AREOLAR TISSUE. HI 



out any dissection. Most areolar tissue may be distended bv 

 forcing air into it, and then innumerable cellular spaces arc 

 seen communicating with each other in it j it is not known 

 whether these are produced artificially, or whether they existed 

 previously. Areolar tissue also frequently contains fat- vesicles, 

 which, according to Gurlt, arc surrounded by a thin and 

 transparent, but not fibrous, pellicle, often have an hexagonal 

 form, and in that respect resemble vegetable tissue. (Gurlt's 

 Physiologie dcr Haussaugethiere, p. 19.) In order to become 

 acquainted with the relation which these constituent parts of 

 areolar tissue bear to the elementary cells, we must refer to 

 the formation of the tissue in the foetus. 



If we examine some areolar tissue from the neck, or from 

 the bottom of the orbit of a foetal pig measuring three inches 

 and a half in length, we shall find it to be a gelatinous substance, 

 somewhat more consistent than the vitreous humour of the eve 

 and, in its earliest state, quite as transparent ; as development 

 proceeds, however, it becomes more of a whitish colour, and 

 loses its gelatinous quality. When examined with the micro- 

 scope, small corpuscles of various kinds are seen in greater 

 or less numbers ; they are not, however, sufficiently numerous 

 in a foetus of the size specified to form the entire gelatinous 

 substance, but must necessarily be situated in a transparent, 

 structureless, 1 primordial substance of a gelatinous nature, which 

 we will for the present call cytoblastema. The whiter this 

 substance appears to the unaided eye, the greater is the 

 number of corpuscles contained in it ; their quantity, there- 

 fore, is continually increasing during development, while 

 that of the cytoblastema constantly diminishes. As in con- 

 sequence of its transparency, the cytoblastema cannot be 

 seen, but is only inferred to exist from the circumstance 

 that the corpuscles, which are visible under the microscope, 

 could not, at the period when they are but few, form the 

 entire jelly, and that when moved, it is plainly seen that 

 they are held together by some invisible medium, so it is no 

 longer possible to convince ourselves of its existence, when the 

 corpuscles are very numerous. It is probable, however, that it 

 remains between the fibres of the areolar tissue throughout life. 



1 Vide note at page 39. 



