December 8, 1922] 



SCIENCE 



663 



■were vitally mterested the story of his eonnee- 

 tion with it might have heen idifferent. As it 

 was Ohio saw a'djo'ining states rapidly develop- 

 ing their mineral resouTces as the result of geo- 

 logical surveys while her own organization 

 seemed to be producdng only beautifully illus- 

 trated volumes concerning fossils. 



There are enough sins legitimately left at the 

 door of state and national legislatures, in con- 

 nection with their 'dealings with science, with- 

 out adding ito their number the failures and 

 mistakes which should i-eally be charged to men 

 of science themselves. 



T. C. MENDENHALTi 



Eavenna, Ohio 

 November 7, 1922 



THE COLLOIDAL STATE 



Editor of Science: It seems that one im- 

 poi'tant basis of the anomalous ibebavior of mat- 

 ter in the colloidal state of subdivision lies in 

 the fact that, in the colloidal zone, increase in 

 dispei'sion is aecompaTiied by a dispi-oportion- 

 aiely large increase in kinetic lactivity of the 

 ultramicrons, which reaches an extreme at 

 atomic or molecular dispersion. The speed of 

 motion of ultramicrons is itself the resultant 

 of several factors (including size, temperature, 

 viscosity of dispersion medimn, concenti-ation, 

 free electronic fields, etc.), but it probably 

 exercises a very considerable influence in re- 

 actions where colloids are involved, e.g., dif- 

 fusion, adsorption, enzyme adtion, etc. 



For some time I have been accumulating data 

 bearing on this quesition, and would be pleased 

 to heaT from any readers of Science who know 

 of pertinent experimental facts. Thus Zsigmon- 

 dy ("Colloids and the Ultramicroseope") has 

 given the size of certain gold ultramicrons and 

 their relative amplitudes of motion. Ultra- 

 microspic examination indicates that gel forma- 

 tion involves aggregation with cessation of 

 visible kinetic aotiviity, and the zone of maxi- 

 mum degree of colloidality (J. Alexander, 

 J. Am. Chem. Soc, 43, p. 434, 1921) may be 

 that zone where the curve of free surface 

 plotted against particle size, approaches and 

 crosses the curvfe of kinetic rndtion plotted 

 against particle size. 



An investigation will also ibe made of the 

 variations in size of ultramicrons and ultra- 

 microseopic activity with changes in free acidity 

 (H-ion eencentration or Pfj value). 



Jeeome Alexander 

 50 East Forty-first Street, 

 New York City, 

 November 13, 1922 



NOTE ON THE FUSARIUM WILT DISEASE 

 OF BANANAS 



In the journal, Phytopathology, of Septem- 

 ber, 19191, j)j. E_ Yf. Brandes described in 

 detail his out-door pot inoculation experiment, 

 demonstrating that Fusarium Cuhense, E. F. 

 Smith is the cause of the very destructive wilt 

 disease of the banana, heretofore generally 

 known as the Panama disease. Since then there 

 has been published in Java a paper by E. 

 Gaumamm on a vascular disease of the banana^, 

 in which the author attempts to discredit the 

 work of American investigators of this dis- 

 ease, but particularly that of Dr. Brandes. In 

 a statement by Brandes, of which the writer 

 has a typewritten copy, he reviews Gaumamm's 

 paper and points out various errors and con- 

 fusion of facts. As the writer, while connected 

 with the United Fruit Company, recently eon- 

 ducted an experiment of exactly the same kind 

 as the one 'by Brandes above mentioned, it may 

 be important to those interested to briefly 

 describe this experiment and the results. The 

 experiment was made just outside the Com- 

 pany laboratory, in Changuinola, state of Boeas 

 del Toro, Panama. In this ease the common 

 Gros Michel banana was empiloyed, instead of 

 the variety Chamalueco employed by Brandes. 

 Othei-wise the two experiments were almost 

 perfectly parallel except as to locality. 



This experiment was begun November 1, 

 1921. Twenty-five cement pots were employed, 

 set in corresponding holes in the ground, and 



1 Brandes, E. "W., Banana Wilt. Fhytopath. 9. 

 No. 9, pp. 339-389, pi. 22-34, 1919. 



2 Gaumamm, E., Over een bacterieele Vatbun- 

 delziekte der bananen in Nederlandsch., Indie. 

 Meded. V. H. Instituut V. Plantenziekten, No. 48, 

 Dept. N. Landbouw, Nijverlieid en Handel, pp. 

 135, pi. 8, 1921. 



