324 Hoyal Society. 



He finds that the toothed fibre, discovered by Sir David Brewster 

 in the crystalline lens, is formed out of an enlarged filament ; the 

 projecting portions of the spind threads in the filament, that is, the 

 apparent segments, becoming the teeth of that fibre. 



The compound filaments are seen with peculiar distinctness in the 

 blood-vessels of the arachnoid membrane. In connexion with the 

 spiral direction of the outer filament in these vessels, the author refers 

 to the rouleaux in which the red blood-discs are seen to arrange them- 

 selves, in the microscope, as probably indicating a tendency to pro- 

 duce spiral filaments. To form rouleaux, corpuscle joins itself to 

 coqjuscle, that is to say, ring to ring ; and rings pass into coils. 

 The union of such coils, end to end, would form a spiral. But the 

 formation by the blood-corpuscles of these roideaux is interesting in 

 connexion with some facts recorded by the author in a former me- 

 moir; namely, that many structures, including blood-vessels, have their 

 origin in rows of cells derived from corpuscles of the blood. The hu- 

 man spermatozoon presented a disc with a pellucid depression, each 

 of the two sides of the peripheral portion of which was extended into 

 a thread ; these two threads forming by being twisted the part usually 

 designated as the tail. The occurrence of two tails, observed by Wag- 

 ner, is accounted for by the author by the untwisting of these threads. 



The author has noticed very curious resemblances in mould, arising 

 from the decay of organic matter, to early stages in the formation of the 

 most elaborate animaltissues,morepartIcularly nerve and muscle. Flax 

 has afforded saiisfactorj^ evidence of identity, not only in structure, 

 but in the mode of reproduction, between animal and vegetable fibre. 



Valentin had previously stated that in plants all secondary deposits 

 take place in spiral lines. In the internal structure of animals, spirals 

 have heretofore seemed to be wanting, or very nearly so. Should 

 the facts recorded in this memoir, however, be established by the re- 

 searches of other investigators, the author thinks the question in fu- 

 ture may perhaps be, where is the " secondary deposit " in animal 

 structure, which is not connected with the spiral form ? The spiral 

 in animals, as he conceives he has shown, is in strictness not a se- 

 condary formation, but the most primary of all ; and the question 

 now is, whether it is not precisely so in plants. 



In a postscript the author observes, that there are states of volun- 

 tary muscle in which the longitudinal filaments (" fibrill?e") have no 

 concern in the production of the transverse strise ; these striae being 

 occasioned by the windings of spirals, within which very minute 

 bundles of longitudinal filaments are contained and have their origin. 

 The spirals are interlaced. When mature, they are flat and grooved 

 filaments, having the compound structure above described. With 

 the shortening of the longitudinal filaments (" fibrillje") in muscular 

 contraction, the surrounding spirals, and of course the striae, be- 

 come elongated and narrow ; while in relaxation these changes are 

 reversed*. 



[' We learn that the author has satisfactorily deinonstrated to Professor 

 Owen and others, since the reading of tlie above paper, tlie leading facts de- 

 scribed in it. — Edit.] 



