found on all sides 

 and may be studied in pathological and descriptive 

 treatises. The first indication of a hypertrophic 

 transformation may be said to be given by the fact 

 to which Cornu 3 has called attention, that spots on 

 leaves and fruits occupied by such Fungi as Erysiphe 

 guttata (Aceris), Cladosporium dendriticum and the 

 Uredineae have a more abundant and more persistent 

 supply of chlorophyll than their neighbours which are 

 free from the Fungus. Next to this comes the normal 

 accumulation of products of assimilation in cells at- 

 tacked by a Fungus which has been already noticed 

 in a former page, and lastly the mycetogenetic growth 

 of the cells themselves and of the tissues which they 

 compose. For the hypertrophies and transformations 



proceeding from the latter cause, so far as they occur in Phanerogams, it is sufficient 

 to refer to the examples adduced on page 368 and in earlier chapters. We may 

 however add to them in this place the description of the peculiar transformations 

 produced in the Saprolegnieae by certain Ch) tridieae, and especially the one which 

 results in the formation of the plant-form described as a Lichen. 



FIG. 166. Species of Saprolegitia. 

 Extremity of a tube attacked and de- 

 formed by Rozeila icptigena. The 

 upper part is divided by transverse walls 

 into seven sporangia of Rozeila, six of 

 which z are empty, some showing the 

 spot o in the lateral wall where the spores 

 escaped ; the lowest z x is still full of 

 spores. Further down the tube has 

 three outgrowths s resembling oogonia, 

 which contain each of them a resting- 

 si>ore of Rozeila. A diagrammatic re- 

 presentation after Cornu (Ann. d. Sc. 

 nat. S r. 5, XV, pL 6). Magn. about roo 

 limes. 



1 See Bot. Ztg. 1874, and R. Gothe, Ueber d. schwarzen Brenner u. d. Grind d. Reben. Leipzig 1878. 

 a Bot. Ztg. 1881, p. 575. 3 Comptes rend. 93 (1881). 



