722 EEPORT — 1881. 



5. On the Digastric Muscle, its Modifications and Functions. 

 By G. E. DoBSON. 



6. On tlie Causes and Results of assumed Gycloidal Rotation in Arterial 

 Bed Discs. By R. W. Woollcombe. 



The author, having made some experiments with iron discs, given cycloidal 

 rotation as projectiles {vide' Vroc. Royal Society,' March, 1862, and 'Journal of 

 the Society of Arts,' Oct. 24, 1862, the latter being a paper read by author in 

 Section G of the British Association, at Cambridge, in the same .year), in pursuance 

 of the subject of rotation in oblate bodies, has been struck by the oblate form of 

 the red blood-disc, and advances the view that not only may the peculiar oblate 

 form be given it by such rotation, during its development fi'om (as already supposed) 

 the amorphous white corpuscular matter, but that the red corpuscle is, until 

 ' checked in the capillaries, impressed also with rotation imparted by two principal 

 causes f one, momentary translatory hindrance from the concave side of a curve 

 in an artery in passing it — such as the aortic, or the angles at the giving off of the 

 intercostals ; tlie other also given by the curves in the arteries, necessitating 

 a velocity higher towai'ds the distal than the proximal end of the radius of the 

 ciu'vature of the artery. These two causes tending to impart rotation to different 

 discs in opposite directions, he concei\'es the direction of rotation to be of no 

 importance to the disc, so that it does rotate. He relies on tlie natural law 

 that ' rotation always tends to settle about the shortest diameter,' for the change 

 to such diameter in the disc of any other rotation that might be set up, as, for 

 instance, initially about a long diameter, especially in a body so oblate and 

 symmetrical as the red disc. This natural law he illustrates by examples of 

 every-day experience, as the rolling on their edges of irregidarly- shaped leaves, 

 or of scraps of paper on the ground before the wind, or the rolling about its- 

 shortest diameter of even an unsymmetrically-shaped stone when impelled or- 

 kicked on the ground ; it being on the remarkable facility and permanence of such 

 rotation, evidenced as well in the smallest as on the greatest scale in nature, that 

 the author relies for the foundation of his hypothesis. 



While the foregoing familiar instances exemplify the first of the two suggested 

 ways in which rotation may he imparted, so the other way may be illustrated in 

 the well-known experiment of Dr. Plateau with a rotating globule of oil. It 

 remains to mention how, in the author's view, the rotation of the discs is left 

 vnidisturbed until the capillaries are reached, and, lastly, of what use he assumes 

 the alleged rotation to be. 



He assumes that the contents of an artery are permeated by a similar electric 

 state, and that from the known mutual repulsion amongst small bodies when in 

 a similar electric condition, the corpuscles are tlnis virtually isolated, mechanically, 

 from each other, also from the liquor sanguinis, and ordinarilj' (when not at the 

 cui-ves overcome by centrifugal force) isolated also from the serous coat of the 

 artery ; thus that the discs both translate and rotate presumably 171 vacuo. As to 

 the uses of rotation, the author refers to the already recognised augmentation 

 of one of the mechanical sources of heat from tlie temporary check to the translative 

 movement of the discs in the capillaries, and points out that such heat would be 

 supplemented by the necessary total arrest there of rotation in a disc, and that 

 it would be but consistent with the recognised economy of forces in nature that 

 where such supplementing can be done (as he argues it may be) without additional 

 expenditure for either the initial force or for its conservation, and for an end so 

 vital as that of heat, it is a iwiori more probable than less so that the movement of 

 translation of the red arterial discs would be accompanied by the movement of 

 rotation. 



But the author also conceives this supplementing of heat to be not the only 

 use of such rotation. The red disc carries the iron, and if there be magnetism in 

 the system, as we know there is, then polai-ity in each disc is more conceivable in 

 the view of rotation of the disc than of its not rotating. 



