THE EXPERIMENTAL PRODUCTION OF AN INTERNAL HYDROCEPHALUS. 431 



a 5 per cent suspension of lampblack in Ringer's solution was injected into the 

 lateral ventricle of one animal, and the others of the litter were used for injection of 

 other materials or for control. The head of the kitten receiving the intraventricular 

 lampblack enlarged; the fontanelles widened markedly and a typical clinical picture 

 of the desired condition resulted. 



Subsequently the technical procedure was modified in many ways. Experi- 

 ments demonstrated that a somewhat more pronounced pathological change, with 

 less disturbance of the kittens' activities, could be produced by subarachnoid injec- 

 tion of the lampblack through a needle in the occipito-atlantoid ligament. This 

 latter method alone was employed in the experiments on adult cats. In the earlier 

 cases two intraventricular injections of lampblack were sometimes given with an 

 interval of several days between; later it was found that this double injection was 

 useless, provided the concentration of the carbon in the initial injection were great 

 enough. Customarily, in both cats and kittens, as much cerebro-spinal fluid as 

 possible was allowed to escape from the occipito-atlantoid or ventricular needle; 

 injections of 1 c.c. (in kittens) to 10 c.c. (in adults) of a 5 to 10 per cent suspension 

 of lampblack in Ringer's solution were made through the needle after the release 

 of fluid. The lampblack originally injected was found to be more efficacious than 

 any other sample tested; it is sold under the trade name of "Germantown Black" 

 and is manufactured by the L. Martin Co., New York City. Other lampblacks 

 produce a similar condition of hydrocephalus, but not as rapidly or as invariably as 

 does this Germantown Black. Whether this difference in reaction is due to difference 

 in size of granulation or to some other "binder" in the carbon is not known. 



The intraventricular or subarachnoid introduction of these carbon granules 

 was controlled by similar injections of equal amounts of other insoluble granules in 

 suspension. Because of its wide employment as an injection-medium, cinnabar 

 (red mercuric sulphide) was selected as the routine control granule. None of the 

 particular insoluble substance used for this purpose gave rise to an internal hydro- 

 cephalus, but it does not seem improbable that other insoluble granules may be 

 found to produce such a pathological change. 



A point of considerable practical importance in the care of kittens subjected 

 to experimental procedures concerns the return of the animals to the mother with- 

 out apparent change. In these experiments the hair was not shaved in the area of 

 puncture and the kittens were returned to the mother only when fully recovered 

 from the anesthesia. With these simple precautions it was possible to inject kittens 

 one day of age and to have the mother subsequently take care of them as well as the 

 others in the litter. In general, kittens up to four weeks of age were subjected to the 

 experimental injections; these gave the greatest enlargement of the cranium and 

 remained fairly well for the greatest lengths of time. 



At the end of varying periods the animals (both kittens and adult cats) were 

 sacrificed and injected with 10 per cent formalin through the aorta, as were those 

 dying from the experimental procedure or from bronchial infection (a common 

 difficulty in such animals). After hardening for a suitable period further macro- 

 scopic studies were made and the heads were sectioned. 



