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European varieties of grapes. Heat and a certain moisture 

 are necessary for the production by the histologic elements 

 of a callus, which gradually grows and surrounds the zone 

 where stock and scion have been grafted. Before being used 

 the mixture of sea-grass and sawdust is steeped in water. 

 More water is poured on it after the grafted cuttings are 

 laid in layers in the boxes, and the sea-grass, while retaining 

 a suitable amount of that water, lets the surplus escape. 

 The mountain moss was first used instead of the sea-grass, 

 but, apart from being more expensive, had the inconvenience 

 of retaining too much water; with the danger that the 

 cuttings would rot, because the grafted cuttings are kept 

 for about twenty-five days, laid in the mixture at a tem- 

 perature of from 75 to 78 F. In a word, sea-grass is em- 

 ployed in preference to any porous material like sawdust, 

 mountain moss, or sand, because, like them, it enhances 

 the production of a callus, which is the first stage of the 

 knitting of stock and scion, without having many of the 

 inconveniences of those other substances. When the grafted 

 cuttings are planted in the nursery, and vegetation begins, 

 this callus, which is all a cellular mass and nothing else but 

 parenchyma, begins to harden and to undergo the differen- 

 tiation of the histologic elements, and by the end of the 

 vegetative period stock and scion form one whole, and the 

 ascension and elaboration of the aliments is then quite 

 normal." 



