inant spirits come the crowds of war- 

 blers, the cuckoos, the goldfinches — time 

 fails me to speak of them all, but let 

 him who wishes to know go himself and 

 watch and wait for them with due pa- 



tience. And they will come to him, and 

 he will love them during the mad chorus 

 at daybreak and the silence of noonday, 

 and in the plaintive music of the twilight 

 hour. 



Leonora Sill Ashton. 



RIVER MUD AT LAS VEGAS, NEW MEXICO. 



The mud from the rivers usually has a 

 brown shiny coating; on the rocks this 

 gelatinous substance is sometimes more 

 than an inch thick, often, indeed, it floats 

 in long strings or spherical masses re- 

 sembling somewhat the bladderweed so 

 common in the ocean. Under the micro- 

 scope we see that this unattractive mass 

 is in reality very beautiful — made up of 

 thousands of gondolas or tiny boatlike 

 plants called diatoms. 



In the river here I have grown familiar 

 with a dozen species, and I doubt not that 

 by study many more would be found. 

 Some of these diatoms are firmly attached 

 to a support and do not move, but others 

 steer themselves about with great pre- 

 cision. The cell covering of these tiny 

 plants is hardened and resembles a trans- 

 parent shell : it is marked with bands, 

 ribs and curious sculptured patterns just 

 as you have seen shells marked. A very 

 interesting question arises when we try 

 to discover how these one-celled plants 

 move, for there is no cilia to be discov- 

 ered to act as paddles for these small 

 boats. Kerner says : "The cell mem- 

 brane is very hard and consists of two 

 valves shutting together like the valves of 

 a mussel. The strong analogy between 

 the structure of these Diatomacse and 

 that of mussels seems to justify the as- 

 sumption that the two siliceous valves, 

 which are fast shut during the period of 

 rest of the diatoms in question, move a 

 little apart, so that the protoplast living 

 within can push out one edge of its body 



and creep along over the substratum by 

 means of it." 



Livingamongthediatoms are one-celled 

 animals which use the small plants for 

 food. In the protoplasm of a Paramecium 

 I once saw ten diatoms. The living part, 

 that which Kerner calls the protoplast, is 

 absorbed into the substance of the animal ; 

 the cell mebrane is cast out as refuse, and 

 so it is that you will see many of these 

 little boats quite colorless and drifting 

 with every current. The one-celled ani- 

 mals are very numerous in species, and 

 often have the power to move very quick- 

 ly through the water, though at times 

 they are firmly attached to the rocks or 

 plants. One of the commonest of the sta- 

 tionary animals is the bell animalcule. It 

 looks like a small transparent bell moored 

 by a slender colorless rope. But this rope 

 has a queer trick of looking all at once 

 like a watch spring, and sometimes of 

 disappearing altogether, and the little 

 bell is held quite close to the anchorage. 

 But even this animal, which must spend 

 its life in one place and can only move up 

 and down like a jack-in-the-box, lives 

 upon diatoms and desmids, both of which 

 have the power of moving from place to 

 place. 



Among the diatoms in our river you 

 will sometimes see a crescent shaped 

 boat with green instead of brown chloro- 

 phyll. This is a desmid, another one- 

 celled plant which is much esteemed as 

 food by many other animals besides the 

 bell animalcule. 



WiLMATTE Porter Cockerell. 



222 



