28o 



Journal of Agricultural Research 



Vol. VI. No. 8 



moisture. The hygroscopic movements of the lips of the apothecium 

 furnish the method by which the spores are forced or ejected from the 

 asci. As Von Tubeuf ^ has pointed out in the case of Lophodermium 

 pinastri, the spores are shot out from the mature asci under proper con- 

 ditions of moisture. This fact is easily demonstrated by inclosing short 

 pieces of previously moistened needles bearing mature apothecia in the 

 cavities of plate-glass culture slides. A microscopic study of such 

 preparations shows that the spores are shot out from the asci a distance 

 of from I to 2 mm., showing as a plainly visible deposit on the floor and 

 cover of the cavity. The depth of the cavity in the slides used was 2 mm. 



mm 



Fig. 3. — Cross section of an apothecimn of Hypodervia deformans on a needle of Pinus pmtderosa, showing 

 mature asci with spores, the point of first rupture, and the tissues of the leaf most seriously affected by 

 the mycelium of the f vmgus. 



Occasionally an entire ascus was ejected and lay among the spores. In 

 most cases, the asci remained attached and the spores were expelled 

 through their terminal pores (fig. 4). Only the fully developed spores 

 were cast out of the apothecia. After the material had remained in the 

 slides a day and a half, during which time the spores were being ejected, 

 the cover glass of a slide was removed and the material allowed to dry 

 by exposure to the air of the laboratory for 30 days. The material was 

 washed and replaced in the cavity in the slide. Within three hours 

 spores from the same apothecia were expelled in considerable numbers 

 but not so profusely as before. The process was repeated with shorter 



' Tubeuf, Carl von. Op. cit., p. 24-25- 



