400 MR. F. DARWUST 01ST THE GLANDULAR BODIES OK 



lets ; they are about 2 millims. in length, and are shaped like a 

 pear with one side much flattened. Longitudinal sections exa- 

 mined with a low power show that the food-body is made up of 

 cellular tissue continuous with that of the leaf and included within 

 the epidermis. The cells are somewhat elongated, those at the 

 base giving in section a fairly rectangular outline (064 x *016 

 millim.) ; in transverse sections the cells appear nearly circular 

 in outline. A fibro-vascular bundle, continuous with the midrib 

 of the leaf, runs for a considerable distance into the food-bodies, 

 e.g. for 6 or '77 of their length, and terminates blindly in a few 

 short bifurcations of the spiral vessel. 



Methods employed. — Hardly any thing need be said on this 

 head ; the food-bodies are of such a consistence as to allow of 

 sections being cut in the usual way. I have found it convenient 

 to colour the embedding material pink with alkanet, for the sake 

 of the contrast of colour with the pale yellow food-body. The 

 various reagents used will be detailed in the sequel. 



Minute structure. — Examined with a high power, the cells are 

 found to contain a granular protoplasmic body, in which strongly 

 refracting oil-globules are embedded. There is a spherical nucleus 

 •0061 millim. in diameter, staining brightly in carmine, aniline, 

 &c. In some preparations the protoplasm lies free in the cell- 

 cavity ; in others it fills it entirely. It is of a firm texture, and 

 may often be seen floating out in a mass from a ruptured cell. 

 It exhibits the following reactions characteristic of protoplasm: 



1. It takes a deep yellow colour with iodine. 



2. It assumes a fine rose tint on being placed in strong sul- 

 phuric acid after having been soaked in syrup. 



3. Strong nitric acid and subsequent treatment with a solution 

 of caustic potash give the yellow colour of xanthoproteic 



The metaplasmic particles which give it a granular appearance 

 are removed by potash or acetic acid ; under this treatment the 

 protoplasm clears up, and the oil is well shown ; fig. 3 represents 

 a section in this condition. 



The oil, which is seen to consist of globules of various sizes, 

 gives the following reactions : — 



1. It is soluble in ether, absolute alcohol, and in a mixture ot 

 turpentine and creasote, and is not soluble in water or glycerine. 



2. It is coloured green by strong sulphuric acid*. 



* This test has been applied to oils by Heydenreieh and Penot. see Diet, or 

 Chemistry, Watts, iv. p. 182. 



