SCIENCE. 



159 



ever, be dispensed with. Put the cat in a close box, little 

 larger than itself, and pour in 5 cc. of chloroform, or 

 20 cc. of ether. It usually becomes quiet in from 5 to 15 

 minutes. When touching the conjunctiva causes no 

 winking, remove the cat to the large tray, Bring the 

 head and neck nearly into line with the trunk. Part the 

 hair upon the neck along a line between the angle of the 

 mouth and the convexity of the shoulder. Along this 

 line, divide the skin for 6—8 cm., opposite the larynx. 

 This will either expose the Vena jugularis at once, or 

 permit it to be seen when the borders of the skin are 

 raised. 



With the tracer, separate the vein from the adjoining 

 parts for about 1 cm., and pass a bit of string entad * of 

 it. Then turn the cat on the side, with the exposed vein 

 over a bowl ; the string makes it easier to pass the scal- 

 pel or blade of the scissors entad of the vein, which may 

 then be cut. Let the blood flow into the bowl, occa- 

 sionally lifting the body so that the blood may come 

 more readily from the abdomen. 



When the flow ceases, replace the cat in the box, with 

 an additional 5 cc. of chloroform, or leave it upon the 

 tray, and apply the chloroform upon a towel held very 

 closely at the nostrils so as to prevent access of air. 

 Death usually ensues in a few moments. If it be desired 

 to ascertain the weight of the entire animal, the blood 

 should be weighed. 



If the more delicate internal parts or the microscopic 

 structure are to be studied, the remaining operations for 

 the procurement of the brain should be performed within 

 24 hours. But if the specimen is desired only for the 

 Assures or the coarser anatomy, removal may be deferred 

 for a week, provided the head be kept in a cool place. It 

 should not, however, be allowed to freeze. 



Separation of the skull. — Connect the angle of the 

 mouth with the incision already made. If the sk n is to 

 be mounted, this should be the only incision, and the 

 skin must be dissected from the mandible as well as from 

 the rest of the -head. But if, as is more often the case, 

 the skin is not to be preserved, while the muscles etc., of 

 the neck are to be examined, make a corresponding in- 

 cision from the angle of the mouth upon the opposite 

 side. 



In all subsequent operations, unless otherwise stated, 

 both sides are to be treated alike. 



Dissect the skin from the maxilla as far as the ventral 

 margin of the orbit and cut the nasal cartilages. Dissect 

 the skin from the nasal and frontal regions, including the 

 upper and lower lids, but leaving the third lid, Membrana 

 nictitans, attached to the ball. Remove the skin from 

 the rest of the head, dividing the meatus auditorius 

 close to the head. The parotid gland will be removed 

 with the ear, but the submaxillary, of a darker 

 color, will remain with the head. Reflect the skin from 

 the cervical muscles for about 2 cm. caudad of the crista 

 lambdoidalis. 



Dissect the origin of thzM.masselericus from the zygoma, 

 noting that its cephalic and caudal borders are strength- 

 ened by tendinous bands which must be cut. Push a 

 nipper-blade between the eyeball and the cephalic root 

 of the zygoma, and nip the latter as close as possible to 

 the maxilla. Then nip the caudal root at the angle be- 

 tween the transverse and longitudinal parts of the zygoma, 

 just laterad of the Fossa glenoidalis ; remove the zygoma 

 with the bone-scissors. 



Grasp the lateral aspect of the eyeball with the forceps, 

 and rotate it mesad so as to expose its attachments, by 

 the muscles and N. opticus, to the bottom ot the orbit ; 

 cut the attachments with scissors, leaving the Mb. nicti- 

 tans connected with the ball. If the eyes are to be stud- 



* The meaning of this and some other unfamiliar terms may be learned 

 from a paper (o) in "Science" for March 19 and 26. Most of the words 

 employed are to be found in a Human Anatomy, or a dictionary, general 

 or medical. 



ied or preserved, mark them right and left by numbers or 

 tags ; the proper position is always indicated by the Mb. 

 nictitans. 



