INJURIES INDUCED BY PLANTS 157 



GYMNOSPORANGIUM l 



The species of this genus with which we are acquainted are 

 perennial in the cortical tissues of various species of Juniperus. 

 They induce local increase in growth, which takes the form of 

 peculiar swellings on the branches and parts of the stem that are 

 attacked.* Each autumn the teleutospores are developed under 

 the outer cortical layers, and in spring and early summer they 

 break through the cortex in large numbers and appear as fructifi- 

 cations which are conical or sausage-shaped, yellow or brown, and 

 mucilaginous or cartilaginous in texture. These fructifications 

 consist of the very long filamentous basidia whose outer wall 

 has been converted into mucilage, and of the two-celled resting- 

 spores which they bear at their apex. The formation of the 

 promycelium and sporidia takes place in the mucilaginous mass, 

 which in the end is completely dissolved by rain-water. The 

 sporidia gain a footing on the leaves of various pomaceous trees, 

 where they produce the aecidium form of the genus Rcestelia. 



It appears to me desirable that the forms which are already 

 known and described should be subjected to further examination, 

 because the few test trials that I have undertaken have at once 

 led to results which are at variance with what has been accepted. 

 I append here a short description of the three recognised species, 

 without, however, being able to vouch for its accuracy on the 

 strength of my own investigations/)* 



GYMNOSPORANGIUM CONICUM (jUNIPERUM) 



Teleutospore layers on Juniperus communis. They are hemi- 

 spherical or conical, golden yellow, later swelling up to very 

 large, variously shaped (spherical, pear-shaped, ovate, &c.) bodies. 

 Spores spindle-shaped, some brown with a thick endosporium, 

 75 microm. long and 27 microm. broad ; others yellow, with a 



1 Oersted, Sot. Zeit., 1865, p. 291 and elsewhere. 



* [These are often called Cedar-apples in America. See Farlow, Mem. 

 Boston Soc. of Nat. Hist., 1880. ED.] 



t [A good deal of work has been done on the various and very confusing 

 species of late years, most of which occur in this country. See Plowright, 

 /.<:,and Von Tubeuf (Cent. f. Bakt., 1891, and Zeitschr. f. Pflanzenkrankh., 

 B. II. p. no). Also Farlow, I.e., &c. ED.] 



