410 CONSERVATIVE ORGANS. [LECT. VIII. 



case in those radicles which shoot out above the 

 caudex when the soil is heaped up around the 

 stem. From whatever part the radicles proceed, 

 they are always given off in such a direction as to 

 form a right angle with the surface of the part, 

 which would not be the case did they descend 

 from the stem buds, as Dr. Darwin and M. A. 

 Du Petit-Thouars assert ; for, were their opinions 

 correct, the radicles would be given off from the 

 caudex in the same manner as a few threads are 

 separated from a skein of thread. The radicle, 

 on the contrary, receives vessels from the layer 

 of the caudex on which it originates, from both 

 above and below the point whence it shoots. 

 I have not been able to trace the origin of the 

 radicle ; but it is probable that every layer of al- 

 burnum is capable of producing radicles; for it 

 is only necessary to apply moist earth round any 

 part of a stem or branch to make them protrude, 

 c. The Fibrils *, soon after they are visible on 

 the radicles of the Horse Chesnut, are 

 minute, ovate, semitransparent bodies 

 (see a. marginal cut, which represents 

 a fibril considerably larger than in na- 

 ture), and, when placed under the 

 microscope, appear to consist of a 

 spongy mass of cellular matter, en- 

 closed in a thin transparent pellicle, 



* These are the capillame.nta of Malphigi, Anat. Plants, p. 14-5. 



