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 corpuscle, 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 rouleaux 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 Wagner, 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 animal tissues, more particularly nerve and muscle. Flax has afforded satisfactory evidence of identity, not only in struc- ture, 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 herotofore 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 (" fibriUse") have no concern in the production of the transverse striae ; 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 (" fibrillse") in muscular contraction, the surrounding spirals, and of course the striae, be- come elongated and narrow ; while in relaxation these changes are reversed.
January 13, 1842.
SIR JOHN WILLIAM LUBBOCK, Bart., V.P. and Treas., in the Chair.
Edward Hodges Baily, Esq., R.A., William Fishburn Donkin,
