HO FERN GROWING 



allusion is made to growing spores in a very dark place. The 

 impregnation of the prothallus did not seem capable of being 

 accomplished without the action of light ; the growth seemed 

 to be arrested before arriving at that particular stage of 

 prothalloid life. The following experiment is an illustration. 

 In 1874 a large Wardian case was filled at the base with 

 three inches of a prepared compost, carefully pressed down, 

 and this was sown in lines with spores from many varieties 

 of different species, the lines being kept separate by moving 

 flat glasses over the soil, only exposing that portion that was 

 about to be sown. After sowing, the case was placed in a 

 somewhat dark corner, under a brick archway, in a warm 

 greenhouse that faced the north, the opening of the arches 

 facing the south, the case being on the floor. When the 

 spores had been sown about six months, the surface of all 

 those lines was a green mass of prothalloid growth. A second 

 case was then prepared, into which were transplanted rows of 

 patches from each of the lines from the first Wardian case, 

 every patch being lifted on the point of a knife, and deposited 

 in a small hole previously made. This second case was 

 placed in a light part of the same house where there was 

 no sunshine. The transplanted patches grew rapidly, whilst 

 those in the case from which they were taken made little 

 or no progress. Within the next six months the second 

 case was filled with a mass of fronds, but not a frond had 

 appeared in the first case. For three years the first case was 

 kept in the same dark situation, and there was but little in- 

 crease in growth, and no fronds ever appeared ; whereas all 

 the little patches that were from time to time removed into 

 full daylight rapidly developed fronds. These experiments were 

 not then carried on beyond three years, but have since been 

 repeated. The prothalli, although growing very slowly whilst 

 in the dark, kept in a very healthy condition. Whilst making 

 these experiments, a pan of transplanted groups, protected 



