NUCLEAB PHENOMENA OF SEXUAL BEPRO- 

 DUCTION IN FUNGI 1 



I'RoFKSSoR R. A. HARPER 



In the light of recent researches the aid dogma that the 

 parasitic mode of life tends to the disappearance of sex- 

 uality has practically disappeared at least so far as the 

 fungi are concerned. The evidence is now generally ac- 

 cepted that either a typical conjugation of normally dif- 

 ferentiated gametes and their nuclei or some form of sub- 

 stitute for it is everywhere present. 



Kmst and Schmidt on the basis of their studies on the 

 root parasite Babesia have also recently emphasized the 

 fact that there is no evidence in the case of seed plants 

 that the parasitic habit tends to the disappearance of 

 sexualitv. Farmer and Dighv have described a most 

 remarkable substitute fusion in an apogamons fern and 

 a still more striking ease of substitute cell and nuclear 

 fusions in another apogamous fern has been recently dis- 

 covered in my own laboratory. It is proper under these 

 conditions to examine anew and most critically all cases 

 of cell fusions with reference to their accompanying 



The study ef sexuality in the fungi has also brought to 

 light some fundamental modifications of the process of 

 sexual fusion as found elsewhere which enlarge our con- 

 ception of the nature and significance of gametic unions. 

 It has also revealed most curious and striking substitu- 

 tions for sexual fusions. I shall review briefly the most 

 characteristic and significant of these variations from the 



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