622 J. G. GRENPELL. 



If one bears in mind that the little Melosiras have very little 

 silica, possibly none at all at times, and that both they and 

 the Archerinas contain chlorophyll bodies, the resemblance 

 becomes still more striking. It is also a striking fact that the 

 connection of the diatoms by bands of protoplasm finds its 

 counterpart amongst Heliozooid Protozoa, as in Monobia 

 confluens. Another point of agreement is the fact that 

 Archerina at times has very few but very large pseudopodia, 

 just like the Cyclotella. 



A fact about Archerina as yet unpublished is worth notice. 

 In staining with Schnitzels fluid and with iodine and sul- 

 phuric acid I obtained the clearest evidence that the cuticle 

 of the chlorophyll bodies is made of cellulose. In this it is 

 more plaut-like than the diatoms themselves, which do not 

 give the cellulose reaction. Cellulose has been found in a 

 number of animals, but still it is interesting that while the 

 pseudopodia draw the diatoms nearer to the animals, this cel- 

 lulose draws Archerina nearer to the plants. This fact is 

 likely to be used as an argument in favour of Archerina being 

 a case of symbiosis, and such a view may be extended to 

 these diatoms. I will not discuss that view now. I do not 

 think it is conclusive in the case of Archerina, much less in 

 the case of the diatoms, where all the facts seem to point to 

 the pseudopodia being integral portions of the diatoms. 



