A schedule is given for staining the cell walls of young plant tissues in tannic acid and iron alum after the protoplasts have been stained in safranin and orange G. Sections are placed for one minute in 2% aqueous ZnCl2, and are then stained in a 1/25,000 aqueous solution of safranin O. From this they are placed for five minutes in a bath consisting of orange G (2 g.), tannic acid (5 g.). water (up to 100 cc.) and HC1 (4 drops). This is followed by five minutes in 5% aqueous tannic acid and two minutes in a 1% solution of iron alum. A brief rinse in tap water is given between each stage; the slides are raised and lowered about a dozen times at each change to ensure that the new solution reaches the material quickly. The method was originated for shoot apices but it also works excellently on more mature tissues and on adult material. It has the advantage of allowing extremely easy detection of protophloem in the strands even at the very onset of vascular differentiation.