200 THEORETICAL BIOLOGY 



It remained only to disentangle the separate elements from 

 their interlacings and interminglings, and, from their sum- 

 total, we should be able to reproduce in the imagination the 

 construction of organisms. 



But Mendel's discovery went much further than this. 

 In addition to knowledge of the fundamental biological 

 elements, it also gave us the rules controlling their suppression 

 and exchange in the germ. The properties of the fully-grown 

 organism are, as we know, passed on by the male and female 

 sex-cells, which possess these properties only in the form 

 of rudiments. The competition between the paternal and 

 maternal rudiments takes place as early as the fertilised ovum. 

 Accordingly we are justified in regarding as processes in 

 the germ the results of this competition, which reveal 

 themselves in the offspring. 



In his seven famous series of experiments, Mendel proved 

 that in peas, form, colour, size and position of the organs 

 are to be regarded as independent characters, which, even as 

 rudiments in the germ, have become involved in a competition 

 regulated by fixed laws. According to his doctrine, the pro- 

 perties can be divided into " dominant " and " recessive," 

 irrespective of whether they come from the father or the 

 mother. The dominant rudiments suppress the recessive, 

 without exterminating them, i.e. if, in the germ of an animal, 

 the dominant and recessive rudiments have been in com- 

 petition, the full-grown animal displays in its development 

 only dominant properties, but it remains capable of trans- 

 mitting recessives as well as dominants to its successors. 

 Thus the offspring of the first generation from the crossing 

 of short and tall races of peas all grow to be tall, but they 

 retain the power of producing short pea-plants. 



By establishing this, Mendel discovered the presence of a 

 law of supplant ation of the rudiments of properties, which 

 affects these quite independently of whence they come. 



