490 Royal Society : — 



particles, all apparently of the same composition, and of a more or 

 less globular form, but of very different sizes, some being so minute 

 as scarcely to be visible by one- eighth of an inch lens, others 

 being almost as large as the handle of a perfect booklet, while 

 the rest are of all dimensions between these extremes. The next 

 condition of a booklet is the apparent fusion or coalescence of 

 some of these particles into the hooked part of the organ. Then 

 the handle and tubercles are added, these having been previously 

 formed by the fusion of the smaller particles, and these latter by 

 the coalescence of the minutest and the minuter ones. Before 

 the several parts are perfectly consolidated, their points of junction 

 can be distinguished, and in other groups the fragments corre- 

 sponding to those recently united can be recognized. Directly a 

 booklet is found, it is of its full dimension ; and some of its parts 

 are even larger and more clumsy-looking than in older booklets. 

 The substance of the particles entering into these organs, after 

 they are once formed, undergoes no change in its microscopical 

 characters, but is the same after as before their union. It is im- 

 possible to single out any one particle from the rest, which can be 

 taken for the nucleus of a cell, or for what physiologists would call 

 a nucleated cell; and thus there is nothing which indicates that 

 these organs have been formed by transformation of previously ex- 

 isting cells, but, on the contrary, there is every appearance that 

 their formation is due to the simple coalescence of homogeneous 

 molecules. 



Up to the present point, the facts which I have stated are so 

 obvious, that their accuracy will, I think, not be questioned ; also 

 the interpretation of them is not only that which appears to 

 me the most natural, but is almost self-evident. There remain, 

 however, some considerations of a more theoretical kind, though 

 not of less importance. It will be asked, how the entozoon, in its 

 earliest condition, such as I have described it, finds access to the 

 interior of a primary fasciculus. Before attempting to answer this 

 question, I must observe that my description commences from a 

 condition of this entozoon so complete, that no one, on examining 

 it in this state with the microscope, will deny its perfect similarity 

 to those of the higher form. But there are other links in the chain 

 which I must now consider, and which so far have been omitted 

 only because I wished to keep that which is certain distinct from 

 that which is probable. Before the cells and molecules already 

 described accumulate in sufficient quantity to present the undoubted 

 character above mentioned, they are found aggregated in smaller 

 groups, and even occurring individually in all the primary fasciculi 

 of the diseased muscle ; their quantity, and the size and form of 

 these groups, present the greatest possible irregularity in the dif- 

 ferent fasciculi. In some the molecular deposit looks like an early 

 stage of fatty degeneration, but it has characters very different; 

 one is the shape of the molecules, which resemble in all respects 

 those in the growing ends of an entozoon ; and another is, their 

 situation, which seems to be between the primary fibrillije, tending 



