284 CHARLES R. STOCKARD 



most speculative nature and are intended merely as such. In 

 my experiments many of the embryos which possess supernum- 

 erary lenses show, as Spemann has called attention to, that the 

 accessory lens may actually lie more anterior than the eye. Nev- 

 ertheless, others, show free lenses in lateral positions. 



The presence of a lens in the cyclopean eye is explained by the 

 fact, well established for several species, that an optic vesicle 

 or cup possesses the power to stimulate lens formation from any 

 region of the head ectoderm with which it comes in contact. 

 There would be no necessity of imagining a condition of ''cyclo- 

 pia of the lens" even though a median lens should be observed 

 in an anophthalmous monster. Normal lateral lenses have been 

 observed in anophthalmic monsters (see figs. 1 and 5, and fig. 

 3, plate II, 1910 b). 



The embryo from which my figure 4 ('10 b), was taken is of 

 new interest in connection with a hypothetical case called for 

 by Spemann (p. 81 '12 a). He states as a possibility that 



der cyclopische Defekt nur die Epidermis betrifft, so dass Riechgruben 

 undprimare Linsenbildungszellen median zusammenriicken, wahrend die 

 Augenbecher, wie normal seitlich gelegen, sich ihre Linsen aus der dor- 

 tigen Epidermis bilden. Durch solche Falle wiirden in der Tat an einem 

 und demselben Kopf beide Fahigkeiten demonstriert, die der Linse zur 

 Selbstdifferenzierung und die des Auges zur Linsenerzeugung. Bis jetzt 

 liegen aber derartige Falle nicht vor. 



The case however, was, recorded at the time and seems to. fill 

 the requirements set forth. The independent origin and differ- 

 entiation of the lens is demonstrated in a median position slightly 

 more anterior than the eyes, and the more or less lateral eyes have 

 derived lenses from the ectoderm with which they came in con- 

 tact as is shown by figs. 9 and 10, 1910 b, yet this ectoderm is 

 part of the usual region from which an optic cup has the power 

 to derive a lens. The power to form lenses, as Speman and I 

 have claimed, is possessed by the ectoderm of the head. 



According to Spemann's assumption, the embryo (fig. 4) pre- 

 sents true ''cyclopia of the lens." The condition, however, may 

 better be interpreted as an illustration of the high lens-forming 



