A HISTORY OF SCIENCE 



"As only one areola belongs to each cell, and as in 

 many cases where it exists in the common cells of the 

 epidermis, it is also visible in the cutaneous glands or 

 stomata, and in these is always double one being on 

 each side of the limb it is highly probable that the 

 cutaneous gland is in all cases composed of two cells of 

 peculiar form, the line of union being the longitudinal 

 axis of the disk or pore. 



"This areola, or nucleus of the cell as perhaps it 

 might be termed, is not confined to the epidermis, be- 

 ing also found, not only in the pubescence of the sur- 

 face, particularly when jointed, as in cypripedium, but 

 in many cases in the parenchyma or internal cells of 

 the tissue, especially when these are free from the de- 

 position of granular matter. 



" In the compressed cells of the epidermis the nu- 

 cleus is in a corresponding degree flattened ; but in the 

 internal tissue it is often nearly spherical, more or less 

 firmly adhering to one of the walls, and projecting 

 into the cavity of the cell. In this state it may not 

 unfrequently be found in the substance of the column 

 and in that of the perianthium. 



"The nucleus is manifest also in the tissue of the 

 stigma, where in accordance with the compression of 

 the utriculi, it has an intermediate form, being neither 

 so much flattened as in the epidermis nor so convex 

 as it is in the internal tissue of the column. 



" I may here remark that I am acquainted with one 

 case of apparent exception to the nucleus being solitary 

 in each utriculus or cell namely, in Bletia Tanker- 

 villicB. In the utriculi of the stigma of this plant, 

 I have generally, though not always, found a second 



116 



