AREOLAR TISSUE. 119 



most of tliem being much larger than the fibre-cells, and some 

 as large as the largest adipose cells. They can very rarely 

 be seen without the aid of the most favorable Light, but when, 



under such circumstances, the observer has once detected one 

 of them, and become familiar with the degree of its trans- 

 parency, they may be recognized in great numbers. They 

 have a distinct nucleus attached to the internal surface of their 

 wall, containing one or two nucleoli. The nucleus always 

 attracts attention first ; the cell surrounding it is either quite 

 transparent, and void of granules, or has granulous contents, 

 and this granulous deposit is first formed in the neighbourhood 

 of the nucleus, the remaining portion of the contents being 

 still transparent. (See the figure.) Gradually, the entire con- 

 tents appear to become granulous. These cells are distinguished 

 from the fibre-cells of areolar tissue by the circumstance of 

 their becoming much larger than the latter, and their not 

 being elongated into fibres, and from the adipose cells, in that 

 they do not contain fat. I have found them in areolar tissue 

 taken from the bottom of the orbit, and from the neck of a 

 foetal pig, but do not know whether they occur in the areolar 

 tissue of all parts of the body ; nor can I determine their sig- 

 nification. They might be regarded as cellular spaces which 

 had been produced by the distension of the areolar tissue with 

 air. In such case, thev must communicate with one another 

 in the course of their further development. But this appears 

 to me to be somewhat improbable j and those spaces may be 

 merely artificial productions. I should rather regard the cells in 

 question as a modification of the adipose cells. For since, ac- 

 cording to Gurlt, the ordinary adipose cells in the adult may 

 contain mere watery fluid, one may also conceive the cells 

 destined to the formation of fat becoming completely developed, 

 without that formation actually taking place within them. 

 There are, indeed, adipose cells which contain fat even in the 

 earliest stage of their development, but that is no reason 

 whv the formation should not take place at a much later period 

 in other cells. The granulous deposit in many of them might 

 be regarded as the transitional step to the formation of fat. 



The cellular tissue of the foetus differs in its chemical con- 

 stitution from that of the adult, since we cannot obtain any 



