[ 4 °' ] 
My young Pigeons, fed with the Pafte mixed with 
Madder j died the Third Day ; yet all that had the 
Confiftence of Bone in their Skeletons, was become 
as red as Scarlet. Mr. Belchier was furpnfed to fee 
the Bones of his Cock tinged red in Sixteen Days, 
and here are Bones fo coloured in Three Days. But 
all that Ihould in Courfe of Time have turned to 
Bone in One of my young Pigeons, and as yet was 
but Cartilage, as the Epiphyfes, the great Apophyfis 
of the Sternum^ &e. had not taken the lead Colour. 
In the other, there were fome Spots of a very weak 
red on the Cartilage of the Sternum^ which probably 
began to oHify. Other Experiments, fince tried, 
have taught me with greater Certainty, that the Car- 
tilages in general are not tinged red by the Madder, 
but when they begin to acquire the Confidence of 
Bone. 
If, as I fufped, it is the lymphatic Part of the 
Blood that is the Menfiruum of the colouring Par- 
ticles of the Madder, if this Lymph contains the 
nutritious Juice of the Cartilages and Bones? why 
does it not, in carrying with it the colouring Particles 
it has extracted from the Root, why does it nor, I 
fay, tinge the Cartilages as well as the Bones ? In my 
Opinion this Difficulty cannot be folved but by the 
Difference of the Pores. In the Cartilages they are 
too large, the colouring Matter palles through them 
too eafily, and finding no ofTeous Laminte yet formed, 
for want of a Surface fufficiently extended to retain 
it, it paffes with the fuperabundant Lymph through 
the Pores of the Cartilages. When thefe Cartilages 
begin to take a proper Confidence, where there are 
Strata of odeous Laminae already formed, the Ob- 
dacle 
