102 JOURNAL OF THE [October, 



are characteristic products of the feeding of the living diatoms 

 among the water plants, or other sources of food supply peculiar 

 to their habitat. I would advance the following, bearing upon 

 the subject, viz.: If the diatoms are expressed from the common 

 green algae of springs, or slimy confervae of ditches where the 

 plants are exclusively green, the endochrome is mostly of a dull 

 or bright green, and even emerald gieen. But the student of 

 the Diatomaceae is also, almost always, taught to seek for them 

 wherever moist surfaces are covered with a rusty or ochreous 

 color. It is certain that a brown or ochreous color is not indi- 

 cative of chlorophyll, as the name itself means the "green of a 

 leaf." On the contrary, the contents of the living diatoms de- 

 rived from brackish mud are mostly brown, or possibly olive 

 brown. While one is contemplating diatoms containing brownish 

 contents, he will also note that the associated vegetable debris in 

 various stages of decay is also brown and matches with the color 

 of the endochrome. So, then, the color of the endochrome is 

 probably a result of the character of the food supply found in 

 the local habitat of the diatom, and it may be a product of 

 morphological assimilation and digestion. On examining certain 

 species of Surirella on the Mobile Bay slides, emerald-green 

 stains may be seen at the wedge-shaped end of the frustule, while 

 the balance of the frustule is colorless ; but the slides also illus- 

 trate brown- or green-colored contents of various shades in ex- 

 treme profusion. 



Having, to my own personal satisfaction, witnessed the indispu- 

 table evidence of an intelligence in three representative species 

 of three genera of the Diatomaceae, and having stated in plain 

 terms the manner in which the proof was adduced, and which is 

 duly capable of verification by any one who will take the trouble 

 to review and corroborate the facts and phases established by 

 my experiments, I will now endeavor to make an expansion of 

 these biological phenomena, to draw attention to the fact that 

 any diatomist, expert or amateur, who sees fit to regard the dia- 

 toms as belonging to the protozoa rather than to the unicellular 

 plants, can feel some satisfaction in his own mind, notwithstand- 

 ing all that is upon record excluding the diatoms from the lowest 

 order of the animal kingdom. This inclination with me has been 

 the outcome of accumulated experience in the study of the 



