In these features, and in the fact that the gonads are local proliferations of the coelomic epithelium, which have undergone no further changes in the simpler forms, the coelom of this group shows in a particularly clear fashion the general characters of the coelom in the higher Metazoa.
The two testes lie in the tail and are formed by lateral proliferations of the living peritoneal cells.
When we come to phenomena such as proliferations, vivipary, the development of Lammas shoots, adventitious buds, epicormic branches, and to those malformations of flowers known as peloria, phyllody, virescence, &c. while assured that definite, and in many cases recognizable, physiological disturbances are,at work, we find ourselves on the borderland between patho~gical and physiological variation, where each case must be examined with dtie regard to all the circumstances, and no generalization seems possible beyond what has been sketched.
Crowson, Neil A., et al. The Melanocytic Proliferations: A Comprehensive Textbook of Pigmented Lesions.