82 DUCTS MOHI/S VIEWS. [BOOK r. 



" Very frequently also the spiral fibre, placed between two 

 rings, does not proceed to a junction with the rings, but its 

 extremities become attenuated, and terminate at some 

 distance from the ring. In the stem of the Gourd this is 

 nearly as frequent as the preceding case. Often, also, from 

 two diametrically opposite points of a ring proceed two fibres 

 in a continuous parallel direction. 



"Cases are sometimes met with, although rarely, where 

 two rings are united by fibres slenderer than the annular fibre, 

 which generally form a single coil, or at least only a small 

 number of coils, This occurs in a very evident manner in 

 the vessels whose rings are not homogeneous, but where the 

 spiral fibre is divided by several fissures into threads united 

 in net-work. The width of the fibres uniting the different 

 rings presents no exact proportion to the width of the annular 

 fibre, being sometimes about the half of it, sometimes con- 

 siderably less. The point of union of the spiral fibre with 

 the annular fibre is especially deserving of consideration. 

 When examined with a sufficient magnifying power, we 

 sometimes find that a part of the annular fibre separates 

 itself to ascend in a spiral direction ; but that, in general, at 

 the point of junction of the two fibres, the annular fibre does 

 not become thinner, the spiral fibre being attached only to 

 the lateral edge of the annular fibre, which preserves an 

 uniform thickness throughout its entire extent. There are 

 even instances in which this union does not take place in the 

 direction of the spiral, but where the spiral fibre terminates 

 in two divergent branches separating right and left, and 

 confluent with the annular fibre. 



" An examination of the proportions above mentioned be- 

 tween the annular fibres and the spiral fibres which unite them 

 must excite doubts of the accuracy of Schleiden's theory of 

 the origin of annular vessels. In fact, the division which takes 

 place in many rings is, as we have seen, nothing less than 

 a proof of the ring being composed of the two united fibres 

 of a spiral fibre ; whilst, on the other hand, the direction of 

 this division parallel to the edges of the rings is quite opposed 

 to Schleiden's theory, and shows us that, in these more or less 

 divided rings, we see a transition from the simple ring to two 



