110 PATHOLOGY [Box. Absts., Vol. X, 



ing, after treatment with hot formaldehyde (50°C.), facilitates disinfection. Increasing the 

 concentration increases the toxicity of this chemical to both scab and scurf. Surface 

 disinfection is seldom complete, which introduces a variable factor into field treatment 

 experiments. The extent of soil infestation is best measured in clean, treated seed. 

 Untreated, clean seed in 1919 carried to the field a sufficient number of Rhizoctonia 

 sclerotia to cause 6 per cent infection on the progeny. All of the methods of seed treatment 

 reduced the percentage of infection over that of the checks, showing that seed treatment is 

 worth while from a practical standpoint. It was found that the germination of seed tubers 

 was injured with mercuric chloride 1-500 and formaldehyde 1-120, when the temperature was 

 raised above 55°C. for more than 5 minutes. No injury was induced by formaldehyde 1-120 

 at 50°C. for 2^ minutes followed by covering for 1 hour. Laboratory methods were devised 

 by means of which the value of a given seed treatment can be predicted without the necessity 

 of field trials. The laboratory methods were confirmed in the field trials. The data obtained 

 suggest that formaldehyde solutions used changed strength only slightly on being exposed 

 at room temperature in an open container for 26 days. Dilute solutions of formaldehyde 

 heated to 50°C. and held at this temperature from 5-60 minutes showed no appreciable change 

 in concentration. The concentration of formaldehyde solutions is somewhat lowered when 

 potatoes are treated at 48-50°C. The loss in concentration was greater when steam was used 

 as a source of heat than when employing a heater. The greater loss is probably due to the 

 condensation of the steam in the solution. — J. C. Gilman. 



713. Pantanelli, E. Azione fungicida e fisiologica degli anticrittogamici. [Fungicidal 

 and physiological action of anti-cryptogamic compounds.] Mem. R. Staz. Pat. Veg. Roma 

 1920: 1-54. 1920. — The paper is divided into 2 parts, the 1st dealing with the action of the 

 anti-cryptogamic agents on the fungous parasites, the 2nd with the action upon the host plants. 

 The action of Bordeaux mixture, calcium polj^sulphides (lime-sulphur), barium polysulphides, 

 soap-silver mixtures, and copper oxychloride ("Caffaro paste") was studied upon Plasmopara 

 viticola, Oidium leucoconium, Fusarium niveurn, and Botrylis cinerea. The various functions 

 of the mixtures were studied by 2 different methods. The toxic action was investigated by 

 spraying the substances on glass slides; after drying these were sprayed with a suspension of 

 conidia in 5 per cent saccharose. The attitiseptic action, on the other hand, was studied by 

 replacing the nutritive fluids, in which the spores had germinated, first with water and this 

 in turn with the substance under investigation, the operations being carried out under the 

 microscope. The results of the treatment based upon the viability of the spores were as- 

 certained by staining with non-vital stains (of the aniline blue type), by plasmolysis reactions, 

 and by swelling, by increase in granulation and other visible manifestations, and by germina- 

 tions in a moist chamber after removal of the fungicidal substance. Sugar, as well as glycerine 

 and mannite, when used as a suspension medium was found to increase the antiseptic proper- 

 ties of the dry films of material studied; this the author attributes to the solvent action. 

 The principal results of the 1st part of the investigation lie in the demonstration of the fact 

 that the salts of heavy metals possess a strong antiseptic power, while when once dried, 

 the polysulphides under these same conditions failed to inhibit germination of the spores. 

 Silver salts are the most active, followed by those of copper. The fungicidal power of the 

 mixtures follows a different order, the polysulphides being sometimes far more effective than 

 the others. As preventive agents copper sprays are efficient for long periods, since the hy- 

 droxide of the metal is slowly acted upon by CO2 and rendered less basic and more soluble. 

 Bordeaux mixture prepared by the commonly accepted formulae is acid although it will turn 

 litmus blue. Soap-silver mixtures are also of value in preventive treatments since the silver 

 carbonate, formed by a reaction similar to the reactions with copper, is distinctly soluble. 

 The oxidation of the polysulphides is enhanced by the alkaline reaction of the mixtures so 

 that under atmospheric conditions the dry crust on the sprayed leaves is made up of the 

 following components: calcium carbonate, elementary sulphur, thiosulphates, sulphides, 

 and sulphates. Even though sulphur may be slowly oxidized to sulphur di- and trioxides 

 these products are not necessarily toxic at the low concentrations resulting. Barium polysul- 

 phides are always more effective than the corresponding calcium mixtures. — The 2nd part 



