58 THOMAS HICK, B.A., B.SC, A.L.S. 



small compared with the size of the elements in which they lie, and 

 two or more are frequently seen in the same element, especially in 

 longitudinal sections like No. 113. In the specimen figured by 

 Williamson 1 they are very numerous, and are carefully represented, 

 but are not referred to in the description. In most instances where 

 the black bodies are present, the granular and utricular forms of cell 

 contents are absent, but not in all. Thus, in No. 115 the contents of 

 the hypoderma are utricular, while those of the inner parenchyma are 

 represented by the peculiar black bodies. In No. 106 we have both 

 the black bodies and the granular contents, but the distribution of 

 each is irregular. 



The nature and origin of these peculiar black bodies are points not 

 easily determined. The first question that arises is whether they are 

 actually portions of the cell contents or adventitious bodies that have 

 found their way into the plant from without. Against the latter view 

 must be set the fact that they are absent from the tissues of other 

 plant fragments, and found in all preparations of Rachiopteris cylindrica 

 which have been fossilised simultaneously and under the same con- 

 ditions. Moreover, an examination of numerous sections of other 

 species of Rachiopteris found in the same situations has so far failed to 

 show their presence as regularly and as copiously as in the species 

 under consideration. In some sections of the roots of Psaronius black 

 bodies are occasionally met with which might be compared with them; 

 but they lack the uniformity of shape and the definiteness of contour 

 of those found in Rachiopteris cylindrica. On the other hand, their 

 frequency in this species is remarkable. Leaving out doubtful cases 

 where fossilisation has caused the disorganisation or disappearance of 

 the cell contents, we have in the "Cash" Collection 17 preparations of 

 the plant which show cell contents. Of these only three fail to show 

 the black bodies, viz. : Nos. 102, 103 and 104, and they are all cut from 

 the same specimen. It follows that out of 15 different specimens, we have 

 only one in which these bodies do not occur. Lastly, there are reasons for 

 regarding this specimen as younger than the rest, and it may be that 

 the contents of the cortical cell have not assumed their final form. It 

 is not desirable to place too much weight on these points, but taking 

 the whole of the facts together, they seem strong enough to warrant the 



1 Loo. cit. Plate XXIV., Fig. 80. 



