110 



KNOWLEDGE. 



[Mav, 1902. 



it more ooniplote oxampln of apoHponj thau that of 

 Athijrium FiJix-fivmina, var. clarisiiima "* Two yt'ars 

 liitiT. Mr. Druorv subjected a different form of the var. 

 pulrherruuHm above-inentioiied — in this second case a 

 Dorsetshire tind — to close culture, with the result that 

 not only did the pinnule-tips produce such a uuuil)er of 

 ]>rotli:illia that " flic ]iinu!e were absolutely fringed with 

 thcni," but prothaili also ai)pcared which were produced 

 in ([Uite another manner. Certain veinlets rose out from 

 the surface of the (linnules, and arching over, were pro- 

 longed into pendant pear-shaped bodies, which sent out 

 root-hairs, and, under favourable conditions, grew into 

 prothallia.f In 18i»2 Mr. Druery made another step by 

 discovering prothalloid growth proceeding, not from any 

 one part, but over the whole surface and edges of a seed- 

 ling crested Male Fern, Lastrea Psendo-mas, var. cristala, 

 which, however, lost this pvothallium-bearing character as 

 it grew older.* In this variety, it should be pointed out, 

 another abnormality of reproduction was already known 

 to occur, namely, the production of the yo\ing fern-plaut 

 by j>urely vegetative growth from the prothallium, without 

 the aid of sexual action {upotjamtj). So that in this Fern 



Fig. 6. — Portion of frond of Scolopendrium 

 riiUiare, vac crixpum DrummondiB, s)iowm;i pro- 

 duction of protliallia (P, P) along the edge of the 

 frond. Natural size. After Druery. 



two remarkable short-cuts in reproduction occur, the 

 sporophore sometimes growing direct from the oophore 

 (by this the sexual organs are eliminated in the life-cycle 

 of the plant), and the oophore sometimes growing direct 

 from the sporophore (by which the spore is eliminated). 

 Mr. Druery continued his investigations, and next an- 

 nounced§ an aposporous Hart's-tougue, a frilled variety, 

 found many years before near Falmouth hy Miss Drum- 

 mond, in which prothaili were produced from the tips of 

 the lobes, into which the margin of the frond is in this 

 form divided. He also discovered another form of 

 darissbna Lady Fern, which showed the phenomenon of 

 apospory, not only in the fructification, but also at the 

 apices of the divisions of the frond. Mr. E. J. Lowe,iJ in 

 his ex])erimeuts in prolonging the prothallium generation 

 of Hart's-tongue. by cbntinually subdividing the ]iro- 

 thallia (in order to keep the two sexes apart), produced, 

 when sexual action was at length allowed, some extra- 

 ordinary little Hart's-tongues, of which the fronds were 

 simply masses of prothalloid growth. A characteristic 

 example of apospory occurs in a densely-crested form 

 of the Lady Fern, Athijrium Fili.r-fwmina, var. vnco- 

 (jlomeratum, an offspring of var. aerodadon, which was 



• Loc, cit. + Druery, Journ. Linn. Soc , Vol. XXII. 



I Juurn. Littti.'Soc, Vol. XXIX. 

 !i Ibid, Vol. XXX. II IHd, \\,l XXXII. 



found wild in Yorkshire in 1800. Dr. Stanstield ob8erve<l 

 that in the autumn of 189tj, when the fronds were dying 

 down, tile extreme lips of their ijushy crests remained 

 greeu. He planted these, whereuiwii they kept, growing, 

 slowly unrolling and branching, and the tips eventually 

 exjiauded into jjiotliallia, which produced young feru- 



FlO. 7. — Jlht/riuiii Filix-frmnna, var. unco- 

 illomeratnm. Young plant arising by budding fnjiri 

 prolonged tip of portion of the frond. Enlarged. 

 After Stansfield. 



jjlants by sexual actioB. Young plants were likewise 

 produced by direct budding, both on the tips of the frond 

 and on the prothallia, so that in this remarkable instance 

 no less than three abnormal processes of reproduction 

 were going on at the same time ! * 



Apospory in the forms described above is now known to 

 occur in quite a number of Fern varieties of the kinds 

 named above — plumose, crested, and pnlcherrimum forms 

 — which have been for many years known to be barren 

 varieties, so far as the production of offspring by means of 

 spores was concerned. 



So it will be seen that to the normiil alternation of gene- 

 rations in Ferns some very remarkable exceptions have been 

 discovered, chiefly among wild British varieties, in which 

 the parts of the frond are very much divided. The pheno- 

 menon has been noticed in Athyriuni, Polysiichmn, Scolo- 

 'pendrium, Lastrea, and probably Polypodimn rnhjare, and 

 to these may be added the Bracken, Pteris (iquilinn, of 

 which an a|>osporous form has beeu found in the United 



■ Fio. S.—Athy rill III Fitix-ficminii, var. iinco-nloineraluiii. 

 Prothallium produi-ed bv vegetative growth from tip of 

 )iortiou of frond, bearing voung plant (A) produced by 

 budding on the surface of the prothallium and ulfo young 

 plants (B, B) produced by normal sexual action. Enlarged. 

 After Stansfield. 



States. t The curious outgrowths which result in prothallia 

 may take place in the aborted fructification, on the tips 

 of the pinnules or of crestings, from any portion of the 

 margin or surface of the frond, or from the extremities of 

 projecting veins. The production of these premature 

 oopLores ai>pears to be much stimulated by cultivation in 

 a close damp atmosphere — without which, indeed, the 

 delicate prothallia, and the young fern-plants arising from 



* Stansfield, in Journ. Linn. Soc, Vol. XXXIV. 

 t Farlow, in A«nals of Jiofant/, Vol. II., p. 383, 1888. 



