334 The Ohio Journal of Science [Vol. XIX, No. 6, 



plants than the undisturbed ash deposits. But further study 

 led me to doubt the correctness of this view, and this doubt was 

 confirmed when it was found that pot cultures of this material 

 were no hiore successful than those in which the undisturbed 

 ash was used. 



Meanwhile the field study was carried out on the hypothesis 

 that the water content of the soil was inadequate. It was 

 reasoned that numerous seedlings should have started in periods 

 of wet weather, even in very unfavorable places. If this had 

 happened many of these seedlings would have been caught in 

 the drought and their dead and dying remains would have 

 been easy to find. But, as a matter of fact, prolonged search 

 failed to disclose any such, except in one solitary instance. 

 This was considered remarkable, since, even under the con- 

 ditions of the Central States, it would be easy to find numbers 

 of seedlings which had perished in any considerable drought, 

 even though mature plants had not suffered seriously. More- 

 over, since the bare ash surface is free from plant debris of any 

 kind over considerable areas, seedlings if present could not 

 have been overlooked. It became evident that there had never 

 been any seedlings on the general surface. 



Here, then, was another significant fact which required 

 interpretation. The most obvious explanation would be that 

 the ash contained some substance deleterious to the germi- 

 nating seeds. In the vicinity of the crater and in certain other 

 special localities* some such chemical is evidently present, 

 but it is certain that no such deleterious substance is generally 

 present. It has been shown, both by chemical analysis and by 

 the experience at Kodiak, that there is nothing injurious to 

 plants in the ash deposited at that distance. The pot cultures 

 made on the return to the States showed, except in special 

 instances, that plants do not behave differently when grown 

 in ash from the mainland than in that from Kodiak. 



It was then suspected that the reason for the barrenness of 

 the undisturbed ash might lie in the fact that its smooth surface 

 afforded no lodgment for seeds which, distributed largely by 

 the terrific gales that sweep the country, are carried across the 

 smoother surfaces and dropped in situations better adapted 

 to catch them. 



*Dr. Shipley, in the sixth paper of this series, pages 224-229, has shown 

 that in a few localities the ash bears so strong a concentration of ferrous sulphate 

 as to be toxic to plants. But the occurrence of such deposits is limited to very- 

 special situations. 



