12 ORGANOGRAPHY. BOOK 1. 



single membrane. (Plate I. fig. 2. a; Plate III. fig. 3, 4, 

 he.) 



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 Parencliyma. 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-cELLULAU 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. a, 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 Maurandva 

 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 odbratus. 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 Pvu'kinje has shown, 

 by a series of excellent observations and drawings, that it 



