A. D. Imms 
109 
mass of minute dark olive coloured granules which are very refractive. 
It is in this layer that metabolism appears to be most active, for the 
granules are much less abundant in other parts of the animal. A good 
deal of the greenish colour of the larva is due to the fat-body shining 
through the transparent integument. The fat-body cells are much 
vacuolated, and the cell boundaries are only to be distinguished with 
considerable difficulty. Their nuclei are for the most part small and 
inconspicuous, and are irregularly stellate in form. The protoplasm of 
the cells contains, in addition to the granules just mentioned, a number 
of clear spherical globules which stain very readily with Orange G. 
The structure of the fat-body agrees in all respects with Berlese’s 
description of the same tissue in the larva of Gulex spatlmepalpis Rond, 
and he states that the globules are of an albuminoid nature (1901, p. 98, 
and Tav. V, Fig. 60). 
The sub-hypodermal cells have the general characters of fat-body 
cells and, moreover, their protoplasm contains similar granules. As 
already stated in the previous part of this paper ( Journ. of Hyg., 1907, 
p. 296) Viallanes concludes that they come under the category of this 
tissue. 
The various areas of the fat-body are not to be regarded as being 
quite separate and distinct from one another. The divisions here 
adopted have been used because they appear to be convenient for 
descriptive purposes, and in certain parts of the body one layer merges 
into the other. The parietal layer is interruped at each segment, and 
in this respect shows a metameric arrangement. The visceral layer, 
however, is in the form of a continuous sheet passing directly from one 
segment to another. 
The Reproductive Organs. 
The rudiments of the gonads differ in form in the two sexes, the 
male rudiment being short and somewhat globular, while that of the 
female is relatively longer and fusiform. 
The male rudiment in a larva measuring 2'5 mm. 1 in length 
(Fig. 14) consists of a germinal region, a long anteriorly directed 
terminal filament or, so-called Muller’s thread, and a slight rudiment 
of the future generative duct. The organ is situated in the sixth 
abdominal segment. In larvae measuring 5’5—7'5 mm. long, the 
proportions of these three regions have undergone considerable altera- 
1 The measurements are taken from the tips of the brushes to the extremity of the 
abdomen, and do not include the dorsal tuft of setae on the ninth segment. 
