540 EXPERIMENT STATION RECORD. 



AGRICULTURAL BOTANY. 



Experiments showing- the effects of mutilation, or cutting 1 , on growth, G. 

 E. Stone {Massachusetts Sta. Bui 105, pp. 28-33).— A series of experiments is reported 

 which show tlie influence of mutilation of various kinds upon the growth of plants. 

 The experiments were carried on with seedlings of sunflowers, broad beans, and 

 lupines, as evenly paired plants as possible being selected and different lots subjected 

 to mutilation by cutting the primary roots, splitting the primary roots, cutting the 

 secondary roots, etc. 



The effect of mutilation on growth, as shown in the experiments, gives some idea 

 of the shock produced by this form of stimulation. The first effect is a disturbance 

 of the normal activities of the plant, which, so far as growth is concerned, is more 

 or less retarded. This is followed by an attempt of the organism to recover. The 

 maximum period of retardation appeared shortly after cutting, and the maximum 

 period of acceleration took place about 24 hours later. The degree of retardation 

 and acceleration appears to be more marked in rapidly growing plants, or those that 

 are more plastic, and is especially marked in the less differentiated cryptogams. In 

 some of the lower organisms the retardation was so brief and the acceleration and 

 growth so rapid that very close intervals in time of measurement were necessary to 

 observe the effects of mutilation. 



The experiments have a practical bearing in indicating the effect of pruning sec- 

 ondary organs on the growth of primary ones, and, conversely, the effect of pruning 

 primary organs on the growth of secondary ones. The pruning of primary organs 

 induces a marked stimulus to secondary organs and the pruning of secondary organs 

 induces changes in the grow 7 th of primary organs. In the splitting of roots the 

 injuries were of an insignificant character, since none of the essential organs were 

 removed from the plant. By the destruction of the leaders of any terminal organ 

 the normal geotropic irritability was interfered with, and mutilation of this charac- 

 ter was sufficient to induce quick and decided responses. The degree of irritability 

 or response to stimulation was more marked in secondary organs when the primary 

 ones were cut, and vice versa. 



The author concludes that " mutilation acts as a severe shock, and sets the self- 

 regulatory functions of the organism into activity, inducing a series of changes and 

 responses which manifest themselves according to the nature, degree of intensity, 

 and method of applying the stimulus, and they are also dependent upon the nature 

 of the organism stimulated." 



The effect of light and Bordeaux mixture on plants, R. Ewert (Landw. 

 Jahrb., 34 {1905), Xo. 2, pp. 233-310, pis. 3). — The author carried on a series of 

 experiments with potatoes to ascertain the effect of light and Bordeaux mixture on 

 the physiological processes of the plant, the investigation being in part designed to 

 test the claim of Schander (E. S. R., 17, p. 451) that the principal beneficial effect of 

 Bordeaux mixture is to be attributed to the protective action that the film of the 

 fungicide exerts on the chlorophyll of the leaf. 



After briefly reviewing some recent literature relating to the subject, the author's 

 experiments are described at length. These consisted of growing potatoes in pots 

 under varying conditions of light and shade and with and without applications of 

 fungicides. The effect of the varying degrees of light and of the presence of Bordeaux 

 mixture on the yield of tubers, the starch and water content of the tubers, the foliage, 

 etc., is described. It is said that the cultural and respiration experiments showed 

 that the activity of the plant was reduced in direct proportion to the reduction of 

 the sun's energy when cut off by the Bordeaux mixture. 



In the practical use of fungicides the author thinks best not to recommend too 

 complicated mixtures or those which are too expensive. Care should be exercised 



