200 ■« Mr. Griffith on the Ovulum o/'Santalum, 



give my own a better claim perhaps to notice. With the exception of this, 

 and such part of my own observations as would refer the embryo, for the 

 greater part, or perhaps entirely, to a growth from the ends of the pollen 

 tubes, except in f^iscum, I cannot but hope that these present observations 

 will be considered to be striking corroborations of the general views of 

 M. Schleiden. Of M. Wydler's obsei-vations I have no knowledge but that 

 very lately derived from an able summary by Dr. Giraud of the recent doc- 

 trines of vegetable embryology in the 'Annals of Natural History,' No. 31, 

 June 1840, and which therein only go so far as to establish the points of non- 

 inflection of the sac, and of the entrance of the pollen tubes into it. On the 

 general subject of the vegetable ovulum I hope to enter into detail as soon 

 as the proper opportunities offer, not so much in the hope of producing any- 

 thing new on a subject on which Mr. R. Brown, and MM. Schleiden, Mirbel 

 and Brongniart have been engaged, but to extend the application of the facts 

 established by them to plants out of the reach of European savans. 



The growth of a tissue from the ends of the pollen tubes, from which tissue 

 the embryo of Loranthus is directly formed, appears to me to open to view 

 glimpses of the most beautiful analogies. 



In the sporula, so called, of the more developed Acotyledonous plants, we 

 have organs consisting of two envelopes ; the inner of which contains granular 

 matter, has remarkable powers of growth, and, so far as function is concerned, 

 appears to be alone essential. The proper stimulus calls this membrane into 

 growth, and from the apex of its extension cells are developed ; from these 

 others again are produced ; and from the centre of the mass thus formed, 

 originates at a certain period the growth of the true axis. 



Similar pheenomena take place in the formation of the seed of Pheenogamous 

 plants, with this difference, that the albumen, unlike perhaps the thallus* of 

 the Acotyledonous plant, is not a direct growth from the pollen tube. Such 

 other differences as appear to exist are of minor importance ; they consist in 

 the different nature of the stimulus calling forth the extension of the inner 

 membrane, in the condensation of the growths forming the seed, which may 

 be reasonably inferred to arise from the confined situation in which they 



* Am I right in the use of the term thallus ? hy which I mean, the confervoid mass first formed in 

 the germination of Acotyledonous plants, such, for instance, as Equisetum. 



