468 LESLIE B. AREY 
ent remain skeptical concerning the value of data obtained from 
these animals both as regards the corpuscles of their undiluted 
blood or from the use of their blood sera and lymph as diluting 
media. On the other hand in my experiments (p. 454) in which 
the blood of the cat, dog, and man (four individuals) was ex- 
amined both in their own sera and each of the other sera, I con- 
stantly obtained biconcave discs almost exclusively. Further- 
more, the necessity of diluting human sera one-third with water 
to obtain the cup-shape is to my mind incompatible both with 
the doctrine that the cup shape is normal and with the view that 
a 0.6 per cent salt solution is isotonic with human plasma. 
In studying the circulating blood of living mammals the re- 
sults recorded in this paper were obtained without involving the 
possible distortion of corpuscles through pressure from a cover 
glass and oil immersion objective as has formerly been the case. 
Although I am not altogether certain that this is a real danger, 
as Jordan ('15) believes, it is, nevertheless, easily and properly 
avoided. If capillaries of too small calibre to possibly allow the 
assumption of the disc shape (p. 461) be not chosen and if blood 
which is not, and has not been in stasis be observed in non- 
anesthetized cats or dogs, I feel sure that my observation of a 
great preponderance of discs can be verified, Here, again, the 
animals formerly used have largely been either guinea pigs or 
rabbits whose appropriateness is questionable. Since ether and 
chloroform visibly change discs to cups or spheres (p. 462) those 
who make use of anesthesia must disaprove its effect intra vitam. 
Weidenreich ('03) reported cups in the wing of the living bat 
and asserts that the discs seen by Jolly ('05; '06 a; '06 b; '09) in 
the same location represent cups which had previously formed 
rouleaux, these being again resolved into their constituent ele- 
ments and then appearing as discs. One would like to know 
more about the details of these experiments. Were anesthet- 
ics used? Jolly animals were brought out of hibernation and 
showed excessive rouleaux formation which he considers a normal 
intravital condition but which is more likely referable to the 
recent hibernating condition or to partial stasis. No details of 
his observations are given by Weidenreich except that he used 
