Notes and correspondence Free

Under this head is a short communication in the ‘Archiv fiir Anat. and Phys. 1862/p. 275, from Dr. A. Schneider, relating to the so-termed Spiroptera Hominis of Rudolphi, an entozoon, which, from its apparently extreme rarity, has been a puzzle to helminthologists for more than fifty years. The case in question occurred in London, and will be found described in detail by Mr. Lawrence in the ‘Medico-Chirurgical Transactions.’ It was that of a woman in St. Sepulchre’s Workhouse, and the worms were said to be passed from the urethra, and they were occasionally even drawn off through the catheter, so that no doubts with respect to deception appear to have been entertained at the time.^*

Specimens, having been forwarded by Mr. Barnett to Rudolphi, are still preserved in his collection now in the Zoological Museum at Berlin, and it is these specimens which have formed the subject of Dr. Schneider’s observations.

They are contained, as described by Rudolphi, in three bottles. When Dr. Schneider first looked at those contained in one of the bottles, they appeared to be well-known forms, and nothing more, in fact, than the very common Filaria piscium, Auct. (Agamonema piscium, Dies.), a name under which several species of asexual nematoid have been described, which are found in the abdominal cavity and among the muscles of several marine fishes. The specimens in this bottle were the commonest species of all, as was proved by a number of the most distinctive characters. The mouth is surrounded by three indistinct labial lobes, one of which supports a tooth. The vascular system is very peculiar, and presents a disposition met with in but few nematoid worms, the oesophagus having posteriorly a cæcal prolongation. Not in this point only, however, but also in the histological details to which the comparison was extended, did Filaria piscium agree with the supposed Spiroptera hominis.

But the worm is said to have come directly from the urethra, that is to say from the bladder—how did it get there ? It is impossible that a nematoid worm, whose proper habitat is the body of a fish, should, even in an exceptional case, inhabit the urinary bladder of a warm-blooded animal. Such a supposition is contrary to all that we know of the developmental history of the Entozoa. It is far more probable to suspect that the person had herself introduced the worms into that situation. Instances of a similar kind, with various articles, are common enough. The Filaria piscium could be readily procured in London, and would be well known to any one in the custom of eating fish. How well known and abundant they are may be gathered from the circumstance, that in Copenhagen the haddock is not eaten in summer, owing to its containing too many of these parasites. There is no reason, therefore, for surprise at the circumstance that the patient in question, in the course of two years, passed 1,000 of these worms, and that the deception was carried on for so long a time.

A second bottle contains several slender shreds of matter, about an inch in length, which have also been noticed by Rudolphi, who describes them as “concrementa lymphatica.” Their structure and origin Dr. Schneider could not determine with any certainty, but considers it not improbable that they are portions of intestine cut fine.

But if any doubt could be entertained as to a deception in this case, none whatever can attach to the contents of the third bottle. This contains round, tolerably firm, vesicular bodies, which passed through the catheter when introduced into the bladder. Mr. Barnett regarded these bodies as the ova of the worm, and Rudolphi as “concrementa lymphatica,” But it is clear beyond all dispute that they are the ova of a fish, of which they exhibit every distinctive character—the facetted outer membrane covering the cells of the membrana granulosa, beneath which is the shagreen-like coat, and lastly, the vitellus, with its large oil-globules.

In an article^* that appeared in the ‘Bibliothèque Universelle de Genève,’ written by Professor Thury, a rule is given for finding the equivalent focal length of a compound object-glass, which rule being freely translated may stand thus :

To find the equivalent focal length of the compound objective, replace the ordinary negative eye-piece with a positive eye-piece micrometer, the scale of which has a known value, and place in the focus of the objective to be measured a stage micrometer of the same value.

Let N he the number of divisions of the eye-piece micrometer which measures one division in the stage micrometer, and let D be the distance between the two micrometers.

Then F, the equivalent focal length, is equal to

This rule was new to me, and may be so to other readers of the Journal. I have, therefore, sent you the results obtained by applying it to my instrument, adding, for the sake of comparison, and to show the correctness of the rule, the power of each glass with the A eye-pieces, as obtained with the camera lucida a long time ago.

