ON EGGS OF MARINE ANIMALS 6i 



Table 

 WEAK STRONG 



Flemming Flemming 



I per cent chromic acid 25 cc. i per cent chromic acid 15 cc. 



I per cent osmic acid 10 cc. 2 per cent osmic acid 4 cc. 



I per cent glacial acetic acid. . . 10 cc. Glacial acetic acid i cc 



Water 55 cc. 



Benda 



1 per cent chromic acid 15 cc. 



2 per cent osmic acid 3 to 4 cc. 



Glacial acetic acid 3 drops 



Meves 



0.5 per cent chromic acid 15 cc. 



2 per cent osmic acid 3 to 4 cc. 



Glacial acetic acid 3 drops 



The Strong Flemming I find superior to the Weak Flemming. 

 In turn, the Meves, as I use it, is better than the Strong Flem- 

 ming — a statement that I make on the basis of experience in 

 fixing animal cells, other than eggs, from Protozoa to mammals, 

 including normal and pathological human tissues. 



Author's method of using Meves' solution 



Although, as I have said before, there is no all-purpose 

 fixing solution, the Meves solution as I modify it comes nearest 

 to being such. (Just, 1933.) Where it fails, Altmann's potas- 

 sium bichromate solution succeeds when I vary the proportions 

 of the ingredients until I get just the right combination for the 

 cell under study. I would greatly urge cytologists to overcome 

 the prejudice against, or fear of, the use of these osmic acid 

 containing fixatives. 



My modification of Meves is very simple: it consists merely 

 of varying the amount of the osmic acid used for each species of 

 Q^g or cell. Instead of using only 4 cc. of the 2 per cent, osmic 

 acid solution, I use, in addition, 3.5, 3, 2.5, 2, 1.5, and i cc. 

 before I decide which is best for the object under study. I take 

 finally that modified solution of the Meves that contains the 

 least amount of osmic acid that blackens the cells. Others, 

 botanists and zoologists, who have used this simple method since 

 it was published (1930) have told me that they find it eminently 

 superior to the Flemming or to the Meves. 



