Sl'ONGOSPORA 



57 



Icnticils. instead of the imlirokoii ciJidtTinis, to he 

 flif i)riiu-i|)al .-imihu' of initial infection, with sonu" 

 luni'lration tliroiigli wounds. 



.\feordin<t to Kunki'l. tlif resting spores jienninate 

 readily on initrient agar and form plasniodia in enl- 

 ture. By weekly transfers, sneli jilasinodi;! may be 

 kept in an active growing condition on synthetic me- 

 dia for a long time, and under these conditions they 

 are strikingly similar in api)ear;ince, sha])c. he- 

 havior, and locomotion to the ])l;ismodia of the 

 Myxomycetes (fig. 23). Wlien subjected to drouglit 

 they encyst or sclerotize, and if transferred to fresh 

 media the plasniodia may often break up into 

 smaller masses which move away and form stalked 

 fruiting structures like those of Dictiinxti-liiim 

 and Poliixphoncli/lium. The erect, single or branched 

 sporojihores bear sori of rod-shaped spores like 

 Dicti/oxtcliiim, and in germination give rise to 

 niyxamoebae which later aggregate to form pseudo- 

 plasmodiu. These in turn form sporophores again. 

 Kunkel's observations have not been confirmed, and 

 since species of the Acrasiales occur in soils with 

 S poll f/os pore it is not improbable that he may have 

 introduced coiit.-iminants of this type in his cultures. 

 It is to be particiilarli) noted, however, that the Plas- 

 modium which he |)lu)togra)ilHd looks like a true 

 myxomycctous plasmodium. .Since it has none of the 

 characteristics of an acrasiaceous pseudoplasmodium 

 in wliich the individual niyxamoebae retain their in- 

 dividuality as cells, it is difficult to conceive how 

 Kunkel got Dicti/osffliiim- and Poli/xphonili/Iiiim- 

 like sorocarjis from a |)lasmodium of the ty|)e shown 

 in figure 23. His photographs and descri])tions sug- 

 gest that he may have had more tiian one type of 

 Plasmodium at hand. The possibility that .S'. spoiif/o- 

 spora may form large plasniodia on nutrient agar 

 remains thus to be proven by pure culture studies. 



S. SUBTERRANEA (Wall.) Lafrfrlieim, 1891. .Tourn. 



Mycol. 7: 104. 

 Eri/yihfi »n1>tirraiii<i Wallmth. IH-l.'a. Mnnaea Ifi: 3.3^!. 



\»MK Beitr. zur. Bot. 1: IIH. 

 Prnlotniires Tuliir-Sotinii .Martius. \Hi2a. Die Kartoffel- 



e|)i(lemie der Irfzten .lahre order die .Stockfiiule und 



Hiiude drr KartofTeln, .Miinchen. IHl.'l), C. R. Acad. 



.Sci. Paris IJ:3U. 

 Hhhd.iiKiriiim Stiliiiii Hahenhorst. 184.S. .Arcli. Pharin. 



83: 300. 1844, Kryjit. Fl. Dputs<li. Oisttrr.. uiid der 



Schweiz I. 

 Tiilierrinia grahHn Berkeley, 18Hi. .lour. Hurt. .Scic. I.(in- 



don 1: 33. PI. 4. fip. 30-31. 

 Soronporhim Krnhieti Waldheim, 1877. .Xpcriii .System. 



des L'stilag. Paris, p. 33. 

 Spon<i<»i><)rti Solan! Brunchorst, I.e. 

 .S. srnltieg Massee, 1908. Jour. Bd. \^t\v. Knjriand 1.5: 



.594. Fip. 1-1:?. 

 .S. siihltrrnnm ri(tllriri>hi Blattny, 19.3.5. Hee. Inst. Kecli. 



.\(rr(in. Rep. tclieeosl. 137: ii. 

