306 ANIMAL NATURE OF DIATOMEJ3. 



detected on comparing individuals of the same species, 

 those which take place under direct observation merit 

 particular mention. The lobes described by Kiitzing are 

 seen to swell, and in some places to project and retract 

 successively. 



The identity of this substance with endochrome is con- 

 tradicted by Kiitzing's own experiments, which will be 

 found very exact, by any one who may repeat them. 

 These prove it to be very rich in nitrogen ; it emits 

 ammonia copiously when decomposed by heat, and this 

 can only proceed from a substance abounding with it, 

 which such a decomposition compels to yield it up. Nor, 

 on the contrary, do I believe that there is any weight in 

 the argument from the solubility of its colouring principle 

 in alcohol, for this is not a property peculiar to chloro- 

 phyll or to any substance of vegetable origin. Finally, I 

 may add that if a portion of chlorophyll could be demon- 

 strated in the interior of Diatomeae, this would by no 

 means invalidate their animal nature; we might still 

 suppose that they had swallowed it for food. 



As to the oil globules, I fully agree with Kiitzing 

 that they have this appearance ; for some of them liquefy, 

 possess a high refractive power, and may be artificially 

 squeezed out, so to speak. Without any discussion of 

 the instances in which oily substances are met with in 

 vegetable cells, 1 argue that they are equally present in 

 the two kingdoms. For, I ask any one habituated to 

 the use of the microscope and to observations on In- 

 fusoria, whether the presence of globules of an oily ap- 

 pearance be not a constant fact, not merely in minute 

 animalcules, but in almost every portion of animal sub- 

 stance? The so-called Sarcode, of the French micro- 

 scopists assumes, in fact, the form of oil globules. I 

 observe, too, that the number and volume of these 

 globules increase considerably after death, and that 

 during life they are situated upon a longitudinal line 

 extending from one extremity to the other. And I rely 

 upon the observation that there is some motion and sue- 



