GENERAL ARRANGEMENTS FOR EXPERIMENTS 131 



spring necktie-clips with lead weights of various size attached to them by string, so that the 

 weights can hang over the table-edge. In addition, a bent-wire hook with a heavier weight, 

 e.g. 250 grm., attached is required for certain experiments, as for retracting sternal flap in 

 exercs. IV and VIII, for scapula in exerc. VII, and occipital stump in exerc. XVI. 2. 

 Mounted curved needles for carrying threads round tissues to be ligated. For these a 

 glover's needle. No. 3 size, is pushed point downward into the end of a wooden pen-holder. 

 The glover's needle has a triangular shaft ; the ordinary sewing-needle tends to rotate in the 

 handle under use. After mounting, the needle is bent in the flame to a right angle about 

 6 mm. from the eye-end. It will carry thread or cotton of suitable size, i. e. Nos. 35 and 20. 



3. A packing-needle with hole drilled near its point, the hole being large enough to carry 

 string, is useful in the exercises in which the chest has to be opened or a loop of intestine or 

 other hollow viscus removed between ligatures. It serves also as an efficient and cheap 

 substitute for the surgical aneurism needle usually employed for ligating a cannula into the 

 trachea. Several sizes can be obtained and can be given any desired curvature in the flame. 



4. The ' midget ' Bunsen, besides being economical in initial cost and in use of gas, has the 

 advantage of avoiding the overheating of the Ringer-Locke. Experience shows that the 

 student, while engaged in the experiment, is very liable to neglect the warming of the saline, 

 which in the quantity, i.e. half-litre, allowed him requires repeated attention with the 

 ordinary Bunsen flame, but with the ' midget ' can be left with the flame adjusted under it. 



For some of the exercises a hypodermic syringe is supplied ; the ordinary cheap form 

 answers well, preferably graduated in fractions of 1 c.c. For most exercises are wanted an 

 ordinary inductorium with a Daniell or other cell, and the wires and two ordinary brass keys 

 for the two circuits. The wires from the bridge-key of the secondary circuit to the electrodes 

 are preferably a light twisted double-flex with the colour of one strand different from that of 

 the other. The lightness and combination to a single cable facilitate manipulation of the 

 electrodes ; the differentiation by colour helps identification of the pole, e.g. kathode of 

 break-induced current, where that is required. A few of the exercises require a pair of bone- 

 cutting surgical pliers ; these are supplied. Special items of apparatus suited to certain of 

 the exercises are mentioned below under the exercise to which their use applies. 



Experience shows that students when entering upon the course are prone to proceed in 

 physiological dissections by ways permissible enough in the anatomical room with the dead 

 subject, but highly detrimental to living tissues. Thus, he is likely to pick up with his 

 forceps the nerve-trunk or blood-vessel which he has to isolate for some step in his experi- 

 ment, and in this way will crush the nerve-fibres in the former or cause intravascular clotting 

 in the latter. Also his favourite scalpel is prone to be one with its blade shortened and worn 

 to a tooth-pick shape, a sort of tiny one-edged dagger, and with this, held like a pen, he is 

 at first prone to scrabble in the living tissues, making slow progress with the dissection and 

 confusing his wound with frayed edges of connective tissue, fat, and muscle and small 

 haemorrhages from wounded veins. He has usually to be taught to prefer a full-bladed 

 scalpel and to use with freedom the greater length of the blade. For the skin incisions 

 it has to be impressed on him to clip short the fur, to wet the skin where it is to be incised, 

 and, holding his scalpel as a fiddle-bow is held, to make a swift clean cut of the required 

 direction and length. He also does not realize at first that a 5 cm. skin cut will in most 

 cases mean a 6 cm. skin wound owing to retraction of the cutaneous tissues. 



A practical fact of some utility brought home to the student by carrying through the 

 exercises is the importance of reasonable speed as an element of success in dealing with 

 warm-blooded tissues and organs. With them undue slowness in procedure brings 



S 2 



