CHAP. 111. THE PROCESS OF AGGREGATION. 45 



independently of the absorption of any matter. So it may pos- 

 sibly be in the case of the carbonate of ammonia. As, how- 

 ever, the aggregation caused by this salt travels down the 

 tentacles at a quicker rate than when insoluble particles are 

 placed on the glands, it is probable that ammonia in some form 

 is absorbed not only by the glands, but passes down the 

 tentacles. 



Having examined a leaf in water, and found the contents of the 

 cells homogeneous, I placed it in a few drops of a solution of one 

 part of the carbonate to 437 of water, and attended to the cells 

 immediately beneath the glands, but did not use a very high 

 power. No aggregation was visible in 3 m. ; but after 15 m. 

 small spheres of protoplasm were formed, more especially 

 beneath tne long-headed marginal glands; the process, how- 

 ever, in this case took place with unusual slowness. In 25 m. 

 conspicuous spherical masses were present in the cells of the 

 pedicels for a length about equal to that of the glands ; and 

 in 3 hrs. to that of a third or half of the whole tentacle. 



If tentacles with cells containing only very pale pink fluid, 

 and apparently but little protoplasm, are placed in a few drops 

 of a weak solution of one part of the carbonate to 4375 of 

 water (1 gr. to 10 oz.), and the highly transparent cells beneath 

 the glands are carefully observed under a high power, these 

 may be seen first to become slightly cloudy from the formation 

 of numberless, only just perceptible, granules, which rapidly 

 grow larger either from coalescence or from attracting more 

 protoplasm from the surrounding fluid. On one occasion I 

 chose a singularly pale leaf, and gave it, whilst under the 

 microscope, a single drop of a stronger solution of one part to 

 437 of water; in this case the contents of the cells did not 

 become cloudy, but after 10 m. minute irregular granules of 

 protoplasm could be detected, which soon increased into 

 irregular masses and globules of a greenish or very pale purple 

 tint ; but these never formed perfect spheres, though incessantly 

 changing their shapes and positions. 



With moderately red leaves the first effect of a solution of the 

 carbonate generally is the formation of two or three, or of 

 several, extremely minute purple spheres which rapidly increase 

 in size. To give an idea of the rate at which such spheres 

 increase in size, I may mention that a rather pale purple leaf 

 placed under a slip of glass was given a drop of a solution of 

 one part to 292 of water, and in 13 m. a few minute spheres of 

 protoplasm were formed ; one of these, after 2 hrs. 30 m., was 

 about two-thirds of the diameter of the cell. After 4 hrs. 25 m 



