1874.] On the Blood-corpuscles of Mammalia. 243 



of didymium acetate, which decomposes with separation of a basic salt, 

 the lines thickened oil heating. 



Thermo-chemical Experiments. 



Eegnauld (Institut, 1864 ; Jahresbericht, 1864, p. 99) has shown that 

 on diluting a saturated solution of a salt, as a rule there is an absorption 

 of heat ; but in one or two cases he noticed that heat was evolved. The 

 change in colour that takes place on the dilution of saturated solutions of 

 cobalt iodide, cupric chloride, bromide, and acetate is very remarkable. 

 There is every likelihood that this phenomenon is due in each case to the 

 formation of a liquid hydrate. It is impossible of belief that accompanying 

 such a circumstance there should be no measurable development of heat; 

 and the author's experiments have proved that in the above cases, at any 

 rate, the heat disengaged is very considerable amounting, for instance, 

 on the part of cupric chloride, at least to about 2565 units when 1 grain 

 molecule of the crystalline salt is dissolved in its minimum of water at 

 16 C. and brought into contact with sufficient to make the addition of 

 40 Aq. These numbers only roughly approximate to the truth. On 

 diluting a solution of cobalt iodide till the red colour appears, the thermal 

 effect must be much greater, as not only does it register several degrees 

 on an ordinary thermometer, but it may be perceived by the hand. 



The conclusions indicated by these results are obvious, but it is beyond 

 the scope of this paper to refer to them. The writer hopes before long 

 to complete his experiments with the view of having them communicated 

 to the Eoyal Society. 



II. " Note on the Intracellular Development of Blood-corpuscles 

 in Mammalia." By EDWARD ALBERT SCHAFER. Communi- 

 cated by Dr. SHARPEY, V.P.E.S. Received January 22, 1874. 



If the subcutaneous connective tissue of the new-born rat* is exa- 

 mined under the microscope in an indifferent fluid, it is found to consist 

 chiefly of an almost homogeneous hyaline ground-substance, which is 

 traversed by a few wavy fibres, and has a considerable number of exceetj- 

 ingly delicate, more or less flattened cells scattered throughout the tissue. 

 The cells here spoken of are of course the connective-tissue corpuscles. 

 They are not much branched as a rule (at any rate their branches do not 

 extend far from the body of the corpuscle), and they are mainly distin- 

 guished by the extraordinary amount of vacuolatiou which they exhibit 

 by which is meant the formation within the protoplasm of minute clear 

 spherules, less refractive than that substance, and probably, therefore, 

 spaces in it containing a watery fluid. The nuclei, of which there is 

 generally not more than one in each cell, are frequently obscured by the 

 vacuoles, but, when visible, are seen to be round or oval in shape and 



* The animal employed was the white rat, 

 TOL, XXII, IT 



