MISCELLANEOUS: EXPERIMENTAL TERATOSIS 609 



cut away (upper 4 to 5 leaves) mostly for the titration experi- 

 ments described on page 600. 



Result in November: Dormant buds just under these tops 

 have now pushed stunted small shoots (2 to 4 inches) and these 

 are covered with cork, some almost entirely, others partially, 

 and where not very corky they have also pushed adventive 

 shoots. The leaves are small (stunted) and many of them have 

 fallen. These small upper side shoots most of which were un- 

 developed, but some of which were an inch or so in length when 

 the top was removed, are the only corky parts of the plants, and 

 each of the 59 plants (all of which were cut back) shows this cork 

 phenomenon to a very striking degree. Some of the plants also 

 show cork-formation on the main axis immediately under the 

 cut (the upper inch or so of the stub). These are the stems 

 which were softest at the time the tops were removed, and which 

 lost most water, as shown by their contracted and flattened 

 shape. It is a striking confirmation of my idea that loss of water 

 induces cork formation and the adventive shoots. 



26. Why loss of water should shock dormant cells into growth 

 I have undertaken to discuss in the preceding chapters. It 

 seems to me likely that the initial stimulus to all spring growth 

 of land plants may be conditioned on gradual winter losses of 

 water through stems and twigs. This would be more rapid in 

 mild winters than in cold ones. When the removal of water 

 from the dormant buds has reached a certain point then they 

 will begin to grow. Etherized plants also push their shoots 

 earlier than normal plants and in this case also we may suppose 

 that there is excessive loss of water from cells of the buds through 

 the temporarily paralyzed protoplasmic membranes. We should 

 distinguish, I believe, between the initial shock or stimulus, the 

 cause of the first cell-division of a dormant totipotent cell, and 

 the subsequent growth, which latter depends on renewed food- 

 supply, water-supply, proper temperature, etc., and will proceed 

 as a matter of course, once the initial dormancy has been 

 overcome. 



27. The prolification usually is most pronounced on the upper 

 surface of leaves and petioles, that is, it is negatively geotropic, 

 but sometimes it occurs, although less freely, on their under- 



39 



