464 LESLIE B. AREY 



In view of the rapid action of hypo- or hypertonic salt solu- 

 tions in changing the shape of corpuscles an attempt was made 

 to discover whether the concentration of the fixative could influ- 

 ence the shape of the corpuscles before fixation occurred. Zen- 

 ker's fluid was practically saturated with cane sugar or with 

 sodium chloride and fresh human tissue fixed as before. The 

 result w^as unchanged; the corpuscles became cupped. 



When to drawn human blood, diluted in human serum, is 

 added the fluids of Zenker, Helly, or Orth, cups, discs, and dis- 

 torted forms are seen. The action is more violent than when 

 blocks of tissue are preserved in the same fluids. With Zenker 

 an especially curdy coagulum forms, w^hereas in Orth there is 

 only a fine granular coagulum; in the first named fixatiye cups 

 are abundant, in the latter many fine discs may also be obtained. 

 In Perenyi's fluid the corpuscles assume a peculiar pitted 

 appearance. 



If the finger be pricked through a drop of 1 per cent osmic 

 acid solution, the fixed corpuscles show many cups as well as 

 discs, wedge shapes, and distorted forms. If a drop of blood be 

 first exposed to the air and the osmic acid then added, a greatly 

 increased number of discs are seen, although discs are by no 

 means exclusively present as Weidenreich ('05 b; '10) would have 

 us believe. These facts have been advanced in support of the 

 normality of the cup shape, for it is argued (Weidenreich '08 c) 

 that osmic acid must give faithful preservation since it fixes not 

 only the cup but also discs which have been formed from cups 

 after exposure to air. 



The query immediately arises as to the weight which should 

 properly be given to evidence derived from the action of fixa- 

 tives. Weidenreich ('02), for instance, considers this evidence 

 alone sufficient to establish the cup form (cf. also Lewis '13). 



The fact, however, must not be lost sight of that these cor- 

 puscles are plastic structures of extreme delicacy, mere contact 

 with adjacent corpuscles or obstacles sufficing, when gentle 

 streaming is induced, to cause excessive and varied temporary 

 distortions. Fixation is essentially a coagulation process and it 

 has been shown (Weidenreich '06 b) that the so-called best fixa- 



