112 Historical Sketch of Improvements in [Aug. 



of the mesenteric glands, he found that the white colour of the 

 fluid issuing from them depends upon an infinite number of white 

 globules floating in a clear perfectly colourless fluid, in the same 

 manner as the red globules do in the serum of the blood. About 

 eight-tenths of these globules varied in size from the smallest 

 speck to the size of the lymph globules, about one-tenth were 

 of the size of the red globules deprived of the colouring matter, 

 and about one-twentieth were of the size of the red globules 

 enclosed in their colouring matter. When this fluid was left a 

 few minutes in the glass, not only many new globules were 

 formed,, but the original small ones visibly increased in the field 

 of the microscope, not by several globules uniting, but by acces- 

 sion of substance, and several were watched till they acquired 

 the size of blood globules enclosed in their colouring matter. In 

 that state they became more opaque and white. The addition 

 of water prevented the further formation of globules, and acted 

 upon those already formed in the same manner as it does on the 

 red globules ; viz. by dissolving their colouring matter, and 

 reducing their size. Mr. B. concluded from these observations, 

 that the blood globules acquire their full size in the mesenteric 

 glands, and afterwards assume their red colour on exjiosure to 

 the air in the lungs. (Phil. Trans. 1820, p. 1.) 



Menstrual Blood, Fatal Blood, tSr. — Dr. F. Lavagna has been 

 led to conclude, from some experiments on the menstrual blood, 

 that it differs from pure blood only in the want of fibrin. He 

 also found that blood collected from the vessels of the funis um- 

 bihcahs relating immediately to the placenta, formed a tena- 

 cious coagulum, and contained a considerable proportion of 

 fibrin, though it was rather more soft and gelatinous than that 

 collected from the blood of an adult in the state of health ; and 

 that on the contrary the blood contained in the vessels of the 

 funis relating to the foetus, hardly coagulated at all, and 

 seemed to contain a very small proportion of fibrin. This phy- 

 siologist is induced to conclude from these observations, that 

 the uterus in a gravid state acquires the power of furnishing 

 blood provided with fibrin, which is subtracted from it by the 

 embryo, to be appropriated to its own use for the means of its 

 growth. (See Esperienze sopra il Sangue Menstruo : de Fran- 

 cesco Lavagna guiniore, M.D. &c. in the Annali Universali di 

 Medicina di Milano, No. 17.) 



Respiration and Circulation of the Blood. — Dr. Carson has 

 lately made some important experiments on the elasticity of the 

 lungs in different animals, and he has found by the application 

 of a simple apparatus that in oxen, and animals of their size, it is 

 more than equal in power to the weight of a column of water a 

 foot and a half high. In calves, sheep, and large dogs, it 

 is balanced by a column of water vaiying in height from one foot 

 to a foot and a half; and in rabbits and cats by a column of 

 water varying from six to ten inches. To this elasticity of the 

 lungs alternating with the irritability of the diaphragm, Dr. C. 



