A reliable and widely applicable means of determining fluorine in organic compounds has long been needed. Increased interest in this field of research in recent years has intensified the need. Fluorine in organic combinations may be determined by combustion at 900" C. in a quartz tube with a platinum catalyst, followed by an acid-base titration of the combustion products. Certain necessary precautions and known limitations are discussed in some detail. Milligram samples suffice, and the accuracy of the method is about that usually associated with the other halogen determinations. Use of this method has facilitated the work upon organic fluorine compounds in this laboratory and it should prove to be equally valuable to others.

New groups 4 and 5 imido complexes derived from the diamidoamine ligand Me3SiN(CH2CH2NSiMe3)2 (N2N) are described. Reactions of Li2[N2N] with [Ti(NR)Cl2(py)3] gave compound 1 in which the N2N ligand adopts a fac-coordination mode. With [Nb(N t Bu)Cl3(py)2], two different Nb(V) products were formed.

and done a final evidence as to the identity of these doubtful stones is the ureterogram. I have never yet seen a ureterogram fail if properly interpreted. I recognize the value of the method that Dr. Lewis has suggested in these particular cases. Dr. H. L. Kretschmer, Chicago: A contribution such as Dr. Lewis' is responsible, in part at least, for the fact that the entire treatment of stone in the ureter, for instance, has come back to the urologist, and that we have more cases referred to us for treatment for intravesical manipulation Fig. 7.-Latest model of ureteral dilator, with detail of parts.instead of having them operated on by the open method. Surely I believe that all of us, if we had a ureteral stone, would want to be operated on by the intravesical rather than by the open operation. Any improvement in the technic or in the instruments is always a step in the right direction. In reference to localizing shadows in the ureter, I think his method is very novel and very good; but it means that Dr. Lewis passed a shadowgraph catheter first, subjecting the patient to a second cystoscopic to accomplish his object. It required a second cystoscopy. Recently we have been doing that in another way. We make a double exposure with one plate. After the shadowgraph catheter has been passed an exposure is made. Then, without changing either the position of the patient or without changing the position of the plate, a Fig. 8.-Use of dilator: A, in strictured ureter; B, entering stricture; C, dilating stricture; D, making traction on a stone in the ureter.second exposure is made on the same plate by changing the position of the tube. In cases of ureteral stone two shadow¬ graph catheters are seen and two ureteral calculi, both in exactly the same relationship to the catheter. In cases in which we suspect a stone, but the suspected stone shadow is produced by an extra ureteral shadow-producing body, we then obtain a double exposure, one of which shows a distinct interval between the suspicious shadow and the ureteral cathe¬ ter. It seems to me in that way we can avoid two cystoscopic examinations. MINNEAPOLISSince 1897, when R. D. Batten1 reported two cases in brothers, each of whom showed symmetrical affections in the two eyes consisting of dark spots in the macula and pallor of the optic nerve heads, a small number of cases in families have been reported.These cases belong in the classification of familial degenerative diseases, among which those affecting the eye are the amaurotic family idiocy of Tay and Sachs; the juvenile type of amaurotic family idiocy of Spielmeyer,2 Vogt, F. E. Batten3 and others, and familial macular degeneration with and without dementia. Between Tay-Sachs' disease on the one hand and macular degeneration without dementia on the other there are, of course, great differences; but analysis of many cases of familial disease seems to show a gradual transition from one to the other. In fact, when one attempts to put together syndromes and to give them definite names, one is at once confronted by n...

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