362 LIBBIE H. HYMAX. 



tion of his method of procedure is necessitated. But, as has 

 already been pointed out, this is impossible because no description 

 is given by Banus concerning his material, his methods, or his 

 experimental conditions. We need to know the season of the 

 year, the temperature, the vegetative condition of the material, 

 the length of time material was kept in the laboratory before 

 being used, the presence or absence of lateral buds on the stems 

 employed (since buds mark the limits of the individual), and 

 particularly the level from which the pieces were taken, with 

 reference to the original hydranth. We have repeatedly pointed 

 out that metabolic gradients are not fixed and static things, but 

 markedly dynamic and labile, and particularly in the lower forms, 

 they may result from external conditions and may be readily 

 modified and altered by conditions. The failure of Banus to 

 describe or consider the various factors mentioned, any one of 

 which might alter the experimental result, is evidence that he 

 really does not understand the metabolic gradient conception 

 and has not interested himself in understanding it. This is 

 further shown by certain remarks made in his paper such as for 

 example the naive statement on p. 268 that the pieces were 

 "long enough to show a marked difference according to Child's 

 opinion," whereas in fact "according to Child's opinion," and 

 as even a hasty perusal of the work put out from this laboratory 

 would show, the axial differences are most clearly marked in 

 most respects in relatively short pieces. 



In order, therefore, to obtain any information concerning the 

 experiments of Banus, it has been necessary for me to com- 

 municate with him. Mr. Banus replied to the first letter which 

 I wrote to him, but did not reply to two others requesting further 

 details. It is therefore not possible for me to furnish all of the 

 details necessary for a correct evaluation of these experiments 

 but the information I was able to obtain is sufficiently astonishing. 

 Banus states that his experiments were performed in New York 

 City in November and in Woods Hole in December. Since 

 most of the other researches on Tubularia were carried out in 

 the summer season, it was at first thought that seasonal differ- 

 ences in the vegetative condition of Tubularia might account for 

 Banus's results. I found, however, that Tubularia is in prac- 



