402 THE THYMUS. [SECT. 1 83. 



ment of fat within them, fat-cells also appearing in the interlobular 

 connective tissue. At the same time, the concentric bodies multiply 

 more and more, and, at last, according to Ecker, connective tissue 

 develops itself in the lobules, and thus the glandular structure 

 becomes entirely effaced. 



We have above traced the fetal thymus, from its origin in a solid thread 

 of blastema to the condition of a lobulated body with a central canal. In 

 the organ developed thus far, some cells become changed into vessels, some 

 into fibres ; while, by the coalescence of another series, the cavities of the 

 lobules are produced. The remainder of the embryonic cells, in the form of 

 cells and nuclei, constitutes the special parenchyma of the gland ; such a view 

 of their origin explains why the cavities have no sharply defined walls. The 

 nuclei in the tissue of the lobules appear to be the successors of the em- 

 bryonic cells, multiplied by continual partition, so that there is no need of 

 supposing for them any new mode of formation. — The relationship of the 

 thymus would appear, from its microscopical character, to be principally 

 with the lymphatic glands and allied structures ; although the resemblance is 

 not complete in details. This view, which I myself first propounded, appears 

 so probable as to have received the sanction of Leydig and Jendrassik. If, 

 however, the statements of Friedleben, a very untrustworthy observer, 

 should be founded in truth, an affinity would appear to be shown to the 

 spleen. At any rate, we are unable to gain a distinct clue to the functions of 

 the organ from any anatomical considerations. 



The investigation of the thymus is not easy. I especially recommend that 

 the organ should be prepared by boiling. This is very well adapted for the 

 investigation of the connection of the lobes with the central canals, and 

 for the examination of the cavities in the lobules ; such a preparation, when 

 hardened in alcohol, becomes suitable for. making fine sections. The fresh 

 gland, too, may be hardened in alcohol, or pyroligneous acid, or chromic acid, 

 or by boiling in vinegar. The thymus of small mammalia, which is mem- 

 branous at the borders, is also well adapted for furnishing a general view of 

 the part. Moreover, injections of the human thymus are absolutely neces- 

 sary, for without them no satisfactory information can be obtained. 



Literature. — S. C. Lucae, Anat. Untersuchung : d. Thymus im Menschen und 

 in Thieren Frankfurt am M., 1811-12 ; and Anal. Bemerk. iiber Divertikel am 

 Darm u. die H'uhlen der Thymus, Niirnberg, 18 13. F. C. Haugsted, Thymi 

 in Horn, et per ser. Anim. Descr., Hafn, 1832. A. Cooper, Anatomy of the 

 Thymus Gland, Lond., 1832. J. Simon, A Physiological Essay on the Thymus 

 Gland, Lond., 1845. Ecker, Art. Blutgefassdriisen, in Wagner's Handw. der 

 Phys., iii. ; and in Icon. Phys., tab. vi. Restelli, De Thymo. Obs. Anat. Phys. 

 Path. Ticini Regii, 1845. Gunsburg, Ueb. d. geschichtl. K'urpcr der Thymus, in 

 Zeitschr.f. Klin. Med., vi. p. 456. A. E. Jendrassik's Researches, in Sitzungsber. 

 d. Wien. Akad., Oct., 1856. A. Friedleben, Die Physiol, der Thymus druse, 

 Frankfurt, 1858. 



