PLANT REPRODUCTION 175 



layer of stock and cion in contact, the physiological flow 

 of sap is retarded. This becomes apparent later in the 

 process of development, by the formation of a gall-like 

 body at the junction of stock and cion. After the grafts 

 are wound firmly, the plants are ready for the grafting 

 case in which they should be placed before they show any 

 tendency to wilt. 



140. Manipulation of the grafting-case. The grafting- 

 case should be divided by cross partitions into a sufficient 

 number of sections to hold the plants grafted in one day. 

 As soon as the grafted stock is placed in the case, the cover 

 is lowered and fastened firmly that no outside air may 

 enter. The cover is not raised for at least five days unless 

 it is found that too much moisture is accumulating on the 

 foliage, then it should be raised only the thickness of a 

 plant label, for a very few minutes. After five days, a 

 little air may be given for perhaps ten minutes in the 

 morning and the same in the afternoon. The following 

 day a little more air is allowed to enter, and the periods 

 of ventilation are gradually increased until full air is given. 

 This period is the most critical in the grafting process, and 

 it requires exceptionally good judgment on the part of the 

 propagator to carry the grafted stock successfully through. 



141. Treatment of plants when they are removed from 

 the case. At the end of three weeks, stock and cions 

 should be joined sufficiently to permit them to be taken 

 from the case. The plants are then placed on a green- 

 house bench with low sides (Fig. 20, lower). They should 

 never be placed in a deep bench, where atmospheric condi- 

 tions are necessarily inferior and where disease is liable 

 to infect the point of union. Also, in a deep bench it is 

 almost impossible to syringe the lower sides of the leaves 

 to prevent the attacks of the red-spider, 



