IN THE LEAF-CELLS OF ANACHARIS ALSINASTRUM. 279 



Aiiaclmris was a deception, caused by oblique sunlight, which 

 though favourable for discovering the existence of minute 

 markings is entirely unsuited for the purposes of truthful 

 investigation. The mobile investment round the margin of 

 the cells has a well-defined boundary : in an instance where 

 tlie progressive circulation was very rapid I measured the 

 thickness of the layer, and found it not more than 1-25, 000th 

 of an inch (in general it is rather more than this, or about 

 l-20,000th). Now if this should represent the extreme length 

 of each ciliary filament, in order to possess the requisite 

 elasticity and tenuity, the proportion of length to diameter 

 should be at least ten to one ; this would at once place the 

 thickness of the filament beyond the limits of microscopic 

 vision, and clearly proves tliat if a series of cilia really existed 

 of these dimensions it would be impossible to see them. By 

 examining detached portions of the cell-walls with the largest 

 apertures and most careful illumination, I cannot discover any 

 rugose indications in its apparently uniform outline, 



t have made numerous examinations of this marvellous and 

 beautiful object, under different circumstances and conditions, 

 and will now describe the facts I have observed relating to 

 its structure and vital functions. The thickness of the di- 

 vision between the cells is about l-14,000th of an inch. In 

 certain stages of disease, or decay, this sometimes becomes 

 equally divided, showing that each cell has its own inde- 

 pendent membrane. No particular structure can be dis- 

 covered in the cell-wall : all the cells are filled with a thin 

 fluid, and contain a number of chlorophyll granules, varying 

 from three or four to upwards of fifty. The granules very 

 much resemble those of the Valisneria, but are rather larger. 

 Their dimensions are from l-3000th to l-5000th of an inch. 

 They are somewhat irregular in shape, some being of an oval 

 form, and others a nearly circular, flattened disc. Each 

 spherule has a granulated appearance, arising from six or 

 eight separate nuclei ; they are rendered more apparent by 

 a solution of ammonia, which also changes the green colour of 

 the granule to a yellowish tinge. 



The chlorophyll gianules are entirely dissolved by dilute 

 sulphuric acid. Treated with tincture of iodine they are 

 changed to a brown colour, with a nucleus of a darker shade, 

 and the apparent development of an external membranous 

 envelope. 



When the rotation is active the greater number of the gra- 

 nules travel round the margin of the cells. A few remain 

 fixed in the centre, chiefly consisting of those whose form 

 approaches to that of a round flattened disc. 



