356 JO VENA L, B021BA 7 NA TURAL HISTOR Y SOCIETY, Vol. IX. 



whitish crust on some of the leaves of Plumbago rosea. But I 

 have never been able to account for its appearance there. 

 Viewing the crust now in the light of Dr. Wilson's researches, I 

 am able to attribute the occurrence of it to Mittenian glands. I may 

 observe here that the critical eye of Mr. Jaikisson Indraji, of Pore- 

 bundar, has not failed to notice this crust. In a Ghijrati work, entitled 

 Arya Aushadh, published in 1889 by Dr. Virji Jhina Raval, L. M. 

 & S., in describing Chitrak, it is stated that in the space between 

 the amplexicaul petiole and the stem a kind of saline substance is 

 found which, he says, is used medicinally (p. 243). Mr. Jaikisson 

 Indraji, in describing the leaves of Plumbago rosea, says that " they 

 are covered with a white or brownish bloom.'" When I read this state- 

 ment eight years ago, and observed later on for myself the white crust 

 or bloom as he calls it, I was disposed to attribute it to external agencies. 

 I thought that the saline deposit was due to salts contained in the 

 water sprinkled over the plant in the process of watering. But, thanks 

 to the researches of Dr. Wilson, this calcarious deposit has now a 

 morphological interest, readily affording the happy solution of a 

 question which has struck very few before, but which now appears 

 to be a special phenomenon connected with the glandular appendages 

 of the genus Plumbago. Were it not for the explanation given by 

 Dr. Wilson, I should still have gone on imagining that the white crust- 

 spots seen on many leaves in Plumbago rosea were merely due to the 

 watering of the plants and to the deposit of the salines from the water- 

 ing fluid rather than to the inherent power possessed by the glands of 

 secreting saline ingredients by virtue of the chemical process going 

 on in their ultimate cells. Dr. Wilson has now shown us that the so- 

 called Mittenian glands which the Plumbagos contain in large 

 numbers are the producers of the white saline crust, which consists of 

 calcium carbonate. 



The next set of glands seen in the Natural Order Plumbaginece 

 constitutes, what Dr. W T ilson calls, "mucilage-glands" A few of 

 them are seen in the leaf-axils of Plumbago rosea, the largest being 

 •38 mm. in diameter. The stalked glands on the exterior of the 

 calyx of Plumbago rosea belong to this class. They are well known 

 for the viscidity of their mucilaginous secretion. They are " spherical, 

 bright red, and formed of very numerous polygonal cells. When fully 



