ACCOMMODATION AND CONVERGENCE 67 



In all mammals in which the ciliary muscle is rudimentary 

 its fibers run longitudinally (Pigs. 11, 12, 13 and 14). It 

 is only when we come to the more highly developed ciliary 

 muscle of Primates that we meet with the addition of radial 

 and circular fibers internal to the longitudinal ones (Figs. 

 15, 16 and 17). It is in these animals also that we meet 

 with a considerable displacement backward of the anterior 

 part of the ciliary body, due to disappearance of the pillars 

 of the iris, and alteration in the arrangement of the fibers 

 of the pectinatum already referred to. The ciliary processes 

 in Primates, instead of projecting out from the back of the 

 iris, have become displaced outward and backward beyond 

 its root, thus altering the shape and direction of the lymph 

 spaces immediately external to them. The innermost of 

 these spaces assume a circular direction, and those more 

 external a radial course; the muscle fibers developing in 

 these spaces from the cells lining them take the same 

 direction. 



1 Bonders 33 pointed out that the construction of the ciliary 

 muscle varies with the refractive condition of the eye. He 

 found that in actual myopia it was flatter and longer than 

 in emmetropia or hypermetropia, and that its point of 

 origin from the fibers of the ligamentum pectinatum was 

 situated farther back. 



IwanofT 34 described how, in myopia, the ciliary muscle 

 consists almost entirely of longitudinal fibers, 'Briicke's 

 muscle," the circular fibers, 'Miiller's muscle," being 

 absent, while in hypermetropia he found that the circular 

 fibers were more numerous than in emmetropia, and formed 

 a considerable inward projection from the anterior part of 

 the muscle. This inward projection of the muscle is accom- 

 panied by an inward projection of the ciliary processes 

 behind the root of the iris. In myopia the ciliary processes 



