158 



SCIENCE. 



HOW TO OBTAIN THE BRAIX OF THE CAT. 

 Felts domestic a. 



BY PROFESSOR B. G. WILDER, M.D. 



In the first number of " SCIENCE," under the title " A 

 Bit of Summer Work," the writer suggested that teachers 

 and students of the several sciences in which an acquaint- 

 ance with the brain is required should try to gain some 

 definite and personal knowledge of the organ by the pre- 

 paration and dissection of the brain of the domestic cat. 



The publication of the article was followed by numerous 

 expressions of a desire to adopt the suggestion, but ac- 

 companied often by requests for reference to some work 

 containing explicit directions as to the best methods of 

 manipulation. 



No such work is known to the writer. The " Dissect- 

 or's Guides " and some general treatises on Human 

 Anatomy give more or less complete instructions for the 

 removal of the human brain : but the conditions are 

 usually such that the most expert manipulator can hardly 

 avoid some injury to the organ. 1 



For the removal of the brains of the lower mammals, no 

 adequate directions have been published, so far as the 

 writer is aware, although Chauveau enters (A, 716) 2 into 

 some detail with regard to the horse's brain. Straus- 

 Durckheim expressly states (B, 1, 321) that the method for 

 animals is the same as that for the human subject, and 

 the " Practical Physiology " (Foster & Langley, A, 215) 

 contains merely the caution that " the brain of the dog or 

 sheep should be removed from the skull as carefully as 

 possible, especial pains being taken to cut the internal 

 carotid arteries and the cranial nerves close to the skull," 



As guides to practical work for beginners in anatomy, 

 the works just mentioned may, in respect to the brain, be 

 likened to some " Manuals for Young Housekeepers," whose 

 accomplished authors seem to realize neither the inex- 

 perience of their readers nor the possibility of conditions 

 very different from their own, and whose teachings, there- 

 fore, prove ill-suited to the comprehension and the circum- 

 stances of those whom they desire to assist. 



Now it is probable that few readers of " SCIENCE " have 

 had the benefit of a full medical education, and it is cer- 

 tain that the anthropotomical method for the extraction of 

 the brain does not answer for the removal of the brains 

 of most other mammals. The skulls are usually so ir- 

 regular in outline that the use of the saw is difficult and 

 apt to do injury to the brain ; moreover, at least for the 

 purposes of preliminary study, the integrity of the brain 

 should be ensured even when it involves the complete 

 destruction of the skull. 



The writer is therefore led to hope that the number of 

 those who desire to obtain and dissect the brain of the cat 

 is large enough to warrant the publication in " Science " 

 of the directions which are followed by the students in 

 the Anatomical Laboratory of Cornell University. Any 

 criticisms or suggestions will be thankfully received. 

 The method here described in detail is to be preferred 

 when the brain is wanted entire, and especially when the 

 length of the nerve roots is an object. The more expedi- 

 tious methods which may be adopted under other con- 

 ditions will be described hereafter. 



Instruments and Materials. — Medium scalpel ; 3 

 sharp scalpel ; arthrotome ; tracer ; curved scissors ; 



1 The writer has employed a modification of the ordinary method, and 

 will take an early opportunity of submitting it to other anatomists. 



a The system of references adopted in the present paper is the same as 

 that described by the writer in No. 38 of this journal, p. 122, excepting 

 that the numbers of papers published since 1873 are in smaller type thin 

 those oi the papers which appeared prior to that date, and which are in- 

 cluded in the Royal Society Catalogue." 



