•^tl THE 
MONTHLY MICROSCOPICAL JOURNAL. 
JULY 1, 1869. 
I. — On the Redal PajoiUse of the Fly. 
By B. T. LowNE, M.K.C.S. 
{Bead hefore the Eoyal Microscopical Society, May 12, 1869.) 
The organs for wMcli I have retained the name given to them by 
Weismann, are four in number, situated near the termination of the 
ahmentary canal. They are hollow, conical, glandular organs, about 
^Vth of an inch in length, enclosed in a dilatation of the rectum, and 
having their bases only external to its cavity. I think I shall be 
able to show that their function is the excretion of a urinary fluid ; 
I have, however, retained an anatomical name, instead of giving 
them a physiological one, because its apphcability is obvious, and 
admits of no difference of opinion ; it is not a new name ; and, 
lastly, had I called them kidneys, or even renal organs, I should 
have been comparing them to the totally dissimilar structures found 
in vertebrates. 
Each papilla consists of three parts : an internal central cavity, 
surrounded by a transparent structureless membrane ; around this 
a hollow cone of gland cells, the secreting portion of the organ, is 
disposed ; and external to this again, a tough transparent cone of 
membrane, which I shall call the calyx of the papilla, perforated by 
numerous minute pores, surrounds the whole of that portion of the 
organ which is internal to the rectum. By a little dexterous mani- 
pulation these parts may be separated completely from each other 
DESCKIPTION OF PLATE XVIII. 
Fig. 1. — The rectum with its papillae. 
„ 2. — Base of a papilla, showing the muscular layer x 75 diam. 
„ 3. — A flattened muscular band from the same x 250 diam. 
„ 4. — Calyx of the papilla x 75 diam. 
„ 5. — Central cavity and portion of the gland structure x 75 diam. 
„ 6. — Apex of the calyx x 250 diam. 
„ 7. — Base of a papilla, the muscular layer removed, showing the arrangement 
of the tracheae. 
„ 8. — Transverse section through the middle of a papilla x 75 diam. 
„ 9. — Crystals of uric acid from the urinary secretion of the fly. 
VOL. II. p 
