AMPHIOXUS LANOEOLATUS. 
397 
words in inverted commas constitute the definition of a primi- 
tive or typical nephridium if we add to them these additional 
words, “ the tube opening at one end on the surface of the 
body, at the other into the general coelom.” We recognise a 
variety of modifications of this primitive structure, more 
especially the loss of one or both of the openings of the tube, 
and the cessation of excretory glandular activity on the part 
of its lining cells. We can even admit the dwindling of the 
tube and its total disappearance, with survival of the external 
aperture only. But in all these modifications we start with 
the conception of a tubular modification of part of the coelom, 
open to the exterior, and renal in the function of its lining 
cells. A pore which has had no such antecedent history is 
not nephridial, nor to be classed with nephridial structures. 
It appears to me that we have not at present any grounds 
for assigning the atrio-coelomic funnels of Amphioxus to either 
category. It is not improbable that the developmental 
history of the later stages of the Amphioxus-larva will furnish 
the necesary data. 
The Connective Tissue. — I am desirous of saying a few words 
about the connective tissue of Amphioxus before concluding 
these observations. 
In Plate XXXVI I have, for diagrammatic purposes, coloured 
the connective tissue and the gonad-cells of a uniform purple 
tint. Nevertheless we can readily distinguish in Amphioxus 
varieties of the connective tissue differing from one another in 
density and massiveness. The varieties pass over into one 
another at several points. One of the most important state- 
ments that can be made about all of them is that, like the other 
tissues of Amphioxus, they differ very greatly from the cor- 
respondingly placed tissues in other Vertebrates, and do not 
closely resemble those of any other animal. I am not 
acquainted with any chemical examination of either the con- 
nective tissues or the notochord of Amphioxus. 
The structural varieties presented by the connective tissue of 
Amphioxus may be enumerated as (1) the lamellar; (2) the 
gelatinous ; and (3) the cartilaginoid. When we examine 
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