Slightly ventriduct the mandible and move it from side 

 to side so as to indicate the position of the Ath. temporo- 

 mandibulare. Often the capsule has been opened already 

 in nipping the caudal root of the zygoma. If not, it is 

 to be cut while on the stretch by inserting the arthrotome, 

 and cutting until separation is complete on that side. 



Dissect the M. temporalis from its cranial origin, and 

 then from its insertion upon the processus coronalis of the 

 mandible. Then bring the mandible to a right angle with 

 the rest of the head ; feel for the caudal border of the 

 hard palate, and for the tips of the processus pterygoidei ; 

 at a point midway between them push a scissor-blade en- 

 tad of the soft palate, and divide it ; then divide the mu- 

 cosa forming the dorsal wall of the postnares, and dissect 

 it from the basis cranii to the atlas. 



The mandibles are now attached to the rest of the head 

 by some muscles, by the mucosa at the angles of the 

 mouth which may now be divided, and by the slender 

 piers of the hyoid arch. These last join the skull at the 

 lateral side of the bullae, where they are to be divided 

 with the arthrotome ; if it be desired to examine the mode 

 of their attachment, they may be cut with the bone-scis- 

 sors at a little distance from the attachment. 



Turn the tip of the mandible still farther ventrad and 

 caudad, and dissect off the muscular masses that are in- 

 serted between the bullae ; near the caudal ends of the 

 mesal borders of the bullae emerge several nerves, which 

 should be divided with the scissors or a sharp scalpel at 

 about 1 cm. from the skull. By continuing the re- 

 moval of the muscles across the Ath. atlo-occipitale this 

 is exposed. Put the membranes upon the stretch, and 

 divide them with a sharp scalpel along the cephalic border 

 of the atlas. This exposes the myelon, which is to be 

 divided in the same way. The remaining ligaments and 

 the cervical muscles may be cut with the arthrotome and 

 the skull proper is then separated from the rest of the 

 body. Place the skull in the n. s. s., and wash the hands 

 and the instruments which have been used. 



Exposure of the Brain. — The method here de- 

 scribed is by successly removing bits of the skull with the 

 nippers. 



Caution. — In the later stages of the operation there is 

 considerable risk of injuring the brain by the unintentional 

 pressure of the nippers. In whatever way the bone is 

 grasped, when force is applied, the tendency is to approxi- 

 mate the cutting edges as nearly as possible, and thus to 

 bring their planes into right angles with the surface of the 

 bone. This of course crowds the convexity of the ental 

 blade against the brain, and may crush it seriously. It 

 may occur either from the turning of the nippers in the 

 hand, or more frequently from the escape of the skull from 

 the grasp of the other hand. The accidents may usually 

 be avoided by keeping the matter in mind, by having the 

 right hand dry, and aiding the grasp of the more or less 

 slippery skull by a small towel or bit of coarse muslin ; 

 this last is also desirable during some stages of the opera- 

 tion as a protection of the hand itself from abrasion. 



In using the nippers another precaution is to be ob- 

 served. If the bit of bone to be removed is attached only 

 to bone it may be either cut or broken, or twisted off ; but 

 if it adheres to the dura or other soft parts, only cutting 

 should be employed, and that done with care. 



During the exposure of the brain the head should be 

 frequently dipped into the n. s. s. If obliged to suspend 

 the operation for more than an hour, wrap the head in a 

 cloth wet with the n.s. s., and set in a cool place. 



Nip off the caudal root of the zygoma, including the Fs. 

 glenoidalis. Insert a nipper-blade ir.to the meatus audi- 

 torius, and remove the bulla in fragments. With the 

 scissors cut away the membranes attached to the margin 

 of the Fm. magnum. Nip off the occipital condyles, 

 with the intervening area of the basioccipital for 2-3 mm. 



