382 SUMMARY OF CURRENT RESEARCHES RELATING TO 



matopliore. The fact that the reduction in size of the sjiermatozoid 

 is accompanied by a loss of jn-otoj^lasm, and that the nuclear substance 

 predominates in the mass of the spermatozoid, has led to the conclusion 

 that what takes place in impregnation is chiefly a transport of 

 nuclear substance, while the cell-jirotoplasm in the zygote or impi'eg- 

 nated oos^ihere plays the part of a storage of force. Impregnation is 

 therefore essentially a union of cell-nuclei, although any union of 

 cell-nuclei is not necessarily an act of impregnation. The coalescence 

 of the Plasmodia of Myxomycetes he does not regard as an act of 

 impregnation. 



The ordinary mode for the protoplasm of the male element to 

 reach that of the female element is by permeation through pores 

 already in existence, though in certain instances it would seem as if 

 it made use of pores specially prepared for the occasion. 



Pollination of Araceae.* — G. Arcangeli has observed the mode of 

 pollination of several species of Araceae, especially Arum italicum, 

 Dracunculus crinitus, vulgaris and canariensis, and Sauromatium gutta- 

 tum. In all of these a very great rise of temperature is observable 

 within the spathc for a very short time at the moment of flowering, 

 accompanied by a powerful odour. The object of these is to attract 

 insects to assist in the fertilization. These are detained by the 

 parastemona as in a cage from the time when the stigmas are 

 mature until the dehiscence of the anthers ; A. italicum at least being 

 distinctly proterogynous. The author does not consider there is 

 sufficient evidence to warrant the theoiy of the carnivorous habits of 

 these i^lants, there being a comjjlete absence of any digestive fluid and 

 of any special digestive glands in the spathe. 



Pollen-tubes. t — J. Kruttschnitt disputes the ordinary view that 

 the ovule is fertilized by the entrance of the pollen-tube into the 

 embryo-sac. He has never been able to detect that such an entry 

 actually takes place. He believes, on the contrary, that the pollen- 

 tube discharges the fovilla or contents of the i^ollen-graiu into the 

 conducting tissue of the style, whence it is conducted by the funicle 

 to the papillfe which surround the micropyle, and then absorbed by 

 endosmose. In the case of Cereus grandijlorus he states that the 

 ovary contains on an average about 3000 ovules, and that it is 

 imjjossible, on the ordinary theory, that all these ovules could become 

 fertilized, for there is not nearly space, either in the conducting 

 tissue of the style or in the ovarian cavity, for this number of pollen- 

 tubes. 



Autoxidation in Living Vegetable Cells.J — Traube has given 

 the name of autoxydahle Korper or, as we must clumsily translate the 

 new term, autoxidizable substances, to those bodies which, at a low 

 temperature, and by the action of free j)assive oxygen, can be oxidized, 

 forming, in the presence of water, jieroxide of hydrogen. Starting 



* Nuov. Giorn. Bot. Ital., xv. (1883) pp. 72-97. 



t Amer. Mou. Micr. Jourii., iii. (1882). 



X Bot. Ztg., xli. (18S3) pp 05-76, 89-103. Cf. Science, i. (188.3) pp. 229-30. 



