Polycephalic Poppies 385 



moment no further change of external condi- 

 tions is able to produce a corresponding change 

 in the degree of the anomaly. The indi- 

 vidual strength of the whole plant may still be 

 affected in a more or less manifest degree, but 

 the number of converted stamens of the flower 

 has been definitely fixed. The sensitive period 

 has terminated. 



In order to determine the exact moment of 

 this termination of the period of sensibility, I 

 have followed the development of the flower- 

 buds during the first weeks of the life of the 

 young plants. The terminal flower may al- 

 ready be seen in young plants only seven weeks 

 old, with a stem not exceeding 5-6 cm. in 

 height and a flower-bud with a diameter of 

 nearly 1mm., in which the stamens and sec- 

 ondary pistils are already discernible, but still 

 in the condition of small rounded protuberances 

 on the thalamus. Though it is not possible at 

 that time to observe any difference between the 

 future normal and converted stamens, it does 

 not seem doubtful that the development is so far 

 advanced, that in the inner tissues the decision 

 has already definitely been taken. In the next 

 few days this decision rapidly becomes vis- 

 ible, and the different parts of the normal 

 stamens and the metamorphosed carpels soon 

 become apparent. From this observation it 



