20 On Pigment- Flakes Pigmentary Particles, &c. 
tides and cell-like bodies (or celloids). . . . The cell-like particles 
have a peculiar appearance, very difficult to explain. They never 
present an unmistakably cellular character ; they appear flat, never 
spherical. Their outline is generally an oblique ovoid. Within 
this outline, which is generally of exceeding delicacy and of perfect 
definition, lie masses of red or orange pigment, exactly resembling 
the free amorphous particles already described.” 
Frerichs, after pointing out somewhat similar objects, says* that 
accurate diagnosis can be made in malarial fever by examining the 
blood for them, since a few drops “ are sufficient to determine the 
presence or absence of large quantities of pigment.” 
Drs. Meigs and Pepper report finding pigment-particles in the 
blood of eighty-nine patients ; but later these acute observers seem 
to have had shrewd misgivings respecting their importance, although 
without feeling satisfied as to their real origin. 
My own suspicions were excited years ago by Frerichs’s pig- 
ment-scales, and experiments on hundreds of specimens of blood 
from malarial and other cases convinced me of their delusive 
character. 
Very recently, Dr. James Tyson, of this city, whilst examining 
in committee some ovarian fluid, pointed out to me several of 
Roberts’s pigment-flakes, and said he had prepared drawings of 
these bodies for his forthcoming work. His statement naturally 
led me to a careful and prolonged study of the objects in question, 
and this in turn forced upon me the conviction above expressed. 
Excluding carbon-particles (from the air), which can generally 
be found in fluids which have not been secluded from the atmos- 
phere, I attribute the peculiar shape of pigment-flakes which 
Roberts finds so “ very difficult to explain ” (admirably shown by 
Dr. Tyson in his plate), to the conchoidal figure of the minute 
chipped-out cavities in plate- glass; which little pits have, indeed, 
proved veritable pitfalls to unwary travellers over the microscopic 
field. These same shallow shell-like excavations, before being 
filled up with dirt, are, probably, Frerichs’s “ coagula of a hyaline 
character, which resemble in form ” (as they have a perfect right 
to do) the pigment-flakes, and are also Roberts’s “ bluish mother-of- 
pearl ” celloids. 
Dr. Roberts concludes, “ I have been in the habit of noticing 
these objects for many years, and have regarded them as derivatives 
of haematin, but how they come to assume their peculiar forms I 
cannot conjecture.” With him, I believe them occasionally to be 
“ derivatives of haematin,” but only by the rubbing process detailed 
above ; and I trust that my “ conjecture” as to how these haematin- 
flakes “ come to assume their peculiar forms ” will be satisfactory. 
It seems almost incredible that the recorded appearance of these 
* Op. cit., p. 355. 
