ool] Trypanosoma gambiense 7 Glossina palpalis. 525 
x 2000. e 
Fig. 73.—Trypanosoma gambiense from salivary glands, 34 days after infected feed. 
Fic. 74.—T7. gambiense from salivary glands, 42 days after infected feed. 
Fie. 75.—T. gambiense from salivary glands, 43 days after infected feed. 
Fias. 76, 77, and 78.—Z. gambiense from salivary glands, 46 days after infected feed. 
Figs. 79 and 80.—7. gambiense from salivary glands, 56 days after infected feed. 
When alluding, generally, in a previous part of this paper to the types of Trypanosoma 
gambiense found in the salivary glands, it was said that in the salivary glands, and here 
alone, the trypanosomes are found to revert to the normal type found in the blood. 
Figs. 73—80 illustrate this reversion. By comparing them with figs. 1, 2, and 3, which 
represent normal blood trypanosomes, it will be seen that they are very similar to the 
short and stumpy form found in the blood. No such forms have ever been seen in any 
other part of the fly, and we would suggest that the occurrence of these forms in the 
salivary glands, coinciding as it does with the renewed infectivity of the fly, is more than 
mere coincidence. 
INFECTIVITY OF TRYPANOSOMA GAMBIENSE AFTER ITS DEVELOPMENT IN 
GLOSSINA PALPALIS, AS SHOWN BY THE BITES OF THE FLIES GIVING 
RISE TO THE DISEASE IN HEALTHY ANIMALS. 
As has been shown in a previous paper,” the fly ceases to be infective by 
biting within a short time of its infective feed. From this time on for some 
28 days the fly remains non-infective. Table II (p. 526) illustrates this. 
From that Table it will be seen that in this series of experiments the 
flies first became infective 28 days after the infective feed, and that after 
this time the flies are usually found to be capable of giving rise to the 
disease by their bites. 
It was stated above that the most important discovery made in this 
research is the connection between the invasion of the salivary glands 
and the infectivity of the fly. That this appears to be so is shown in 
Table ILL. 
* ‘Roy. Soc. Proc.,’ B, 1911, vol. 82, p. 498. 
VOL. LXXXIII.—B. 2. Q 