* Cases of dissecting instruments containing the arthrotome, tracer, 

 scalpels of three sizes, curved scissors, forceps, fine-pointed forceps and 

 curved scissors, and blow-pipe, are sold by Messrs. Codman & Shurtlcff, 

 of Boston, for $q.oo. The nippers and bone-scissors must be obtained 

 separately, as will be explained presently. 



bone-scissors ; forceps ; nippers ; a cat's skull ; large 

 tray for the cat ; small tray, or a folded cloth, for the 

 head ; block ; small towel, or piece of muslin, for aiding 

 the grasp of the head ; paper for scraps ; basin and towel ; 

 dish of 7 p.c. brine, about 6 cm. deep, and 20 wide, con- 

 taining some well-soaked cotton ; bowl of normal saline 

 solution (15 grains of salt to 2000 cc. of water) sufficient 

 to cover the head after its separation from the body ; 

 bowl for catching the blood ; wide-mouthed jar or covered 

 dish, of 60-70 p.c. alcohol, with some well-soaked cotton 

 at the bottom. 



Some of these items need explanation. The arthrotome 

 — sometimes called " disarticulator "— is a short and 

 strong double-edged scalpel, with a steel handle like that 

 of the common "cartilage knife." The same use can be 

 made of any short strong scapel ground down so as to 

 have two edges of only moderate sharpness. Such an in- 

 strument saves the keener and thinner edges of the or- 

 dinary scalpels. The tracer looks something like the or- 

 dinary dental excavator, but its end tapers to a blunt 

 point, which is so curved as to form about the quarter of 

 a circle, and moderately sharpened on the concavity. 

 This is used for tracing and isolating nerves and vessels, 

 and is not only safer than the scalpel, but less liable to 

 injury. Its cost is only 25 cents. The bone-scissors are 

 simply a strong pair of curved scissors, employed for com- 

 paratively rough work. The nippers here referred to are 

 the " diagonal side-cutting pliers " of the dealers in hard- 

 ware. Instead of being parallel with the handles, as with 

 most "bone-nippers," or at a right-angle therewith, as 

 with the ordinary " cutting-pliers," the blades of these 

 form with the handles a very open angle, confering upon 

 the user an advantage similar to that which is gained by 

 the employment of curved scissors. The nippers are to 

 be had of seven sizes, from 10 to 20 cm., (4 to 8 inches) in 

 length, and cost from 70 cents to $2. 25, according to the 

 size and the maker, those of Stubbs being the more ex- 

 pensive and highly finished. For use upon cats, those 

 which are 5 inches long are to be preferred, and their 

 points, if too wide, may be ground off. 



The writer has been accustomed to use the nippers since 

 1872 for the removal of the brains of cats, dogs and young 

 human subjects. It was not until after the year men- 

 tioned that he noted, in Flower's paper (3, 194), a remark 

 as to " clipping away the skull from the brain of a 

 monkey," the instrument, however, not being specified. 



The nippers are equally applicable to living animals ; 

 with the rabbit, cat, and all but the larger dogs, the skull 

 may be penetrated with them, and the opening easily en- 

 larged to any extent desired. Perhaps the surgical 

 "bone-forceps" have been employed for this purpose, 

 but the " Hand-book for the Physiological Laboratory " 

 (Sanderson, A, 305 and 418), directs that even so thin a 

 skull as the rabbit's should be removed with the trephine 

 and the scissors, and Dalton's recent paper (2) mentions 

 only the trephine for exposing the brain of dogs. 



Alcohol of the proper strength is readily prepared by 

 adding 1 part of water to 2 parts of 95 p. c. alcohol. Ac- 

 cording to the size of the bowl or jar, the amounts may 

 be 100 and 200, or 150 and 300 cc. 



For the hardening and temporary preservation of the 

 brain, the common deep finger-bowl is convenient. It 

 may be covered with a piece of window-glass. Flat- 

 bottomed dishes, with wide edges ground for the recep- 

 tion of covers, are made by Messrs. Whitall, Tatum & 

 Co., of New York and Philadelphia, and the same firm 

 have on hand wide-mouthed vials and specimen-jars of 

 many sizes. 



Killing and bleeding the cat. — When the brain 

 is to be studied the animal should not be "pithed," on 

 account of the injury to the medulla, and the settling of 

 blood at the base of the organ. The cat may be 

 drowned, but the following method is to be preferred as 

 less distressing, more convenient, and permitting the evac- 

 uation of most of the blood. The bleeding may how- 



