FIMTION.] SELF IMPREGNATION. 239 



know of no one else who maintains this last opinion ; but it 

 deserves to be noted that Morren observed a circulating move- 

 ment (he calls it cyclosis) in the fluid filling the papillae of 

 Cereus grandiflorus at the period of impregnation. 



Notwithstanding the great mass of evidence which botanists 

 possess in favour of the sexuality of plants, there are certain 

 facts which appear to be irreconcileable with that property ; 

 and which wait for further examination. 



Mr. John Smith has described in the Linncean Transactions, 

 vol. xviii. p. 510, a Spurge wort, named Coelebogyne ilicifolia, 

 which, although absolutely female, not possessing a trace of 

 pollen, nevertheless produces perfect seeds. He inclines to 

 the belief that a viscid fluid issuing from glands below the 

 ovary, may produce an effect by exciting the action of the 

 pistil, a supposition which receives some support from the 

 young stigma being often smeared with this fluid. The state- 

 ment that no male apparatus is discoverable on this plant is 

 confirmed by Francis Bauer and others. We ourselves have 

 often examined the plant without perceiving a trace of stamens 

 or pollen. 



Dr. Fresenius has observed that in Datisca cannabina, 

 when female plants remain isolated, they are able neverthe- 

 less to produce ripe fruit in abundance; and he concludes 

 that this and other purely female forms are, in the absence 

 of male organs, endowed with the capability of developing, 

 by a purely vegetative process, the highest vital product, the 

 terminal bud (or seed.) In the summer of 1837, a female 

 specimen of the above plant, in the Frankfort Botanical 

 Garden, threw up a stem which now bears male flowers also. 

 (Linwea, 1839.) 



Spallanzani, Girou de Buzareingues, and others affirm that 



speculations have all arisen out of the undoubted fact, that the development 

 of spores and pollen grains takes place in the same manner, and that there 

 is considerable resemblance in their final structure. This was, I think, first 

 noticed by Mohl (Ueber die EntwicUtmg der Sporen, <fec.), in 1833 ; Mirbel, in 

 1835, stated that there was a marvellous resemblance between these parts (Ann. 

 Sc., n. s., iv. 9.) ; Morren declares that the spore is organised like a grain of 

 pollen (Anat. des Jungermann. p. 10.) ; and, finally, Wydler admits a great 

 analogy between the formation of pollen and the spores of many foliaceous 

 cryptogamic plants. (See page 110 of the present volume.) 



