106 THE AMERICAN MONTHLY [May, 



Ciliary action in Mussel. — This is one of the most attractive phe- 

 nomena. The mussel being opened, a fringe-like expansion of the man- 

 tle is seen spreading itself as a lining over the inside of each shell. A 

 piece of this may be snipped of with the scissors and laid on the slide, 

 with some of the fluid out of the shell. A cover-glass may be placed 

 on it, when it may be examined. The cilia will be found in rapid 

 vibration, becoming slower after a time, when the nature of the action 

 can be more readily seen and followed. 



Circulation in the Frog's foot. — This, like the last, always excites 

 considerable interest wherever exhibited well. To do this the frog 

 must be made as comfortable as circumstances permit, by being placed 

 in a linen bag, kept wet and well supported by the piece of apparatus 

 known as a frog-plate. If the frog is comfortable, it does not try to 

 move its foot about, which would seriously interfere with the view. 

 The leg must not be tied in the mouth of the bag too tightly, or the cir- 

 culation will be stopped. Two threads tied around two adjoining toes 

 must be so fastened to the pins of the frog-plate that the distended web 

 may be over the aperture in the stage. If this tieing is done carefully 

 and neatly, the web may lie evenh' in the field ; it will require an occa- 

 sional moistening with cold water. 



Circulation in the Characece and Anacharis may be observed by 

 placing portions of these plants in a trough. The Characeje are a family 

 of aquatic plants which might be classed with the fresh-water algae, did 

 not their reproductive organs tend to lift them to a higher grade. They 

 are properly known as " stoneworts " from the habit they exhibit, in 

 common with many algjE, of attracting to themselves calcareous salts 

 dissolved in the water they inhabit, and depositing it on their outer 

 tissues. This occurs in some individuals to such an extent as to de- 

 prive them of that transparency which the inicroscopical observer 

 wishes to utilize in studying the circulation of the sap. They may be 

 found in many ponds which are exposed to plent}' of sunlight, where 

 they present the appearance of feathery whorls disposed at intervals 

 around an elongated stem. At first sight it is hard to distinguish them 

 from Myi-iofihvlliim^ but on being landed with the hook on the collect- 

 ing stick, it will be. seen that in Chara the stem seems twisted, while 

 in Myriop/ivlhini it is straight. The circulation in Chara maybe most 

 easily seen in the terminal leaflets, which, being newer in growth, are 

 likely to be free from incrustations. Anacharis alsinastrum^ the leaves 

 of which, when slightly yellow and older than the rest, show the circula- 

 tory movements of the protoplasmic contents of the cells, may be found 

 in many ponds, although in many parts of the country it is disappear- 

 ing. It is one of those plants which grow in water without being rooted, 

 and in this way it keeps water containing infusoria and small animals 

 in a healthy condition by reason of its evolving oxygen, and therefore 

 capable of sustaining aquatic life. It thus serves the microscopist in a 

 double capacity, affording him specimens in which circulation may be 

 studied, and ministering to the wants of those minute animalcules which 

 without it would die of suffocation. Vallisneria also exhibits the phe- 

 nomenon of the circulation, but it needs splitting into two layers to see 

 it well. There are many other vegetables possessing hairs in which 

 this circulation may be seen. Should the circulation be languid or 

 movement be entirely absent, by carrying the plant in a small bottle of 



