32 Verm. 
VERMES. 
course of the blood (see Bourne), author says that it seems to be different 
in Microchceta , V rochceta, and Megascolex. Attention is called to the fact 
that the nephridium of Arenicola and other Polychcuta is intercellular, 
while that of the Oligpchcuta is mainly intracellular. The nephridia are, 
however, presumably homologous in the two groups, so that the genital 
ducts of the Oligochcuta , although the lumen is intercellular, may be 
modified nephridia. 
Bourne (1), in considering the question as to how the blood comes 
into the dorsal vessel of earthworms, comes to the same conclusion as 
Vejdovsky [see also Horst (1)], as opposed to that of Perrier and Ben- 
ham, that the blood enters the dorsal vessel in each posterior segment 
through the dorso-intestinal vessels, and leaves it by the dorso-tegu- 
mentary vessels. Perrier maintained the precise opposite. , 
Horst (5) discusses the morphology of the various parts of the genital 
system of the Eudrilidce. 
See also Horst (3, 4). 
Embryology, Gemmation, Regeneration. 
Benham (4), budding of Nais elinguis , O. F. M., pp. 212-214. 
Bourne (2), gemmation of the Naidomorpha. 
Kingsley (1). 
Randolph finds that in the regeneration of the tail in Lumbriculus , 
the new mesoderm arises in great part from specialised cells in the region 
of the peritoneal epithelium of the ventral longitudinal muscles, which 
are distinguished by their large size and presence of a cell-body. They 
occur in nearly every somite, and are called “ neoblasts.” After fission, 
the neoblasts of the end segment, which are arranged in a definite way, 
and consist of median and lateral elemouts, begin to divide, and give rise 
to great part of new mesoderm. The circular muscles arise from other 
smaller, probably mesodermic cells, and not from the neoblasts. The 
presence of neoblasts in Naids and Tubifex shows how closely related are 
the processes of budding and regeneration. 
Vejdovsky (1 ; see also 2) gives a most detailed account of everything 
connected with the origin of the genital glands, maturation, and fecun- 
dation of the ovum, formation of cocoon and oviposition, &c., not only 
of Rhynchelmis but of other Lumbricidce. The ovaries of Rhynchelmis 
arise in the septum between the tenth and eleventh segments, but in 
course of growth are carried back to the fiftieth to fifty- fourth segments. 
With regard to the fate of the spermatozoon in the egg, author says that 
when it has reached the centre of the egg, its tail swells up enormously, 
and forms a hyaline sphere from which cytoplasmic striae radiate out into 
the egg. This hyaline sphere is called the “ periplast ” — closely appressed 
to it lies the nucleus of the spermatozoon, which, however, does not long 
remain in that position, but wanders into the interior of the periplast. 
Author has observed this in the living egg (see pi. vi, fig. 14). Later the 
periplast begins to flatten at right angles to main axis of egg, and does so 
