102 



SYUCIIYTRIUM GALLS 



She galls of tlie Synchytrla (Ohytridiaceae) furnisli 

 Insti'uctive exajnples which may be cited first cf all Tsecause 

 of thsir simplicity. !Ehe course of development of these 

 f^gij' parasitic pn different phanerogams, and their rela^ 

 ui'U'iS to the host plant are euctraordinarily simple in as 

 much as the whole life of one generation is enacted in one 

 cell of tiie host plant. The swarm e;pores of the S3mchytria 

 penetrate into the epidermal cells of the parts of the plants 

 above ground and incite the infected cells to active growth. 

 Figure 35a shows the simplest ca,^e: the cells attacked by 

 the fungus ( Synchytrium Drabae Ludi) have been enlarged, the 

 form of taie hypertrophied cells , however, not varjring es- 

 sentially from the normal, . If the growth of the infected 

 epidermal cells becomes greater, they push the raesophyll 

 aside and grow into it as spherical or egg-shaped pouches, - 

 often extending as far as the opposite epidermis,- or they 

 swell out towards the outside and produce small hairs, as in 

 the gall^product of Synchytrium l^osotidis shown in fig. 35b/- 

 In -the case of other Synonytria the nutritive cells assume 

 still more complicated forms, 



Besides the nutritive cell, in which the parasite re- 

 mains the neighboring cells of the epidermis can be incited 

 to abnormal growth, in which they do not change their form 

 essentially. (Compare fig. 36a.) Finally, if cell division 

 takes place near the nutritive cell, more or less extensive, 

 (109^ often round warts, or warts with stalks, are produced, in 

 whose centre, or at whose apex the nutritive cell may be 

 found. (Fig. 36b) . In the production of such multicellular 

 galls, therefore, hj^-perplastic tissue-changes are also in- 

 volved. 



It is not yet sufficiently clear, what 

 factors determine whether only the nutritive 

 cell of the parasite hypertrophies, or other 

 cells undergo an abnormal grov/th and division. 

 Ihis much is certain, that the nature of the 

 parasites and the specific character of the host 

 plants alone do not determine it, that there- 

 fore, the form of the galls cannot be ascribed 

 throughout and unreservedly to the systematic 

 characteriSj^ics of the different Synchytrium 

 species, ludi especially has referred to the 

 change of the gall-form in the species named :- 

 "Usually when the v/arts are close together, Syn- 

 ch ytrium Drabae showed only those v/hose resting 

 spores lie in, more or less distended epidermal 

 jCfills, and which have no further influence on 

 the neighboring cells,- therefore, simple warts, 

 Uot infrequently and usually where there is more 

 space at the disposal of the nutritive cell in its 

 development, where therefore the warts are not so 

 close together, the nutritive cell is distended 



1* Schroter, Die Pflanzenparasiten aus d. Gattung Synchy- 

 trium, Oohn's Beitr. z, Biol, d. Pfl. 1875, Bd. I, 1, p. 1. 



