88 SCIENCE PROGRESS 



heaven. He describes them as nucleated amoeboid bodies, 

 which protrude processes and are actually locomotive, though 

 this property is impeded by their adhesion to the cover-glass. 

 The normal shape is a small sphere, which flattens out under 

 the cover-glass. Deetjen's platelets can be fixed with osmic acid 

 vapour, and will then be found to stain well with basic dyes. 

 For the further demonstration of their structure he employed 

 eosin and haematoxylin. 



All these statements can be and have been abundantly 

 verified. Puchberger, 1 who used a weak solution of brilliant 

 kresyl-blue, which is allowed to dry on a slide, has examined 

 the platelets in various diseases. A drop of blood is simply 

 allowed to spread out on the stained surface. He states that 

 Deetjen's plates are admirably stained by this procedure, and 

 finds that they are completely absent in pernicious anaemia, in 

 purpura haemorrhagica and certain other cases of purpura. His 

 figures also show that in myelogenous leukaemia the platelets 

 may be so hypertrophied and swollen as to nearly equal the 

 size of an erythrocyte. 



When repeating Deetjen's work we have noticed that should 

 the agar become altered in its salt-content by any bacterial 

 growth, the demonstration of the platelets is greatly im- 

 paired, or may even be impossible. With the medium 

 when used without the agar, it is equally easy to observe the 

 platelets ; and these can be seen to actually form when a drop 

 of this fluid and one of mammalian blood (cat, dog, or rabbit) 

 is allowed to come in contact under a cover-glass. The experi- 

 ment, as might have been anticipated, entirely fails if serum, 

 defibrinated blood, or oxalated plasma free from platelets is 

 used instead of blood. The experiment is negative with the 

 blood of frogs or toads, and no bodies which in any way 

 resemble those described by Deetjen can be seen. 



Since Deetjen's observations were made many observers 

 have contributed to the " Blutplattchenfrage," and there is a 

 tendency to return to the older views of Engel, Arnold, and 

 Wlassow, and attribute the origin of these bodies to a process 

 of fragmentation of the red corpuscles. Outside the body the 

 red discs, as Hayem observed many years ago, often execute 

 spurious movements. Nothing similar to these has been 



1 " Bemerkungen zur vitalen Farburg der Blutplattchen des Menschen mit 

 Brilliantkresylblau," Virch. Archiv, clxxi. 1903. 



