Biparental Inheritance and Conjugation 153 



whole, are due to its origin from the united germinal ma- 

 terial from two parents; if the individual had been derived 

 from but one parent, it would have shown other peculiarities. 

 Thus when two kinds of white flowers produce by their union 

 plants with red flowers, this is an example of biparental in- 

 heritance (and one of not uncommon kind), for the red 

 color would not have occurred if the two parents had not 

 united, as for example in reproduction through cuttings. 



Now, the resemblance between the offspring of the two 

 members of a pair of infusoria is due to the fact that they 

 have received germinal material (the two halves of their 

 micronuclei) from both parents. It is therefore an example 

 of biparental inheritance. 



I have given this brief exposition of what heredity means, 

 and particularly of what biparental inheritance means, be- 

 cause to persons not familiar with experimental work in 

 heredity, it appears surprising that we should speak of bi- 

 parental inheritance when we haven't proved that the off- 

 spring resemble their two parents; this objection has been 

 made by Dobell (1914). But as a matter of fact we speak 

 of inheritance equally when we know that the offspring do 

 not resemble their parents, provided their peculiarities are 

 due to the germinal material derived from their parents. 

 The other significance for heredity would exclude a large 

 proportion of the best known cases of Mendelian inherit- 

 ance. 



We find then that in these Protozoa, as in higher organ- 

 isms, mating results in inheritance from both parents. In 

 what respects does such inheritance occur? Our knowledge 

 on this point is scanty ; until recently it was confined to cer- 

 tain characteristics of Paramecium ; to this has now been 

 added important knowledge of these matters in Chlamydo- 

 monas. This is one of the lines of work in which there is 



