Inheritance of Size 59 



terial contribution which perpetuates for a time traits 

 that are not transmitted in the relatively inviolable 

 hereditary constitution. 



2. Other Soft-Bodied Species 



Bacillus coli. Some of the earliest observations 

 upon inheritance of size in unicellular species were 

 made by Barber ('07) upon Bacillus coli communis. 

 He first secured a clone by the isolation with a micro- 

 pipette of one individual, allowed its progeny to multi- 

 ply, and then selected individuals which appeared un- 

 usually large in order to see if their size was a genetic 

 characteristic or not. Out of 140 large individuals 

 which were isolated, only 16 survived in cultures. One 

 of these 16 kept its long-bodied character; it bred true 

 for 32 months at least. In another clone 50 large in- 

 dividuals were isolated, but only 14 multiplied in cul- 

 ture; yet one of these also maintained its large size. 

 Incidentally a third long-bodied race was established 

 by a single selection. In Bacillus typhosus none of the 

 long individuals selected within a clone bred true. In 

 a yeast, Saccharomyces anomalus; repeated selections 

 within a clone were made; these also were negative. 



Barber published no measurements of size in these 

 organisms, and possibly a micrometer was not used. 

 It cannot be ascertained just how significant the differ- 

 ence was between the three selected clones and the 

 normal-sized sister cultures. That the size difference 

 was marked to comparative inspection should, how- 

 ever, have made it a significant one. The possibility 

 therefore remains, though unconfirmed, that differen- 

 ces of size biotype, which were independent of cultural 

 conditions, arose. 



That extensive work upon the inheritance of size in 

 bacteria has not been carried out, merely indicates, it 



