MINUTE ANATOMY OE THE PAPILLAE OF THE FROG’S TONGUE. 
453 
The so-called nuclei or masses of germinal matter in connexion with these fine mus- 
cular fibres present several points which will well repay attentive study. These masses 
of germinal matter are sometimes twice or three times the width of the fibre with which 
they are connected. In a paper published in Part XIV. of my ‘Archives,’ I have adduced 
facts which render it probable that these nuclei or masses of germinal matter change 
their position in a very remarkable manner during life. 
The conclusions I have arrived at upon this point are as follows : — 
The masses of germinal matter appear to move along the surface of the already-formed 
muscular tissue, and as they move part of their substance becomes converted into muscle 
(Plate XXII. fig. 13). It is in this way that new muscle is formed and new muscular 
tissue is added to that already produced. The germinal matter itself does not diminish 
in size, because it absorbs as much pabulum as will compensate for what it loses of 
its own substance by conversion into tissue. In the young muscle the nucleus increases 
in size. 
From what I have observed, I think that these oval masses of germinal matter move 
in different directions, but always in a line with the fibrillated structure, so that in 
a muscle some will be moving upwards, some downwards; and when the nuclei are 
arranged in rows or straight lines, the nuclei lying in adjacent lines will be moving in 
opposite directions. During the formation of a muscle these masses undergo division 
in two directions, longitudinally and transversely. The two masses which result from 
the division of one will pass in opposite directions. 
As is well known, the position of these nuclei with respect to the formed muscular 
tissue is very different in different cases. Sometimes they are in the very centre of 
the elementary fibre, as in the constantly-growing fibres of the heart, sometimes upon 
its surface only, sometimes distributed at very equal distances throughout its sub- 
stance. Wherever these nuclei are situated new muscular tissue may be produced, 
and it is only in these situations that muscular tissue ever is produced ; so that by the 
position of the nuclei we learn the seat of formation of new muscle at different periods 
of life. 
The facts which I regard as favourable to the view above expressed concerning the 
movements of the masses of germinal matter of muscle, are derived from many sources, 
but I will refer to some observed in the case of the muscles of the papillae of the tongue. 
Here the muscular fibre is very thin and delicate, and very favourable for observation. 
The mass of germinal matter is very much wider than the muscle. Often three or four 
of these masses are seen close together (Plate XXI. fig. 9), while for some distance above 
and below the muscular fibre is destitute of nuclei. The narrowest extremity of the 
oval mass is directed in some cases towards the terminal extremity of the muscle, in 
others towards its base. There are often three or four fine fibres branching off from one 
stem, and gradually tapering into fine threads towards their insertion at the summit of 
the papilla (Plate XXI. figs. 1 & 9). The nuclei are three or four times as wide as these 
fibres. The greatest difference is observed in the distance between contiguous nuclei 
3 Q 2 
