80 
J. E. BLOOMFIELD. 
liura, of whicli it appears to be a local modification. The 
position of the testes is seen in the diagram woodcut. Each 
testis consists of a mass of spherical cells (Plate YI, fig. 1), 
those at its free edges tending readily to separate and fall into 
the coelomic space or body cavity. These readily separated cells 
have, moreover, often advanced in development beyond those 
which lie more deeply in the mass, and have attained the con- 
dition of spermospheres or sperm-polyplasts described below. 
I have not been able to determine the line of demarcation 
between coelomic epithelial cells of the ordinary kind and those 
which build up the substance of the testis. There does not 
appear to be a complete investment of the testis by normal 
coelomic epithelium as there undoubtedly is of the ovary. 
The large lobular, yellowish- white masses which are frequently 
taken for the true testes of Lumbricus are, as Bering pointed 
out, really seminal reservoirs or vesicles^ into which the incom- 
pletely developed cells thrown off by the true testes are received, 
and where they undergo further development. I am indebted 
to Mr. A. G. Bourne, assistant in the Zootomical Laboratory of 
University College, London, for the demonstration of the truth 
of Hering^s views on this subject. Mr. Bourne showed that 
the true testes are usually overlooked, owing to the fact that one 
naturally selects a well-grown specimen of an earth-worm with 
fully developed cingulum for dissection. In such specimens the 
periodic development of the seminal Vesicles or reservoirs has 
proceeded so far that they form the two well-known anterior 
bilobed and posterior unilobed pairs of so-called testicular sacs, 
the middle portions of which stretch across the middle line 
coincidently with the septum between rings 10 and 11, and 
with that between rings 11 and 12. In this state the true 
testes are completely hidden from view, and being at this time 
completely enveloped by the enlarged seminal reservoirs cannot 
be demonstrated. Mr. Bourne, however, found in a series of 
earth-worms dissected for the purpose of tracing the development 
of the seminal reservoirs, when these bodies are in an incom- 
plete or in the periodic undistended condition, that it is quite 
easy to exhibit the four testes, as represented diagrammatically 
in the woodcut here given. 
The SEMINAL VESICLES or RESERVOIRS are seen in immature 
specimens of Lumbricus as six small light-coloured vascular 
growths on the three septa 9-10, 10-11, 11-12, arranged in 
three pairs. The anterior pair grow forwards so as to project 
into the ninth ring, the second grow backward into the 
eleventh ring, and the third pair grow backward into the 
twelfth ring (see woodcut). In the tenth and the eleventh ring 
are the four ciliated rosettes or expanded mouths of the seminal 
