Observations on Squamosis and Exanthema of the Citrus. 117 
t. HISTORICAL. 
The phenomenon of gummosis has long been known in the genus 
Prunus, The malady has been more frequently noted in the cherry and 
peach, though, as modern authors have shown, it affects also the apricot, 
almond, and the plum, both the American and European species. At no 
time, however, has the disease attained great economical importance, and, 
unlike other maladies, it has no history. Gummosis has always affected the 
Prunus, now more, now less, but in no sense hasit ever been a scourge. In 
the case of the Czérus, on the other hand, gummosis was hardly known, and 
then not as a malady, before 1834, when, Fouqué! informs us, it suddenly 
appeared in the groves of San Miguel. Watt,’ however, mentions Czérus 
medica, C. decumana, and C. Aurantium as yielding an unimportant gum, 
samples of which were exhibited at Madras in 1855. The orange and citron 
gums were sent from Masulipatam, but the place of collection of the shaddock 
gum is not given. Gummosis must, therefore, have been a sufficiently 
common phenomenon to attract attention, though not so intensive a one as 
to affect the health of the trees, hence the gum was collected and sent to 
the Madras Exhibition, as being perhaps of some economic value. Gum- 
mosis, we may therefore safely conclude, was no unusual occurrence in the 
eyes of the natives, and had been for years past a common affection of the 
trees, The disease was known in India in all probability before it was’ 
first observed in the Azores; in fact, there is evidence that the malady, in 
a very benign form, was in the orange groves of Europe in 1818 ; it appears 
even to have been described ‘briefly and precisely’ as long ago as the 
middle of the seventeenth century.2 However this may be, gummosis does 
not appear to have been a malady of much economic importance prior to its 
sudden and virulent outbreak first in the Azores, and then in the different 
orangeries of Europe, towards the middle of the nineteenth century. 
The malady was first observed in San Miguel in 1834, where it 
became, within a few years, enormously destructive. In 1840 the disease 
was atitsheight. ‘Entire orangeries were destroyed, others partially ruined, 
and it is estimated that one-quarter of the orange trees on the island had 
to be dug out.’* In 1842 the disease had become less virulent and in 1873, 
though still extant, was no longer feared.? In Portugal gummosis appeared 
in 1845, affecting first the groves around Lisbon, and was at the height of 
its destructiveness between 1858 and 1861. In 1851 it was present in the 
orangeries of Hyéres,° and in 1855 appeared in the groves at Limone on 
1 Fouqué, F:: Voyages géologiques aux Acores. III: Les oranges de San Miguel, les cultures 
et le monde organique aux Acores. Revue des Deux Mondes, civ, 1873, p. 836. 
2 Watt, G.: Dictionary of Economic Products of India. ii, pp. 344, 349- 
8 Ferrare, J. B,: Hesperides sive de Malorum aureorum cultura et usu 1646, cited by Sava- 
stana, L. Della cura della gommosi e carie degli agrumi. Comizio Agrario, Napoli, iv, 1887. 
4 Fonqué : loc. cit., p. 836. * Ibid., p. 836. 
6 Rendu, V. ; Note sur une maladie des orangers d’Hyéres. Comptes Rendus, xxxiii. 
