THE PARASITIC K\OASI KAE. 157 



Exoascus communis Sad. This produces pocket-plum- on 

 Priam* americana, P. />//,,n7<>, n,/</ ]'. maritima in America. 



Similar "pockets" also occur on Priamx snl,r<ir<l<it<i, /'. Chicasa, 

 and P. pennsylvanica, in America, as a result of some Exoascus. 



Exoascus Farlowii Sad. produces similar 

 deformation of carpels and tloral envelopes on 

 /'//'////* serotina in North America. 



Exoascus Johansonii Sad. produces carpal- 

 enlargement on the female catkins of /'<////'///s 

 fr> inii/n, I'. ti->'nitili<li'x and P. i/i-it/ti/iifi nt'itii ; the 

 contents of the asci are yellow. (Fig. 5 '2.) The 

 anatomy of the deformed ovaries has just been 

 described by Sadebeck. 1 



Exoascus rhizophorus Johan. causes similar fto. 



. - . 1. "H 



enlargement <>t the female catkins oi ropulus >~ . (v. 



Tubeuf deL) 



Cuba, 



Exoascus alni-incanae Kiihn (>: amentorwm Sad.) Tin- 

 species is readily distinguished l>y the absence of a stalk-cell 

 on the ascus. It causes increased growth and enlargement 

 of the seed-scales of alder catkins, the fruit itself being seldom 

 attacked. The fleshy bladder-like outgrowths at first appeal 

 as little red processes; later, the asci are developed on the 

 outer surface as a whitish coating. On many of the-e red 

 processes may still be recognized the tritid apex of the normal 

 scale, (this is really formed from live smaller scales fused into 

 .1 -inine large one with a tritid apex). A number of the-e 

 red outgrowths are generally present on each infected catkin, 

 yet. the alders continue to tlower vigorously every year. 



\Vakker,- in investigating the anatomy of the deformed -.-ales, 

 found the following alterations : the scales are increased to many 

 times their original si/e and contain two cavities; Ml paienehy- 

 matous cells become regular and iso-diamctric ; lignification of 

 i he elements of the wood is more or less interfered with, and 

 fewer wood-fibres are produced; there is an accumulation of 

 trau-itorv starch. 



Exoascus alni-glutinosae Tubeuf. This is a new sp 

 distinguished by v. Tubeuf in IS'.).". It occurs in the Sndctic 

 mountains, Italy, I >enmark, and Sweden, on Ainu* ///////'// 

 It- habit i- similar to that of /.' . alni-incanae, but the 



Jadebeok (See l.it.'i.nur.-i, i. p. iti. - l'rin>i-lu ///('- J<i/u-iti-h. 



