268 THEORETICAL CONSIDERATIONS 



diastatic activity in resting ' seeds is very feeble, varying with the 

 species, and with the conditions under which the seeds are kept. 

 Their diastatic power varies with their power of germination, being 

 lowest in old seeds. In seeds which have lost their ability to 

 germinate the diastatic power is diminished or entirely annulled. 

 External agents, such as temperature, light, and chemical stimulants, 

 affect enzymes and the germinating power of seeds alike. He con- 

 cludes that the energy for the changes going on in seeds originates 

 in the action of enzymes, but that the changes take place more gradu- 

 ally in resting seeds than in those that are germinating. 



In 1907 Brocq-Rousseu and Gain *^ reported the existence of a 

 peroxydiastase in dry seeds of Nymphaeaceae, Ranunculaceae, 

 Malvaceae, Umbelliferae, Cupuliferae, Juglandaceae, Liliaceae, 

 Gramineae, Coniferae, and other families of plants. This substance 

 colors blue a tincture of guiacum in the presence of oxygenated water. 

 It is stated that there may be more than one peroxydiastase in dry 

 seeds, but the ferment does not exist in them indefinitely. Later the 

 same authors ^^ investigated the occurrence of the peroxydiastase in 

 seeds of authentic ages of from 2 years to 5)000 years, taken from 

 museums and herbaria. The oldest seeds were from the Collections 

 ■pharaonique du Musee de Boulaq. They found that the peroxy di- 

 astases may disappear in a few years (in Galium^ c. g., 20 years); 

 and that they may also be preserved for very long periods. The 

 oldest seeds in which they determined its survival belonged to the 

 i8th century. Seeds which could germinate, however, always con- 

 tained the peroxydiastase, but those which have lost that faculty may 

 still conserve it. 



In connection with this last point may be mentioned the researches 

 of Gain *^' ^^ who found that the embryos of cereals from the tombs 

 of the ancient Pharaohs, notwithstanding the seed's external appear- 

 ance of good preservation, do not possess a cellular organization 

 suitable for germination. The stored food is well preserved and 

 may be utilized by a living embryo, but the embryo of the ancient 

 seeds has undergone a chemical transformation, and is no longer 

 viable. The relative age (and thus viability) of the embryo may be 

 detected by a peculiar coloration which grows darker with age. 



With reference to the effects of radium rays on dry seeds and on 

 germination, the possibilities, suggested by the above discussion, 

 hardly need a formal statement. The rays may act directly on the 



