974 



witli the iron-liematoxjlin (HEiDENHAiN)-eosin stain. I proceeded as 

 follows : 



1. xylol; 2. alcohol 100%; 3. alcohol 96 "/„ ; 4. alcohol 70%; 

 5. water; 6. for six hours in Sy^ Vo iion-alnm nsed as mordant; 

 7. washing in water ; 8. allowing to overstain in iron-heniatoxylin after 

 Heidenhain; 9. washing in water; 10. ditferentiating in iron-alum; 

 11. washing and examining under the microscope; repeating 10 and 

 11 till the ditTerentiation is sutllicieni and after this 12 washing for 





Fig. 1. Spleen of cat, 2 weeks. Zenker. Iion-hematoxylin-eosin, + 250 X 

 natural size. a. megakaryocyte degenerating in a vein with only slightly stainable 

 protoplasm-loop. /). dissolving protoplasm-filaments, c. pyknotic nucleus of a 

 megakaryocyte, some protoplasm still surrounding it. d. megakaryocyte protruding 

 into the vein. e. normal megakaryocyte against the vessel-wall. f. vessel-wall. 



one hour in tapwater. Lastly after treatment with the successive 

 alcohols, the usual after-staining with eosin. 



To secure a good set of animals I killed some young kittens of 

 the same litter, one of a day's lifetime, the following after 1, 2, 3 

 and 4 weeks. To fill up the number I took another kitten, 46 days 

 old, from another litter. Afterwards, of course, also some control- 

 animals. 



When studying a preparation from a one-day-old kitten we see 

 in the spleen numerous giant-cells, mostly in groups of 2, 

 3 or 4, and often close to the trabeculae, so also close to the large 

 vessels that enter the trabeculae. This typical arrangement is even 



