108 Transactions of the Botjal Microscopical Society. 
The first changes consist in the formation of a number of distinct 
wrinkles on the surface of the corpuscle (Fig. 55, a), which, how- 
ever, disappear again with the continued action of the reagent ; at 
the same time numerous granules appear in the protoplasm (6), 
while the membraneous layer manifests itself by the usual double 
contour. An interesting specimen with which I met is repre- 
sented at c; here the membraneous layer of the blood-corpuscle 
has burst, and the homogeneous protoplasm is seen to escape from 
the interior. Next, if the action of the reagent continues, the 
granules in the protoplasm disappear again, the corpuscle appearing 
perfectly clear {d) ; and finally, even the membraneous layer is dis- 
solved, so that nothing remains but the nucleus. 
The Coloured Blood-corpuscles of the Tree-frog (Eyla), repre- 
sented at Fig. 56, a and h, resemble in every respect those olBana 
pipiens, except in size ; for they only measure about yffo- mm. 
in length. The frequent occurrence of blood-corpuscles with 
certain portions of their bodies wanting, and appearing as if these 
had been removed by means of a sharp instrument (Fig. 56, c), 
has already been mentioned in the beginning of this article, with 
an attempt to explain this phenomenon. The changes observed to 
take place in these corpuscles by the action of a weak solution of 
chromic acid, as represented in Fig. 57, a, h, and c, have also been 
referred to before.* 
The Coloured Blood-corpuscles of Man. — The investigation 
of these blood-corpuscles, together with those of all other Mam- 
malia, is, in consequence of their small size, rendered much more 
difficult than that of the large blood-corpuscles met with in the 
* I take the opportunity of mentioning the presence of an Infusorium in the 
blood of the Tree-frog, which I observed during three successive years in every 
individual of the species examined. Mr. E. Kay Lankester described a similar 
animal, in the ‘ Quarterly Journal of Microscopical Science ’ for 1871, which he * 
had discovered in the blood of liana esculenta^ and which he named Undulina rana- 
rum. As I am not sure of the exact identity of the animals observed, I do not 
hesitate to allude to the subject in this place, if only for the purpose of cor- 
roborating the fact previously discovered. The Infusorium which I observed 
(Fig. 58) belongs to the Flagellata, as the long whip or flagellum wdth which it 
is provided indicates, and is found in constant motion, alternately coiling its body 
in one or the other direction into a spiral form. On the convex side of the coil a 
number of teeth-like processes are observed in constant and rapid motion, giving 
to this part of the body the appearance of a cog-wheel turning in one direction. As 
the animal is never seen at rest, but alternately coiling and uncoiling its body, 
the examination of this part of its locomotive apparatus is rendered very difficult. 
The motion appears not to be owing to the vibration of cilia ; it rather seems to 
be produced by minute transverse folds successively arising in one direction in the 
integument of the creature, in the same manner as waves do in the water when 
a heavy body falls into it. With the object of rendering the motions of the animal 
slower for observation, I have treated the preparation with several reagents with- 
out any advantage ; for the animal, in dying, rolls itself up into a confused mass. 
These Infusoria exist in considerable numbers in the blood of the Tree-frog ; a 
small drop, of the size of a pin’s head, when spread into a thin layer under the 
microscope, may be found to contain about a dozen individuals or more. 
