33$ LOUIS M. HICKERNELL. 



tion are almost the exact opposite of those just described. In 

 cases where the karyosome has entirely disappeared it begins to 

 form again in its proper position a short time after water is added 

 to the dried animals. The thickened nuclear membrane de- 

 scribed above shows a greater affinity for stains at this stage 

 and gradually assumes its normal thickness. Cytoplasmic 

 changes are quite noticeable at this time. In the vitellarium 

 (Fig. 6) it is frequently noticed that the material surrounding 

 the nucleus is aggregated into strands or other irregular patterns. 

 This would seem to indicate that the cytoplasm is more freely 

 permeable to water in certain regions than in others and that the 

 stage represented in Fig. 7 shows a step in the gradual redistribu- 

 tion of extranuclear substance attending recovery from desicca- 

 tion. In the case of the other organs, as before, the process of 

 recovery is very similar. The elements are much smaller in 

 some cases and hence more difficult to observe but the mechanism 

 as well as the result seems to be the same. 



It has been suggested to the author that the cytoplasmic and 

 the nuclear changes taking place in dry seeds might be analogous 

 to the ones in the rotifers just described. With this in mind, 

 sections of the embryo of the common Indian corn, Zea mais, 

 were cut, (i) at the time the seeds were fully ripened but had not 

 become entirely dried ; (2) after the seeds were thoroughly dried ; 

 and (3) after the seeds were well germinated. A section of a 

 typical procambium cell from each of these stages is shown 

 herewith. Fig. 14 shows a cell from a germinating embryo. It 

 will be noticed that the cytoplasm contains many spaces filled 

 with cell sap. The nucleus has a ring of chromatic material 

 just within the nuclear membrane. The nucleolus is vacuolated 

 and does not stain in the same manner as the chromatic ring at 

 the periphery of the nucleus. The nucleolus is surrounded by a 

 clear area which probably consists of fluid material. Fig. 15 

 shows the conditions which exist when the embryo is partially 

 dried. The chromatic ring thickens, diminishing the space 

 between it and the nucleolus. The latter becomes more compact 

 and the vacuoles disappear. An extreme case of drying is shown 

 in Fig. 1 6. The cytoplasmic granules are closely and regularly 

 packed together. The clear space in the nucleus has disappeared 



