238 University of California Publications in Zoology [Vol. 20 



In 1910 Nirenstein demonstrated by the use of Sudan III that 

 fats are digested, in Paramaecium, during the time of the alkaline 

 reaction. Fat-containing vacuoles appeared in organisms that were 

 first starved, then placed in dilute solutions of glycerol and sodium 

 oleate. Mcissner (1888) demonstrated that starch is digested and 

 stored as glycogen in the Protozoa. 



The above account shows that food of Paramaecium is separated 

 from the endoplasm bj- a membrane just as trul.y as is the food in 

 tlie intestine from the adjoining protoplasm in the Metazoa, where 

 the digestive tract has a continuous lumen. Furthermore, the dige-s- 

 tive processes of the Protozoa are in fundamental respects similar to 

 those of the Metazoa. It was thought, therefore, that a.skaron might 

 be found toxic to Paramaecium when injected into the living cyto- 

 plasm. 



In order to accomplish micro-injection, a special method of isola- 

 tion was devised (Rees, 1921). Barber's micro-injection pipette 

 (Barber, 1914) was used. 



One of the surprising observations of this work was the exceeding 

 toughness of the pellicle of Paramaecium. Organisms were frequently 

 bent double on the point of the pipette and the pellicle still not 

 pierced. It was always easj', however, to determine whether or not 

 the injection was successful. A characteristic flash (gelation?) is 

 seen in the cytoplasm, caused by the disturbance of the protoplasmic 

 granules and other inchisions. If this disturbance extends to the 

 anterior end of the bod.y, the animal disintegrates. It may extend 

 over the entire posterior half of the body, as it asually does in suc- 

 cessful injections, and then the organism recovers. 



At first the askaron used in injection was dissolved in nonnal salt 

 solution as it is when injected into mammals. But the controls showed 

 that injection of the normal salt solution alone was fatal to Para- 

 maecium. It was then dissolved in tap water, and this solution Para- 

 maecium survived. 



The results of the injections and controls are recorded in the fol- 

 lowing tables. Table I shows that, of fifteen organisms successfullj' 

 injected with normal salt, seven were dead in fifteen minutes and 

 the other eight in thirty minutes. As is shovra by Table II ten organ- 

 isms successfully injected with tap water were all alive and normal 

 at the end of three hours but thej' dried out overnight. Eight others 

 injected with tap water, as shown in Table III, were normal at 

 the end of one hour. The injections with askaron are recorded in 



