i9o8] CURRENT LITERATURE 349 



is justifiable to speak of a localized phototropic irritability as merely a localization 

 of sensitiveness to light. For this purpose he chose seedlings of Panicum milia- 

 ceum, in which the tip of the cotyledon alone is phototropically sensitive, and 

 determined how the growth in length of the part not thus sensitive was affected 

 by direct illumination and by illumination of the cotyledon tip, preliminary inves- 

 tigations having shown that the growth, which is restricted almost entirely to 



In light of moder- 



ate intensity the growth of the hypocotyl is checked almost equally, whether the 

 cotyledon alone or the hypocotyl alone is illuminated; but only half so much as 

 when the whole seedling is illuminated. At higher intensities, on the contrary, 

 the illumination of the cotyledon retards the growth more; from which it is 

 evident that the effect of the light is transmitted downward to the hypocotyl. 

 But if one illuminates all but the uppermost 2-4'"'" of the hypocotjd, the growth 

 of the parts above is not retarded, and the light effect is clearly not transmitted 

 upward. The retarding effect of illumination of the cotyledon does not proceed 

 from its tip, which is phototropically ver)' sensitive, for illumination of this tip 

 alone produces far less retardation of the growth of the hypocotyl than does the 

 illumination of a greater part of the hypocotyl. Clearly the Hght acts as a stimulus 

 and both cotyledon and hypocotyl are sensitive to it. Although, as Rothert 

 has shown, the hypocotyl is in general not phototropically sensitive, FiTilXG 

 found that 17-25 per cent, of the seedlings whose cotyledons were darkened curved 

 phototropically after one-sided illumination. These facts show that the distribu- 

 tion of phoiotropic sensitiveness does not indicate which part of the seedling ^t- 

 ceives light. Similar results were obtained with Sorghum Dora, S. vulgare, Lea 

 Mays, and Tinantia fugax (Commelinaceae). 



Fitting found nothing to indicate that phototropic sensitiveness proceeds 

 from any other process of light perception than that which expresses itself m retar- 

 dation of growth. He su-ggests "that the localization of phototropic sensitiveness 

 may perhaps be referable to the fact that the polar condition characteristic ot 

 induction of phototropism can be produced only m the phototropically sensitne 



zoriG " 



He discusses also the problem of etiolation, but adds nothing new merely 

 emphasizing the existing ^dew that the normal form of leaves in dicotyls depenas 

 upon the direct action of light as a stimulus without the correlations which are 

 usually considered.— C. R. B. 



Javanese Anthocerotales.-As one of the results of his recent ^-islt to the 

 oriental tropics, Campbell^3 has published an account of ^^-^^^j^ J ^' ^'^ 

 Anthocerotale. An..n. . number of soecies of Anthoceros collected at the Dase 



found two forms 



Megaceros 



Campbell 



Anthocerotaceae. Annals 



Botany 21:467-486. ph. 44-46. 1907; 22:91-102. i'/i- P,JO. 19^- 



