There are many different cell types and sub-types involved in the immune system. Some of the main types include: Lymphocytes: are white cells which circulate between blood and lymph. They play an important role in fighting infection.
After about 50 to 60 days, beets are ready to harvest. Not only can the roots be dug up and chopped to add flavor to a meal, but the greens of the beets can be harvested periodically and put in salads. Given how well these beets fare in different weather conditions, they can be grown several times in a summer.
Peas are ready to harvest in approximately 60-70 days. When pods of the peas appear to be swelling with rounded pea forms visible, they are ready for picking. Take a test picking every day or so, and note the appearance of the pods with the sweetest peas. If the pods are left on the vines too long, they become tough and starchy. Pick black eyed peas slightly before maturity. They should still be a light green with a purplish eye. They are still easy to shell at this stage and taste delicious.