378 LOUIS MAX HICKERNELL. 



years showed the cytoplasm gathered in one corner of the cell. 

 The nucleus, which normally is of lenticular form and contains 

 vacuoles, was still embedded in the cytoplasmic mass. It had 

 decreased to one fourth or less of the size of the normal nucleus. 

 The vacuoles had disappeared and the chromatic elements had 

 for the most part become aggregated in a ring in the region of 

 the nuclear wall. 



In the palisade cells of a cactus which had been desiccated 

 only ten months the cytoplasm did not deviate from the normal 

 condition as in the first case mentioned, at least in so far as its 

 position was concerned. The nuclei decreased almost as much 

 in size and assumed practically the same form as those in the 

 palisade cells desiccated six years. In the specimen which was 

 desiccated forty-two months and then returned to normal con- 

 ditions for twenty-two months, the cytoplasm was found to be 

 normal as to quantity and position, while the nuclei, although 

 increased slightly in diameter, still retained the ring form char- 

 acteristic of the dried condition. 



In the other tissues the results were quite similar to those 

 recorded for the palisade cells. In the integument the cuticle 

 thickened slightly in the specimen desiccated six years. The 

 outer epidermal cells were thinner in the plant dried six years 

 than in that dried only ten months, while in the one desiccated 

 forty-two months and returned to normal surroundings for 

 twenty-two months the epidermal walls were of about the same 

 thickness as in the normal tissue. 



The nuclei of the epidermal cells decreased to about one half 

 normal size in Echinocactus No. 7. The characteristic peri- 

 pheral chromatic ring appeared. In specimen No. 6 which after 

 desiccation was returned to a normal environment, the epidermal 

 nuclei resumed their normal condition. 



In the cells of the outer cortex below the palisade layer, the 

 cell walls increased perceptibly in thickness as desiccation pro- 

 ceeded and they recovered somewhat their normal thickness as 

 moisture was again admitted. The nuclei shrunk to about half 

 size and assumed the ring form. In the deeper cortex practically 

 the same things happened as were just described for the outer 

 cortex. The cytoplasm decreased almost to the point of dis- 

 appearance in the cactus dried six years and gradually increased 



