CUCUMBEKS, TOMATOS, AND FUNGUS PARASITES. 



145 



The proof that the solution of sulphate of copper is actually absorbed 

 by plants is well shown in the garden Nasturtium, Tropceolum major, L., 

 where the effect of too strong a solution is first indicated by a bleaching 

 of the tissue surrounding the water- stomata, situated at the margin of the 

 leaf. When Grasses are similarly treated, the tip of the leaf, where the 

 water-stoma or its equivalent crack in the epidermis is present, is the first 

 part to bleach and die. 



In what particular way sulphate of copper is capable of rendering 

 certain plants immune against parasitic fungi is not definitely known, 

 neither is this the place to discuss in detail this phase of the subject. It is 

 certainly not due to the solution present in the leaves killing the germ- 

 tubes of the spores on their entry through stomata, because spores of all 

 three species of parasites alluded to in this paper germinate readily in a 

 solution of one in seven thousand of this substance. The probability is 

 that the copper arrests or modifies the production of some substance in 

 the leaves, which favours the entry of the fungus into the plant. 



Danger arising from the presence of fungi or eelworms in the soil can 

 be guarded against by sterilising the soil yearly with gas-lime. It is 

 equally important to treat in this manner fresh soil, about to be placed 

 in the houses, as that already there. 



Practical Directions for Treatment. 



Commence watering Cucumbers and Tomatos, when a fortnight old, 

 every third day with a solution consisting of one ounce of sulphate of 

 copper dissolved in 50 gallons of water. After treating for six weeks 

 as above commence watering every fourth day with a solution containing 

 one ounce of sulphate of copper in 35 gallons of water. 



The sulphate of copper should be pure, and rain-water should be used 

 if possible. 



M 



