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146 APPENDIX 



EXEKCISE X 



The decapitate preparation for this exercise is preferably female, absence of prostate 

 making easier the assurance that the bladder end of the urethral cannula lies actually in the 

 viscus suitably beyond the sphincter vesicae. The failure of the end of the cannula to lie free 

 beyond the sphincter is a not infrequent difficulty for the student at the start of the experiment • 

 the remedy is, of course, the insertion of a longer cannula or of the same cannula through a 

 more proximal opening in the urethra. 



Obs. 44. The assumption is made that the pituitary extract does not cause contraction of 

 the bladder itself. The assumption is based on control observations with the ureters tied off 

 near the kidneys and the employment of intravenous doses of the extract up to twice as 

 large as used in the exercise. Occasionally a slight and very transient contraction was found 

 to follow the injection, at an interval of 2-3 minutes, long after the circulatory effect had 

 appeared. This contraction may indeed have had some other source than the pituitary 

 extract injected. Usually no bladder contraction at all resulted from the injection. 

 Contraction of the bladder, is, however, among the effects sometimes ascribed to pituitrin. 

 Under the conditions of the observation in the exercise it does not seem to be usual in the cat. 



Obs. 45. The cat preparation exhibits caffeine citrate diuresis reliably in my experience 

 with the exercise. 



Obs. 46. As a variant of the exercise this observation may be replaced by one on reflex 

 contraction of the bladder. For this, to the rubber tube from the urethral cannula a piece 

 of bent glass-tubing is attached. The distal end of the glass tube is curved upward and then 

 down for a couple of cm., so as to hook over the edge of a low beaker, the tube's free end 

 being about 5 cm. above the bladder level. Before attaching the tube to the rubber from 

 the urethral cannula the amount of fluid in the bladder is adjusted, by injection through the 

 urethral cannula, so as to suffice for providing a short column of fluid in the proximal part 

 of the glass tube. This fluid column exhibits slight rhythmical oscillations of niveau with 

 the respiratory (pump) movements of the chest, but usually no contractions of the bladder 

 occur, even though the viscus contains a considerable volume of fluid, so long as the prepara- 

 tion lies undisturbed. 



The arrangement being adjusted and the preparation at rest, stimuli to the fore-limbs, 

 e.g. squeezing of the foot, are found to produce no effect upon the bladder, although they 

 evoke local reflex movement of the limb. But stimuli to the tail and, especially, to the 

 the perineum provoke bladder-contraction, the niveau of the fluid in the glass tube rising 

 after a short latent period and falling back as the contraction passes off. A cotton-wool 

 pledget from cold water laid against the perineum evokes the reflex well. The bladder does 

 not empty itself completely. The student's attention may be drawn to Head and Eiddoch's 

 paper describing vesical reflexes in human paraplegia, Brain, vol. xl, p. 188 ; 1918. 



EXEECISE XI 

 Obs. 47. The capillary pipettes provided are short pieces of 5 mm. diam. glass tube drawn 

 at one end to small capillary size for a length of 6-7 cm. The terminal 4 mm. of the capillary 

 is bent to a right angle with the stem, so that when the tube is inserted vertical into the 

 sp. gr. fluid the blood issues horizontally from the capillary end, and its rising or falling in 

 the fluid is more easily examined. 



