2i2 botanical gazette. [September, 



imens. That there are two forms of spores in G. clavaria?- 

 forme and also in other species has been known for a long 

 time. Among the more important references are those of 

 Oersted, 1 who figures both kinds of spores in the case of 

 G. clavariceforme, of Rees, 2 in G. fuscum and G. conicum, 

 of Kornicke, 3 and also of Farlow, 4 and further search would 

 doubtless show other references. Although, as I have just 

 said, the existence of two forms of spores was well known to 

 writers before Kienitz-Gerloff, no particular significance was 

 attached to the fact and they were both considered as forms 

 of teleutospore produced by difference in exposure or time of 



development. 



That the conditions of my work might be as nearly as pos- 

 sible like those of Kienitz-Gerloff, and the results readily com- 

 pared with his, I took G. clavariceforme, the species used by 

 him in his investigation. As it is quite common on the Juniper- 

 us communis in the neighborhood of Boston, I had no difficulty 

 in getting all the material I wanted. That which I used was 

 obtained from Saugus through the kindness of Mr. Seymour. 

 It was collected on the nth of April, and being at that time 

 still young the spore masses had scarcely appeared on the 

 bark of the Juniper, but it was easily ripened when kept for 

 a short time under a bell-glass in a moist atmosphere. At 

 the time the first observations were made the young spore- 

 masses were only slightly convex and had not swelled to the 

 conical form attained at maturity. At this stage sections 

 across the spore-mass show that all the spores resemble each 

 other closely, being long and fusiform, and no distinction 

 can be made between the blunt thick-walled and the acute 

 thin- walled spores. 



When mature differences in the spores are seen. One 

 kind, which is found in the inner portion of the spore-mass, 

 is composed of two acutely conical cells which are joined at 

 their bases, making a long, symmetrical, fusiform, or lance- 

 olate spore (fig. i) ; the other is commonly met with nearer 

 to the periphery and consists, like the first, of two cells, but 

 is not symmetrical, the upper cell being quite blunt and 

 rounded off, thus making the spore clavate in form (fig- 2 )' 

 as is described by Kienitz-Gerloff. Both forms are of about 

 the same size ; the clavate variety being perhaps a little 

 shorter in proportion to its width than the other ; and both 



iBull. Acad. Roy. Sci. Copenhagen, 1867, Plates III and IV, figs. 3 and 7. 

 2 Die Rostpilzformen der deutschen Coniferen, pp. 17 and 26, 1869. 

 *Hedwigia, xvi. 27, 1877. 



*The Gymnosporangia of the U. S., 1880. 



