40 Dr. M. J. Schleiden’s Observations on 
differences existing between the membrane of various plants 
and groups of plants inter se. Since Mohl and I have arrived 
at this result independently, and in part by a very different 
ath, it is, in my opinion, a great presumption of its correct- 
ness. I gladly follow the steps of Mohl, whose memoir ap- 
peared some months earlier, as a confirmation only of a view 
already advanced ; and would with joy always renounce in his 
favour all claim to priority, could I thereby for ever purchase 
an agreement of our convictions. 
Scarcely more than in expression do Mohl and I differ in 
our views respecting the structure of the secondary deposits. 
If he admits an arrangement of the smallest parts in the di- 
rection of a spiral in the cases by far most frequent, and 
if I,—believing that I frequently have actually seen this ar- 
rangement even in cases where soon an apparent homoge- 
neity occurs, and also as the changes produced by the expan- 
sion of the cells prove that the connexion of the molecules, 
in any other direction than that of the spiral, is in the 
younger stages almost nothing,—consider myself justified in 
speaking in all cases of a spiral striping or band, there is in 
this, with respect to the essential point, little discrepancy. I 
also believe that many differences of opinion, in subordi- 
nate points, will still disappear if Moh! keeps more accurately 
in view individual development, and especially pays more 
attention to the momentum of the expansion of the cells 
after the appearance of spiral deposits. Thus, for instance, 
in all my inquiries into the structure of the ligneous body, I 
have never contented myself with comparing the parts of 
different age of the same individual, but have constantly, 
as far as the material was at my disposal, at the same time 
pursued throughout a whole year the development of the 
same annular ring, by regularly repeated observations on the 
most varied parts of the plant. Highly instructive likewise 
is an accurate history of the development of the Spiroidea 
in the large Monocotyledonous vascular bundles, for mstance, 
in Arundo Donax, where it must also be borne in mind not 
merely to compare on the same individual the younger with 
the older internodes, but to examine the homologous inter- 
nodes on several individuals of different age. In this plant 
the spiroidea are situated in the perfectly developed fasciculus 
in a series radial from the axis to the periphery, arranged 
between the two large so-called porous vessels. The an- 
nular vessels, with the rings furthest from one another, are 
nearest to the axis of the internode, from thence towards the 
circumference the rings approach closer together, then pass 
