814 FRANCIS DARWIN. 



mation of numberless only just perceptible granules, which 

 rapidly grow larger."' Ultimately, when the aggregation 

 becomes intense, and especially Avhen produced by a solu- 

 tion of carbonate of ammonia, the cell contains a single 

 spherical mass or only one or two large spherical ones (fig. 3). 

 These are of a deeper colour and refract light more strongly 

 than the earlier formed masses. The change of colour con- 

 nected with an alteration in the degree of condensation is 

 shown in fig, 7; the masses here drawn were in process of 

 dissolution ; in A we have two dense and dark masses at one 

 extremity of the cell (nearest the gland) and some lighter- 

 coloured ones at the other end ; the process of dissolution 

 travels up a tentacle from the base towards the gland, so that 

 in B, which represents the same cell drawn at a later period, 

 we find the masses which were separate, and dark coloured 

 in A, coalesced, and of a lighter tint. 



In the early stages of aggregation the masses are extremely 

 motile, and seem to be carried by the currents round and 

 among each other in that peculiar plastic way that one sees 

 in the coloured blood-corpuscles, where currents are set up 

 among them. 



In the strongly aggregated condition they become nearly 

 or quite motionless, and seem to be of a fairly dense nature, 

 and on pressing the cover glass they assume the star-like 

 aspect with radiating fissures, described by my father^ and 

 shown in fig. 5. The change in motility might be due ac- 

 cording to my father's views to the crimson protoplasm assum- 

 ing a passive instead of an active condition ; according to the 

 second theory, it might be due to aggregated cell-sap becom- 

 ing too dense to be influenced by the protoplasm which sup- 

 plies the motive power. When tentacles die in an aggregated 

 state, the masses usually become turbid instead of remaining 

 clear, and gradually break down into a granular debris, 

 which fills up a large part of the cell. The fact that the 

 death of the cell affects the condition of the masses is more 

 in favour of their being of a protoplasmic nature than of 

 their being mere mechanical aggregates. Oil globules, for 

 instance, are not affected in this way by the death of the 

 cells in which they are contained. On the other hand, tur- 

 bidity is a characteristic sign of the death of such proto- 

 plasmic structures as are transparent during life, e.g., cornea 

 corpuscles. 



Effects of Reagents. — These eflfects are most advantage- 

 ously studied on dense and firmly aggregated masses which 

 * ' Insectivorous Plants,' p. 45. 

 « ' Insectiv. PI./ p. 47. 