If there were no cause of error, the right hand column, divided by that next to it should give, in every case, the same quotient, viz., the power of the eye-piece. But the slight discrepancies that will be found are readily accounted for by the impossibility of obtaining exact measurements with a micrometer eye-piece of this description, particularly when the lines on the stage micrometer are magnified with high powers. Besides which the draw-tube was sometimes pulled out a little, which would obviously make a difference, i.e., make the powers obtained in this way differ from those obtained by the camera lucida, when the draw-tube was not moved.

Focal length, &c., of a set of objectives obtained by the rule,

The l–12th is Powell and Leland’s, the remainder were made by A. Ross.

It will be observed that with the exception of the l-8th, which ought to be about “125, every objective has less than its nominal focus, notwithstanding which all have not their nominal power ; for by Mr. Ross’s catalogue the l–6th should give 320, and the l-12th 600 diameters. He calls the power of the 2-inch 20, which gives a power of 4 to the eye-piece ; but if we apply this number (4) to the l–6th we find that 320 is the proper power of the l–8th, and that the so-called l-8th, with a power of 420 assigned to it, is something less than a l–10th.

This to me appears very unsatisfactory, and although M. Thury observes in a foot-note that “Les opticiens Anglais semblent ne se faire aucun scruple de ces petites surprises, par la raison que les objectifs coûtent d’autant plus qu’ils ont une distance plus courte et qu’ainsi le constructeur donne plus qu’il ne promêt; entre deux excès, celui la est assurément le meilleur…. C’est celui dont nous avons le moins le droit de nous plaindre,” it seems to me it would be best to call a spade a spade. As to the gain to the customer, if I want a glass of a certain power, what satisfaction is it to be told that, although I have not been supplied with what I asked for, I have got more for my money than I had any right to. An argument of that kind would be simply impertinent, and such as no man with the reputation of our best makers would, I think, use. But the fact remains, that they do make “les petites surprises,” as my l–4th, l–6th, and l–8th are perpetually reminding me.

But these little “surprises” may do the makers themselves injury in a way they little expect. It may happen that a good honest glass is compared with another of the same nominal power but of less pretension, and may fail to show the same objects, the consequence of which is that the work would be said to be “falling off.” I say this is possible because it has happened to me. If I had an opportunity of getting at the true focal length of the “new and improved” l-4th,^* I should probably find why it is not better than the old one, but I have not had that opportunity..

It must not be supposed from the foregoing that I am finding fault with the workmanship of my microscope. On the contrary, I feel bound to say that I consider the finish of everything that I have seen from Featherstone Buildings as second to none, and I believe that everything about my microscope is (like the stand) A 1. Nevertheless, I should like a l–4th to be a and a l-Sth a ISth, or else to be told what they really are.

Some time near the end of 1858 I resolved to treat myself to a l–12th. I had read in the Journal Mr. Shadbolt’s remarks upon Mr. Wenham’s method of effecting this adjustment, and I determined my l–12th should have it. Mr. Wenham, to whom I am an utter stranger, was kind enough not only to explain to Messrs. Powell and Leland his method of applying it, but also to examine the objective when finished. This adjustment is such a luxury compared with the old method, that it will perhaps justify the inquiry, why has it not been adopted by our makers? It is just as easy to make, I think easier, and I do not think any one who has used it for a week could by any possibility be satisfied with the old method ; I may therefore ask again, why has it not been adopted ?

A good deal was written some time ago about the best form of micrometer. I do not wish to provoke a fresh discussion of this subject, and will therefore only say that no man who has conscientiously endeavoured to meke exact measurements of minute objects can by possibility be satisfied with anything less refined than the cabinet micrometer. With a fixed scale like the glass micrometer there never can be anything but guess-work. Who, for instance, would undertake to measure the blood-corpuscles with such imperfect means ? No one, I am certain, who was qualified for the task.

But in using a cabinet micrometer with, high powers and the ordinary stage movements, it is very difficult to make exact contact with the fixed filament ; and although it may be done in time, it is an exceedingly great trial of patience when it has to be repeated, and, what is worse, a great loss of time.

