316 SEA-SIDE STUDIES. 



union of different sexes which in higher organisms becomes 

 the normal process. 



From the fission of one cell into two similar cells, and the 

 conjugation of tAvo similar cells, we now pass to the third 

 and final mode of Eeproduction, namely, the union of two 

 dissimilar cells. To this union the special name of Genera- 

 tion has been applied ; but the difference of name must not be 

 allowed to mask the identity of the process. It is a fact, that 

 for the production of the more complex organisms, union of 

 germ-cells and sperm-cells is indispensable. Speculative 

 physiologists have likened this union of germ-cell with 

 sperm-cell to the union of an acid with its base. But the 

 deeper our researches j)enetrate, the more erroneous does 

 such a comi^arison appear. I cannot pause here to trace 

 the genesis of ovum and spermatozoon, but must content 

 myself with the assertion, which the reader can verify by 

 consulting any embryological authority, that in their origin, 

 and in the earlier phases of their development, these two 

 cells are identical. It is only in their subsequent history 

 that they differ.* If one convincing argument be needed to 

 crown all these indications, we may find it in the now indu- 

 bitable fact, that animals which normally are developed from 

 fertilised eggs, are also normally developed from eggs unfer- 

 tiUsed. It is clear, then, that if the egg, previous to fertil- 

 isation, has within it the elements and conditions ivhich will 

 produce the same animal as woidd have issued from the 

 fertilised egg, the influence of the sperm-cell on the germ- 



• That is the rea-son wliy plants can be developed into male or female 

 according to the will of the experimenter. 



