i. fart of a Letter to Dr Mead^ concerning Secretions 
m an Anunal Body, Jof. Morland^ M. D. 
A Nd| indeed no one who has endeavour- 
ed to explain the manner, by which 
cretiom are performed, feems to me to have given a fatis- 
faftory account of that matter 5 nor do I doubt, but that a 
man of your (agacity and skill in thefe affairs, can difcovcr 
the defers of the feveral opinions of the Authors concern- 
ing them. 
I dial I therefore propofe my opinion as briefly as Icgn» 
It feems tome, that the whole Bufinefs may be reduced 
to this double enquiry, ift, How a thin Fluid ffuch as is 
theVrwe) may be feparated from the Mafs of Blood, and 
the remaining parts of the Blood, circulate back to the Heart. 
3dly, How a thick Fluid ffuch as is the Bile or Semn for 
example ) may be feparated from the Mafs of Blood, and 
the other Fluids both thinner and thicker than this particu- 
lar Fkidto be feparatedjCirculate back to the Heart.And that 
I may be the mor^ plain, I (hall give a general Idea ot the 
ftrufture of the Glands. A Gland I conceive to be com- 
pofed. 
I ft, Of the Ramifications of the Blood Veflels inclofed in 
a comsaon Membrane, which fends off feveral Fibres, by 
which thefe minute VelTels are. tied together ^ and that the 
Veins are a continuation of the Arteries. Of this Dr Areskitt 
has fully corrvinccd us, by an inieftion of Wax in an Humane 
Body, fo dextroufly performed, that the Wax being injeft- 
ed by the Arteries filled the Veins at the fame time 5 and af- 
terwards by a nice difleftion* of the part, where the conti- 
nuatipn of the finall Ramifications of the Arteries and Veins 
appeared to the naked Eye. 
