482 PROF. G. GULLIVER ON [June 15, 
Birds almost always have the corpuscles larger than those of Mam- 
malia, here, too, are a few irregularities, as will appear on a compa- 
rison of the corpuscles of Linaria, Dolichonyz (fig. 61), and Trochilus 
(fig. 66) with the largest apyreneematous corpuscles (figs. 14, 23, and 
47). In Birds the largest corpuscles belong to the Cursores (fig. 53), 
the next in size to the Rapaces (fig. 58), Palmipedes (fig. 65), Gral- 
latores, and the Hornbill (fig. 62); the smallest corpuscles occur in 
some of the little Granivore (fig. 61) and Insectivore, in the Hum- 
ming-bird (fig. 66) and other Anisodactyli. Throughout the class 
of Birds there is so far a relation between the size of the species and 
the size of the corpuscles, that no instance is known of the largest 
corpuscles in the small species, or the smallest corpuscles in the large 
species. And herein this entire class rather resembles an order or 
family than the class of Mammalia ; and so, too, as regards the con- 
stant oval figure of the avian corpuscles. In some single apyrene- 
matous orders there are greater diversities in the size, and in a few 
instances in the shape, of the corpuscles than in the entire class 
either of Birds or Reptiles ; in neither of these two pyrenzematous 
classes is there any exception to the elliptical form of the corpuscles, 
nor are the corpuscles ever twice as large in one species as in another 
of the same class. 
APYRENZMATOUS VERTEBRATES. 
As already described, in all the oviparous or pyrenzematous Verte- 
brates there is a nucleus distinctly demonstrable in the red corpuscles. 
And now we come to the Mammalia or Apyrenemata, in which, on 
the contrary, no such nuclei can be made visible by the very same 
treatment which plainly displays them in the Pyrenzmata; that is 
to say, a nucleus cannot be disclosed in the majority of the red blood- 
corpuscles of Apyrenemata. The oval blood-disks of the Camels 
(figs. 37-41) conform in this respect, and in smallness of size, to 
the circular corpuscles of other Apyreneemata ; in no pyrenzematous 
vertebrate are the corpuscles so small as in the Camels. Of course we 
are not dealing now with the large temporary red corpuscles which 
have nuclei in the early mammalian embryo, nor with phases of de- 
velopment and decay in the adult, but with the majority of the regular 
corpuscles. Neither are we concerned with Mr. Wharton Jones’s 
valid doctrine as to their origin, nor with any speculations as to their 
real nature. So far as is yet known this is peculiar; for the free 
apyrenzematous corpuscles have no known homologue, and are devoid 
of the true characters of nuclei. 
Form of the corpuscles.—This is regularly a circular biconcave 
disk (figs. 1 and 2), the concavities very shallow and deepening to- 
wards the centre ; and this is characteristic of Apyrenemata. At 
the circumference the thickness is between a third and a fourth of 
the diameter of the corpuscle. But a body so soft, so readily affected 
by osmosis and other causes, is liable to assume many odd shapes 
which may be seen to occur during the examination. Thus appear 
such forms as plano-convex, biconvex, crenate, puckered, granulated, 
dinted, cup-shaped, and several others. Sometimes their circum- 
