LUCERNAllliE AND THEIR ALLIES. 57 



and tlie muscular cords {fig. 46, r). In the former it consists in a thickening 

 of its mass to double its measurement on the shaft, and the embedding of adhesive 

 vesicles (coUetocysts, a) just beneath its outer, free surface. These cysts are very 

 numerous and tolerably well crowded all over the flat face of the disk, but do not 

 extend forward beyond its edge. The sucker-like shape of this organ is not, tliere- 

 fore, indicative of a sucker-like function on its part, and the power of adhering to 

 bodies by its mere edge confirms the most warrantable inference, that the cysts are 

 the true organs of adhesion. Some minor modifications are yet to be mentioned ; 

 but as they are already described in previous paragraphs (54, 63) on the form of 

 the peduncle they need not be repeated here. The same may be said in regard to 

 the muscular cord, which is described in paragraphs 59 and 88, but we will draw 

 attention to the position of the two main furrows which cross each other at right 

 angles {fij. 18, y') on the face of tlie disk, as corresponding to the line along which 

 the muscular cords {fiy. 19, ?■') run. These furrows are but continuations of the 

 four which trend at equal distances apart (ninety degrees) along the shaft, 

 opposite the muscles, toward the umbclla, and become there slight depressions, 

 opposite the partitions, extending to the periphery. The most obvious relation 

 of the furrows to the muscles is one of cause and effect. The muscles must have 

 a point cVapind, and the furrows are simply indicative of the line of traction, which 

 is nearest to the point where the contractile force is least expanded. From these 

 lines it dift'uses systematically all over the body. The minor furrows {fiij. 18) on 

 the disk, anastomosing into a network, probably correspond to the greatly varying 

 irregular thickness of the chondrophys (see ^ 57, 58, 72), which tends to become 

 bent and folded in the direction of the lines of the least rigidity when the muscles, 

 which are embedded in it, are contracted. The same feature is observable in the 

 liiglily muscular anchors, in which we have also described a great inequality and 

 want of regularity in the depth of the chondromyoplax. 



§ 15. The Di(jitlform Bodies (Di(ji(v,U). 



116. Form {figs. 47", 65, 80, 98,99, 100, 101). Notwithstanding the apparent 

 relation of the dlgittfonn bodies to the reproductive organs they are preeminently 

 allies of the exterior prehensile organs, and, therefore, are most fittingly described 

 here, no niatter in what connection or for what purpose they perform their duties. 

 The position and form of these bodies have already (^f 52) been described in a general 

 way, but the peculiar features for which they are so eminently remarkable remain 

 to be illustrated here. Their elongate lanceolate outline is only observable when 

 the flattened sides {^figs. 47", 65) arc turned toward the observer. Seen thus they 

 appear narrow at the base and gradually expand to about their midlength and then 

 as gently taper to a rounded point. Viewed at right angles to this {fig. 98) they 

 taper, from a slightly constricted neck, uniformly to the tip. The thickness, at thc^ 

 broadest part, is to the breadth as one is to four or five. Usually they are single, 

 but occasionally two or even three have a common stem for a short distance {fig. 

 65), and these pass on separately with the same form as the single ones. They are 

 capable of a great range and variety in form and pr()[)()rti()ns. At one time they 



8 April. 1877. 



