470 Scientific Proceedings, Royal Dublin Society. 



another had germinated. On examining the soil the seeds were found to be 

 as hard as when they were planted. A thin slice was cut oil the seed- 

 coat, and tlie seeds were replaced in the soil. After a month seven had 

 germinated, and three weeks later eight more had germinated. Water could 

 not pass through tlie seed-coat until part of tlie impermeable layer had been 

 removed. 



The seeds of stone-fruits do not usually germinate until the hard 

 protective covering has decayed in the soil. If it germinated sooner, the 

 radicle would be unable to force its way through the enclosing envelope. In 

 order to determine whether the delayed germination is inherent, the hard 

 stone was removed in the case of some seeds of Hawtliorn and Sloe, and the 

 seed only planted. It was found, however, that removal of the hard 

 enclosure imprisoning the seed did not in any way facilitate the process of 

 germination. 



Considerable differences were exhibited in the size of the cotyledons of 

 the same species, doubtless depending la.rgely on the particular spot where 

 the seed fell or was planted. In a dry situation the parts of the plant would 

 be more stunted than would be the case if the seed germinated in a moister 

 soil or in the shade of other plants. The measurement of cotyledons was as 

 far as possible made after the first ordinary leaf had expanded. 



Some species showed irregularities in the number of cotyledons. Tiiree 

 were found in Anthriscus sylvestris, dqiseUa Bursa Pasloris, Carlina tulgaris, 

 Eujy/iorbia exigua, Primus Persica, Rhamnus catliarticus, Sanibucus nigra. A 

 specimen of Mercurialis annua had the cotyledons united nearly to the tip, 

 while a seedling of Sycamore had one of the two cotyledons cleft almost to the 

 base. 



In the subjoined list the classification adopted is that of Engler, and tiie 

 families are grouped for convenience of reference in alphabetical order. The 

 genera of each family and the species belonging to eaoli genus are also 

 arranged alphabetically'. 



AqUIFOLIACEjE. 



Ilex AquifoUum Linn. — Seeds (1910) planted on 14th July, 1911. None had 

 germinated on 25th July, 1912 ; on 10th October, 1912, none had 

 germinated. Seedlings were found at Lucan on 12th June, 1911. 



B 



ETULACE.E. 



Alnus rotundifoUa Miller. — Seeds (1910) planted on 18th April, 1911. None 



had germinated on 8th June, 1912. 

 Betula alba Linn. — Seedlings found in peat bog at Edenderry, King's County, 



on 19th July, 1906. 



