704 SUMMARY OF CURRENT RESEARCHES RELATING TO 



to the internal surface of the tube ; hence the importance of washing 

 after each, experiment. 



In order to supply carnivorous species easily with food, it is neces- 

 sary to find among the more common infusoria a species of small size 

 that can be readily cultivated. 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 temperature of 60° C. for the pur- 

 pose of destroying strange species. Allow the infusion to stand two, 

 three, or four days, according to temperature, until Schizomycetes have 

 developed in it, then sow some Cryptochila in it, taking care not to intro- 

 duce other species at the same time. The vessel containing the infusion 

 should always be covered by a closely fitted plate of glass. The Crypto- 

 chila, finding abundance of food in the Schizomycetes, thrive and multiply 

 by myriads. When the culture begins to decline, as it always will in 

 regular course, it can be revived two or three times 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 GryptocMla 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 species would undoubtedly serve the 

 purpose of food as well as Cryptochilum — for example, Colpidium colpoda. 



In the culture of herbivorous species, M. Maupas used boiled flour as 

 food. A pinch of flour is placed in a sufficiently large quantity of rain- 

 water, and boiled two or three minutes. With this pap one can easily 

 supply the needs of Paramsecium, Colpidium, Glaucoma, Vorticella, and 

 probably all species that ordinarily feed almost exclusively on Schizo- 

 mycetes. 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.* 



Foster, K. A. — Investigation of Bacteria by means of Cultivation. 



A7ner. Mon. Micr. Journ., X. (1889) pp. 124-6. 

 FouBEUE, A. — Etude sur la culture des microorganismes anaerobies. (Culture of 

 anaerobic micro-organisms.) 73 pp., 25 figs. 8to, Paris, 1889. 



Jefeeies, J. A. — A new method of making Anaerobic Cultures. 



Med. News, 1889, pp. 347-8. 



(2) Preparing- Objects. 



Preparing Eggs of Petromyzon.t— Dr. A. A. Bohm treats artificially 

 fertilized eggs with Flemming's fluid, containing a larger admixture of 

 osmic acid than is prescribed in the original formula. 



* Amer. Nat., xxiii. (1889) pp. 277-9. 



t Arch. f. Mikr. Anat., xxxii. (1889) pp. 634-5. 



