. Cyclopedia of farm crops. Farm produce; Agriculture. thought by others to be imperfect buds which could repro- duce the plant. They were classed as fungi of the genus Sclero- tium by some, or as pathological out- growths. Since Wor- onin, in 1866, discov- ered in the nodules bacteria-like bodies, which he thought to be the cause of their formation, the theory has been generally accepted that they are galls produced by the presence of fungi or bac- Fig. 589. Root nodules of alfalfa I clustered on small side root- lets in this case). Two-thirds n.'itural size. teria, which enter through root-h
. Cyclopedia of farm crops. Farm produce; Agriculture. thought by others to be imperfect buds which could repro- duce the plant. They were classed as fungi of the genus Sclero- tium by some, or as pathological out- growths. Since Wor- onin, in 1866, discov- ered in the nodules bacteria-like bodies, which he thought to be the cause of their formation, the theory has been generally accepted that they are galls produced by the presence of fungi or bac- Fig. 589. Root nodules of alfalfa I clustered on small side root- lets in this case). Two-thirds n.'itural size. teria, which enter through root-hairs and stimulate the tissues of the root to the production of an abnormal rootlet, which is called the tubercle or nodule. The organism enters near the tip of the root- hair and stimulates the latter to curl into the form of a shepherd's crook. It travels down the interior of the root-hair in the form of a homogeneous strand, as seen in fresh preparations. In sections of young galls this strand is seen branched through the tissues from its point of entrance from the root-hair. These strands pass through the cell- walls by minute perforations and then enlarge again in the cell-lumen. Often the strand swells into a large body in the cell, with irregular pro- , which led some to think that the bacteria- like bodies found in abun- dance at a later stage were budded off from these swel- lings. These strands present in the young tubercles led a number of students to be- lieve in the fungous nature of the organism, perhaps related to the smuts; but especially by some it was considered to be one of the slime-molds similar to the Plasmodiophora brassicm, which causes the "clubfoot" of turnip, cabbage, radish and certain other crucif- erous plants. For this rea- son Schrceter, a German botanist, named it Phytom- yxa leguminosarum, and this seems to be the earliest sci- entific name. More recent investigations seem to show that the organism is one of the bacteria. Man
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectagriculture, bookyear
