916 



SCIENCE 



[N. S. Vol. XXIX. No. 753 



white colonies. The bacterium liquefies gelatin, 

 gives an alkaline reaction in litmus milk and 

 produces no gas in fermentation tubes containing 

 peptone-water and 1 per cent, solutions of diffused 

 sugars. 



The organism is not killed when kept at a tem- 

 perature of — 2° C. for six days. It grows best 

 on agar at about 25° C, and its thermal death 

 point, found by exposing ten minutes in nutrient 

 solution, is between 49° C. and 50° C. 



The bacterium is pathogenic on the leaves of 

 sweet pea, lettuce, pepper and sugar-beet and on 

 the leaves and pods of the bean. 



Decay of Potatoes Due to Rhizopus nigricans: 

 W. A. Oeton, U. S. Department of .Agriculture, 

 Washington, D. C. 



A study has been made by the Bureau of Plant 

 Industry of potato diseases in the peat lands of 

 San Joaquin County, Cal. 



The most prevalent form of decay is a rapid 

 soft rot, caused by Rhizopus nigricans Ehrdt. 

 This is characterized by a dull-brown discoloration 

 of the outer skin and a slight brown discoloration 

 of the flesh, which when cut open soon oxidizes to 

 a reddish-brown. The tissue becomes soft, owing 

 to a solution of the cell walls, and on squeezing 

 there is liberated an abundance of clear brown 

 liquid. This feature has given the disease the 

 local name of " leak " or " melters." There is no 

 bad odor until the invasion of secondary sapro- 

 phytes. 



The large, hyaline, non-septate hyphae of the 

 fungus are abundant in the tissue. No other 

 organism occurs in the typical " leak." Pure cul- 

 tures are readily obtained, and a similar decay 

 may be produced by inoculation of sterile raw 

 potatoes under suitable conditions of temperature 

 and moisture. Differences were observed in the 

 rate of decay produced by Rhizopus from different 

 sources, that from potatoes producing decay in 

 potatoes sooner than a culture from bread. 



Rhizopus 7iigrieans is a wound parasite, capable 

 of affecting potatoes only through abrasions of the 

 epidermis. It appears to spread most rapidly 

 during the " sweat " following the digging of 

 early potatoes in warm weather and gives no 

 trouble after frost comes. 



The same fungus causes a destructive rot of 

 sweet potatoes, and will quickly liquefy apples 

 and pears. Rhizopus necans Mass., a related spe- 

 cies, causes a decay of lily bulbs in Japan. 

 Some Devices to Facilitate Work in Plant Pathol- 

 ogy: E. Mead Wilcox, University of Nebraska, 

 Lincoln, Nebraska. 



The method recommended in this paper is, in 

 brief, to arrange all of the material used in 

 pathology work according to one method. It has 

 been found very useful to arrange lantern slides, 

 negatives, index cards, herbarium material and 

 publications alphabetically by the scientific name 

 of the diseased plant, with sub-headings for the 

 several diseases. The herbarium specimens are 

 kept in the ordinary envelopes, which are attached 

 to cards arranged behind guide cards in a vertical 

 file case. The color of the card indicates the 

 part of the plant which is diseased. For example, 

 on the green card would appear specimens of leaf 

 disease, etc. The publications bearing on plant 

 pathology are gathered together and bound by 

 subjects; this necessitates in many cases the par- 

 tial destruction qf a larger publication containing 

 articles on several subjects, but the result is a 

 compact mass of literature on one subject. 



The following papers were read by title : 



The Spraying of Cedars for "Cedar Apples": 



F. D. Heald, University of Texas, Austin, Tex. 

 A Fusarium Disease of the Pansy: Feederick A. 



Wolf, University of Texas, Austin, Tex. 

 Studies in Sclerotinia; Sclerotinia fructigena 



(Pers.) Schrot.: J. M. Reade, University of 



Georgia, Athens, Ga. 

 Experiments in the Production of an Anthracnose 



Resistant Clover: S. M. Bain and S. H. Essaby, 



University of Tennessee, Knoxville, Tenn. 

 Two Interesting Smuts: L. H. Pammel, Iowa 



Agricultural College, Ames, la. 



Henby C. Cowles, 



SOCIETIES AND ACADEMIES 



THE NEW YOEK ACADEMY OF SCIENCES 

 SECTION OF BIOLOGY 



A EEGULAE meeting of the section was held at 

 the American Museum of Natural History, on 

 March 8, 1909. In the absence of the chairman, 

 Professor Bashford Dean presided for the evening. 

 The following papers were read: 



Genetic Relations of the Insectivora to other 

 Orders of Mammals: IMr. W. K. Geegoby. 



The Harpsioell Biological Laboratory: Mr. Max 



SIokse. 



The speaker showed a series of slides illustra- 

 ting the Harpswell region and environs. The 

 laboratory was founded by Dr. J. S. Kingsley in 

 1898 in the little fishing village of South Harps- 

 well, Maine, eighteen miles from Portland. The 

 immediate region is rich in interesting forms of 



