Manchester Memoirs, Vol. xli. (1896), No. 1. 5 



utricular, while those of the inner parenchyma are repre- 

 sented 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 prepara» 

 tions of Rachiopteris cylindrica which have been fossilised 

 simultaneously and under the same conditions. 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 



