MICRURGY 



63 



C. V. Taylor of California has taught us much about the 

 behavior of the protozoan Euplotes by micromanipulative 

 methods. He was able to sever various parts and thus learn 

 their function. By cutting all of the neurofibrils (Fig. 50), or 

 selected ones among them, with quartz microscalpels, he could 

 observe the effects of the cutting and subsequent regeneration 

 upon the previously analyzed stereotype behavior of the organ- 

 ism. But the most dramatic of micrurgical operations done by 

 Taylor was the isolation of the micronucleus, by means of which 

 he discovered its function. Euplotes (Fig. 

 28) has two nuclei, a large worm-shaped 

 one, the macronucleus ; and a very small 

 globular one, the micronucleus. Taylor 

 neatly extracted the micronucleus with a 

 micropipette and observed the subsequent 

 behavior of his patient. Fifty-four Eu- 

 plotes were thus operated upon, and none 

 lived more than five days. The absence of 

 the micronucleus is therefore not immedi- 

 ately fatal, but without it Euplotes can 

 neither eat nor divide (reproduce). The 

 organism lives only as long as the food _ ._ ^, 



"= JO Pjq 5q — ^Yhe neuro- 



within it lasts. A justified criticism would fibrils of Euplotes cut 

 be that the operation itself and not the by a microneedle. {From 



^ C. V. Taylor.) 



absence of the small nucleus was the cause 



of the inability to eat. That this is not true was shown by 

 extracting some of the cytoplasm elsewhere in the cell, i.e., by 

 performing an operation similar to the first but leaving the 

 nucleus untouched, and further, by removing parts of the large 

 nucleus from 22 individuals, each of which continued to live and 

 form thriving colonies. But the final and most convincing proof 

 that the loss of the micronucleus and not the operation was the 

 cause of the abnormal behavior was had when Taylor extracted 

 the micronucleus from each of two Euplotes and immediately 

 replaced them. Both organisms gave rise to thriving colonies. 

 George Scarth has done valuable micrurgical work on plant 

 material, to which we can best refer in subsequent chapters. 

 Freundlich and Hauser have applied micrurgical technique to 

 the study of the structure of the latex globule in rubber solutions. 

 These globules, which are present in all latex-producing plants 



