CERTAIN DERIVATIVES OF THE PROTEIDS. 281 



chemical products than the earlier workers had at their com- 

 mand, or where this has been attempted there has in some 

 cases at least existed a certain degree of indefiniteness con- 

 cerning the exact nature of the substances employed. This is 

 the more to be regretted as there are many facts which tend 

 to show that the primary cleavage products of the proteids 

 may differ from each other in their chemical constitution, and 

 if so one might naturally look for pronounced variations in 

 physiological behavior. Further, it unfortunately happens 

 that previous experimental data obtained with isolated pro- 

 teoses and peptones are frequently deficient or entirely wanting 

 on many points of interest. We therefore present our results 

 obtained with various types of proteid cleavage products in 

 the hope that they may contribute somewhat to a broader and 

 more concise knowledge of the subject. The several products 

 we have made use of are fully described as regards mode of 

 preparation, composition, and chemical characters in another 

 section of this paper. Their physiological action is described 

 in the following pages. 



THE PHYSIOLOGICAL EFFECTS OF SOME CLEAVAGE PROD- 

 UCTS OF THE PROTEIDS WHEN INTRODUCED DIRECTLY 

 INTO THE CIRCULATION. 



Technique Our experiments were carried out exclusively 

 on dogs. The animals were made to fast for at least twenty- 

 four hours previous to the operative procedure; they were 

 narcotized by a subcutaneous injection of morphine mixed 

 with atropine, and a mixture of chloroform and ether was ad- 

 ministered during the operative interference and at other tunes 

 when necessary. Arterial pressure was recorded by a mer- 

 curial manometer connected with the carotid or femoral artery, 

 and the injections were made into one of the facial veins from 

 a burette attached to a glass cannula. Intervals of one second 

 were recorded beside the blood pressure curve by means of a 

 metronome time-marker. In observing the rate at which the 

 blood coagulated, portions were drawn from the right femoral 

 artery. The cannula was removed after each withdrawal of 



