20 Messrs. Brown arid Escombe. On the Depletion of the 



embryos on artificial nutrients, it was found, as we have already 

 stated, that it is possible to u graft " the embryo from one grain on 

 to the endosperm of another, and to obtain such close apposition of 

 the two surfaces, by means of binding with a loop of thin silver or 

 platinum wire, that the "graft" develops into a young plant almost 

 as readily as if it were still nursed by its own endosperm. This fact 

 afforded an opportunity of more closely studying the relative parts 

 played by the embryo and endosperm in producing the initial 

 changes in the reserve materials ; for it is evident that if a clegermed 

 endosperm is subjected to some process which will with certainty 

 kill its tissue, and a living embryo " grafted " on this endosperm 

 will bring about in the reserve substances of the latter all the 

 changes incidental to normal germination, then the whole idea of 

 residual vitality in the endosperm-cells being a necessary condition 

 of germination would become superfluous. Experiments in this 

 direction were in the first place made by treating grains of barley 

 with chloroform- vapour for twenty-four hours, a course of treatment 

 Avhich we now know must have been insufficient to have killed the 

 resting protoplasts ; it is, therefore, not to be wondered at that 

 embryos " grafted " on endosperms so treated should have grown 

 perfectly. In a further set of experiments, also described in the 

 1890 paper, grains of barley were soaked in absolute alcohol for six 

 months, and after drying off the alcohol, soaking well in water, 

 and degerming, fresh embryos applied to the endosperms were 

 found to produce in them all the ordinary visible signs which 

 accompany germination. This experiment was deemed to con- 

 clusively prove that the degradation of the reserve products is con- 

 ditioned by the embryo itself, and that the endosperm-cells do not 

 take part in it. 



We have now, however, every reason to believe that the " aleu- 

 rone-layer " was not killed by this drastic treatment with alcohol, 

 for we have found that these cells are much more resistant to in- 

 jurious influences than the tissue of the embryo itself, and we have 

 seen cases in which even the embryo will sprout after the grain has 

 been immersed in alcohol for about four months.* 



We have recently found, in repeating and varying these experi- 

 ments, that when the grain is immersed in a dry state in chloroform- 

 water (i.e., a saturated aqueous solution) a few hours suffice to 



* Giglioli (' Nature,' Tol. 52, 1895, p. 541) found that seeds of Medicago sativa 

 retained their vitality after submersion in absolute alcohol for more than sixteen 

 years. Ewart ('Liverpool Biolog. Soc. Trans.,' vol. 8, 1894, p. 207) also states that 

 the resistance of seeds to absolute alcohol is very considerable, and that those of 

 Hordeum, although killed very quickly by alcohol of 50 per cent., require submersion 

 in absolute alcohol for seven weeks before all germinating power is lost. It will be 

 seen, from what has been said above in the text, that the embryos of some grains of 

 Hordeum may be made to grow after a much longer submersion than this. 



