mon infusoria a species of small size, that can be readily cul- 
Cryptochilum nigricans answers perfectly these conditions. 
It is herbivorous, and occurs everywhere in abundance. In 
order to utilize it as food for carnivorous species, proceed as 
follows : — Prepare an infusion by cutting up a few pinches of 
hay in water, and heat the same for a few minutes to a tem- 
perature of 6o<' C. for the purpose of destroying- strange spe- 
cies. Allow the infusion to stand two, three, or four days, 
according to temperature, until Schizomycetes have devel- 
oped in it ; then sow some Cryptochila in it, taking care 
not to introduce other species at the same time. The vessel 
containing the infusion should always be covered with a close- 
ly-fitted plate of glass. The Cryptochila, finding abundance 
of food in the Schizomycetes, thrive and multiply by myriads. 
When the culture begins to decline — as it always will in reg- 
ular course — it can be revived two or three tinies by adding 
crumbs of bread in small quantity. Too much bread causes 
acid fermentation which destroys the infusoria. Instead of 
hay, pepper might be employed for these infusions, but it 
would be necessary to determine by experiment the quantity 
that could be safely mixed with a given volume of water. 
Too large quantities have been found to give infusions that 
checked the development of the infusoria. 
Having thus obtained a well stocked infusion, the mode of 
serving the Cryptochila to the carnivorous species isolated 
in the manner above described, is as follows : — Place a drop 
of the infusion on a slide, and cover it with a cover-slip. It 
will then be seen that the Cryptochila collect round the 
edge of the cover, and in this position they are easily drawn 
into a pipette, and then delivered over to the carnivorous 
species. This mode of feeding enables one to make sure that 
no foreign species is introduced into the culture. Other spe- 
cies would undoubtedly serve the purpose of food as well as 
Cryptochilum, for example, Colpidiiim colpoda. 
In the culture of herbivorous species, Maupas uses boiled 
flour as food. A pinch of flour is placed in a sufficiently large 
With this pap one can easily supply the needs of Paramaeci- 
um, Colpidium, Glaucoma, Vorticella, and probably all spe- 
cies that ordinarily feed almost exclusively on Schizomy- 
cetes. This food is easily prepared, and is readily served by 
allowing it to flow in small quantity under the cover-slip of 
the preparation. It keeps only a short time, and hence must 
be renewed every day or two. 
