304 DISEASES OF THE SPINAL MARROW AND ITS MEMBRANES. 



nucleated connective-tissue substance, corresponding to the ordinary 

 neuroglia and resulting from its proliferation, in which we find only a 

 few granular cells, molecular fatty masses, and numerous corpora 

 amylacea. The vessels passing out from the pia mater have a greatly- 

 thickened adventitia, and thus cause the firm adherence of the pia 

 mater to the surface of the medulla. Corresponding to the extent of 

 the degeneration in the posterior columns, the posterior roots of the 

 spinal nerves are atrophied. They resemble thin, vascular, translucent 

 connective-tissue cords, far more than they do nerves with medulla. 

 This is especially true of the posterior roots of the cauda equina. The 

 anterior roots of all the nerves, cauda equina included, are normal, cor- 

 responding to the general nutritive condition of the spinal medulla. 



In the later stages the degenerated gray parts of the medulla 

 shrink greatly. They become a hard tissue, and are less transparent. 

 If the degeneration be limited to the posterior columns, the medulla 

 acquires a cylindrical form. The points of exit of the posterior roots 

 are approximated. If, on the other hand, the degeneration extend to 

 the posterior parts of the lateral columns, the medulla shrinks more in 

 an antero-posterior direction, and we may readily receive the impres- 

 sion that it has become broader. The neuroglia, which in the early 

 stages of the degeneration corresponds exactly with the normal neu- 

 roglia, during the shrinking acquires the appearance of a fine filament- 

 ary substance. A secondary atrophy and induration succeed the 

 growth of the neuroglia. 2 



SYMPTOMS AND COURSE. Although Duchenne is to be reproached 

 for ignorance of Momberg's works, or else for ignoring them, when he 

 published his first writings on ataxie locomotrice progressive, we cannot 

 deny that he has done much for the correct interpretation of the symp- 

 toms of tabes dorsualis. He originated the doctrine, at present almost 

 generally adopted, that in tabes there is not paralysis, but disturbed 

 coordination of muscular movements. To use our muscles properly, it 

 is not enough that we can contract each muscle, we must also be able 

 to cause a harmonious action of all the muscles participating in any 

 motion. Acts apparently the most simple fail or are clumsily performed, 

 if any of the muscles participating in them be contracted too much or 

 too little, too quickly or too slowly ; or if the antagonists be not re- 

 laxed just enough or exactly at the right moment. This power of 

 causing the muscles to act properly together, or, as it is usually called, 

 the power of coordination, is much impaired in patients with tabes ; 

 and the symptoms resulting from this anomaly are peculiarly charac- 

 teristic of the disease. But, along with this, there is almost always a 

 decided diminution of the cutaneous and muscular sensibility, which 

 Romberg has excellently described : "The floor is no longer distinct! v 



