139 



it kilh. This outgrowth contains the spores of the fungus, and should 

 be destroyed hy fire wherever seen. 



The diseases of the orange tree arising from errors of assimilation, 

 etc., are Chlorosis, Brontosis, " Die-back," Withers (Maltese Lupa) 

 Antomania, Carpoptosis, Antoptosis, etc. Of these, Chlorosis is a di- 

 sease common to all vegetables containing chlorophyll, the green 

 colouring matter of plants. Its principal signs are the following ; the 

 foliage assumes a yellowish green, then a yellow colour ; the tree ceases 

 io grow on the summit, and throws out very feeble, thin yellow twigs 

 from the trunk and larger branches. The flowers drop without bloom- 

 ing ; the few flowers which may bloom produce tiny yellowish short 

 lived fruit which never reaches maturity The upper twigs wither and 

 die, and the tree losing its foliage, falls into a state of cachexy from 

 which it cannot recover. In the early stages of this disease, the tree 

 may be saccessfully treated with ferrous sulphate (green vitriol) or with 

 bone-meal. 



" Withers" or Lupa is the sudden death of a part or whole of a tree, 

 caused by the sudden supervention of a cool breeze after a protracted 

 sultry calm in the hottest days of summer. It is a purely physical di- 

 sease, and frequent irrigation is the only remedy which I can suggest. 

 Brontosis, the sudden death of a tree in winter ; Anthomania, the pro- 

 duction of an extraordinary quantity of flowers ; Anthoptosis the fall of 

 the flowers without blooming, and therefore before fertilization can take 

 place ; Carpoptosis the fall of the y^ung fruit and other diseases of the 

 same nature are due to a defective nutrition, and are largely influenced 

 by the meteorological conditions of the season in which they oppear. 



In the discussion that followed the delivery of the lecture. Dr. Borg, 

 in reply to a question stated that : — 



The blood orange is native variety of the Maltese islands. There 

 were several opinions about the origin of the blood orange. Some 

 said it was produced by a gra^'t of the pomegranate on the orange tree 

 which was quite impossible as those two trees belong to very different 

 orders in the natural system of botany, and they cannot be grafted on 

 each other. Of course this opinion was formed from the colour of the 

 pomegranate which appears in the blood orange. I think it is a na- 

 tive hybrid, and that it was raised from a seedling of the common 

 .orange being influenced by a highly oxidized soil, which caused those 

 blood red spots in the pulp. There was formerly another opinion 

 which was that the blood orange of Malta was a hybrid of the ordi- 

 nary blood red orange (Citrus hierochunticum) but afterwards I found 

 tOut that this opinion could not b^ held, as it could not be proved that 

 the 0. hierochunticum was ever cultivated in Malta. The oval or long 

 blood orange is a very recent introduction into Malta. It originat 3d about 

 40 years ago, upon a tree of the oval orange, a branch of which, pro- 

 .duced oval blood oranges, a freak of nature which was propagated by 

 budding. In fact we have no oval blood orange trees more than forty 

 vyears of age. These are only subvarieties of the orange tree, and any 

 difference between them is so slight that a botanist should not and 

 : cannot consider them as being different. In fact there is no differ- 

 ence at all, as the blood orange tree may produce common oranges 

 :without the blood-spots. The ordinary or flat blood orange of Malta 



