12 
ORGANOGRAPHY. 
BOOK I. 
single membrane. (Plate I. fig. 2. a; Plate III. fig. 3, 4, 
,&c.) 
9. The sinuous; in the cuticle, and also sometimes beneath 
it, as in the leaf of Lilium candidum. (Plate III. fig. 5.) 
Cellular tissue is frequently called Parenchyma. Professor 
Link distinguishes Parenchyma from Prosenchyma ; referring 
to the former all tissue in which the bladders (Plate I. fig. 1. 
3. 6, 7, &c.) have truncated extremities; and to the latter, 
forms of tissue in which the bladders taper to each end, and, 
consequently, overlap each other at their extremities. ( Plate II. 
fig. 8. 19.) 
FiBRO-CELLULAR TissuE is that in which the sides are 
composed either of both membrane and fibre together, or of 
fibre only. 
It is only lately that this kind has been recognised. The 
first observation with which I am acquainted is that of Mol- 
denhauer, who, in 1779, described the leaves of Sphagnum as 
marked by fibres twisted spirally. (Fig. 1. «, p. 6.) Link 
afterwards stated, that the supposed fibres were nothing but 
the lines where small cells contained in a larger one unite to- 
gether; and his opinion was received. It is nevertheless cer- 
tain, that the tissue of Sphagnum is as Moldenhauer described 
it. In November, 1827, I described the tissue of Maurandya 
Barclayana as consisting of bladders formed of spiral threads 
crossing each other, interlaced from the base to the apex, and 
connected by a membrane. A few other solitary cases of this 
kind of tissue had subsequently been observed when the ad- 
mirable investigation of a modern anatomist suddenly threw 
an entirely new light upon the subject. 
Instead of being very rare, cellular tissue of this kind 
appears to be found in various parts ; it has been already 
mentioned as existing in the leaves of Sphagnum ; it is also 
found in the pith of Rubus odoratus. I originally discovered 
it in the parenchyma of the leaves of Oncidium altissimum, 
and in the coat of various seeds. Mr. Griffith has detected 
it abundantly in the aerial roots of Orchideous plants, observ- 
ations since confirmed by Brown ; and Purkinje has shown, 
by a series of excellent observations and drawings, that it 
