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XVI. — The Prostate Glands of the Earthworms of the Family MegascolecidEe. By 
J. Stephenson, D.Sc., M.B., Lieut. -Col. Indian Medical Service; Professor 
of Zoology, Government College, Lahore ; and Haru Ram, M.Sc., Professor 
of Zoology, Hindu University, Benares; late Demonstrator of Zoology, 
Government College, Lahore. (With One Plate.) 
(MS. received September 17, 1918. Read December 2, 1918. Issued separately April 15, 1919.) 
CONTENTS. 
PAGE 
Introduction 435 
Historical 436 
Material and Methods 438 
Pheretima haway ana . . . . . .439 
Structure of the gland as seen in dissection . 439 
Microscopical structure of the gland . . 440 
Structure of supernumerary prostates without 
ducts 443 
The prostate in the young Pheretima . . 444 
The earliest stages in the development of the 
prostate 445 
Other stages in the development . . . 446 
Conclusions from the study of the prostate of 
Pheretima 447 
PAGE 
The Prostate of Eutyphceus . . . . 447 
The adult gland as seen in dissection . . 447 
Microscopical structure of the gland . . 448 
The ducts (prostatic ducts and vasa defer- 
entia) 449 
Regeneration of glandular tissue, and 
summary 450 
The Prostate of Dichogaster 450 
The Prostate in the Young Ocnerodrilus . . 451 
Conclusion 452 
References to Literature 452 
Explanation of Figures 452 
Introduction. 
The prostates or spermi ducal glands form a prominent feature in the anatomy of 
the large family of the Megascolecidse. Occurring in the neighbourhood of the termi- 
nation of the sperm-ducts, they assume one of two forms, the tubular or the lobular. 
In the first, the gland typically takes the form of a bent, undulating, or coiled tube, 
cylindrical, with a single central lumen ; in the second, it consists of a loosely or 
tightly packed aggregate of lobules, each with its ductule. The prostatic duct is in 
the first case a continuation of the glandular tube ; in the second, the duct is formed 
by the union of the ductules ; in both cases it is as a rule firm and muscular. 
In the original condition, still maintained in certain genera of the sub-family 
Acanthodrilinse, the terminations of the vasa deferentia are situated on the eighteenth 
segment, and two pairs of tubular prostates open in front and behind the male 
pores, on the seventeenth and nineteenth segments respectively. In the sub-family 
Megascolecinse the male pore retains its position, while the prostates are reduced to 
one pair, which open in common with the vasa deferentia ; in the more primitive 
genera of the sub-family this single pair of prostates have the tubular form, but in 
the more recently evolved genera the tubular has given way to the lobular form. 
In all the other sub-families the tubular prostates have been retained, though their 
number, situation, and relation to the vasa deferentia vary. 
TRANS. ROY SOC. EDIN., YOL. LII, PART II (NO. 16). 
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