a PHENOMENA OF ORGANIC NATURE 395 
and the pollen-grain, as in the flowering plants, or 
the ovule and the antherozooid, as in the flower- 
‘less. Among all forms of animal life, the sperma- 
_tozoa proceed from the male sex, and the egg is 
the product of the female. Now, what is remark- 
able about this mode of reproduction is this, that 
_ the egg by itself, or the spermatozoa by themselves, 
“are unable to assume the parental form; but if 
they be brought into contact with one another, 
the effect of the mixture of organic substances 
proceeding 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 intercourse of the two sexes, and is called 
- the-act of impregnation. 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 cr egg soon begins to be divided 
_and subdivided, and to be fashioned into various 
ae organs, and eventually to develop into 
the form of one of its parents, as I explained in 
4 the first lecture. These are the processes by 
_ which the perpetuation of organic beings is secured. 
Why there should be the two jncdewioahy this 
-re-invigoration should be required on the part of 
the feriale element we do not know ; but it is most 
assuredly the fact, and it is presumable, that, how- 
ever long the process of non-sexual multiplication 
‘could be continued—I say there is good reason to 
believe that it would come to an eid if a new 
