Mayi, I920 Artificial and Insect Transmission of Mosaic 135 



300 healthy Lahaina cane plants, from cuttings supplied by Dr. Smith, 

 were placed therein. These plants were from the same source as the ones 

 previously mentioned. The second greenhouse was divided into halves 

 by a tight glass partition. One compartment was used for propagating 

 healthy stock, and the other compartment was used for artificial inocu- 

 lation experiments. Both compartments were kept free from insects 

 by frequent fumigation. In the banana house, or "pesthouse" fumiga- 

 tion was not practiced on account of cage experiments with insects. The 

 greatest precautions were taken to prevent accidental infection of plants 

 in the house where healthy stock was growing. This house was invariably 

 the first one visited by the gardener for routine work such as watering, 

 and both houses were kept padlocked at all times. Probably because of 

 this care no single case of mosaic has appeared there or on control plants 

 in either house in any of the experiments. 



INOCUL.-^TlOiNS WITH INSECTS 



Experiment i. — On October 8, 1919, 10 individuals of Aphis maidis 

 were transferred with a camel's-hair brush from mosaic sorghum to each 

 of four young healthy cane plants in separate cages. A fifth cage was 

 reserved for two healthy plants as controls. On October 28 all four 

 plants showed incipient signs of mosaic. On November 18 they were all 

 unmistakable, well-advanced cases. The two control plants remained 

 healthy. 



Experiment 2. — On February 2, 1920, 12 to 15 individuals of Aphis 

 maidis were lifted from mosaic sorghum and placed on each of three 

 healthy cane plants in separate cages. Two healthy cane plants were 

 placed in a fourth cage for controls. On February 28 two of the treated 

 plants showed signs of mosaic and on March 5 were typical cases. The 

 two control plants remained healthy. 



Experiment 3. — -On February 2, 1920, one mosaic sorghum plant in- 

 fested with Aphis maidis was placed in a cage with a healthy cane plant 

 in such a way that the leaves of the two plants intermingled. On March 

 21 the cane plant showed unmistakable signs of infection. 



Experiment 4. — February 2, 1920, 10 individuals of Aphis maidis 

 were lifted from a diseased cane plant of variety G. C.-701 and placed on 

 a healthy cane plant in a cage. No infection was apparent on March 15. 



Experiment 5. — On October 8, 191 9, 15 specimens of Draectdacephala 

 molipes were placed in each of five cages containing one healthy and one 

 mosaic cane plants. On January 5, 1920, approximately three months 

 later, there was no evidence of infection. 



Experiment 6. — On January 5, 1920, 15 specimens of Draectdacephala 

 molipes were placed in each of two cages containing two mosaic sorghum 

 plants and two healthy cane plants. On March 1 1 there was no sign of 

 infection on any of the cane plants. 



