414 . TRANSACTIONS AND PROCEEDINGS OF [Sess lvi. 



gamete developes " activity and delicate sensibility " to be 

 able to hunt up the megaganiete, is a purely teleological 

 view of matters, and must be abandoned. Microgametes 

 and megagametes are developed, due to certain physiological 

 causes inherent to the parent, and that they are capable by 

 their union to give rise to a vigorous zygote, is only a 

 secondary accident, which is of the highest importance for the 

 maintenance of the species, but, in multicellular organisms, 

 of no interest to the parent organism, and not only of no 

 interest to the individual, but directly injurious. 



Weismann's view as to " sex " may be shortly summed up 

 thus : — Nothing, if not teleological in his view, he considers 

 the simplest form of sexual reproduction to have arisen from 

 conjugation, and the latter to have been brought about by a 

 desire to strengthen the organism in relation to reproduction, 

 whenever, from some external cause, such as want of oxygen, 

 warmth, or food, the growth of the individual to the extent 

 necessary for reproduction could not take place. 



After conjugation had once been established, the process 

 soon acquired a new significance, for the mixing and blending 

 of various hereditary tendencies which it necessarily implied, 

 conferred upon forms possessing it a higher degree of heredi- 

 tary variability, or, in other words, the power of adapting 

 themselves to surrounding and varying conditions. This 

 power of adaptation to changes in environment is obviously 

 of so profound importance to the survival of the various 

 organisms, as to account for the all-pervading existence of 

 sexual reproduction. 



A fundamental difference between male and female, or 

 between the nuclei of the reproductive elements, Weismann 

 does not believe in, and to prove their physiological iden- 

 tity, he refers to Boveri's experiments, in which echinoderm 

 ova were enucleated, and spermatozoa introduced in their 

 place, whereupon the ova in several cases underwent normal 

 segmentation, and even produced a larva. He also refers to 

 the case of Edocarpus, where in certain cases the normally 

 male element may germinate and give rise to a new plant. 



Pi. Hertwig,* in his book, p. 52, considers the chromatin 

 of nucleus as that part of the cell which determines the 

 character of a cell, which influences all activities of the 



♦ L(;l)ibucli ;]. Zofil., Jena, 189]. 



