Secretion of a Highly Sulphated Acid Mucopolysaccharide by the Brittle-star, Ophiocomina nigra
THE secretion of a mucus from the tube-feet of ophiuroids is well known1, although the chemical nature of this substance has not been investigated. In a study of the feeding mechanisms of ophiuroids, I find that Ophiocomina nigra (Abildgaard), a common littoral species widespread in the north-east Atlantic and Mediterranean, in addition to the mucin of the tube-feet, secretes all over the body surface an abundant mucus used in conjunction with a detritus-feeding mechanism. Attempts to find the source of this secretion have revealed two types of mucus glands previously undescribed for the species.
The Structure and Function of the Tube Feet in Certain Echinoderms
Comparison of the methods of adhesion and locomotion of the typical members of the four classes of the Eleutherozoa reveals a similarity of the adhesive mechanism in the Asteroidea, Echinoidea and Holothuroidea in that adhesion is due in part to suction and in part to the secretion of mucus. The ophiuroid, on the other hand, has tube feet which, because of their lack of a well-defined sucker, must adhere merely by their intrinsic stickiness. The ability to make use of suction results from the possession of a sucker so fashioned that the median part of the disk may be withdrawn from the surface of contact, with the resultant production of a vacuum. The sucker of the asteroid, echinoid or holothurian tube foot is well adapted for this purpose. An essential feature of such a disk is the presence of an arborescent system of connective tissue fibres extending from the basal plate to the outer limit of the ectoderm. By means of this system, the pull initiated by contraction of the longitudinal musculature of the podium is transmitted to the ectoderm of the sucking disk, the central part of which is thereby lifted up. Where suction plays no part in adhesion, as in the Ophiuroidea, the arborescent system of fibres is lacking.
Augusta Klumpke: pioneering female neurologist.
The latter part of the 19th century was an exciting period when women at last were succeeding in their battle to obtain their medical training and qualifications to practice in the UK, continental Europe and in the USA. Moreover, and perhaps not surprisingly, many of these determined and doughty pioneers showed themselves to be exceptionally able in their chosen specialities. Perhaps the best example of this was Augusta Klumpke (Figure 1), who became an outstanding neurologist in Paris. This year marks the 150th anniversary of her birth.