Mr. H. J. Carter on Difflugia pyriformis. 355 



in the situation of the nucleolus. Iodine alone, however, does 

 not alter the colour of the spherules, even when, by forcibly 

 bursting the nucleus, they are pressed out into the surrounding 

 liquid. 



6. Lastly, portions of food are always present, which show, 

 by the yellow and brown state of their chlorophyll, that they 

 are undergoing digestion, while they thus contrast strongly with 

 the fresh green colour of the chlorophyll -cells, which form part 

 of the organized structure of the Difflugia. 



Thus we have gone through the contents of the body of 

 Difflugia pyriformis under its gi-een colour, and have seen that 

 the bulk of these contents chiefly consists of chlorophyll-cells 

 and starch-granules. Let us now examine the body in the co- 

 lourless animal, where we shall find our attention drawn from 

 the striking characters just mentioned, which so strongly con- 

 nect D. pyriformis with the vegetable kingdom, to that part in 

 the economy of this species which is intimately connected with 

 the process of generation. 



Taking, then, one of the colourless specimens and placing it 

 in the field of the microscope under similar circumstances to 

 the green one, we shall observe that in the body there is now — 



1. The same kind of protoplasm as in the green state, but 

 much more plentiful and much more plastic. 



3. An entir-e absence of the green or chlorophyll-cells. 

 3- The number of starch-granules more or less reduced. 



4. Little or no appearance of oil-globules. 



5. The greater part of the bulk of the mass, now consisting of 

 small, colourless, acapsular, granuliferous cells, of a globular or 

 oval shape, about ^-^'o-o^h of an inch in diameter, most of which 

 are undergoing multiplication by duplicative division, in which 

 condition they are just twice the length of the single ones. 

 These bodies are smaller in some colourless specimens than in 

 others, indicative of an earlier state of development. 



Iodine gives them a light amber tint, which is slightly deep- 

 ened by sulphuric acid. 



6. The nucleus, of the same size as in the green specimens, 

 viz. the T^st part of an inch in diameter, but now more or less 

 effete, inasmuch as the spherules have nearly or wholly dis- 

 appeared, as the case may be, from the nuclear protoplasm, and 

 have left a delicate deciduous structure, apparently sacciform, 

 which, by the aid of chemical tests, is now found to be detached 

 from the nuclear utricle at all parts, except where the nucleolus 

 still connects it with this utricle. But the nucleolus, now that 

 it can be more distinctly viewed, is seen to be composed of a 

 circular compressed cell, which, while it unites the eff'ete proto- 

 plasm to the nuckus, also presents a number of small spherules 



