60 DROSERA EOTUNDIFOLIA. CHAP. III. 



for a length equal to that of the glands. On the other 

 hand, in the fresh leaf similarly treated, aggregation 

 was plain in many of the tentacles after 15 m. ; after 

 65 in. it had extended down the pedicels for four, five, 

 or more times the lengths of the glands; and after 

 3 hrs. the cells of all the tentacles were affected for 

 one-third or one-half of their entire lengths. Hence 

 there can be no doubt that the exposure of leaves to 

 carbonic acid either stops for a time the process of 

 aggregation, or checks the transmission of the proper 

 influence when the glands are subsequently excited 

 by carbonate of ammonia; and this substance acts 

 more promptly and energetically than any other. It 

 is known that the protoplasm of plants exhibits its 

 spontaneous movements only as long as it is in an 

 oxygenated condition ; and so it is with the white 

 corpuscles of the blood, only as long as they receive 

 oxygen from the. red corpuscles ;* but the cases above 

 given are somewhat different, as they relate to the 

 delay in the generation or aggregation of the masses 

 of protoplasm by the exclusion of oxygen. 



Summary and Concluding Remarks. The process of 

 aggregation is independent of the inflection of the 

 tentacles and of increased secretion from the glands. 

 It commences within the glands, whether these have 

 been directly excited, or indirectly by a stimulus 

 received from other glands. In both cases the pro- 

 cess is transmitted from cell to cell down the whole 

 length of the tentacles, being arrested for a short 

 time at each transverse partition. With pale-coloured 

 leaves the first change which is perceptible, but only 



* With respect to plants, Sachs, ' Quarterly Journal of Micro 

 'Traitu de Bot.,' 3rd edit., 1874, ^copical Science,' April 1874, \\ 

 o. 804. On blood corpuscles, see 185.' 



