1880.] Mr Taylor, Newton s organic description of curves. 381 



The glomerulus increases in size, and the bay anteriorly widens 

 out very much, while behind it remains deep, and finally passes 

 into the closed posterior portion. The glomerulus fills up this 

 passage which clearly runs obliquely backwards and dorsalwards, 

 and eventually, as far as I can ascertain, the opening becomes com- 

 pletely closed, the epithelium on the external glomerulus being 

 no longer continued through the opening on to the internal glome- 

 rulus. 



The external glomerulus, then, in the chick which has hither- 

 to been known as the glomerulus of the head-kidney, is nothing 

 more than a series of glomeruli of primary Malpighian bodies pro- 

 jecting through the wide openings of the segmental tubes into tli» 

 body cavity. Their extreme antero-posterior extension may be said 

 to be within the 9th and 13th segments. 



In the chick the primary segmental tubes corresponding to 

 these external glomeruli are apparently never fully developed. 



I may mention that the external glomeruli are present in 

 greater numbers and attain a greater development in the duck 

 than in the chick. 



I defer the details and all discussion of this extraordinary and 

 unexpected development until I am able to publish a fuller paper 

 with fiofures. 



May 17, 1880. 

 Peofessor Newton, President, in the Chair. 



The following communications were made to the Society : — 



(1) C. Taylor, M.A., On Newtons organic description of 

 curves. 



1. If two angles of given magnitudes BBM, DGM turn 

 about their summits B and G as poles, ivhilst the intersection M 

 moves along a fixed straight line or directrix, the remaining inter- 

 section D traces a conic passing through B and C. 



The above is well known as Newton's method of generating 

 conic sections, but it is not so generally known that he also ex- 

 tended his organic description to the higher curves. M. Chasles, 

 in his Ajjergu historique, &c.. Note XV., p. 337 (^'"^ ed., 1875), first 

 extends the theorem above stated by supposing the point M to 

 move upon a conic through B and G (instead of a straight line), in 

 w^hich case also D traces a conic through B and G as before. He 

 then goes on to remark : — 



