Drs Fantham and Porter, Further Researches, etc. 137 
Further Experimental Researches on Insect Flagellates intro- 
duced into Vertebrates. By H. B. Fanrnam, D.Sc. Lond., M.A., 
‘Christ’s College, Cambridge, and Liverpool School of Tropical 
Meaicne and ANNIE PorTER, D.Sc. Lond.,.F.L.S., Beit Memorial 
Research Fellow, Quick Laboratory, Cambridge. 
j [Read 10 May 1915.] 
i Contents. 
| PAGE 
I. Introduction. : : : : : 5 : ; : 137 
‘II. Material and Methods — . : . ° 5 : 5 : 138 
Ill. Experimental Work 
(a) Experiments with Pisces . ‘ : : E 5 138 
a 5» Amphibia . : ? ; : 139 
(c) ra cies » Reptilia . : : : ; : 140 
(d) s » Mammalia . i F ; : 141 
IV. Some Remarks on the Foregoing Researches . : 5 144 
_Y. Significance of Experimental Results .  . : Baa 145 
| VI. Summary . : ; 5 : : 5 : 3 ; ‘ 146 
. References 3 : : : : ; 6 : : : 147 
I. Introduction. 
The experiments summarised in this paper were made together 
with and in continuation of those presented to the Society on 
November 23 last, and published in this volume, pp. 39—50. 
‘They record the results of the experimental introduction into 
vertebrates of flagellates belonging to the genera Herpetomonas 
and Crithidia, which live naturally in the digestive tracts of 
various insects. The range of experiment has been extended to 
include examples from most of the great classes of the Vertebrata. 
The work is necessarily prolonged and tedious, as some of the 
animals used live for months, and consequently relatively few 
experimental vertebrates can be managed and observed at any 
one time. We commend this remark to the would-be critic, who 
may say that enough experiments have not been performed; we 
would also remind him that destructive criticism is very common 
in these days, but of little value per se, unless accompanied by 
a constructive policy. Indeed, after the important and suggestive 
‘researches of Rogers in 1904—05 on the cultural herpetomonad 
forms of Leishmania donovani, and the work of Patton in 1907 on 
the complete life-cycle of a Herpetomonas, it is little short of 
amazing that experiments of the nature described in this paper 
‘were not immediately undertaken in endemic areas of Kala-azar. 
In other words, little regard was given primarily to the possible 
VOL. XVIII. PT. III. 10 
