OBSERVATION AND DESCRIPTION OF PENICILLIA 59 



conidium-bearing mycelium. Such a colony is regarded as homotypic if 

 the parent conidium was uninucleate, or heterotypic if the conidium was 

 binucleate. In any case, wherever two or more conidia are involved, 

 branches of the different mycelia quickly anastomose to establish a hetero- 

 karyotic condition in the developing mycelium. The regular develop- 

 ment of anastomoses resulting in heterokaryotic mycelia in P. notatum 

 is likewise reported by Pontecorvo and Gemmell (1944a) and by Linde- 

 gren and Andrews (1945). 



