258 L October, 



erect position of the lower spurs, as compared with their supine state 

 when at rest. It is most important. In the first place, it must be 

 effected by muscular agency, and by just such muscles, too, as I have 

 shown some good reason for believing* are actually inserted into the 

 points of these spurs. In the second place, the raising of the spurs 

 to an erect position draws back the supplementary knives attached to 

 them by means of the rods ("backs "), whilst at the same time the 

 main knives are being thrust forwards by the great protrudor muscles, 

 and the effect of these two opposing forces upon the tip of the 

 instrument will be to remove its upward curve and straighten it. 

 Tet this is not quite the whole matter. The instrument is practically 

 double, one side remaining idle, whilst the other is sawing away at the 

 leaf, and if we suppose that, instead of the opposition being between 

 the parts of the same side, it is between those of opposite sides, that 

 is, that when the main knife of one side is pressed forwards, the sup- 

 plementary knife of the other side is pulled back, then not only is the 

 point quite as effectively straightened, but also at the same time the 

 instrument is given the bow-like figure it puts on at work. 



It may be objected that the movement of the knives upon each 

 other, which must take place before the point can be straightened, is 

 rendered impossible by the union between the whalebone blades ; but 

 it must be remembered that the required movement need only be very 

 small, that the blades are only united along the edge, and that their 

 peculiar fibrous nature not only favours, but has probably been de- 

 signed to allow of, a slight gliding motion upon each other, and at the 

 same time provides by a natural recoil for the resumption of the curve, 

 directly the muscular action ceases. But it may be asked, why is the 

 point of the knife curved at all ? I believe it is that the egg may 

 escape injury or displacement from the saw coming in contact with it, 

 whilst the instrument is being withdrawn ; either of which accidents 

 would, it seems to me, be liable to happen in so cramped a space as 

 the leaf-pocket, were the end of the instrument flat. Such are the 

 facts connected with this complex organ, and the conclusions that 

 have been drawn from them. That they have in every particular been 

 rightly observed and interpreted is, perhaps, scarcely to be expected, 

 yet I think that in the main they will be found to be correct. 



Tarrington, Ledbury : 



November 17th, 1890. 



* The existence of these muscles is no longer doubtful, as has been pointed out in a previouu note. 



