LABOR A TOR Y G UJDE JN PH YSIOLOG Y. 



of the fixed glass which covers the hole. Run a film of 

 normal salt solution under the web; place a drop of the 

 same liquid upon the upper surface of the web ; place a 

 small cover glass over it ; fix the board upon the micro- 

 scope stage so as to admit of illumination by transmit- 

 ted light; illuminate; focus under low power. 

 ?. Observations. 



(1) Observe the movement of corpuscles within blood 

 vessels of varying size and irregular course. Make a 

 drawing of the field of observation showing the rela- 

 tive size, the course and anastomoses of the blood 

 vessels. 



(2) Observe whether the motion is equally rapid in all 

 vessels ; if not, observe whether the slower currents 

 are in the larger or the smaller channels. Determine 

 which of the vessels are arterioles, which capillaries, 

 and which venules. 



(3) Have you seen evidence of intermittent force acting 

 upon the corpuscles? If so, desciibe its influence. 

 Determine whether this intermittent force makes 

 itself evident in all of the vessels ; if not, in which 

 class of vessels is it present? 



(4) Do the corpuscles change shape? If so, under 

 what circumstances? 



(5) Remove the cover glass, dry the web with filter 

 paper, touch a point with a pin that has been dipped 

 into dilute croton oil. Without replacing the cover 

 above the web observe whether the presence of the 

 croton oil effects any change in the diameter of the 

 vessels, or in the rate of the blood flow. If there is a 

 change in both, has one a causative relation to the 

 other ? 



(6) Note and describe minutely all changes which take 

 place at and near jthe place touched with the croton 



