170 THE MVXOMYCETES OF I'lCTOU COUNTV. — MOOKE. 



A series of careful experiments erindncted l)v Kosanoif (Mem. 

 de la SCO. Imp. der;. Se. nat. dc ('lHM'l)iinra\ T. XIV) on the 

 Plasmodium of FuIkjo ardla scenn to e^^tal)li-^ll iliat. in this case 

 at least, the plasmodium is strongiv negativcdy u'eotropic, the 

 general movement of tlu^ plasmodimn on an iutdinod surface 

 invariably taking ])lace against tiie force of gia\ity. The same 

 investigator ol)served a like tendency to ]irogress against the 

 centrifugal force wlien the ])hismodium \va> placed upon a 

 rotating ])late. 



This negative geotropi-^m is exhihitod by many species in 

 connection with the fruiting jdiasc. and a])pears to he an adap- 

 tion to ])rovid(' for more etfertual spore disposal. Preparatory 

 to fruiting, the plasmodic mass will ascend and often almost 

 completely en\(do]) blades of gras-^, moss plants, etc., and lhcse 

 points of vantage gained the transformation into nature spor- 

 angia takes ])lace with astonishing ra])idity. Particularly 

 noticea])le foi- tin's tendency are the jdasmodia of J'In/Sfinoii 

 riresceiis and I'hi^sanim cincreinn ; hut. the characteristic is 

 exhibited in a greater or less degree by almost all species. 



]-*lasmodia also shew a marked sensitiveness to tenqierature 

 changes. That of Fidirio ovata is positively thermotropic up to 

 3,'' degrees ('. — -'54 degrees C but l)ecomes negatively so above 

 that point. An. ex]iosure to a tem]>erature of 2 degrees C. does 

 not kill thi- ])lasmodiuni, i)ut all niovement ceases and a pro- 

 longed exposure at that ])oint eventually results in death. The 

 maximum temperature in the case of this s])ecies is 52 deg\ C. — 

 53 deg. r. 



Intense illumination has al-o been foun<l to checdv Jiiovc- 

 ments of the plasnii>dinin, and in uneipial illnminatioiT it moves 

 towards the shade; in varying moisture towards tJie more moist 

 side. The direction and rapidity of movement is also strongly 

 influenced by the presence of a])])ro])riate uonrishnient and, 

 moreover, the jdasmodium shews a marked power of discrimina- 

 tion in this crmne/^tion. A series of very interesting observations 



