94 



Sir J. B. Lawes and Prof. J. H. Gilbert. [Jan. 9, 



this date, the plants in pots 2 and 3 with the soil-extract, gradually 

 gained upon those in pot 1 without it, both in number of leaves, and 

 in leaf-surface ; until, when the plants were taken up on December 14, 

 those in pots 2 and 3 showed 540 and 390 leaves, against only 382 

 on those in pot 1 ; and the plants of pots 2 and 3 showed 481 and 

 434 of leaf-surface, against only 267 in pot 1. It is seen that there 

 is here clear evidence of increased growth under the influence of 

 the soil-extract seeding. 



Photographs of the 4 pots of plants were taken on September 1, on 

 September 22, on October 6, and lastly on November 3, about five 

 weeks before the taking up of the plants, and they indicate relative 

 progress consistently with the estimates given in the foregoing 

 table. 



In regard to the general character of growth it should be stated that, 

 in all the pots, the upper portions of the plants obviously developed 

 at the expense of the lower ; the leaves of which gradually lost colour, 

 and died off, whilst the stems and the leaves of the upper portion 

 increased in growth ; those in pots 2, 3, and 4, continuing to vegetate, 

 and to maintain their bright green colour, up to the end ; whilst those 

 in pot 1 had shown more exhaustion, and maintained much less 

 colour. There was, however, as was to be expected so late in the 

 season, no indication of flowering in any of the pots. 



It should be further stated, that the plants in all the pots com- 

 menced rather early to show signs of mildew, which increased very 

 considerably, especially on the lower portions of the plants, in the 

 later stages of growth. This was, perhaps, not to be wondered 

 at, considering that the greenhouse was in the midst of allotment 

 gardens, and that the plants were unavoidably subjected to consider- 

 able changes as to temperature and moisture of the atmosphere. 

 Ventilation was, however, secured as far as practicable. 



The next point to consider is, the actual and comparative develop- 

 ment of the roots, and of nodules on them, in the different pots, with 

 their different soil conditions. As the roots had to be preserved 

 without any loss, for analysis, the mode of dealing with them for the 

 purposes of examination had to be very carefully considered, and was 

 necessarily more restricted than if examination had been the only 

 object. After the above-ground growth had been cut off and 

 removed, the pots, with their moist soil and roots, were kept in a 

 warm dry place until the examination commenced. The block of 

 soil was carefully turned out on to glazed cartridge paper, with as 

 little shaking or disturbance as possible, and notes were at once taken 

 as to the distribution of the roots, so far as it was then apparent. 

 The sand or soil was then removed little by little, until the roots 

 were left nearly bare. Further notes being then taken, the remaining 

 sand or soil was removed as far as possible by washing in a beaker 



