Mr. H. J. Carter on Difflugia pyrlformis. 253 



the microscope, and^ watching it while it gradually becomes 

 crushed and its contents issue, by abstracting part of the water 

 with a little bibulous paper we shall observe that these contents 

 are composed of — 



1. A small quantity of thin protoplasm, with its imbedded 

 " moleculse," which suspends and holds together the general 

 mass. This frequently oozes out, too, in spherical portions, of 

 different sizes, each of which may contain more or less of the 

 moleculse, but must not be mistaken for separate cells — the 

 variety in size helping to show that they do not belong to any 

 special set of cell-organs. 



2. A great number of spherical cells, of a fresh green colour, 

 about (jo'ooth of an inch in diameter, containing chlorophyll 

 and granular protoplasm. 



Iodine with sulphuric acid causes their contents to assume a 

 dark brown colour. Sulphuric acid alone gives them first a sea- 

 green or bluish-green tint, and then extracts the colour*. 



These cells are exactly like the chlorophyll-cells of Hydra 

 viridis, with the exception of being a little smaller. Fortunately 

 this animal was present for me to make the comparison. 



3. A nearly equal number of colourless refractive granules, of 

 globular, oval, and irregularly round forms, more or less com- 

 pressed, and of different sizes, varying from 3-oL_.th to -g-^th of 

 an inch in their greatest diameter respectively, the smallest 

 being the most numerous. 



Very diluted sulphuric acid, followed by iodine, gives them 

 for the most part a deep claret colour, and, to many, very fre- 

 quently the deep blue colour characteristic of genuine starch. 

 Strong sulphuric acid, preceded by iodine, causes on its approach 

 much blue colour to appear, indicative of the presence of amor- 

 phous starch in the mass, which colour disappears on the strong 

 acid reaching it ; it also causes a pellicle to appear on the large 

 granules, which swell up and, bursting, frequently display a 

 crevice in the centre, or radiating cracks which show that the 

 interior of the granule is filled with a homogeneous, semitrans- 

 parent, pulpy substance ; while the small granules lose all their 

 colour, but the pellicle remains, and still retains their forms re- 

 spectively. Indeed the indications, both physical and chemical, 

 in these granules, of an amylaceous composition are so strong, 

 that although the genuine blue colour may not always be 

 brought out in them by chemical means, yet no doubt can re- 

 main that they are starch in some form or other. 



4. There are also a few oil-globules frequently present ; but 



* By " iodine " I mean a solution of iodine in one of iodide of potas- 

 sium. 



