COMMUNICA.TIONS. 335 



attached to the germs, such as are seen in zoospores of fungoid 

 origin. It is true that they have these cilia or Hagella, as they 

 are usually termed, but the bodies are sometimes seen in motion 

 when the cilia are at rest, and sometimes they move rapidly while 

 the body remains at rest. Another explanation given is that it 

 is caused by the presence of oxygen, and the assimilation of food. 

 How this process can lead to the movements seen is not clear. 

 The probabilities are that when we can explain the movements 

 seen in many forms of living protoplasm in the higher orders of 

 life, we shall get at the cause here also. 



Up to a comparatively recent date, many supposed that these 

 bodies were composed of protoplasm in a solid form, but later re- 

 searches have demonstrated that they are perfect cells, with a cel- 

 lular membrane resembling the cellulose of larger vegetable cells, 

 which are filled with a nitrogenous fluid or substance, usually 

 transparent, and refractive, resembling protoplasm of plants of the 

 higher orders. In the smaller species this protoplasm seems to be 

 alike throughout, but in the larger ones and also in some of 

 medium size, granules, vacuoles and, sometimes, points highly 

 refractive, and of different shades of color are seen. Where tem- 

 perature and nourishment are favorable, these granules and 

 shining points develop into spores or sporangia, and form the per- 

 manent germs and the most important means for the widespread 

 dissemination and perpetuation of the organisms. 



In most of the varieties the mature organism has two cilia or 

 arms. This fact was for a long time called in question, but is 

 now generally conceded. They are so fine and delicate as to test 

 the highest power of the strongest instruments in use, and it is 

 only by a careful adjustment of light and the focus that they can 

 be seen at all. 



Having the regular cellular structure, it is generally conceded 

 that they obtain their nutrition in the same manner with other 

 vegetable cells, by endosmotic absorption. They are known to 

 take nitrogen from ammonia itself as well as from its compounds, 

 and to assimilate carbon and other elements from the organized 

 substances containing them, not by " nibbling the grains of starch 

 like mice and rats," as has been stated in illustration of the move- 



