HEREDITARY TRANSMISSION AND VARIATION. 87 



ceeding from two sources appears to confer an altogether 

 new vigour to the mixed product. This process is 

 brought about, as we all know, by the sexual inter- 

 course of the two sexes, and is called the act of impreg- 

 nation. The result of this act on the part of the male 

 and female is, that the formation of a new being is set 

 up in the ovule or egg ; this ovule or egg soon begins 

 to be divided and subdivided, and to be fashioned into 

 various complex organisms, and eventually to develop 

 into the form of one of its parents, as I explained in 

 the first lecture. These are the processes by which 

 the perpetuation of organic beings is secured. Why 

 there should be the two modes — why this re-invigora- 

 tion should be required on the part of the female 

 -element we do not know ; but it is most assuredly the 

 fact, and it is presumable, that, however long the 

 process of asexual multiplication could be continued, — 

 I say there is good reason to believe that it would 

 -come to an end if a new commencement were not 

 obtained bj^ a conjunction of the two sexual elements. 

 That character which is common to these two dis- 

 tinct processes is this, that, whether we consider the 

 reproduction, or perpetuation, or modification of 

 organic beings as they take place asexualh^, or as 

 they maj' take place sexually, — in either case, I say, 

 the offspring has a constant tendency to assume, 

 speaking generally, the character of the parent. As 

 I said just now, if you take a slip of a plant, and 

 tend it with care, it will eventually grow up and de- 

 velop into a plant like that from which it had sprung ; 

 and this tendency is so strong that, as gardeners know. 



