GEOWTH OF AMPHIBIA AFTER THYROIDECTOMY 49 



relatively larger testes than do normal larvae. Synapsis in the 

 testis is hastened in point of time by thyroidectomy. 



The condition in thyroidless larvae cannot be called experi- 

 mental neoteny, according to the present definition of the term. 

 The females do not produce mature ova nor develop oviducts, 

 and hence the larvae cannot reproduce. 



LITERATURE CITED 



Allen, B. M, 1917 The results of extirpation of the hypophysis and thyroid 



glands of Rana. Anat. Rec, vol. 11. 



1918 The results of thyroid removal in the larvae of Rana pipiens. 



Jour. Exp. ZooL, vol. 24. 



1918 Several abstracts in proceedings of Amer. Assoc, of Anat. and 



Zool., Anat. Rec, vol. 13. 

 AtwellW. J. 1918 The development of the hypophysis of the Anura. Anat. 



Rec, vol. 15. 

 Ceni 1905 Effets de la thyroidectomie sur le pouvoir de procreer et sur de- 



scendents. Arch. Ital. d. Biol., T. 42. 

 Ekman, G. 1913 Experimentelle Untersuchungen uber die Entwicklung der 



Kiemenregion (Kiemenfaden u. Kiemenspalten) einiger anuren Am- 



phibien. Morph. Jahrb., Bd. 47. 

 GuDERNATSCH. J. F. 1912 Feeding experiments on tadpoles. 1. Arch. f. 



Entw., Bd. 35. 



1914 Feeding experiments on tadpoles. 2. A further contribution 



to the knowledge of organs with internal secretions. Amer. Jour. 



Anat., vol. 15. 



1917 Studies on the internal secretions. 4. Treatment of tadpoles 



with thyroid and thymus extract. Anat. Rec, vol. 11. 

 Harrison, R. G. 1904 An experimental study of the relation of the nervous 



system to the developing musculature in the embyro of the frog. Amer. 



Jour. Anat., vol. 3. 

 Herring, P. T. 1908 The effect of thyroidectomy on the pituitary. Quar. 



Jour. Exp. Physiol., vol. 1. 

 Hofmeister, F. 1894 Experimentelle Untersuchungen liber die Folgen des 



Schilddriisenverlustes. Beit, zur klin Chir., Bd. 2. 

 HosKiNS, E. R. 1916 On the growth of albino rats as affected by feeding various 



ductless glands (thyroid, thymus, hypophysis, and pineal). Jour. 



Exp. Zool., vol.21. 

 HosKiNS, E. R., AND Morris, Margaret 1917 On thyroidectomy in amphibia. 



Proc Amer. Assoc. Anat., Anat. Rec, vol. 11. 

 HosKiNS, E. R., AND HosKiNs, M. M. 1918 Further experiments with thyroid- 

 ectomy in Amphibia. Proc Soc Exp. Biol. Med., vol. 15. 

 Jackson, C. M. 1915 Changes in the relative weights of the various parts, 



systems and organs of young albino rats held at constant body weight 



by underfeeding for various periods. Jour. Exp. Zool., vol. 9. 



