194 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Myxomyeetes . 



Cell and Nuclear Division in Fuligo varians. * — Prof. W. A. 

 Harper has followed out these processes in detail, and finds that they 

 differ considerably from those described by Strasburger in Trichia. 

 The following are among the more interesting points brought out. 



The author dissents altogether from Rosen's statement that there 

 are two kinds of nucleus, believing the apparent difference to be the 

 result of inequalities in fixation. In the formation of the sethalium 

 the segmentation is very clearly a progressive process proceeding from 

 the periphery toward the centre. There is no such thing as a simul- 

 taneous breaking up of the protoplasm into uninucleated fragments. 

 Nuclear division proceeds during the whole process of cleavage, but 

 without any relation to the latter process. Karyokinetic figures can be 

 found oriented in all possible ways to the cleavage furrows. The dif- 

 ference in this respect is striking between Fuligo and Trichia. With 

 the formation of uninucleated segments whose nuclei divide no more, the 

 process of cleavage is complete. 



In spite of their very small size, the structure of the resting nuclei 

 conforms to that in fungi and the higher plants ; but the prophases in 

 spindle-formation cannot be clearly followed. All stages of the separa- 

 tion of the daughter chromosomes and their migration to the poles of 

 the spindle can be found in the greatest abundance. 



The gethalium and the sporanges of the Myxomyeetes differ from 

 the sporanges of Synchytrium, Pilobolus, and Sporodinia. in that the multi- 

 nucleated condition in the former originates at least in the formation of 

 the plasmode. The plasmode is clearly equivalent physiologically to 

 the multinucleated masses of protoplasm in these and other fungi. 

 Fuligo differs from these fungi in the fact that the uninucleated seg- 

 ments formed by the completion of the cleavage process (protospores) 

 become the functional spores directly without further growth or nuclear 

 division. 



Crown-Gall.f — J. W. Toumey has studied the disease to which this 

 name is given, and which causes fleshy outgrowths on the roots of 

 deciduous fruit-trees, usually at the crown. He attributes it to an un- 

 described Myxomycete which he makes the type of a new genus Dendro- 

 phagus, somewhat resembling the Plasmodiophora which causes club-root 

 in cabbages. The species is named D. globosus. The plasmode is found 

 in the enlarged cells of the wen, where it destroys the protoplasm, and 

 induces the formation of a mass of spongy parenchyme, in the cells of 

 which the plasmode multiplies. Under favourable conditions sporanges 

 are formed on the outside of the wen, appearing at first like small trans- 

 parent drops. The sporange is about 1 mm. in diameter, nearly globular, 

 and dark orange. The orange-yellow spores germinate almost the moment 

 they are placed in water. 



Protophyta. 



/8. Schizomycetes. 



Influence of One Organism on the Growth of Another.! — Dr. A. 

 Cantani, jun., records some observations which indicate that the growth 



» Bot. Gazette, xxx. (1900) pp. 218-51 (1 pi.). 



t Arizona Agric. Exp. Stat. Bull. No. 33. 1900, 64 pp., 1 pi., aud 31 figa. 



X Centralbl. Bakt., 1" Abt., xxviii. (1900) pp. 743-7 



