96 



COLLECTING ANIMALCULES 



numerous. Dr. Ehrenberg states that lie has met with good success 

 in the winter under bridges, around the piers and outworks, and 

 even in frozen ditches beneath the ice. When you have filled your 

 vessels, cork them carefrdly, so as to exclude the air, for the shaking 

 in the caniage, when a quantity of air is left in the vessels, will 

 often destroy them before you anive at your place of destination. 

 In this respect, my mode of proceeding differs, from that of Dr. 

 Elirenberg, who always leaves a small proportion of air in the 

 vessel ; judging, therefore, from my own experience, I should con- 

 clude that he is more careful than myself as to their conveyance. 

 The only inconvenience I have experienced from keejiiag the vessels 

 entirely filled with water, during the short time of transporting 

 them home, has arisen from those creatures which appear to live on 

 the surface, as Euglena, &c., attaching themselves to the cork, and 

 remainiag so when required to be taken out. Remove the corks as 

 soon as you get home, and place the vessels upright ; for which a 

 mahogany stand, famished with a number of holes adajited for the 

 vessels, will be very convenient. A gauze covering, fitted to the 

 fi'amc, will keep out the dust and blacks, without obstruetirig the 

 fr'ec ingress of air. 



We now proceed to the mode of investigating these minute 

 creatures xuider the microscope. If the kind to be examined are 

 those which swim freely, and are visible to the naked eye, as the 

 Volvox, Bursaria, and other large Polygastrica, and also the free 

 Rotatoria, take a sin;dl open glass tube, such as is described m the 

 Microscopic Cabinet, p. 236, (edition 1832) and select 

 the specimens with it in the manner there recom- ^^:iii»* 

 mended. The figure of the tube I here insert fr-om "^ *^" - 

 that work. The diameters of these tubes may vary 

 fr-om one- eighth to one-twelfth of an inch, and their 

 length fr'om four to eight inches. It may be useftd 

 occasionally to di'aw out and slightly bend the ex- 

 tremities which are to be immersed in the water. 



When the creatures are more minute than those 

 above mentioned, pour a little water fr-om the vessel 

 containing them into a watch glass, and place it upon H 

 a piece of cardboard, coloured half hlach and half 

 white. The white groimd will make the dark specimens apparent, 



