Special Methods 131 



The following is Strasburger's modification of Meyer's method, 

 and shows the connections with great distinctness: 



1. Treat the fresh sections with 1 per cent osmic acid, 5 to 7 minutes. 



2. Wash in water 5 to 10 minutes. 



3. Treat with a solution of iodine in potassium iodide (0.2 per cent 

 iodine and 1.64 per cent potassium iodide), 20 to 30 minutes. 



4. Transfer to 25 per cent sulphuric acid, which should act for at least 

 half an hour; 24 hours may be necessary. 



5. Bring the sections into 25 per cent sulphuric acid which has been 

 saturated with iodine. Add a drop of Meyer's pyoktanin solution 

 (1 g. pyoktanin coeruleum as sold by E. Merck in Darmstadt in 30 c.c. 

 of water). 



In about 5 minutes the sections will be stained sufficiently and 

 can be examined in glycerin. If there are annoying precipitates, 

 remove them with a soft brush. 



According to Meyer, the swelling is an advantage only when 

 the walls are very thin. When the walls are thick, the connections 

 show better without any previous swelling. 



Try the following method with the seeds of Diospiros, Latania, 

 Chamerops, Phoenix, or Phytelephas: Soak in w r ater and cut thin 

 sections. Extract the oily and fatty substances with xylol; wash 

 in 95 per cent, or in absolute alcohol; stain in anilin blue (Hoffman's 

 blue 1 g. dissolved in 150 c.c. of 50 per cent alcohol) for a few minutes. 

 Examine in glycerin. This method succeeds very well with seeds of 

 the date, which is sold at all groceries. 



Permanent preparations may be secured by the following method: 



1. Fix in 1 per cent osmic acid, or in absolute alcohol, 5 to 10 minutes. 



2. Stain for 24 hours in Delafield's haematoxylin. 



3. Wash for a few minutes in acid alcohol (5 drops of hydrochloric acid 

 in 50 c.c. of 70 per cent alcohol). 



4. Wash for a few minutes in ammonia alcohol (5 drops of ammonia to 

 50 c.c. of 70 per cent alcohol). 



5. Dehydrate in absolute alcohol, clear in xylol, and mount in balsam. 



STAINING CILIA 



The cilia of the large spermatogoid of Ginkgo and the cycads 

 take a brilliant stain with gentian- violet, whether the gentian- violet 

 be used alone or in combination with safranin. The cilia of the 



