with descriptions of new genera and species. 163 



cisely similar in every respect, except in size, to that of the or- 

 dinary frustule, would seem to indicate very slight, if any, differ- 

 ence in the qualities of their respective endochromes. The spo- 

 rangium — the product of this mixed endochrome — undergoes 

 fissiparous division too in like manner with the ordinary frustules, 

 and is thus converted into a number of sporangial frustules. In 

 what way the small ordinary frustules are produced from these 

 has not yet been observed. 



Why should not this conjugation of the endochrome in the 

 lower plants be considered essentially the same process as what 

 takes place during impregnation in the higher tribes ? The most 

 eminent physiologists seem to be arriving at the opinion that the 

 fertilization of the ovule, as it is termed, consists in the union of 

 a part of the contents of a pollen-grain with certain matter con- 

 tained in the ovule, and that the embryo originates from this 

 mixed matter. The correctness of this opinion is rendered still 

 more probable by the consideration of what takes place under 

 the circumstances of hybridization of species. The phfcnomcna 

 which present themselves in these cases are of the highest phy- 

 siological interest, and it seems impossible after a careful consi- 

 deration of them to doubt that the hybrid plant owes its ex- 

 istence to — consists in its earliest condition of — an endochrome 

 made up of a portion of the endochrome of each of the parent 

 plants ; for the development of the hybrid embryo into the ma- 

 ture plant indicates a quality of the contents of this embryonic 

 cell of a character combining that of the endochrome of each of 

 the two parents. A few facts will best illustrate the meaning of 

 the foregoing observations. The ovules of Fuchsia coccinea fer- 

 tilized with the pollen of Fuchsia fulgens produce plants of every 

 intermediate form between these two species — some of the seed- 

 ling plants closely resembling one, and others the other species, 

 but the majority partaking equally of the characters of the two 

 parents : scarcely however will any two be found so much alike 

 as to be undistinguishable from each other. With respect to 

 each of the hybrid seedlings separately considered, there is a uni- 

 formity throughout in the mixed character of its various parts ; 

 80 that it is easy from the examination of the foliage to arrive at 

 a tolerably correct idea of what will be the character of the 

 blossom. Some persons perhaps will be disposed to believe that 

 an endochrome may be modified in its character — that the pecu- 

 liarities of the hybrid plant may be produced — by the situation 

 in which it is at first developed ; but, if this were the fact, it is 

 clear that the hybrid seedlings ought all to resemble each other 

 9» much as do individuals of one species, which is far from the 

 tmth, as has been just now stated. Moreover, a fact came under 

 the observation of the writer which completely sets aside the 



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