208 



SCIENCE. 



[X. S. Vol. XXIII. No. 580. 



a yeast. These mixed cultures have now 

 been grown in the laboratory for some six 

 months. Several other cultures were ob- 

 tained, but these were soon outgrown by 

 the accompanying bacteria. 



The cultural forms of these two organ- 

 isms are exactly the same as that seen in the 

 gut of the mosquito, thus confirming the 

 view expressed that the flagellates found 

 growing in the intestinal tube of insects 

 represent cultural forms in vivo, and, as 

 such, correspond to those obtained in vitro. 

 In both conditions not only was the form 

 and size the same, but the blepharoplast 

 was anterior to the nucleus. The Herpeto- 

 monas was characterized by the presence 

 of two diplosomes in the posterior part of 

 the cell. These bodies were found in the 

 parasites within the mosquitoes as well as 

 in those grown in culture. Animals inocu- 

 lated with the cultures failed to show an 

 infection. 



When mosquitoes are allowed to feed on 

 T. Brucei or T. Lewisi these parasites may 

 be detected in the blood in the intestine of 

 the mosquito twenty-four hours after feed- 

 ing, and even later, and rats inoculated 

 with such stomach contents develop typical 

 infection. 



The trypanosomes which have been met 

 with by various investigators in the stom- 

 achs of tsetse-flies, lice, leeches, etc., are 

 distinctly ' cultural forms,' since they show 

 the blepharoplast in a position anterior to 

 the nucleus. This fact indicates that all 

 such forms can be cultivated in the test 

 tube. The Herpetomonas forms found in 

 flies and mosquitoes are true cultural 

 trypano.somes, and, without doubt, future 

 studies will reveal the blood parasite from 

 which they are derived. The Crithidia 

 show no undulating membrane, in the or- 

 dinary truncated form, and on account of 

 their peculiarity for the present at least 

 are to be considered as representing a dis- 

 tiiiet genus. 



Isolation of Trypanosomes from Accom- 

 panying Bacteria: F. G. Novy and R. S. 

 Knapp, University of Michigan, Ann 

 Arbor, Mich. 



In general, it may be said that bacteria 

 once introduced into a culture of trypano- 

 somes tend to outgrow and check the de- 

 velopment of the flagellates. In excep- 

 tional-instances, however, the bacteria thus 

 introduced exert little or no interference 

 and may be even apparently beneficial. 

 While in the former case the trypanosomes 

 die out, in the latter instance the mixed 

 culture may be kept for six months or 

 longer. 



The isolation of the trypanosomes in 

 pure form from such mixed cultures is a 

 matter of some importance, especially when 

 it is desired to study the pathogenic action 

 of the flagellates. The need of some meth- 

 od of separation was particularly felt in 

 connection with the study of the mosquito 

 trypanosomes which, since they are present 

 in the intestinal canal, are always accom- 

 panied by various bacteria and yeasts. 

 After many ineffectual attempts the fol- 

 lowing method was successfully employed 

 for the isolation of pure cultures of Her- 

 petomonas and Crithidia. 



By means of a small glass spatula, made 

 by drawing out the end of a glass rod, a 

 little of the mixed ciilture was spread in a 

 series of streaks over six Petri dishes con- 

 taining solidified blood agar. The Petri 

 dish, known as the 'Kriegsmiuisteriums- 

 Modell 2, ' made by Greiner and Friedrichs, 

 is particularly adapted for this purpose, 

 inasmuch as it can be sealed effectually by 

 means of a wide rubber band. The sealed 

 dishes are then set aside at room tempera- 

 ture for ten to twelve days. The last plate 

 or two of the series will be found to show 

 isolated colonies of trypanosomes which 

 can be transplanted in the usual way to 

 the test tube. This method will undoubt- 

 edly be found useful in future studies of 



