disease but no more so than the canes in the Experiment Station 

 fields. In all studies of root disease made heretofore, however, this 

 form has been beyond much doubt confused with other forms present, 

 and the presence of root disease has been assumed where it occurred. 

 This form may easily be confused with the much less common 

 species 0. sacchari, which is treated under minor fungi. To quote 

 Dr. Burt, "0. saccharicola is thinner and is composed of shorter- 

 celled hyphae which are not suberect, not nodose-septate and do not 

 bear spores in the interior of the fructification. The stellate crystals 

 are present abundantly in all specimens * * * and appear to 

 be of aid for recognition of this species." 



Odonitia saccharicola Burt, Mo. Bot. Garden 4, No. 3, 1917. 



Fructification resupinate, efl'used, adnate, very thin, pulverulent, 

 not cracked, whitish, drying cartridge-buff, the margin narrow and 

 thinning out, granules minute but distinct, about 6-9 to a mm., in 

 structure 30-50 mu. thick with the granules extending 45-60 mu. 

 more, composed of loosely and somewhat horizontally arranged 

 branched, short-celled hyphae, 2.5-3 mu. in diameter, not nodose- 

 septate, not inerusted but having in the spaces between hyphae nu- 

 merous stellate crystals 4.5-7.5 mu. in diameter from tip of ray to 

 tip of opposite ray, cystidia hair-like, flexuous, not inerusted, septate, 

 weak, often collapsed, tapering upward to a sharp point, 1.5-3 mu. 

 in diameter, protruding 8-18 mu., about 1-3 to a granule at the 

 apex; basidia simple, cylindric-clavate, with 4 sterigmata; basidio- 

 spores hyaline, even 5.5X5.5 mu.. flattened on one side. Dr. Burt's 

 description. 



Porto Rico. — On cane, Vega Alta, July 5, 1912, 4525; Rio Pie- 

 dras, Jan. 9, 1914, 1172, Jan. 13, 1914, 1184, Jan. 1915, 2657. 2657-«, 

 Oct. 5, 1915, 3176, Dec. 1915, 3617, Feb. 9, 1917, 6193, July, 1917. 6589 ; 

 Canovanas, June, 1916, 5502. Also observed at Juncos, Toa Baja, 

 Camuy, Quebradillas, Arecibo, and Fajardo. Very common every- 

 where. Original determination by Dr. Burt, 1916. (PI. XIX, fig. 1.) 



The exact status of root disease with respect to the pai-a'«;itism of 

 Marasmiiis, Himantia, Odontia, or possibly other forms is uncertain 

 and Avhile it is generally held that Marasmius at least is a true para- 

 site, really definite evidence is lacking. Studies under controlled 

 conditions must be carried out working with pure cultures of the 

 fungi, which has not 3^et been possible. As is the case with so iiuk-Ii 

 of the work in tropical pathology to date, root disease studies of a 

 necessity have consisted of field observations only, valuable \u as 

 far as they go, but hardly to l)e used as a basis for exact determina- 

 tions of matters of parasitism. 



189 