 S. .iiilitirriniiii liihi rirohi Blattny. I.e. 



Resting spore clusters or balls oval, elongate, ir- 

 regular, 19-8.5 p. in diameter, somewhat spongy with 

 numerous irregular channels. Resting spores loosely 

 l)acked together, angular, polygonal, spherical, 3..5- 



i.a i-i, with smooth, thin, yellow to yellowish-green 

 walls. Plasniodi.i uiiusu;illy large, u)) to 70 /( or more 

 in length, amoeboid, irregul.ir ; giving rise to one or 

 more sjiore w.alls. Zoospor.-ingia single or in clusters, 

 U)) to a dozen or more in a cell, si)herical, oval, elon- 

 gate, lobed and irregular, hyaline and thin-walled ; 

 ojicuing by the rupture of a small pajiilla which 

 bursts through the host cell wall emitting the zoo- 

 spores. Zoospores from resting sjiores and zoospo- 

 rangi.i oval. si)hcric;il, 2. .5-3. .5 /t, with two unequal 

 Hagella. 



P.irasitic on Sdlaiium tiihi'rosum, S. rcarscczcicsii, 

 S. haematododuin, S. mamusum, S. marc/inatum, S. 

 ciliatum, S. commersomi, S. nigrum, and Li/copersi- 

 coii esciilenitim, causing scabby lesions and cankers 

 on the tubers, and galls on the roots and steins. A 

 further account of the distribution and hosts of this 

 species is given in Chapter W. 



Spoiigospora xuhtcrranca causes the disease of 

 potatoes commonly known as powdery or corky scab. 

 While it is chiefly a parsite of the potato, it may also 

 infect close relatives of this host. In extensive inocu- 

 lation experiments Melhus, et al. ('16), found that 

 it will infect all but one of the hosts listed above but 

 not S. nigrum, S. mauritianum, S. duplo.iumatori , 

 S. Lohelii, S. heteracanthum, S. srafnrthianum, S. 

 lanciniatum, S. iorviim, and Solatium sj). Ferdinand- 

 sen ('23), however, reported that it is transmissible 

 to iS. nigrum in Denmark. Weber ('22) and I.eding- 

 ham ('35) also found it on tomatoes in Denmark and 

 Canada, respectively. It has also been reported by 

 Rybakova and Nedoshivinia ('36) on Ullucus tii- 

 bero.sus of the Chenoiiodiaceae in Russia. Truscott 

 ('Si) found a Spongoxpora-like organism in the roots 

 of strawberries in Canada, but he was not certain 

 about its identity. Blattny's distinction of two forms 

 of S. suhterranea on the roots and tubers, respec- 

 tively, does not seem justified. The two forms may 

 be transferred readily from one organ to another 

 and do not differ greatly in size and color of their 

 s])ore balls. Blattny, nevertheless, believed that the 

 root form may be inycorrliizal instead of l)arasitic. 

 Rybakova and Nedoshivinia also described an aber- 

 rant form near Moscow which differs from the nor- 

 mal type by the occurrence of its spore balls out- 

 side of the host cells. These balls are faintly brown 

 instead of yellowish-green in color, jilicate or ir- 

 regularlv crumpled on the surface, and m.iy be 

 aggregated in a common mass. They vary in size 

 from 20-2.5 /x by 13-19 /x .and show no cellular struc- 

 ture. Khrobrykh ('38) ex|)erimented with various 

 forms of .v. mihtrrraura from different jiotato va- 

 rieties of different geographical origin and con- 

 cluded that these forms are not biotypes or geo- 

 gra))hical races but ecotypes dependent on the host 

 variety, height, and size of the |nistules. In this con- 

 nection it may also be noted that .Sharpies ('23) de- 

 scribed a disease of the ))etioles ;ind le;if stalks of 

 the cocoanut |);ilin in Mal.-iya which appeared to be 

 associated with a species of Spongospora, but he was 

 not certain about the identity of the causal organism. 

 It probably does not relate to Spongospora at all. 



