796 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
consequence, the irritating body becomes enveloped in a network of 
delicate but exceedingly tenacious and sticky threads. A healthy 
Holothurian can emit the tubes five or six times in succession ; the only 
object to which they do not appear to adhere is the slimy body of the 
Holothurian itself. 
Mr. Minchin is of opinion that each Cuvierian tube possesses a sort 
of automatic power of rapidly elongating, the explanation of which must 
be sought for in the structure of the organs themselves, and which, there- 
fore, he is not at present able to give. At any rate in H. nigra the power 
of elongation is not due to the presence of fluid. 
It would appear that the normal process of ejection is this ; irritation 
of the skin of the Holothurian is ultimately transmitted to the base of 
the Cuvierian organs ; certain of these commence to elongate with great 
rapidity, soon find their way out of the body, and continue to elongate 
outside ; as they are generally directed by the animal some of the tribes 
are almost certain to come in contact with, and stick to the irritating 
body or foe. After this they break off at their point of attachment to 
the respiratory tree, and new organs begin to replace them. 
The next question is, how do the tubes pass through the wall of the 
gut? From the observations and dissections which he has made Mr. 
Minchin thinks that the Cuvierian organs, after commencing to elongate 
within the body, are in some way directed to the wall of the cloaca, 
which they break through. It is possible that the powerful contraction 
of the body-walls, compressing the liquid in the coelom, causes the wall 
of the body-cavity to break at its weakest point, which is, presumably, 
the dorsal wall of the cloaca through which the organs are then forced. 
The author has often found pieces of the cloacal wall ejected with the 
organs. 
Mr. Minchin is inclined to agree with Herouard in considering these 
organs as a modified portion of the respiratory tree. It is well known 
that Holothurians easily eject their viscera, and experiments in feeding 
show that these viscera are very unpalatable to a number of animals. 
As the expense of repairing these viscera must be considerable, Mr. 
Minchin suggests that the Cuvierian organs are simply a portion of the 
viscera specially modified for ejection. 
Echinochrome.* — Hr. A. B. Griffiths has some observations on this 
respiratory pigment, which was discovered by Dr. MacMunn in 1883, in 
the perivisceral fluid of certain Echinoids. He finds that it has the 
empirical formula of C 102 H 99 N 12 FeS 2 O 12 . On being boiled with 
mineral acids it is converted into haematoporphyrin, hsematochromogen, 
and sulphuric acid. The first of these, which was found by MacMunn 
in the integument of Asterias rubens and other Echinoderms, is, very 
probably, derived from the pre-existing echinochrome. In somi points 
echinochrome resembles haemoglobin and chlorocruorin, and it is 
probable that it is a respiratory pigment in a lower state of develop- 
ment. 
Organogeny of Amphiura squamata.j — M. L. Cuenot points out that 
Mr. MacBride in his recent paper J on the development of Amphiura 
* Comptes Rendus, cxv. (1892) pp. 419 and 20. 
t Zool. Anzeig., xv. (1892) pp. 343 and 4. 
J See ante , p. G21. 
