VARIATION 419 



point of the new variety " (Article Heredity, Hastings' 

 Encyclopcedia of Religion and Ethics). 



Pointing in the same direction are the well-known experi- 

 ments of Professor Tower, who subjected potato-beetles to un- 

 usual conditions of temperature and humidity when the male 

 and female reproductive organs were at a certain stage of 

 development. The results were strangely lacking in uniform- 

 ity, but some of the oifspring showed striking and persistent 

 changes, not only in colour and markings, but also in some 

 details of structure. Professor Tower's work has met with 

 some adverse criticism, but, taken along with similar experi- 

 ments, it suggests that we must not overlook the possibility 

 of deeply-saturating environmental influences acting as varia- 

 tional stimuli, — affecting not the body of the parent, but the 

 germ-cells within. Here should be included Weismann's 

 view that fluctuations in bodily nutrition may prompt the 

 germ-plasm to vary. 



(2) Some of the researches of recent years, such as those 

 of Dr. R. Euggles Gates on Evening Primroses ((Enothera) 

 and of Prof. T. H. Morgan on the Pomace-fly (Drosophila) 

 have focussed attention on the chromosomes. It is a distinct 

 step to know that certain peculiarities of particular mutants 

 are associated with visible alterations in the chromosomes 

 of the fertilised egg-cell. It is very interesting to know 

 that while the fundamental number of chromosomes for the 

 genus (Enothera is 14, this has become 15 in lata and semi- 

 lata, 21 in semigigas, 28 in gigas, and so on. These are the 

 numbers observed in the fertilised egg-cell and in every ele- 

 ment throughout the plant. 



In this connection a reference may be made to what obtains 

 in Man. Competent observers have stated that the cells of 

 the male negro have 22 chromosomes, and it is probable 



