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l6o MUSCULAR SYSTEM. [SECT. 8 



increase of the length and thickness of the fibres ; and the rudi- 

 ments of all the future fibres appear to be formed as early as the 

 first rudiments of the muscle itself; at any rate, always by the 

 middle of foetal life. In the embryo of from four to five months, 

 many of them are five times thicker than at two months. In the • 

 new-born infant, they measure, for the most part, twice, some 

 even three or four times as much as in the fourth or fifth month; 

 and in the adult, they are almost five times larger than in the new- 

 born infant. With the increase in thickness of the fibres, the 

 fibrils must increase in number, since, according to Harting, they 

 are but very little thicker in the adult than in the foetus (compare 

 Harting, Rech. Micrometr. and Hepp, I. c.) . In accordance with 

 Valentin and Schwann, I find that the perimysium is developed 

 after the type of common connective tissue, from the union of 

 fusiform formative -cells. 



The elements of the tendons are in no case earlier developed 

 than those of the muscles ; as, in embryos, from the eighth to the 

 ninth week, I have never been able to detect a distinct trace of 

 them, whilst the muscular fasciculi appeared very evident. It is not 

 till the third or fourth month, when the tendons become visible to 

 the naked eye, that their elements can be distinctly followed. 

 They then appear as long parallel bands, with elongated nuclei, 

 which bands, as Schwann's, and my own observations (§ 26) upon 

 very young mammals, show, take their rise from coalesced fusiform 

 cells. Even in the fourth month, they are distinctly recognisable 

 as primitive bundles, with an undulating course, and bearing at 

 various points elongated nuclei, of 0-0035'" to o'bo6'" in length, 

 and o*oo 1 6'" in breadth, but without distinct fibrils, and not 

 exceeding 0-0012'" to o - ooi6'" in breadth. From this period on- 

 wards, to the end of embryonic life, the fasciculi slowly increase in 

 breadth, so that, in the new-born infant, they measure 0-002'" to 

 0-0025'" : at the same time their fibrils become developed, and 

 between the fasciculi there appear fine elastic fibres, derived from 

 special fusiform formative-cells. (See above, § 25). 



With respect to the pathological conditions of muscles, the following 

 remarks occur. The substance of the transversely striped muscles is not 

 regenerated, and when divided by a wound, it heals simply by means of a 

 tendinous cicatrix. A new formation of muscular tissue has been seen by 

 Bokitansliy in a tumour of the testicle of an individual eighteen years old, 

 and by Virclww in an ovarian tumour. In the latter case, which I had an 

 opportunity of observing, the new tissue consisted of long, transversely 

 striped, fusiform cells, each with a nucleus. In hypertrophy of the muscles, 

 which never, or, at least, most rarely, occurs in transversely striped muscles, 



