The genus Dujardinia was proposed by Gedoelst (1916) for the reception of a form considered to be identical with Ascaris helicina Molin, 1860. In the same paper another species, Ascaris nigra, was described by Gedoelst, who mentions that it has close affinities with A. helicina, but does not actually refer it to Dujardinia. The present writer (1920) assigned Ascaris halicoris Owen, 1833, to this genus. More recent work renders it somewhat doubtful whether this species really belongs to Dujardinia, for reasons which will be pointed out later, and though for the present it is retained, it must be regarded as a somewhat aberrant form.

In May 1921 and again in February 1923 a specimen of the copepod Acartia clausi Giesbrecht, from which was emerging a parasitic trematode, occurred in the townets. The first, taken between Rame Head and the Mewstone, outside Plymouth Sound, was a full grown female Acartia, nearly dead, which had the skin broken between the first and second segments of the metasome where the trematode was emerging. The second, taken close to the shore from near the mouth of the Cattewater, was a full grown male which was alive but the skin was broken between the cephalosome and metasome where the trematode was emerging in a similar way to the first.

The economic importance of Trematode infections of mammals has been, and is still, felt even in this country. Epidemic liver-rot in cattle and sheep is probably one of the most serious epidemic diseases with which veterinarians have had to deal and its ravages have, on occasion, been severe. Bilharziasis in cattle is possibly of considerably less importance and, so far as I am aware, has never become endemic in this country. As pathogenic agents the Amphistomes are of third-rate importance.

The object of this paper is to develop the ideas put forward in previous publications (Duke, 1919, 1921).

The spiral organism found in the stomach of various carnivora has been investigated by several observers (see the references at the end of this paper). Such studies have been mainly directed to the morphology of the organism, its infectivity and the part it plays in producing a pathological condition. In the present paper I have been concerned rather with the physiological condition of its host as influencing the prevalence and location of the organism in different regions of the stomach. I was anxious further to ascertain if the organism affected the normal processes of digestion in the stomach either to the advantage or the disadvantage of the animal entertaining it.

The present year, 1923, has already witnessed the celebration of more than one scientific centenary. From divers parts of the world men have gathered together to do homage to Louis Pasteur, who was born just over 100 years ago; to Edward Jenner, who died just 100 years ago; and to Christopher Wren, who died just 200 years ago. But probably only a few of those who joined in these public thanksgivings recalled that 1923 is also notable, in the history of science, for another reason. Exactly two centuries have now passed since the death of the first and greatest of all “microbiologists”—Antony van Leeuwenhoek, Father of Protozoology and Bacteriology, the man who discovered those “microbes” now called protozoa,'bacteria, and yeasts, which the illustrious Pasteur studied to such good purpose, and with which he laid, in part, the foundations of his scientific reputation: and it is exactly 200 years also since the death of another precursor of Pasteur—his countryman Louis Joblot, whose name is now almost forgotten, though it deserves to be remembered by all protozoologists.

Christian Gottfried Ehrenberg, one of the outstanding scientific figures of last century, was born on Easter Sunday, 19 April 1795, at Delitzsch. In this town—then in Saxony, but now in Prussia—his father, Johann Gottfried Ehrenberg, was a municipal official, who was thrice married; his second wife being the mother of Christian Gottfried, who was the eldest son. His mother's maiden name was Christiane Dorothea Becker, and she was the daughter of the innkeeper of “The Red Lion” in Delitzsch. The forefathers of these Saxon Ehrenbergs were mostly millers, and they appear to have been unrelated to the noble family of the same name.

In recent years the speciation of parasites as related to their host relationships has presented some of the most interesting and at the same time most difficult problems in the field of parasitology. These problems are by no means of purely academic interest but are of prime importance in connection with the control and prophylaxis of a number of important infections of man and domestic animals.

In rabbits maintained for experimental purposes at this Department, there has been collected from the stomach on a number of occasions a nematode showing certain affinities with the genus Graphidium Railliet and Henry, 1909. The parasite in question, however, differs from the type species of that genus in characters which must be regarded of more than specific value and it has therefore been assigned to a new genus. It has only recently been noticed in our rabbits. I am indebted to Dr Smith for calling my attention to it. Whether the parasite had heretofore been overlooked in autopsy examinations or has been recently introduced cannot be said. It seems probable that it originated from a wild host and is indigenous to this continent. It was first noticed after our rabbits had been transferred to quarters where they had access to the ground.