1891.] Contributions to the Chemistry of Chlorophyll. 143 



(3.) Slowing of the Respiratory Rhythm. The area which, when 

 excited, caused slowing of the respiratory rhythm lies over 

 the continuation of the postero-median column, as it separates 

 from the column of the opposite side, and the part of the floor 

 of the ventricle close to the inner border of the column. The 

 central point of this small area lies between 1 and 2 mm. from 

 the calamus, and between 2 and 3 mm. from the middle line. 



Cardio-inhibition. Whilst cardio-inhibition may be produced all 

 over the floor of the 4th ventricle, as well as just behind the calamus, 

 yet it is best marked both in the frequency of occurrence and in the 

 amount of slowing over the posterior third of the 4th ventricle, and 

 over the inner margin of the continuation forwards of the postero- 

 median column. 



Blood-pressure. (1) Fall. The chief depressor area is in the hinder 

 part of the floor, between 1 and 4 mm. in front of the calamus. 



(2) Rise (cat only). A rise was produced most frequently and 

 most largely from 4 mm. from the calamus forwards to the anterior 

 end of the ventricle. 



These conclusions are exhibited graphically by maps of the 

 ventricle, shaded in various degrees to indicate the intensity of the 

 result ; and a number of tracings are appended as illustrations of the 

 actual changes which were produced by excitation. 



The author concludes with a summary of some clinical applications 

 of this research, as well as of the previous one on " Intracranial 

 Pressure," which forms the subject of a paper in this year's ' Phil. 

 Trans.' by the author and Mr. Horsley. 



IX. " Contributions to the Chemistry of Chlorophyll. No. IV." 

 By EDW. SCHUNCK, F.R.S. Received June 16, 1891. 



(Abstract.) 



This paper is a continuation of the previous ones on the same 

 subject. After describing the action of caustic alkali in a state of 

 fusion on phyllocyanin and the products thereby formed, the author 

 proceeds to give an account of phylloxanthin, the substance formed 

 along with phyllocyanin by the action of acids on chlorophyll. This 

 is followed by a description of the change which chlorophyll under- 

 goes by the action of alkalis, and of the chief product thereby formed, 

 which the author names alkachlorophyll. 



