THE DETECTION OF PREGNANCY 4 73 



To quote a particular experiment. On each of two succes- 

 sive days, five grams of cane sugar was injected intravenously 

 into a dog and on the third day blood was withdrawn from the 

 animal and tested. In making the test, one cubic centimetre of 

 serum was mixed with one cubic centimetre of a 10 per cent, 

 solution of cane sugar and 5 of physiological saline. The 

 initial rotatory power of the mixture was + o 0, 45 ; observations 

 made at intervals during forty-five hours showed a steady fall 

 in the rotatory power, which finally became — o°'5. In a second 

 experiment, in which ten cubic centimetres of a 5 per cent, solu- 

 tion of sugar was injected intravenously, the serum was found 

 to be active fifteen minutes after the injection. In the case of a 

 dog which had only received a single injection, the serum was 

 slightly active fourteen days afterwards ; whilst that from one 

 which had received two injections subcutaneously was strongly 

 active nineteen days afterwards. 



Similar results had been obtained previously by Weinland, 

 who had also made the remarkable observation that when either 

 milk sugar or soluble starch is substituted for cane sugar, the 

 blood acquires the power of hydrolysing cane sugar but that 

 these substances apparently do not provoke the appearance of 

 corresponding enzymes. Raffinose, a more complex sugar than 

 cane sugar, seems to be without action. 



Similar observations have been made with albuminous sub- 

 stances and peptones — but the same remarkable result comes 

 out in these experiments : the response being a perfectly general 

 one, not specific, the blood plasma acquiring the power of 

 hydrolysing substances generally of the class to which the 

 hydrolyte used belongs, not this hydrolyte alone. 



In view of the statement that it is possible to detect 

 invertase in blood plasma fifteen minutes after the subcutaneous 

 injection of cane sugar, Abderhalden's further statement is 

 remarkable that when albuminous ,materials are injected, it is 

 often many days before proteoclastic activity is fully developed. 



It is obvious that much is yet to be learnt before it will be 

 possible to give a consistent explanation of the observations, 

 the evidence at present being far from decisive. 



Perhaps the most interesting outcome of the work is that 

 relating to the peculiar condition of the blood in pregnancy 

 It is well known that during this period chorion cells pass from 



