No. 4, February, 1922] PATHOLOGY 285 



of England) being more readily infected under laboratory conditions than others. The root- 

 system became infected and developed but poorly. (2) Stem-inoculation produced infection 

 readily in the garden-peas when a mycelium-containing medium was applied to artificially 

 produced wounds on the stem, less readily when stems were intact. Infection did not follow 

 when mycelium alone was used on intact stems. Garden-peas seem to be more susceptible 

 than the field varieties, with the exception of Gropart, which readily became infected. (3) 

 With seed inoculation infection followed most readily when seed were inoculated and then 

 germinated. — As only 2-3 per cent of the seed taken from badly infected fields show infection, 

 soil infection is the only one considered important. Proper rotation of crops is suggested 

 as the most practical means of eradicating the disease. — P. A. Rydherg. 



THE HOST (RESISTANCE; SUSCEPTIBILITY; MORBID ANATOMY AND 



PHYSIOLOGY) 



1871. Beauverie, J. La resistance plastidaire et mitochondriale. Esquisse d'une methode 

 applicable i I'etude du parasitisme et des maladies des plantes. [The resistance of plastids 

 and mitochondria. An outline of a method applicable to the study of parasitism and the diseases 

 of plants.] Rev. Auvergne 38: i6 p. PI. 1. 1921. — The author develops further the facts 

 stated in a former article (see Bot. Absts. 10, Entry 444). The chondriosomes and plastids 

 possess a resistance which varies with the age of the tissues, it being weaker for the meristem 

 than for the older tissues. It perhaps varies with the species, and is diminished by the presenec 

 of a parasite, such as a fungus. This increased weakness under the action of a parasite has 

 been the subject of only a very small number of experiments. The reagents which serve to 

 demonstrate the resistance or susceptibility of the organisms may be distilled water, hypo- 

 tonic solutions, etc., but the chloroplasts are particularly resistant to their action and the 

 author has been lead to search for a reagent capable of attacking them. This he has found 

 in saponin solution. A solution of 1/1000 acting on a leaf of Ficaria ranunculoides parasitized 

 by Uromyces ficaria has little effect on the chondrioplastids of healthy tissue, but the action 

 becomes more marked toward the infected zone, where it produces chondriolysis. The author 

 suggests what might be the applications of these facts for studying the intricate mechanism 

 of parasitism, if later studies develop and generalize than: Determining the relative resistance 

 of varieties or even of individuals (for stocks of pedigreed lines) by a preliminary test of the 

 plastidial solidity; study of filterable virus diseases; etc. — /. Beauverie. 



1872. Rao, P. S. Jivanna. Physiological anatomy of the spiked leaf in sandal. Indian 

 Forest. 47: 351-360. PI. 11-12. 1921.— Spiked leaves have G or 7 lines of mesophyll cells 

 packed so closely as to leave no air spaces toward the lower surface. In young leaves the 

 cells in the sheath around the vascular bundles and their ramifications are filled with starch. 

 Older leaves show starch in the central cells and finally throughout the mesophyll. The 

 cells of the lower epidermis also become filled with starch in the later stages. — Starch increases 

 in amount progressively from the youngest to the oldest leaves, but disappears in the advanced 

 stages of the disease, when the plant is dying. — E. N. Munns. 



1873. Weimeu, J. L., and L. L. Harter. Respiration and carbohydrate changes produced 

 in sweet potatoes by Rhizopus tritici. Jour. Agric. Res. 21: 027-635. 1921. — The relative 

 amounts of carbon dioxide given off from 2 halves of the same sweet potato [Ipomoea], 1 of 

 which was inoculated with Rhizopus tritici, were determined. The fungus usually caused 

 complete decay of the inoculated half in 3 days. From 6.3 to 7.8 times as much carbon dioxide 

 was given off from the inoculated half as from the healthy half. Analyses at the end showed 

 smaller amounts of starch, cane sugar, and reducing sugars in the decayed samples than in 

 the healthy ones. The total quantity of carbohydrates lost in the decayed samples was 

 greater than is indicated by the amount of carbon dioxide given off, which suggests that 

 carbohydrates were used in other processes, such as production of fungous material, alcohol, 

 acids, etc. Tests with sterilized tissue showed a similar reduction of carbohydrates by the 

 fungus. — The fungus grows in Czapek's nutrient solution plus glucose, but makes practically 

 no growth when cane sugar is the only source of carbon. When the 2 sugars are used together 

 cane sugar only is reduced. — D. Reddick. 



BOTANICAL ABSTRACTS, VOL. X, NO. 4 



