QUARTERLY CHRONICLE OF MICROSCOPICAL SCIENCE. 175 



as a line, but in the shape of a comparatively broad band 

 ■with closely-set transverse lines. Just as above described in 

 the embryOj SO also in the adult tendon. Boll observed that the 

 cells more or less completely surrounded the fibrillar bundles ; 

 and thus is in opposition to the views of Ranvier, who 

 regarded the cellular stripes as hollow cylinders, consisting 

 of a number of superimposed tubular elements, each formed 

 of a single cell rolled up so that its opposite edges meet. 

 Boll contends that it has never been found possible to fill 

 these supposed " plasmatic channels" by injection or imbibi- 

 tion, and relies also on the fact that closed hollow cylinders 

 and others entirely or partially open are never seen in the 

 same preparation ; the cells always have the same form and 

 the same relative dimensions. This must naturally be the 

 case if, as Boll (agreeing with Giiterbockj supposes, the 

 ])lates are always stretched out upon and closely applied to 

 the bundles, and the variations in size of the cells, sometimes 

 longer, sometimes shorter, depend upon the degree of tension 

 to which the object is or may have been exposed. That is 

 to say, when the tension is very high, the cells will appear 

 as quite narrow staff-shaped bodies; if less extended they are 

 rectangular, and when the tendon is contracted, as after the 

 application of acetic acid, they are more or less nearly square. 

 This explains also the variable appearance of the "elastic 

 stripe " the changes of which are tlius comparable to those 

 in an india-rubber baud when pulled out and allowed again 

 to contract. 



Beside tlie incomplete cellular investment of the fibrillar 

 bundles just described, there is also a fibrous investment, the 

 presence of which has long been known through the intense 

 colour assumed by the peripheral parts of the bundles with 

 carmine. According to Boll's observations, there is a direct 

 continuity between the cellular plates and the remaining 

 fibrous vesicular system of the fibrillar sheath, the sub- 

 stance of the former becoming more and more homogeneous, 

 and gradually passing into the latter. A progressive diminu- 

 tion of the cellular and increase of the fibrous constituents of 

 the investment is found to take place with great regularity 

 corresponding with advanced age. With respect to the 

 elastic fibres which are found in the fibrillar bundles. Boll 

 adopts Virchow's view, that they are outrunning processes 

 from cells. This view was supported by finding numerous 

 delicate and often extraordinarily long processes coming off 

 from many cell-plates, which agreed in their size and appear- 

 ance with the intra-fascicular elastic fibrilla3. It was notable 

 also that these elastic fibres were sometimes absent, some- 



