4 Transactions of the Boyal Microscopical Society. 



The leaf of i^inguicula possesses similar bodies, but somewhat 

 diflferent in structure. Fig. 6, gl represents their ordinary form. 

 They are considerably larger than in Drosera, nearly circular (but 

 apparently flat rather than spherical), and about •0014 inch in 

 diameter, divided into four quarters, filled with a similar yellowish- 

 brown protoplasmic substance, and each of the quarters distinctly 

 enclosed (in the young state of the gland) in a transparent cell- 

 wall. A circular transparent wall encloses the whole ; but there 

 are no enveloping cells similar to those dehneated in Fig. 1 ; nor 

 have I ever observed any papillae or other processes proceeding from 

 them. They sometimes, however, form shght elevations above the 

 surface, as seen in Fig. 8. At a later period, as shown in Fig. 7, 

 the number of divisions increases, sometimes amounting to as 

 many as eight, and the separating walls of cellulose nearly or quite 

 disappear. A stoma is here again represented, to show the com- 

 parative size. 



Before commencing my investigations of Drosera, my attention 

 had been directed to the occurrence of bodies of a similar nature in 

 a corresponding position in the floating leaves of a common little 

 water-plant, Callitriche verna, i. e. beneath the cuticle of the upper 

 sm-face.* These bodies were described as long ago as 1850,t by 

 the late Dr. Lankester, who, however, ascribed no special function 

 to them. The glands themselves are more minute even than in 

 Drosera, about '0005 inch in diameter, nearly spherical, and dis- 

 tinctly quadripartite, each division being again filled with a yellowish- 

 brown substance. These are surrounded by a circular border or 

 cell-wall of cellulose, also divided into four, and less opaquely 

 filled up with a similar substance They are entirely concealed 

 beneath the sm-face, and do not appear to develop into papillae. 

 One is represented at Fig. 9, together with a stoma. From the 

 extreme similarity of these bodies to those already described in 

 Drosera and Pinguicula, the idea suggests itself whether Calli- 

 triche is not also carnivorous. 



The question now arises. What is the j)urpose of these organs, 

 which present so similar a structure in the plants now described ? Is 

 it connected with the absorption and digestion of nitrogenous food 

 . presented to the leaves ? A direct answer to this question is at- 

 tended with almost insurmountable difiiculties. Unlike the secretive 

 glands of Drosera and Pinguicula, they are buried in the tissue of 

 the leaf, and it is impossible to place them under the microscope 

 without altogether destroying the surrounding tissue. It is cer- 

 tainly remarkable that bodies more or less analogous to these are 

 present in every plant which has been, down to the present time, 



* I had formerly, but erroneously (/. c, p. 358, footnote), supposed the " rosulate " 

 appearance of the leaves to be due to these bodies, 

 t ' Proe. Linn. Soc.,' ii., 1848-,'i5. pp. 94. 05. 



