MEMORANDA, 165 



from rain or other sources, might collect upon the surface of 

 the leaf, whose edges, being turned up as a bulwark against 

 the surface ripple of the water, would prevent its speedy 

 escape otherwise ; and we well know that such a huge mass of 

 cellular tissue shut out from the air by a covering of Avater 

 soon dies. But, I believe, neither hypothesis explains the 

 real nature of the so-called stomatodes. It is desirable to 

 understand their homology before we speculate on their func- 

 tions. They have none other than a fanciful relationship 

 with stomata. In their own structure they present no cha- 

 racters in common with stomata, nor are they even connected 

 with true stomata ; on the contrary, there is an absence ol 

 stomata around their margin on the upper surface, the thin- 

 ning of the tissue at that part rendering such organs un- 

 necessary. 



W hile the perforations may serve both the purposes indi- 

 cated above, and thus afford an example of the modification of 

 a structure to suit the requirements of a plant, such as we see 

 every day in the organs of animals and plants, I believe that 

 thev are meiely the simplest form of a reduction of tissi es 

 more fully brouglit out in other plants. We well know the 

 tendency of phanerogamous plants growing in water to lose 

 the soft tissues of their leaves ; Rammculus aqiiatilis is a 

 familiar example wherein the submersed, as well as some of 

 the floating leaves, exhibit only a very partial development of 

 parenchyma; we also know that this reduction of parenchyma 

 is not confined to leaves actually submersed, but is parti- 

 cipated in by those which float upon the surface. Ouvirandra 

 fenestralis is a striking example, the parenchyma being so 

 much reduced as to give the leaf the appearance of a skeleton 

 leaf. In the Victoria it appears to me that the perforations 

 indicate the beginning, as it were, of a reduction of this 

 kind, which if it proceeded far enough would result in a 

 lattice-work leaf like tlie Ouvirandra, represented only by tlie 

 strong-ribbed venation with which the Victoria is furnished. 

 In fact, the thinness ot the intercostal parts of the leaf, as com- 

 pared with the ribs, is an equally striking indication of such 

 a reduction. Viewed from this point of view, these pores 

 resolve themselves into a form of development with which we 

 are familiar in other plants, and lose their supposed singu- 

 larity as a feature of structure peculiar to the Victoria. — 

 G. Lawson. Proceedings of Botanical Society. 



The {Stomachs of ihe Polygastiica. — A spirited controversy 

 exists concerning the internal structure of the so-called Poly- 

 gastric Infusoria. In England the subject has not met with 



