SEXUALITY IN FERNS 195 



thence to the nucellus where it depressed or invaginated the 

 apex of the embryo-sac, and in the recess or indentation so 

 produced the tip of the pollen tube was converted into the 

 embryo its actual apex being represented by the plumule. 

 This theory was the lineal descendant in modernised trappings 

 of the old view expressed by Morland and others at the begin- 

 ning of the eighteenth century that the embryo was contained 

 in the pollen grain, and that the ovule was no more than the 

 brood chamber whither it must be brought to undergo further 

 development. This erroneous interpretation of the true facts 

 was always repudiated by Amici, and was finally overthrown by 

 Hofmeister and Radlkofer in the early fifties. In this con- 

 nection we may note in passing Henfrey's careful paper on 

 the impregnation of Orchis Morio, published in 1856, which 

 fully corroborated Amici. In this paper the relations of pollen 

 tube, embryo-sac, egg-cell, suspensor and embryo were correctly 

 interpreted, and the new point established, contrary to the 

 assertions of previous observers, that the ovum or "germinal- 

 vesicle," prior to fertilisation, was a naked, unwalled cell. 



Sexuality in Cryptogams. By far the most important question 

 that came to a head in Henfrey's time was that of the morpho- 

 logical relationships of the Cryptogams and flowering plants. 

 Hitherto these had remained altogether obscure in the absence 

 of reliable data based on the proper application of the micro- 

 scope to the elucidation of the life histories of the lower plants. 

 Under the influence of the Linnaean school, which had taken 

 deep root in this country, as elsewhere, the systematic study of 

 flowering plants had been widely pursued, and in so far as the 

 ferns were concerned their homologies were commonly inter- 

 preted in terms of the flowering plants. Without any real 

 guidance in fact, a great diversity of views of these homologies 

 found expression. The following, taken from Lindley, may serve 

 to illustrate their general nature. 



The sorus was regarded as a sort of compound fruit, the 

 sporangium as a carpel, the annulus as its midrib, and the spores 

 as the seeds. Speculations such as these are of the same order 

 as the crude conjectures which with less excuse relieve the 

 answer books of examination candidates at the present time. 



132 



