450 C. CLIFFORD DOBELL. 



gether I was able to keep the organisms alive in this manner 

 for a period of 120 days. All attempts to grow the organ- 

 isms in other fluids (solutions of peptone, albumen, etc.) 

 were unsuccessful. The death of the culture was not due to 

 increase in the number of bactei'ia or to a change in the 

 reaction of the medium, both of which remained very much 

 as they were in the beginning. The numbers of the bacteria 

 were somewhat reduced however. Death resulted, I believe, 

 from a too great increase in the amount of katabolic 

 products. 



The method of examination was as follows : — A few drops 

 of the culture were drawn up in a fine pipette (used exclu- 

 sively for tliis purpose), and examined fresh either in a 

 hanging drop preparation or under a coverslip with wax 

 feet, and waxed round the edges. In this latter aneerobic 

 condition I have been able to keep the animals alive and 

 active for thirteen days. For examining the living animals 

 I used almost exclusively a 2*5 mm. apochromatic water 

 immersion objective by Zeiss, with compensating oculars 2, 

 6, 12, and 18. Most of the observations here recorded were 

 made from the living animal. Good permanent preparations 

 were exceedingly hard to obtain owing to the small numbers 

 of the parasites and the large amount of gritty foreign 

 matter in the fluid. However, a few successful preparations 

 were made, the stains employed being Delafield's ha3ma- 

 toxylin, Heideuhain's iron hcematoxylin, and Giemsa's stain. 

 Observation of the living animal was often facilitated by 

 intravitam staining with neutral red. Brillantcresylblau 

 (Griibler) and methylene blue were also tried, but proved to 

 be of but little use. 



From the morphological characters of this parasite there 

 can be no doubt that it is properly referable to the genus 

 Trichomastix, Blochmann. Hitherto this genus has been 

 represented by but a single species, T. lacertas, Butschli. 

 The life-history of this form has been fully worked out by 

 Prowazek. It is, I think, highly probable that the form 

 which I am about to describe will prove to be quite common 



