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Proceedings of the Royal Physical Society. 



Description of Figures. 



The figures, with the exception of Figs. 1, 2, 3, 5, 7. 9, 10, 12, 13, were 

 drawn under the 2 mm. immersion by Zeiss (long tube) and eyepiece 

 No. 27. The above-mentioned exceptions were drawn under the 2 mm. 

 immersion by Zeiss (short tube) and eyepiece No. 18. The drawings 

 were all made with the camera Lucida. 



Figs. 1 and 2. Trypanosoma raice, from the blood of the skate. 



Figs. 3-6.3. Illustrate stages of the trypanosome found in the 

 alimentary tract of the leech Pontohdella muricata. 



Fig. 3. Rounded-off stage, showing nucleus with eight chromosomes and 

 a central karyosome and the kinetonucleus. No locomotor 

 apparatus present. 



Fig. 4 shows trophonucleus with karyosome in shape of a ring. In front 

 of the kinetonucleus the slender red body visible is a very 

 early stage of the locomotor apparatus. 



Fig. 5 shows reticulate trophonucleus. 



Fig. 6. Rounded-oflf stage. 



Fig. 7. Chromidial condition of rounded-off stage ; the condensation of 

 the dark material in the kinetonucleus into two small dark 

 bodies can be seen in this individual. 



Fig. 8. Eiug-shaped karyosome, with condensation of plastin, can be seen 

 in the trophonucleus. 



Fig. 9. Stage, with reticulate trophonucleus, showing basal granule 

 attached to the kinetonucleus. 



Fig. 10. Two very typical rounded-off indi^dduals. 



Fig. 11. Young trypanosome, showing trophonucleus with ring-shaped 

 karyosome. 



Fig. 12. Spear-headed trypanosome, showing reticulate nucleus and the 

 split rod appearance of the kinetonucleus. 



Fig. 13. Stage, with ring karyosome, enclosing a central granule. 



Fig. 14. Slender trypanosome. 



Fig. 15. Large broad form, fixed with osmic acid vapour. The tropho- 

 nucleus shows the karyosome, with condensation of plastin ; 

 cf. trophonucleus with that of Figs. 16 and 17. 



Fig. 15a. Large form. IN'ote the irregular and scattered character of the 

 trophonucleus. 



Fig. 15&. Smallish round trypanosome to illustrate modification in external 

 shape. 



Figs. 16-27 illustrate some of the appearances presented 

 by the trypanosomes. 



Fig. 16. Large broad form, possibly a female form. Note the tropho- 

 nucleus, with blue staining karyosome ; also the increased 

 number of chromatic thickenings at the periphery of the 

 nucleus, and the pink area surrounding the karyosome. 



