WHAT ARE DIATOMS? 



203 



he used in the coarser manipulations, but, owing to the presence 

 of chemicals in this room, none of his finer instruments were kept 

 here. He explained his methods of treatment in clearing the soil 

 and dirt from the land specimens, and also showed me the little 

 silk nets which he uses when fishing for the water forms. Certain 

 kinds grow only on the surface of the sea ; so, to collect these, it is 

 necessary to go out in a small boat and row very slowly, for the 

 cloth of which the net is made must be very fine in order to pre- 

 vent the escape of the tiny plants through its meshes. Owing to 

 this extreme closeness of the meshes, the water drains through 

 very slowly. The form of the net is quite like those used to catch 

 butterflies, but is held with the handle up and close to the boat. 

 At very short intervals of time it must be taken up and the water 

 poured out; the inside of the cloth is then carefully rinsed in 

 clear water, which is kept in a jar or bottle for that purpose. The 

 most difficult part of the process is to row slowly and steadily 

 enough to prevent tearing the nets. 



These diatoms found on the surface of the water are fur- 

 nished with long arms or projections, from which protrude hair- 

 like bodies, which apparatus he conjectures is for the following 

 purpose: One means of deciding that this little organism is a 

 plant, is that it performs the function of assimilation, as it is 

 called, by which it gives out 

 oxygen. Now, this gentleman 

 thinks the little hair-like out- 

 growths are for the purpose of 

 holding the oxygen in their 

 meshes so as to enable the plant 

 to float. 



After looking through this 

 room and learning as much as 

 possible about his methods of 

 treatment, we went into an- 

 other much larger and more 

 elegantly furnished apartment, 

 where all the nice and delicate 

 work of studying forms and 

 making models was done. Here 

 were kept the books, all that 



have been written on this plant, and they filled a case of consid- 

 erable size ; also a very complete collection of microscopical ap- 

 paratus. All that modern artisans can do in the way of fine and 

 delicate instruments may be found here. Nothing less than the 

 best oil-immersion lenses can be used in the study of form neces- 

 sary to understand the inner structure of these plants. Several 

 models have been made by this gentleman, and he told me of the 



Fig. 6. Living Diatoms : a, Cocconenia lanceo- 

 latum ; b, Bacillaria paradoxa ; c, Gompko- 

 nema mariuum ; d, Diatoma hyalina. 



