176 QUARTEULY CHRONICLE OF MICROSCOPICAL SCIENCE. 



times present, in individual bundles, without any fixed rule, 

 and just in the same way as those peculiar processes on the 

 cell-plates were by no means always present. 



(2) " Cartilage'''' in the Achilles Tendon of the Frog. — 

 Boll denies the existence of cartilage in this organ, explain- 

 ing the elements of the structure which has been thus de- 

 signated as analogous to the elastic plates of the tendon. He 

 describes them as large polygonal cells, very abundantly dis- 

 tributed among the broad and closely interwoven bundles ; 

 the cells are arranged in unbroken series on the surface of 

 the bundles, and agree precisely in size and character with 

 the cell-plates in the tendons of mammalia, being mostly 

 homogeneous, with a large distinct nucleus. 



(3) Bundles of Fihi'illar Connectite Tissue and their Sheaths. 

 — Two views have more especially predominated with respect 

 to the existence of sheaths round fibrillar bundles. According 

 to one view (that of Henle and Rollet) each bundle is only 

 partially invested by spiral, or at most reticulated fibres. 

 According to another (that of H. Miiller, Reichert, &c.), there 

 is a complete investing sheath, which is liable to tear after 

 the application of acetic acid, and then produces the appear- 

 ance of hoop-like contractions of the bundle. 



Boll investigated chiefly the arachnoid of the brain, which 

 was examined either fresh or preserved in Miiller's solution, 

 &c., coloured with acid solution of carmine (acetic acid or 

 picric acid solution) and placed in glycerin. On treatment 

 with acetic acid and carmine, each bundle appeared to be 

 clearly surrounded by a sheath, which separated at various 

 points, and left a definite space between itself and the fibrillar 

 bundle. The substance of the sheath is in the main homo- 

 geneous ; but with a high magnifying power various stripes 

 and trabeculae, mostly transverse, may be distinguished, as 

 well as nuclei, which for the most part occupy the centre of 

 such a system of fibres. From the comparison of a large 

 number of objects. Boll concludes that the structure of this 

 tendon agrees precisely with that of the membrana propria 

 of acinose glands, as described by him. In the one, as in the 

 other, there is a quite continuous and uninterrupted mem- 

 brane, consisting of a number of stellate, nucleated cells, 

 fused together, and passing quite imperceptibly into one 

 another, this membrane enclosing, in the one case, the acinus, 

 in the other the fibrillar bundle. 



The processes uniting these cells are thicker than the 

 membrane itself, and thus form projections like a grating. 

 The parts thus strengthened will often escape the rupture, 

 which, in consequence of the swelling up of the fibres under 



