594 SUMMARY OF CUEBENT RESKAECHES RELATING TO 



seed, and leads to the death of the entire fruit. The most favourable 

 intensity, moreover, is relatively low. The light-function in this con- 

 nexion has nothing to do with photosynthesis ; it is a direct influence, 

 operating in the direction of cell-nutrition by organic substances, pro- 

 bably on account of the importance of light in the elaboration of diastases 

 — as has been established by Reynolds Green. The author draws atten- 

 tion to the analogy between this influence of light and the similar 

 influence exerted upon the development of growing points. 4. When 

 once an adequate supply of enzymes has been formed, embryo develop- 

 ment may proceed favourably in complete darkness ; but at the same 

 time the production of dry substance in the fruit, and also the number 

 of seeds, is appreciably lessened if development proceeds in darkness. 

 5. Darkness, therefore, results in enfeebled fruit-development ; and the 

 same result follows if, on the other hand, the illumination exceeds a 

 certain intensity. Even ordinary daylight is somewhat too intense to be 

 the most favourable in this regard. 6. Light has an appreciable effect 

 upon the chemical composition of the fruit-substance. The experiments 

 show that the amount of ash in the case of certain fruits increases as the 

 illumination during development decreases ; and also that light has its 

 effect upon the formation of sugars and acids, the acidity of the fruit 

 diminishing in proportion with the intensity of illumination. 7. Seed- 

 germination is most active either in darkness or under the same light- 

 conditions which prevail during seed-formation. 



The author concludes by pointing out the practical value of such 

 experiments in fruit culture. 



CRYPTOGAMS. 



Pteridophyta. 

 (By A. Gepp, M.A. F.L.S.) 



Development of Angiopteris and Kaulfussia.* — D. H. Campbell 

 gives an account of the embryo and young sporophyte of Angiopteris 

 and Kaulfussia. The Marattiales are of special interest as showing the 

 nearest relationship to the Ferns and Pteridosperms of the Palreozoic 

 period. Existing Marattiales comprise only about thirty species, dis- 

 tributed in five genera. Angiopteris, Kaulfussia, and Archangiopteris 

 are monotypic genera. Dansea contains about fifteen species, Marattia 

 about twelve. Campbell collected prothallia and young sporophytes of 

 Angiopteris evecta in Ceylon, and of Kaulfussia sesculifolia in Java ; also 

 prothallia of three species of Dansea in Jamaica. In order to fill up 

 some gaps in our knowledge of the young stages of these rare ferns, he 

 prints the present contribution. He sums up his results as follows : 

 1. Probably in all Marattiaceae the stem, leaf, and root all arise from 

 the epibasal part of the embryo ; in Dansea the primary hypobasal cell 

 forms a suspensor, and all of the organs, including the foot, are of epi- 

 basal origin. 2. In Kaulfussia and Angiopteris the stem and leaf do 

 not take up all of the epibasal tissue ; a portion also contributes to the 

 foot. 3. The stem apex usually shows a single large initial cell, which 

 possibly may be derived directly from one of the primary quadrants of 



* Ann. Jard. Bot. Buitenzorg, 3e Suppl. (1910) pp. 69-82 (2 pis.). 



