THE CONNECTIVE SUBSTANCE GEOUP. 



71 



used was insufficient to make out such delicate objects. At 

 the present time the actual existence of a network is hardly 

 called in question, for it may be demonstrated with really good 

 glasses, such as some of the immersion lenses (No. 10) of Hart- 

 nack's system, and, indeed, by other lenses made both at home 

 and abroad. As to the question of the corpuscular elements 

 there is more doubt, and it can hardly be said that their exact 

 form and shape have been definitely agreed upon by histolo- 

 gists. We find, it is true, that where there is a considerable 

 deposit of connective mate- 

 rial along the central canal of 

 the spinal cord, we have the 

 ordinary fibres and corpuscles 

 already described, and so, too, 

 near the surface of the con- 

 volutions. When, however, 

 we examine the supporting 

 substances of the white and 

 gray masses there is less cer- 

 tainty. The actual condition 

 may be tolerably well seen 

 by adopting the following 

 plan. Place any portion of 

 the brain or cord a few days 

 in a weak solution of bichro- 

 mate of potash (5 per cent.) 

 or Mueller's fluid, then immerse it in alcohol until hard ; make 

 thin sections and stain for twenty-four hours with the follow- 

 ing solution of hsematoxylin : hsematoxylini, gr. lij. ; aluminis, 

 1 j. ; aquae, 1 viij. ; mix arid strain. 



Wash in distilled water and mount in glycerine, tease with 

 needles and examine with a high power ; there will then be 

 little difficulty in seeing that the delicate supporting substance 

 of both gray and white matter consists of fibres. They may 

 even be distinctly isolated, for the coloring matter darkens them 

 somewhat and they become hardened at the same time so as to 

 be somewhat stiff and unyielding. It will be seen that many 

 fibrils are disposed in parallel rows which perhaps can hardly 

 be called bundles, but rather thin laminae ; other similar fibrils 

 cross them at various angles, giving to the whole, with a 

 moderately high power, the appearance of a very delicato 



FIG. 28. Human brain showing neuroglia. 



