378 Major W. B. Fry and Captain H. S. Ranken. [Dec. 23, 



(1) Dark -ground illumination used in the ordinary way, but with the 

 addition of a practically monochromatic light, which improved the definition. 



(2) A method of " vital staining," the stain used being 075-per-cent. 

 toluidin blue in physiological salt solution. This was mixed with blood, gland 

 juice or other fluid to be examined, in a capillary pipette, blown on to a slide, 

 covered with a cover-slip, and ringed with vaseline. With solid organs an 

 emulsion in salt solution was used. The proportion of stain varied with the 

 material from 1-3 to 1-8, according to the rate at which it was felt desirable 

 to cause the staining to take place. 



New methods of fixation and staining have also been used ; these form the 

 subject of a note appended to this paper. Both of these processes give 

 practically the same results. 



I. On Granules in General in Trypanosomes. 



Besides the nucleus and blepharoplast there are other bodies in many 

 trypanosomes which may, in the ordinary acceptation of the term, be called 

 " granules." 



There are certainly two classes of granules to be seen in trypanosomes : 

 (1) those with which we are concerned — probably of nuclear origin and of 

 infective nature ; and (2) others which probably represent stored food material. 

 The latter are of importance for us only because of the possibility of their 

 being confused with the former, and here it may be stated that it has 

 been found possible to fix and stain preparations so as to show a difference 

 between them in staining reaction. Further evidence in favour of this 

 differentiation was met with as a side issue in the course of experiments with 

 hypertonic and hypotonic salt solutions, to be described later. It was found 

 that when trypanosomes swelled up under the influence of these solutions 

 many granules disappeared, leaving evident only from one to three. The 

 inference seems to be that the granules which disappeared, owing to altera- 

 tion in osmotic conditions, are of a quite different nature. 



In this paper the word " granule " connotes those first mentioned, whilst the 

 food granules are ignored in our descriptions, unless specifically mentioned. 



The following varieties of trypanosomes have been available for study, and 

 granules have been observed in all : — 



(1) T. gambiense (Sudan), (2) T. rhodesiense, (3) T. brucei, (4) T. evansi 

 (Sudan), (5) T. nanum (Sudan), (6) T. pecaudi (Sudan), (7) T. lewisi. 



In all cases the granule, as seen by dark-ground illumination, is a small, 

 sharply defined, highly refractile body, and on vital staining it takes up the 

 toluidin blue rapidly, and shows as a deeply stained, more or less circular 

 body, which contrasts with the lighter tint of the trypanosome body. 



