62 DROSEEA ROTUNDIFOLIA. CHAP. Ill 



the glands, by the glands absorbing various fluids or 

 matter dissolved out of certain bodies, by exosrnose, 

 and by a certain degree of heat. On the other hand, 

 a temperature of about 150 Fahr. (65 0< 5 Cent.) does 

 not excite aggregation ; nor does the sudden crushing 

 of a gland. If a cell is ruptured, neither the exuded 

 matter nor that which still remains within the cell 

 undergoes aggregation when carbonate of ammonia is 

 added. A very strong solution of this salt and rather 

 large bits of raw meat prevent the aggregated masses 

 being well developed. From these facts we may con- 

 clude that the protoplasmic fluid within a cell does 

 not become aggregated unless it be in a living state, 

 and only imperfectly if the cell has been injured. We 

 have also seen that the fluid must be in an oxygen- 

 ated state, in order that the process of aggregation 

 should travel from cell to cell at the proper rate. 



Various nitrogenous organic fluids and salts of am- 

 monia induce aggregation, but in different degrees 

 and at very different rates. Carbonate of ammonia is 

 the most powerful of all known substances ; the ab- 

 sorption of -rg-rVo-o f a grain (-000482 nig.) by a gland 

 suffices to cause all the cells of the same tentacle to 

 become aggregated. The first effect of the carbonate 

 and of certain other salts of ammonia, as well as of 

 some other fluids, is the darkening or blackening of 

 the glands. This follows even from long immersion 

 in cold distilled water. It apparently depends in 

 chief part on the strong aggregation of their cell- 

 contents, which thus become opaque, and do not 

 reflect light. Some other fluids render the glands of 

 a brighter red; whilst certain acids, though nrcich 

 diluted, the poison of the cobra-snake, &c., make the 

 glands perfectly white and opaque ; and this seems to 

 depend on the coagulation of their contents without 



