OF SOUTHERN CALIFORNIA. 457 



uncompromising foe to citrus culture in all known regions of the 

 globe susceptible to its culture. Yet unquestionably there exists a 

 definite cause or causes for their unwelcome presence, although to the 

 present time defying all effort at discovery. And at first view it 

 appears somewhat surprising that no more thorough and systematic 

 investigations have not long ago been instituted with this object in 

 view, for tlie presence and persistence of so formidable an enemy 

 ought to have stimulated more vigorous efforts than heretofore man- 

 ifested for their utter extermination. Yet it may reasonably be 

 asserted, perhaps, that it is a most difficult matter to decide where 

 and how to begin. 



If, however, this noble variety of the citrus family could but speak 

 and tell us of its itchings, its aches and pains during a lifelong 

 struggle to overcome this unnatural and excessive drain upon its 

 vital forces, we could hope for a starting point to begin a systematic 

 course of investigation into the causes that underlie all superficial 

 examination, but if denied all these symptomatic advantages, we are 

 left no alternative but to accept the situation fresh from the hand of 

 aborted or improved nature. And while an attempt is reluctantly 

 made to explore with a flickering taper these unknown recesses and 

 processes of nature, it is accepted more as a duty than as a pleasure, 

 that others may be induced to join in the common cause for a speedy 

 extermination of an acknowledged enemy. Making this the prime 

 object of this discussion, it may be well to bring the mind as near 

 the beginning of plant life, at the outset, as is practicable or interest- 

 ing in pursuing the subject. And for this purpose the tree will be 

 treated as essentially of three distinct parts: the roots, the stem, and 

 the leaves. 



The former may be said to be a counterpart of the latter. The 

 roots penetrating and spreading themselves out through the soil, 

 while the leaves are correspondingly expanding in the sunlight and 

 air; and it is to the life and vigor of root growth, as well as to the 

 luxuriance of the foliage, that the stem is dependent for its food and 

 increase. Starting with this general proposition a necessity arises for 

 an examination into the functions of these different parts, to render 

 intelligible the results predicated in this investigation. A common 

 opinion seems to obtain that the roots contribute the greatest share 

 to the well-being of the tree ; and while it is true that they are the 

 downward and lateral expansion of the stem, it is also equally true 

 that the branches and leaves are the upward extension and expan- 

 sion ; yet each has its special functions to perform, and that which 

 offers the least obstruction to either soon makes an unfavorable 

 impression throughout the entire structure of the tree. The diffi- 

 culty, therefore, surrounding an investigation of the true cause of 

 nature's processes producing conditions of disease and contingent 

 results, is apparent to all who will give it a consideration. 



To project the most critical and extended examination possible 

 consistent with existing circumstances of a scale-begrimed tree, and 

 little or no satisfaction will be afforded or the slightest clue obtained 

 as to its sickly and forlorn appearance. Or if we dig about its roots 

 with equal care, we are still unrewarded for our labor ; but if a cross 

 section of some terminal root is microscopically examined, the trained 

 eye at once detects indications of disease in its cellular tissue. The 

 walls are thickened and less elastic than in health, and the sap is of 

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