xiii, b, i Barber: The Transmission of Malaria 29 



The degree of development of ova is noted in the table, since 

 this gives some indication of the age of the insect and, conse- 

 quently, of the probability of its having had time to become 

 infected. A large proportion of the insects was found lurking 

 in buildings in the daytime, but some specimens were taken 

 by lamplight. The latter are indicated in the column under 

 remarks. Such insects in this series showed little development 

 of ova, the wings were little, frayed, and the indications were 

 that most of these had freshly emerged and were, therefore, 

 less likely to be found infected. 



It will be observed in Table XV that sporozoites in the salivary 

 glands were found only in specimens of A. umbrosus and ludlowi. 

 In some specimens of A. umbrosus the sporozoites appeared ab- 

 normally thick and short, but in other specimens they were 

 apparently normal. In the positive specimens of ludlowi, spo- 

 rozoites, wholly normal in appearance and staining, were found 

 in large numbers in the salivary glands, and besides, four large 

 pigmented oocysts appeared in the mid-gut. The single posi- 

 tive specimens of maculatus had two pigmented oocysts ap- 

 parently about 6 days old. Of the total 667 dissections of 

 the mid-gut, oocysts were found in 3, or 0.4 per cent; in 508 

 dissections of the salivary glands 7, or 1.4 per cent, were pos- 

 itive for sporozoites. In 167, chiefly A. umbrosus, the mid-gut 

 alone was examined. In a few cases the gut showed no trace 

 of infection, but sporozoites were found in the salivary glands. 

 It is evidently best to examine both gut and salivary glands 

 if one is to ascertain the total number of positives in naturally 

 infected mosquitoes. 



It will be noted that all of the specimens of A. kawari, macu- 

 latus, and tessellatus and a large proportion of the specimens 

 of aconitus, sinensis, and fuliginosus were taken at night. As 

 stated in the introduction to Table XV, such material apparently 

 includes a larger proportion of recently emerged insects than 

 does material collected in houses by day. The one positive spe- 

 cimen caught by lamplight, maculatus, had immature oocysts 

 only. 



In the collections in which at least one infected mosquito was 

 found at the same time and place we have the best basis for 

 comparison of the amount of infection in different species. In 

 this series the numbers taken under such circumstances are too 

 small to afford a sound comparison, but the results may be given 

 for what they are worth. 



