162 



Soon after Mr. Ward had made known his plan of growing ferns 

 and other plants in closely glazed cases, a plan admirably adapted 

 also for physiological experiments, I had constructed a small case for 

 the purpose of endeavouring to grow the mosses in the metropolis, in 

 which were placed various species, both in fruit, and having the ten- 

 dency to form fruit; the case being kept in doors, close to a window 

 which faced the south. 



Among the number so planted, was a mass of Tortula fallax, show- 

 ing, at the time, the early condition of the seta, capped with a ca- 

 lyptra. 



After watching the progress of the plants in the experimental case, 

 it was discovered that the Tor tula, which, when placed in it, showed 

 every tendency to produce fruit, now presented a miniature forest of 

 elevated stems, leafy above and below, but in the intermediate portion, 

 destitute of leaves, instead of fruit advancing to maturation ; in fact, 

 all appearance of capsules approaching maturation was entirely dis- 

 sipated. 



On placing some of the plants under the microscope, it was evident 

 that the specimens were furnished with the usual leaves at the base 

 of the plant, — the seta existed, and presented the usual brown colour, 

 quite destitute of leaves, but in the place of the capsule, there was a 

 continued elongation of the seta, of a green colour, bearing several 

 green leaves, varying in number in different specimens, being gene- 

 rally from about twelve to twenty ; no doubt there would have been 

 more, had the plants been allowed to continue growing. (See PI. 

 xix. fig. 5). 



In this condition the specimens were now removed from the case, 

 and dried for the herbarium. 



From the view displayed by the microscope, it appears that the 

 capsule had scarcely commenced to be formed, when the elements of 

 the modified leaves, (which I conceive would have otherwise formed 

 the capsule and peristome), having received an increased degree of 

 heat, combined with more moisture than is natural to these plants, 

 occasioned by the structure of the case, and by its position, instead 

 of being converted into the ordinary capsule and peristome, the mat- 

 ters which entered the plants were appropriated, not in favouring 

 the development of the organs of reproduction, but in effecting a 

 change which carried them into a state fitting them apparently for 

 the purposes of nutrition. 



This change appears to have been accomplished by the columella 

 continuing to elongate, and the leaves, whose apices, which it is con- 



