INTEODUCTION TO CRYPTOGAMIC BOTANY. 59 



composed, and also the medullary rays are considered, the modi- 

 fications are greater than would frequently be found in distant 

 genera of the same natural order; but in M. punctulatum 

 such a difference exists, that Dr. Hooker, speaking of this in 

 comparison with the other species, says, " that no one, from an 

 examination of the wood alone, would hesitate in pronouncing 

 them to be plants widely separated in a natural system."* 



46. It is strange enough to see the medullary rays in M. bra- 

 chystachyum and quadriflorum, consisting of uniform tissue, 

 while in M. linearifolium, they abound in conspicuous masses 

 of woody cells, which exist also in the bark ; but while the 

 pith of other species is simply cellular, in M. punctulatum it 

 consists of a dense mass of woody fibres (pleurenchyme), and as 

 a consequence, there are no true medullary rays. Look again 

 at the strange difference which exists between the dry fruit of 

 Myzodendron, and the viscid fruit of Loranthus and Viscum, 

 and the still more marvellous arrangement by which the dry 

 tissue of the former, in the condition of tendril-like threads, 

 clasps the stems of the plant on which it grows, in order to 

 keep the germinating seed in a fit position for the radicle to 

 exert all its force at one point, so as to enable it to pierce the 

 bark, thus answering the same purpose which is secured by the 

 slime of Loranthus or Viscwm. Or again, amongst the same 

 plants, look at the utter diversity displayed by the anthers ; 

 the bilocular anthers of Loranthus, the unilocular of Myzo- 

 dendron with their central columella, and the cribriform pollen 

 cavities of Viscum. 



47. The structure of the ovules in Grypiocorynej- (Ambro- 

 sinia ciliata, Eoxb.), so different from that of allied plants, 

 will give us another excellent example. The embryo pro- 

 jectiag at an early period beyond the walls of the nucleus, 

 the enormous many-leaved plumule thrusting the radicle 

 on one side, the rapid fall of the cotyledon, even before 

 the seeds have left the capsule ; but above all, the direction 



* Hook. M. Ant., p. 297. The whole of the above information is 

 derived from the Antarctic Flora. I have also a beautiful specimen of 

 the wood of M. hracliystachyum by the kindness of Dr. Hooker. 



t Linn. Tr. vol. xx. p. 263. 



