CHROMATOLOGICAL RELATIONS OF SPONGILLA FLUVIATILIs. 47 
served. Thus the notochord of Vertebrates, perhaps originally 
hypoblastic, has become mesoblastic, as have also Wolfhan 
and Mullerian ducts. The former phenomenon, the atrophy 
of the cephalic nerve-ganglia, is in accordance with a 
principle which appears to have a wide application in 
embryology, namely, the transference or attraction of nutri- 
tion. 
On the CHRoMATOLOGICAL RELATIONS of SPONGILLA 
FLUVIATILIS. By H.C. Sorsy, F.R.S., &c. 
I nap long been anxious to examine fresh specimens of 
Spongilla, since the old and dry specimens which I had 
studied clearly showed that the colouring matters had been 
greatly altered. At length, through the kindness of Mr. E. 
Ray Lankester, I was able to investigate the subject in a 
perfectly satisfactory manner. I had previously examined 
some of the marine sponges growing on the coast of Devon- 
shire, which are often of a fine orange colour, but sometimes 
have a well-marked green tint. In the natural state these did 
not show the band in the red characteristic of chlorophyll ; 
and, though when dried and digested in carbon bisulphide 
the solution contained a small quantity of chlorophyll, yet I 
could not be certain that it had not been derived from a 
small portion of some alga accidentally enclosed in the 
sponge. ‘The exact nature of the green substance is there- 
fore still open to some slight doubt. The chief coloured 
constituent was an orange substance soluble in carbon 
bisulphide, which, when so dissolved, had a pink tint in dilute 
solution. ‘The spectrum had no detached narrow absorption- 
bands, but cut off the whole of the green and blue, and when 
diluted allowed the blue to pass rather more readily than the 
green. I was not able to distinguish any difference between 
it and an orange-coloured substance found in the eggs of the 
crab, but it would be premature to say that the two are 
identical. There is also an orange colouring matter found in 
the soft parts of some species of Cardium, closely allied, 
though not identical, with these, and on the whole it seems 
pretty clear that the coloured compounds found in some 
marine sponges are either identical with or closely related 
to those met with in animals, and unlike those occurring in 
the higher classes of plants. Fungi do, indeed, sometimes 
