46 



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drops of mucilage. I frequently saw two or more of them flow- 

 ing together or clinging to one another like drops of any viscid, 

 semi-fluid substance. In some instances it can be demonstra- 



r 



ted that the mass of mucilage filling the space between some 

 hairs which are not in close contact, is formed of these drops, 

 for not having perfectly coalesced they can be made out 

 individually. How these mucilage drops are formed remains 

 to be investigated ; the internal hairs do not contain any 

 mucilage masses as the external ones do. In many of them 

 active protoplasmic currents and large nuclei may be observed, 

 and others contain a great deal of starch (Fig. 7). These hairs 

 are sure to be found in such intercellular canals as, by some 

 agency or other, have been injured, and it is evident (as Melhnk 

 has pointed out in reference to Nymphcea alba) that the formation 

 of the hairs is an effort of the plant, and in most cases a very 

 effectual one, to repair the damage by closing up the canah The 

 wounds healed in this way may be caused by various mechanical 

 forces. In several stems were found egg or larva cases suspended 

 in the intercellular canals nearest to the surface of the stem. 

 The animal had punctured the superficial layer of cells and 

 deposited its eggs inside in longitudinal rows, which were plainly 

 marked on the outside by distinct dots. These cases or sacs 

 were obliquely suspended in the air-passage and connected with 

 the outer world by a short narrow canal. The plant had 

 promptly surrounded the intruder by numerous hairs of the kind 

 described. It is not improbable that the larvae when they leave 

 their temporary abode, cause at least some of the wounds found 

 on the stems. 



Internal hairs are often met with, as stated above, quite far 

 from the wound. As this was also the case with NymplK^a alba^ 

 Mellink thinks that these outgrowths are caused by a certain 

 "irritation," proceeding from the wound and conducted through 

 considerable distances by the protoplasm, which he assumes to 

 be continuous through the cells of the affected tissues. Without 

 doubting in the least the importance of the doctrine referring to 

 the continuity of the protoplasm, I cannot help thinking that in 

 our case the expansion of cells into an air-canal is rather vaguely 

 explained by the " irritation" theory. Assuming, as above, the 



