236 



HARDWICKE'S SCIENCE-GOSSIP. 



those which are household words. Such change may 

 for a moment or two be a little puzzling, especially 

 as their synonymy is not always indicated ; but there 

 can be little doubt that the compilers of the " London 

 Catalogue " have not acted capriciously in this matter, 

 and doubtless they would be able to give solid 

 reasons for the action, were they interrogated. Mr. 

 "Wheatcroft says he prefers Professor Babington's Flora 

 to that of Sir John Hooker ; for myself, I reverse 

 that choice, and take Hooker as my vade mecum. 

 But neither of us, I suppose, will condemn the other 

 explicitly for making such choice, inasmuch as each 

 has exercised his judgment on the relative value of 

 the two books, and taken that which impressed him 

 most favourably. And yet while we amateur bota- 

 nists claim absolute freedom in our choice of guides, 

 such guides are condemned for exercising a like 

 freedom of judgment in prescribing our pathway. 

 This is scarcely fair. How many of us can legiti- 

 mately claim a botanical knowledge so vast, and 

 experience so extensive and unique as are possessed 

 by Sir J. D. Hooker ? And yet on reference to the 

 preface to the 3rd edition of his Flora, it will be 

 found that, in his anxiety to produce a book worthy 

 of the subject, even he has not scrupled to seek the 

 aid of specialists, in order that he might be able to 

 place in the hands of students the fullest and latest 

 information accessible, and in a form as compendious 

 as possible. — F. y. George, Charley, Lane. 



Prothallia of Ferns. — Mr. J. Morley con- 

 tributes a note on the cultivation of Fern Frothallia 

 for laboratory purposes. He remarked that amongst 

 British ferns the spores most easy to germinate are 

 those of Osmunda regalis and Lastrea filix-mas. 

 Rather less easy are those of various species of 

 Polystichiim and Athyrium. To collect the spores, 

 lay the frond, when the sporangia are dark-brown, 

 between sheets of unglazed paper, and keep dry till 

 wanted. The spores will fall into the paper, and 

 when wanted tip off all that were loose. The spores 

 can be grown on pieces of sandstone, slate, peat, 

 &c, and whatever the growing medium, it should 

 be previously sterilised by pouring over boiling water. 



The Falling of Leaves. — Professor Hillhouse, 

 in a paper on this subject, said he had taken obser- 

 vations on this subject every autumn since 1S82, and 

 hoped in the course of twelve months to complete 

 them. At first sight it might seem peculiar that a 

 question of that kind should be spread over so long 

 a period. The cause was that there was no safe 

 apparent guide as to the exact ripeness of the leaf. 

 The colour of the leaf failed to afford that information, 

 and the fall of the leaf was no guide. His method 

 of experiment had been to tie the leaves to the twigs, 

 so that when the former gave way they were sus- 

 pended by the twine. If the fall occurred during 

 frost or windy nights the leaves were discarded, only 



those being selected that apparently fell in perfect 

 maturity on a comparatively still and not frosty 

 night. The subject had been approached from two 

 points of view — the mechanism of leaf-falling, and 

 the transfer of the cell contents from the leaf to the 

 stem ; the former dealing with the power of the leaf 

 itself, and the latter with the amount of loss that 

 took place to the plant itself by the fall of leaves 

 over and above the actual skeleton, so to speak, of 

 the leaves themselves. He found that the leaf fell 

 from the increased turgidity of the cells and the 

 abcess layer, which became strongly rounded, greatly 

 diminishing their adhesiveness. The turgidity ap- 

 peared to arise from the root absorption continuing 

 at a greater pace than the leaves could pass the 

 water off, so that the accumulation of water caused 

 an expansion of the tissue ; consequently the cells 

 became rounded, and passed out of contact. Tannin 

 and starch were especially abundant in the food- 

 layer at the base of the leaf-stalk, but in naturally 

 fallen leaves starch was rarely found, except at the 

 very base of the stalks, and then in small grains. 



Nitrifying Organisms in Soil. — Mr. R. 

 Warrington read a paper at the British Association 

 meeting on "The Distribution of the Nitrifying 

 Organism in the Soil." He said that previous ex- 

 periments, conducted at Rothamsted, on this subject 

 had led to the conclusion, that the nitrifying orga- 

 nism is always to be met with down to nine inches 

 from the surface, and that at eighteen inches it is 

 sometimes present ; but experiments with soil two 

 to eight feet from the surface had failed to yield 

 evidence of the presence of the organism. Further 

 experiments have been made in 1885, and during the 

 present year, both in the field with the stiff clay 

 subsoil previously worked on, and in another field 

 having a loamy subsoil. In all, sixty-nine new 

 experiments have been made. The new results 

 show a far deeper distribution of the nitrifying 

 organism than was concluded from the earlier ex- 

 periments. The power of producing nitrification is 

 now found to exist generally down to three feet 

 from the surface. Below this point the occurrence of 

 the organism becomes less frequent, though at five 

 and six feet about half the trials resulted in nitrifica- 

 tion. With soil from seven to eight feet no nitri- 

 fication was obtained. The considerable difference 

 between the earlier and later results is to be attributed 

 to the employment of gypsum in the later solutions. 

 The nitrifying organism in the subsoil is indeed less 

 abundant, and probably much more feeble than in 

 the surface soil, and is apparently unable to start 

 nitrification in the decidedly alkaline solution which 

 urine produces in the absence of gypsum. 



Causes of Variation in Plants. — Dr. Patrick 

 Geddes read a paper on this subject. The writer first 

 pointed out that, while the fact of the origin of species 



