CELLULAR TISSUE. 



417 



filamentous tissue may be seen in No. 19, Plate XVI., the fungiform 

 elongated cells from the Mushroom,; only another and more closely 



fig. 198. 



1. Vertical section of root of Alder, with outer wall. 2. Spiral vessels from the 

 Opuntia vulgaris. 3. Section of a Nut, showing cells with small radiating pores. 

 4. Interior cast of the siliceous portion of spiral tubes of the Opuntia. 5. 

 Vertical section of Elm ; in the lower portion small spiral fibres are seen between 

 the pores. 



connected growth of the mucedinous fungi, or, as it is commonly 

 called, the spawn of the mushroom. 



No. 20, Plate XVI., is stellate tissue cut from the stem of a rush ; 

 here we have the formative network dividing into ducts for the pur- 

 pose of conveying the juices to the leaves of the plant. These ducts 

 undergo other transformations ; and the cell itself may become gradu- 

 ally changed into a spiral continuous tube or duct, as seen in No. 21, 

 Plate XVI. ; these are sometimes formed by the breaking down of 

 the partitions, as shown in the previous figure in the centre we have a 

 compound spiral duct, much resembling a portion of tracheae from the 

 silkworm. Another important change occurring in the original cell is 

 that of its conversion into woody fibre, so largely entering into the 

 texture of vegetables. These fibres are elongated cells of a spindle 

 shape, or tubes drawn out to a point at each end, whose internal cavi- 

 ties become gradually filled up, as represented occurring at b, fig. 197. 

 The spiral thread may be either free, or adhering to the side of the 

 tube. In the first case it forms the so-called sperm animalcules of the 

 antheridise of mosses ; its elastic and hygrometric properties giving 

 some resemblance to motion, fig. 198, No. 2. Nageli believes this to 



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