110 Mr. W. Gardiner. The Histology of the Cell Watt, 



Taraxacum dens-leonis. The perianth -leaves of Lilium martagon. The 

 pul villi of Mimosa sensitiva and Robinia pseudacacia (fig. 8). The 

 tendril of Gucurbita pepo. The endosperm of Hordeum vulgare. 



Fig. 8. 



Although the research is still in its preliminary stages, since my 

 attention has been chiefly directed to the elaboration of the new 

 method, yet the results already obtained are sufficiently numerous 

 and suggestive to enable one to make certain remarks and general 

 statements. 



It is impossible to resist the conclusion that the connecting 

 threads consist either wholly or partly of protoplasm, and this view 

 is largely confirmed by the staining reactions. It is, however, not 

 improbable that the protoplasmic filament may be surrounded by a 

 mucilaginous sheath. Osmic acid induces no blackening as it does 

 in the threads of many sieve-tubes, and I am inclined to believe that 

 in ordinary tissue the threads consist for the most part of ectoplasm, 

 and are to be regarded in fact as extensions of it. 



The threads appear to be present ab initio. This fact, coupled 

 with the surface. growth of the cell wall, furnishes a sufficient expla- n 

 nation of the "barrel figures" so generally assumed by the various 

 thread groups. The resemblance to the similar figures which 

 accompany nuclear division is therefore superficial. Nevertheless it 

 seems ceriain that the threads do, as a matter of fact, arise from 

 that part of the cytoplasm which at the period of formation of the 

 cell plate forms the fibres of the so-called "nuclear spindle," and 

 that these fibres become, so to speak, partially imprisoned in the 

 young wall. 



My results appear to indicate that in a given cell the Avhole 

 system of connecting threads arise at this early stage, and that no 

 subsequent development occurs. This statement will, however, 

 require careful confirmation, and has certain bearings on such 

 interesting questions as the theory of grafts and " sliding growth." 



In dead cells, such as those of ripe endosperm, the threads appear 

 to degenerate into mucilage, and this is possibly also the case in adult 

 lignitied and other cells. 



In the particular tissues which I have investigated, the threads 

 can be shown to be present in all cells which still retain their cellu- 

 lose character, and although I have not actually succeeded in 



