DISEA8E8 OF PLANTS. 983 



was removed the previous year resulted in the production of u Bcabby crop. Treat- 



im-nt with formalin gave as g 1 results as with corrosive sublimate; and as it is 



much safer to use than corrosive sublimate, formalin is recommended. The treated 

 potatoes should be planted in new ground and care should be exercised that after 

 treatment they should not In- placed in Backs which have previously held scabby 

 tubers. 



Potato leaf curl, M. C. Cooke ( Gard. Chron., 8. ser., 88 I 1906 I, No. 978, />. 

 The author states that the potato leaf mil. or early blight, as it is known in this 

 country, caused by Macrosporium solani, while previously noted, has only recently 

 become a serious pesl in Engls <<1. The appearance of the fungus and its effect upon 

 the host plant an- described, and, according to the author, tin- only conidia com- 

 monly occurring in the British specimens are those of t he < 'ladosporium form. 



Spraying with ammoniacal copper carbonate or dilute Bordeaux mixture, if com- 

 menced sufficiently early, will hold the disease in check. 



The cytolytic enzym produced by Bacillus carotovorus and certain other 

 soft rot bacteria, L. K. Jones {Centbl. Bakt. [etc.], .'. M>l., U {1905), No. 9-10, />/>. 

 .'.',; /;/). — In an account of Btudies on the soft rot of the carrot previously noted 

 (E. S. K., 13, pp. 362, 567) the author suggested that the possible action of the 

 bacteria was through the presence of a cytolytic enzym, and the corn-cine— of this 

 supposition has been confirmed by subsequent investigations. 



The author believes, as a resull of his studies, that the action of the organisms on 

 the tissues of the host plant is shown in the solution of the middle lamellae of the 

 parenchymatous tissues, and that the organisms do not pass through the undissolved 

 residua] walls. The action upon the cell walls being determined as enzymic in 

 nature, he undertook to isolate and study the characteristics of the enzym. separating 

 it by heat, filtration, the use of germicides, diffusion, and precipitation with alcohol. 



The methods pursued are described at considerable length, after which an accounl is 

 given of the relation of various conditions to the activity of the enzym. The enzym 

 seems to be a stable compound which persists unchanged for a long time in culture 

 broths and may be preserved indefinitely as a dry precipitate. It is most active at 

 temperatures ranging from 40 to 45° C, and "when the temperature was carried to 

 51° or more the enzym was destroyed in all solutions. Other characteristics of the 

 action of the enzym are described, and comparisons were made between its action 

 and a similar cytolytic action observed with other organisms. 



The author has had under observation about 40 strains of organisms isolated in 

 different laboratories from the rotting tissues of cabbage, turnip, cauliflower, kale, 

 iris, etc., and comparative trials have shown that these soft rot organisms, although 

 from different vegetables and widely separated regions, are remarkably similar in 

 enzymic activity. The only exception observed is that found in Pseudomonas iri<n.<. 

 Which, in the author's opinion, is nonpathogenic under the conditions observed. 

 The other- all induce soft rots of various vegetable tissues, and from the cultures of 

 each a cytolytic enzym was secured that was indistinguishable from that produced 

 by /.' carotovorus. In all oi these the action consists in the solution of the middle 

 lamella and ceases before the complete Bolutionof the cellulose layer of the wall, and 

 m all there was an absence Ol any <bastatic action. 



The author comments on the classification and nomenclature of cytolytic eiizyms, 

 showing the presenl tendency to use the words pectinase and cellulase vaguely as 



synonymous with cytase. The author suggests that they be restricted to more exact 

 Usage and that cytase and cvtolyst he retained as convenient and satisfactory terms 

 tor ust' in the broader sense to include in general all enzyms capable of hydrolyzing 

 the cell walls. 



Cactus scab, <;. Masses [Gard. Chron., S. 8er., 88(1905), No. 972, /<. / 95, fig. /).— 

 A disease caused by a parasitic fungus has long been known to cultivators of cacti, 



31080— No. 10—06 5 