To remedy this inconvenience I suggested to Mr. Thomas Ross an alteration of the object-plate, upon which, as a matter of course, with his better mechanical knowledge, that gentleman improved, and I have found it so exceedingly convenient that I feel bound to recommend it to those microscopists who desire to make accurate measurements withthe least expenditure of time. It would not probably cost much to alter a stage or to apply it to a new instrument, but in consequence of my absence from England I was obliged to have a new object-plate made.

There are people who say that stage movements of any kind are a superfluity, or something worse. Of course those nimble-fingered and clever manipulators will not require Mr. Ross’s help, but the clumsy fellows who, like me, still wish to be accurate, perhaps will. I have ascertained that when using the l–12th I can without difficulty move an object on the stage 1–130,000th of an inch. I beg to introduce to Mr. Ross all who desire this convenience and not superfluity.— J. MITCHELL, Captain European Veterans, Madras Museum; June 20th, 1862.

Polycistina off the Orkneys.—I beg to mention the fact that I have found some Polycistina in sand dredged by Messrs. Waller, Gwyn Jeffreys, and Norman, off the Orkneys, in July, 1861, Lat. 60° 30’ N., long. 0° to 1° E. They are very rare, only nine specimens occurring in fifty slides examined with great care. Still, as I have never mounted any Polycistina, their presence cannot be attributed to any other source, and I am forced to conclude that they come from the locality which I have mentioned, although it is north of their previous supposed habitat. — T. G. STOKES ; August 21st, 1862.

Highley’s New Compressorium.—All the forms of compres-sorium I am acquainted with seem to have been designed by the philosophical instrument maker, rather than the anatomist conversant with the practical requirements of microscopical manipulation, for the space placed at the disposal of the operator is far too limited. If the object subjected to compression be only microscopic, such instruments may serve their purpose. The compressorium, however, is generally used by the anatomist to assist in tracing out parts in objects of some magnitude. If, for instance, we wished to follow the anatomy of an annelid placed on a glass slide, three inches by one inch or longer, we should have some difficulty in bringing all the parts under the compressor; for to do so, we should have to reverse the ends of the slide ; and in all the instruments I have handled, the centre of the slide cannot be placed conveniently in position. To obviate this imperfection in the instruments at present in use, I have arranged a compressorium which meets every requirement, whether for microscopic or larger specimens, animal, vegetable, or pathological.

The arrangement will be readily understood by aid of the the annexed illustration. A base-plate for the support of an ordinary 3 inch by 1 inch glass slide is placed at right angles to a projecting portion that carries the arm and mechanism of “the compressor;” in front of the base-plate, a ledge is placed, against which the glass slide can firmly rest, as suggested by my friend, Dr. Lionel Beale (see illustrations to ‘How to Work with the Microscope/xviii, fig. 80). In the centre of the base-plate is an aperture with a sunk ledge, into which a disc of thin glass can be dropped when required for examining both sides of an object. The compressing ring, fitted with a disc of thin, glass, is gimbled on to an arm that rotates upon a centre pin, which arm is acted on by a millhead-screw’ to secure compression by leverage in the ordinary way. If both the upper and under side of an object are to be examined, two pins are to be screwed into the ends of the base plate, and these, with the pin that stops the arm, (to secure the compression, being central with the aperture in the base-plate), form a tripod stand, so as to allow of the instrument being turned over, and either side being placed on the stage of the microscope at pleasure. By this arrangement it will be seen that any portion of a 3 by 1 glass slide can, by traversing, be brought under the compression, and that every movement and requirement is provided for. One of these instruments will be found’in my collection, in Class XIII, at the International Exhibition.—SAMUEL HIGHLEY, 70, Dean Street, Soho Square, W.

Supplementary Note on the Reproduction, of Thaumantias.— Since my note on the reproduction of Thaumantias was written, each of the secondary polyps of the zoophytes in the small vessel which were supposed to be dead have been reproduced. The new polyps are seated on ringed stalks, which rise up from within the original cells, and have each only fourteen tentacles and their cells seven teeth ; a most delicate membrane unites the polyps to the mouths.of their cells.

In some of the young zoophytes in the larger vessel the polyp stalk was ringed throughout, and in others the ringing at the foot was preceded by a slight dilatation. The Clytea vicophora^* of Agassiz is figured with a polyp-stalk having a like variety in its annulations, and his Clytea posterior with cells rising up within each other.—T. STRETHILL WRIGHT.