434 



STATE BOARD OF AGRICUDTURE 



Clover Mosaic 



In order to determine if organisms similar to those found in bean plants 

 affected with mosaic were also present in clover plants showing mosaic 

 symptoms, stems and petioles from affected plants were fixed and sectioned 

 in the same way as the bean material. Unfortmiately several heavy frosts 

 had occurred before this material was collected and it therefore was not so 

 satisfactory as would have been collections made earlier. 



Examination of stained sections showed that the same type of flagellates 

 that were present in diseased bean plants were also present m mosaic clover 

 plants. Since it has been demonstrated that clover mosaic may be trans- 

 mitted to the bean, producing typical bean mosaic, and vice versa, the 

 finding of similar organisms in mosaic clover and mosaic bean strengthens the 

 probability of a causative relation between the bean flagellate and the disease 

 with which it is associated. The organisms in the clover plants were not 



Fig. 8. Photomicrograph of longitudinal section through phloem tissue of clover plant affected with 

 mosaic. A single elongated flagellate is seen lying in a sieve tube. X 1500. 



A. Body of the flagellate. 



B. Flagellum. 



C. Sieve tube. 



found in great numbers and the most of them had apparently been destroyed 

 by the freezing temperatures to which the plants had been subjected. Dis- 

 integrating forms were quite numerous in the sieve tubes and non-flagellate 

 individuals were found in greater numbers than flagellate forms. Fig. 8 

 shows, lying in a sieve tube, a single individual of the same form as type 1 of 

 the bean flagellate. The small biflagellate forms and an occasional broad 

 form found in the bean were also present in clover. The organisms were 

 almost invariably located close to the nucleus and often in contact with it. 



No extensive study was made of the clover mosaic material, but from the 

 sections examined there seems little doubt of the identity of the flagellates 



