The functions of the thymus gland are still a mystery. Even its anatomy is controversial. Generally it is believed that the gland in some way is correlated with the process of growth and that after puberty it undergoes a gradual atrophy and involution. There is also presumed to be some reciprocal relation between the thymus and the reproductive glands. A more precise hypothesis is that proposed by Klose and Vogt,1 who hold that the thymus is concerned especially in the synthesis of nucleic acid.
Hammar,2 who has studied more than a thousand human thymus glands, concludes that the variations in the lymphocytic content of the thymus and the variations in the Hassall corpuscles constitute the essential morphologic changes associated with thymic function. Every theory as to the physiology of the thymus must explain these histologic changes. There is apparently an increase in the development of Hassall corpuscles in