A. D. Imms 
117 
Oenocytes have been found in almost all orders of Insects, but 
practically nothing is known regarding their function. Wielowiejski 
believes that they secrete some unknown substance into the blood, and 
Anglas (p. 405) is of a similar opinion. On the other hand, Pantel con¬ 
cludes from the fact that they absorb methylene blue very rapidly, like 
the cells of the Malpighian tubes, that their function is that of excretion. 
Berlese (in Melophagus ) concludes that they are urinary or excretory cells 
from the fact that they become free during nymphosis, at a time when 
the Malpighian tubes are non-functional, and that they work their way 
among the cells of the fat-body, &c. in order to remove the products 
of metabolism from them. After a while the oenocytes disappear, 
and it is at this period that the Malpighian tubes are fully developed. 
Koschevnokov (1900) from his studies on the honey bee also 
concludes that they are urinary cells. 
The Imagined Buds. 
The larva of Anopheles forms an excellent subject for the study of 
the imaginal buds since they occur in this type in a very generalised 
condition. It is, however, beyond the scope of the present paper to deal 
with this subject in any detail as it needs a much more prolonged study 
than I have been able to give to it. 
Swammerdam appears to have been the earliest observer to correctly 
interpret certain of the imaginal buds, and he discovered those of the 
wings and legs. Culex was among the types he studied, and since his 
time Weismann (1866) has studied the imaginal buds of the larva of 
Sayomyia. A few unpublished observations on those of the former genus 
were made by Hurst, and are mentioned by Miall and Hammond (1892), 
and Thompson has described the buds of the mouth-parts in that same 
genus (1905). I am not aware that there are any further accounts 
which deal with these structures among larval Culicidae. 
I. The imaginal _ buds of the head. The largest and most 
prominent of the head buds are those belonging to the antennae. The 
antennal buds (Figs. 2 and 20) are placed at the bases of the larval 
antennae, but are not in any way enclosed by the latter and are, moreover, 
rather deeply situated within the head. In an Anopheles larva about 
three-fifths grown each imaginal antennal bud is a well developed 
structure and, owing to the growth of the organ within a limited space, 
the basal joints are somewhat folded and telescoped into one another. 
As the appendage enlarges, its outer sheath or peripodial membrane 
Parasitology i 8 
