230 
DR. MARTIN BARRY ON THE CORPUSCLES OF THE BLOOD. 
the Plates will show that here, as in figures of the elements of other tissues, the trans- 
ition from a corpuscle having the same appearance as a corpuscle of the blood, into 
a mass of discs, was quite unequivocal, in colour and in form, as well as in the 
gradual appearance of the discs. It is important to remark, that the mass of discs 
presents, not the entire corpuscle, but its nucleus enlarged. 
135. This mass, already elliptical (fig. 109. 7 ), becomes pointed, and usually at 
both ends (figs. 110 . Ill, fig. 112 . 7 ). The pointed extremity is then elongated into 
a filament (see the same figures) ; and apparently by the following means. The com- 
paratively large discs into which the corpuscle has divided, undergo division and 
subdivision themselves, until discs are produced of extreme minuteness. These co- 
alesce to form the filament ; which has in its interior the means of perpetuation, 
through discs, into threads still finer. (This seems to be the general mode of 
production and thickening of membranes and fibres.) The elongation of the mass 
of discs into filaments, takes place sometimes in more than two directions. The 
whole mass of discs does not at once pass into filaments ; but a part, enlarging, be- 
comes a special centre, apparently for the origin of new substance (fig. 112 . 7 ); as 
we saw in the epithelium, and pigmentum nigrum (pars. 119, 120 .). But every disc, 
large enough to be discerned and traced, seems to exhibit a reproducing property. 
136. The figures present examples of the elements of cellular tissue thus formed, 
from various parts, and, among others, from the thigh (fig. 109.), the neck (fig. 111.), 
and the axilla (figs. 112 , 113.); as well as a drawing of this tissue, entering into the 
formation of the sheath of the spinal chord (fig. 116.). The fibres of cellular tissue 
forming this sheath seemed to be interlaced. 
The Elements of the Corpus luteum derived from Corpuscles of the Blood. 
137- In a former memoir'f--, I described the Graafian vesicle as formed by the ad- 
dition of a covering to the previously existing ovisac. The covering was stated to 
consist of a kind of dense cellular tissue, susceptible of becoming highly vascular. 
In a later communication, I came to the conclusion, that the covering of the ovisac 
becomes the corpus luteum 
138. Confirming these observations, I have now to make the following addition. 
On examining the vessels entering into the formation of the covering of the ovisac, 
and rendering it highly vascular, in a rabbit killed three hours post coitum, I found 
them filled with blood-corpuscles in an altered state. The central part was greatly 
enlarged, colourless, and brilliantly pellucid ; and the contour was lost by the slightest 
pressure, so that the red colouring matter of adjacent corpuscles had the appearance 
of being blended into a mass, filling up the interstices between their round, colourless, 
and brilliant centres. This condition of the blood-corpuscles within the vessels, too 
much resembled that which I had met with in other parts, formed out of corpuscles 
t Researches in Embryology: First Series. Philosophical Transactions, 1838, Part II. par. 24. 
+ Second Series. Philosophical Transactions, 1839, Part II. par. 156. 
